# on 22-Dec-2023 (Fri)

#### Annotation 7607302622476

 General Form for Amplitude Modulation The general form of amplitude modulation of a signal $$s(t)$$ is: $$\displaystyle s_{HF}(t) = (A + \gamma s(t)) \cos(\omega_{c}t)$$ where $$A$$ is the DC offset, $$\gamma$$ is the AM sensitivity factor and $$\omega_{c}$$ is the carrier angular frequency.

#### Flashcard 7607307865356

Question
The general form of amplitude modulation of a signal $$s(t)$$ is: [...]

$$\displaystyle s_{HF}(t) = (A + \gamma s(t)) \cos(\omega_{c}t)$$

where $$A$$ is the DC offset, $$\gamma$$ is the AM sensitivity factor and $$\omega_{c}$$ is the carrier angular frequency.

status measured difficulty not learned 37% [default] 0

General Form for Amplitude Modulation
The general form of amplitude modulation of a signal $$s(t)$$ is: $$\displaystyle s_{HF}(t) = (A + \gamma s(t)) \cos(\omega_{c}t)$$ where $$A$$ is the DC offset, $$\gamma$$ is the AM sensitivity factor and $$\omega_{c}$$ is the carrier angular frequency.

#### Annotation 7607310748940

 Parseval’s Theorem Using the Fourier Transform, Parseval’s theorem establishes a link between the energy of the time domain waveform and the energy of the spectrum: If $$x(t) \circ — \bullet X(j \omega)$$, then $$\displaystyle \int_{-\infty}^{\infty}|x(t)|^2 d t=\frac{1}{2 \pi} \int_{-\infty}^{\infty}|X(j \omega)|^2 d \omega=\int_{-\infty}^{\infty}|X(f)|^2 d f$$

#### Flashcard 7607312583948

Question
Using the Fourier Transform, Parseval’s theorem establishes a link between the energy of the time domain waveform and the energy of the spectrum: [...]
If $$x(t) \circ — \bullet X(j \omega)$$, then $$\displaystyle \int_{-\infty}^{\infty}|x(t)|^2 d t=\frac{1}{2 \pi} \int_{-\infty}^{\infty}|X(j \omega)|^2 d \omega=\int_{-\infty}^{\infty}|X(f)|^2 d f$$

status measured difficulty not learned 37% [default] 0

Parseval’s Theorem
Using the Fourier Transform, Parseval’s theorem establishes a link between the energy of the time domain waveform and the energy of the spectrum: If $$x(t) \circ — \bullet X(j \omega)$$, then $$\displaystyle \int_{-\infty}^{\infty}|x(t)|^2 d t=\frac{1}{2 \pi} \int_{-\infty}^{\infty}|X(j \omega)|^2 d \omega=\int_{-\infty}^{\infty}|X(f)|^2 d f$$

#### Annotation 7607314156812

 Parseval’s Theorem for Periodic signal Using the Continuous-time Fourier series, Parseval’s Theorem for Periodic signal describes that the average power of a periodic signal is the sum of the average powers of its Fourier components: $$\displaystyle \frac{1}{T_{0}}\int^{T_{0}/2}_{-T_{0}/2}|x(t)|^{2}dt=\sum\limits^{\infty}_{k=-\infty}|C_{k}|^{2}$$

#### Flashcard 7607315991820

Question
Using the Continuous-time Fourier series, Parseval’s Theorem for Periodic signal describes that the average power of a periodic signal is the sum of the average powers of its Fourier components: [...]
$$\displaystyle \frac{1}{T_{0}}\int^{T_{0}/2}_{-T_{0}/2}|x(t)|^{2}dt=\sum\limits^{\infty}_{k=-\infty}|C_{k}|^{2}$$

status measured difficulty not learned 37% [default] 0

Parseval’s Theorem for Periodic signal
sing the Continuous-time Fourier series, Parseval’s Theorem for Periodic signal describes that the average power of a periodic signal is the sum of the average powers of its Fourier components: <span>$$\displaystyle \frac{1}{T_{0}}\int^{T_{0}/2}_{-T_{0}/2}|x(t)|^{2}dt=\sum\limits^{\infty}_{k=-\infty}|C_{k}|^{2}$$ <span>

#### Flashcard 7607317564684

Question
Using the Continuous-time Fourier series, Parseval’s Theorem for Periodic signal describes that [...]: $$\displaystyle \frac{1}{T_{0}}\int^{T_{0}/2}_{-T_{0}/2}|x(t)|^{2}dt=\sum\limits^{\infty}_{k=-\infty}|C_{k}|^{2}$$
the average power of a periodic signal is the sum of the average powers of its Fourier components

status measured difficulty not learned 37% [default] 0

Parseval’s Theorem for Periodic signal
Using the Continuous-time Fourier series, Parseval’s Theorem for Periodic signal describes that the average power of a periodic signal is the sum of the average powers of its Fourier components: $$\displaystyle \frac{1}{T_{0}}\int^{T_{0}/2}_{-T_{0}/2}|x(t)|^{2}dt=\sum\limits^{\infty}_{k=-\infty}|C_{k}|^{2}$$

#### Annotation 7607321758988

 Wirth syntax notation (whole page)

Wirth syntax notation - Wikipedia
n Pages for logged out editors learn more Contributions Talk Contents move to sidebar hide (Top) 1WSN defined in itself 2Another example 3Syntax diagram 4References Toggle the table of contents <span>Wirth syntax notation 1 language Français Edit links Article Talk English Read Edit View history Tools Tools move to sidebar hide Actions Read Edit View history General What links here Related changes Upload

#### Annotation 7607327264012

 Nix: Frst steps (whole page)

First steps — nix.dev documentation
ework Style guide How to write a tutorial Acknowledgements Sponsors Email notifications An occasional email about new tutorials, no spam. Repository Suggest edit Open issue .md .pdf First steps <span>First steps# This tutorial series is where you should start learning Nix. In these lessons, you will use basic Nix commands to obtain almost any piece of software, create development environments o

#### Annotation 7607335390476

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Other dyspnea-related chief complaints (eg, cough, chest discomfort) comprise an additional 9 percent of ED visits.

UpToDate
a".) EPIDEMIOLOGY — Dyspnea is a common chief complaint among emergency department (ED) patients, accounting for approximately four million visits (3 percent) annually in the United States [2]. <span>Other dyspnea-related chief complaints (eg, cough, chest discomfort) comprise an additional 9 percent of ED visits. In males and females over the age of 65, dyspnea and related problems were a major reason for ED visits [3].The most common diagnoses among older adult patients presenting to an ED with

#### Annotation 7607336439052

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup The most common diagnoses among older adult patients presenting to an ED with a complaint of acute shortness of breath and manifesting signs of respiratory distress (eg, respiratory rate >25, oxygen saturation [SpO2] <93 percent) are decompensated heart failure, pneumonia, chronic obstructive pulmonary disease (COPD), pulmonary embolism (PE), and asthma [4].

UpToDate
mplaints (eg, cough, chest discomfort) comprise an additional 9 percent of ED visits. In males and females over the age of 65, dyspnea and related problems were a major reason for ED visits [3].<span>The most common diagnoses among older adult patients presenting to an ED with a complaint of acute shortness of breath and manifesting signs of respiratory distress (eg, respiratory rate >25, oxygen saturation [SpO2] <93 percent) are decompensated heart failure, pneumonia, chronic obstructive pulmonary disease (COPD), pulmonary embolism (PE), and asthma [4]. OVERVIEW OF APPROACH — The primary goals for the emergency clinician faced with an acutely dyspneic patient are to: ●Optimize arterial oxygenation ●Determine the need for emergency airw

#### Annotation 7607337487628

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Identify whether a life-threatening condition exists, such as: • Acute coronary syndrome • Acute heart failure • Arrhythmia • Pericardial tamponade • Pulmonary embolism (PE) • Pneumonia or other infection • Chronic obstructive pulmonary disease (COPD) exacerbation • Asthma • Angioedema and anaphylaxis • Poisoning (eg, carbon monoxide) • Trauma (eg, pneumothorax, hemothorax)

UpToDate
mary goals for the emergency clinician faced with an acutely dyspneic patient are to: ●Optimize arterial oxygenation ●Determine the need for emergency airway management and ventilatory support ●<span>Identify whether a life-threatening condition exists, such as: •Acute coronary syndrome •Acute heart failure •Arrhythmia •Pericardial tamponade •Pulmonary embolism (PE) •Pneumonia or other infection •Chronic obstructive pulmonary disease (COPD) exacerbation •Asthma •Angioedema and anaphylaxis •Poisoning (eg, carbon monoxide) •Trauma (eg, pneumothorax, hemothorax) ●Determine the most likely cause of dyspnea (table 1) ●Initiate treatment and stabilize if critically ill Potential pitfalls in the approach of an acutely dyspneic emergency department

#### Annotation 7607338536204

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Potential pitfalls in the approach of an acutely dyspneic emergency department patient include the following: ● Failure to secure the airway in a timely manner ● Failure to recognize and act on abnormal vital signs and signs of impending respiratory failure ● Over-reliance upon a single finding (physical examination or test result) to establish a diagnosis ● Failure to generate a proper differential diagnosis ● Failure to monitor the patient's clinical course ● Failure to consider carbon monoxide poisoning, methemoglobinemia, or PE ● Misinterpreting tachypnea, which may not represent a respiratory abnormality and may reflect nonpulmonary disease (eg, metabolic acidosis or impending herniation of the brainstem)

UpToDate
and anaphylaxis •Poisoning (eg, carbon monoxide) •Trauma (eg, pneumothorax, hemothorax) ●Determine the most likely cause of dyspnea (table 1) ●Initiate treatment and stabilize if critically ill <span>Potential pitfalls in the approach of an acutely dyspneic emergency department patient include the following: ●Failure to secure the airway in a timely manner ●Failure to recognize and act on abnormal vital signs and signs of impending respiratory failure ●Over-reliance upon a single finding (physical examination or test result) to establish a diagnosis ●Failure to generate a proper differential diagnosis ●Failure to monitor the patient's clinical course ●Failure to consider carbon monoxide poisoning, methemoglobinemia, or PE ●Misinterpreting tachypnea, which may not represent a respiratory abnormality and may reflect nonpulmonary disease (eg, metabolic acidosis or impending herniation of the brainstem) ●Allowing patients with a tenuous respiratory status to leave the ED and deteriorate in the radiology suite or inpatient floor ●Discharging patients with inadequate follow-up or unclear

#### Annotation 7607339584780

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup ● Signs that portend imminent respiratory arrest include: • Depressed mental status, which can occur with severe hypoxia or hypercarbia • Inability to maintain respiratory effort (bradypnea, poor inspiratory effort, or agonal respirations) • Cyanosis, which is uncommon and indicates severe hypoxia or methemoglobinemia

UpToDate
ea should be screened for signs of imminent respiratory arrest or significant respiratory distress. A brief physical examination (including pulse oximetry) is often sufficient for this purpose. <span>●Signs that portend imminent respiratory arrest include: •Depressed mental status, which can occur with severe hypoxia or hypercarbia •Inability to maintain respiratory effort (bradypnea, poor inspiratory effort, or agonal respirations) •Cyanosis, which is uncommon and indicates severe hypoxia or methemoglobinemia ●Signs suggestive of severe respiratory distress include: •Retractions and the use of accessory muscles – Retractions occur with airway obstruction (eg, asthma, chronic obstructive pulm

#### Annotation 7607340633356

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Signs suggestive of severe respiratory distress include: • Retractions and the use of accessory muscles – Retractions occur with airway obstruction (eg, asthma, chronic obstructive pulmonary disease [COPD], foreign body) and can be seen in the suprasternal, intercostal, and subcostal areas [5]. They are an ominous sign suggesting extreme respiratory distress, fatigue of the respiratory muscles, and the potential for respiratory failure. Patients with neuromuscular disease may not manifest retractions due to muscle weakness, even in the face of severe respiratory compromise. • Brief, fragmented speech (patient is unable to answer questions with anything more than a few words), which can be quickly assessed by asking the patient to count to 10 in one breath. • Significant tachypnea (ie, greater than 25 breaths per minute). This cutoff is not absolute, and a respiratory rate of over 20 breaths per minute should prompt a timely evaluation. • Inability to lie supine – Many patients in respiratory distress sit bolt upright or in a tripod position. An exception is hepatopulmonary syndrome, where patients may breathe more comfortably when recumbent. (See "Hepatopulmonary syndrome in adults: Prevalence, causes, clinical manifestations, and diagnosis", section on 'Dyspnea'.) • Profound diaphoresis, which reflects extreme sympathetic stimulation associated with severe disease (eg, myocardial infarction, severe asthma flare, diastolic cardiac dysfunction). • Audible stridor or wheezing, which can represent upper airway obstruction or severe bronchospasm. • Dusky skin, which indicates poor perfusion or cyanosis. • Agitation, somnolence, or other altered mental status in the dyspneic patient suggests severe hypoxia or hypercarbia. Patients with a depressed mental status from carbon dioxide (CO2) retention may look comfortable and lackadaisical.

UpToDate
ypercarbia •Inability to maintain respiratory effort (bradypnea, poor inspiratory effort, or agonal respirations) •Cyanosis, which is uncommon and indicates severe hypoxia or methemoglobinemia ●<span>Signs suggestive of severe respiratory distress include: •Retractions and the use of accessory muscles – Retractions occur with airway obstruction (eg, asthma, chronic obstructive pulmonary disease [COPD], foreign body) and can be seen in the suprasternal, intercostal, and subcostal areas [5]. They are an ominous sign suggesting extreme respiratory distress, fatigue of the respiratory muscles, and the potential for respiratory failure. Patients with neuromuscular disease may not manifest retractions due to muscle weakness, even in the face of severe respiratory compromise. •Brief, fragmented speech (patient is unable to answer questions with anything more than a few words), which can be quickly assessed by asking the patient to count to 10 in one breath. •Significant tachypnea (ie, greater than 25 breaths per minute). This cutoff is not absolute, and a respiratory rate of over 20 breaths per minute should prompt a timely evaluation. •Inability to lie supine – Many patients in respiratory distress sit bolt upright or in a tripod position. An exception is hepatopulmonary syndrome, where patients may breathe more comfortably when recumbent. (See "Hepatopulmonary syndrome in adults: Prevalence, causes, clinical manifestations, and diagnosis", section on 'Dyspnea'.) •Profound diaphoresis, which reflects extreme sympathetic stimulation associated with severe disease (eg, myocardial infarction, severe asthma flare, diastolic cardiac dysfunction). •Audible stridor or wheezing, which can represent upper airway obstruction or severe bronchospasm. •Dusky skin, which indicates poor perfusion or cyanosis. •Agitation, somnolence, or other altered mental status in the dyspneic patient suggests severe hypoxia or hypercarbia. Patients with a depressed mental status from carbon dioxide (CO2) retention may look comfortable and lackadaisical. Emergency stabilization of patients with danger signs General measures — The following measures are required in a patient with danger signs (see 'Clinical danger signs' above), who appe

#### Annotation 7607341681932

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Provide supplemental oxygen – For hypoxic patients with respiratory difficulty, provide 50 to 60 liters per minute (LPM) of oxygen via a nonrebreather mask. To deliver this much oxygen, open the flow meter valve until the indicator lies well beyond the 15 LPM mark. An SpO2 of 94 percent is an appropriate target for most patients.Patients breathing 100% oxygen deliver five times as much oxygen to the alveoli per unit of ventilation as those breathing room air and, in the absence of parenchymal disease, can maintain a normal SpO2 with only two or three breaths per minute. However, the best nonrebreather oxygen-delivery systems provide only 85% oxygen.

UpToDate
e following measures are required in a patient with danger signs (see 'Clinical danger signs' above), who appears clinically ill, or is hypoxic (pulse oxygen saturation [SpO2] <90 percent): ●<span>Provide supplemental oxygen – For hypoxic patients with respiratory difficulty, provide 50 to 60 liters per minute (LPM) of oxygen via a nonrebreather mask. To deliver this much oxygen, open the flow meter valve until the indicator lies well beyond the 15 LPM mark. An SpO2 of 94 percent is an appropriate target for most patients. Patients breathing 100% oxygen deliver five times as much oxygen to the alveoli per unit of ventilation as those breathing room air and, in the absence of parenchymal disease, can maintain a normal SpO2 with only two or three breaths per minute. However, the best nonrebreather oxygen-delivery systems provide only 85% oxygen. For patients likely to require tracheal intubation, higher levels of oxygenation are necessary to increase their oxygen reserves for the apneic phase of rapid sequence intubation (RSI).

#### Annotation 7607342730508

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Continue focused history and examination – Assess for a potentially difficult airway and search for rapidly reversible causes (anaphylaxis, tension pneumothorax, pericardial tamponade, upper airway obstruction).

UpToDate
omplete blood count, serum chemistries' below.) ●Begin continuous cardiac and pulse oximetry monitoring. ●Obtain airway management equipment and request a respiratory therapist to the bedside. ●<span>Continue focused history and examination – Assess for a potentially difficult airway and search for rapidly reversible causes (anaphylaxis, tension pneumothorax, pericardial tamponade, upper airway obstruction). ●Determine the need for airway management and ventilatory support – The initial decision to provide noninvasive or invasive ventilatory support is made based upon clinical grounds, not

#### Annotation 7607343779084

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Optimize hemodynamic physiology – Control the rate or rhythm of a tachydysrhythmia and improve right ventricular filing pressures if needed (eg, IV fluids, vasopressors). When volume overload is suspected, can administer diuretics and/or preload and afterload reduction (eg, nitrates) depending on underlying physiology.

UpToDate
able) – Emergency physician-performed ultrasound can rapidly identify pericardial effusions, pulmonary edema, and clinically significant pneumothorax. (See 'Role of bedside ultrasound' below.) ●<span>Optimize hemodynamic physiology – Control the rate or rhythm of a tachydysrhythmia and improve right ventricular filing pressures if needed (eg, IV fluids, vasopressors). When volume overload is suspected, can administer diuretics and/or preload and afterload reduction (eg, nitrates) depending on underlying physiology. (See "Overview of the acute management of tachyarrhythmias" and "Evaluation and management of suspected sepsis and septic shock in adults", section on 'Volume' and "Right heart failure:

#### Annotation 7607344827660

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup A venous blood gas may be useful in the assessment of the patient presumed to be somnolent from CO2 retention. The partial pressure of carbon dioxide (PaCO2) should be low in the acutely dyspneic patient, who is usually hyperventilating. A normal or elevated CO2 in the setting of dyspnea and tachypnea portends respiratory failure.

UpToDate
, pneumonia) or the underlying disease process (eg, neuromuscular disease). (See "Mechanisms, causes, and effects of hypercapnia".) ●Identifying and monitoring hypercapnic respiratory failure – <span>A venous blood gas may be useful in the assessment of the patient presumed to be somnolent from CO2 retention. The partial pressure of carbon dioxide (PaCO2) should be low in the acutely dyspneic patient, who is usually hyperventilating. A normal or elevated CO2 in the setting of dyspnea and tachypnea portends respiratory failure. Capnography (ie, end-tidal CO2 [EtCO2]) can identify CO2 retention and provide dynamic monitoring of ventilatory status in patients with acute respiratory distress. By measuring EtCO2 a

#### Annotation 7607345876236

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Stroke – Although dyspnea is not the chief complaint of patients with an acute stroke, a number of respiratory abnormalities may result from a sufficiently severe injury or one affecting regions involved in respiration. Such abnormalities may include aspiration pneumonia, neurogenic pulmonary edema, and various abnormal respiratory patterns, including apnea.

UpToDate
rt of the resuscitation for the anticipated clinical course. (See "Evaluation and management of suspected sepsis and septic shock in adults", section on 'Immediate evaluation and management'.) •<span>Stroke – Although dyspnea is not the chief complaint of patients with an acute stroke, a number of respiratory abnormalities may result from a sufficiently severe injury or one affecting regions involved in respiration. Such abnormalities may include aspiration pneumonia, neurogenic pulmonary edema, and various abnormal respiratory patterns, including apnea. (See "Complications of stroke: An overview", section on 'Pulmonary complications'.) •Neuromuscular disease – Several neuromuscular diseases, including multiple sclerosis, Guillain-Barré

#### Annotation 7607346924812

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Neuromuscular disease – Several neuromuscular diseases, including multiple sclerosis, Guillain-Barré syndrome, myasthenia gravis, amyotrophic lateral sclerosis, West Nile virus, and enterovirus D68 (seen primarily in children), can cause weakness of the respiratory muscles, leading to acute respiratory failure. Botulism may cause generalized descending muscle weakness involving the respiratory muscles.

UpToDate
spiration pneumonia, neurogenic pulmonary edema, and various abnormal respiratory patterns, including apnea. (See "Complications of stroke: An overview", section on 'Pulmonary complications'.) •<span>Neuromuscular disease – Several neuromuscular diseases, including multiple sclerosis, Guillain-Barré syndrome, myasthenia gravis, amyotrophic lateral sclerosis, West Nile virus, and enterovirus D68 (seen primarily in children), can cause weakness of the respiratory muscles, leading to acute respiratory failure. Botulism may cause generalized descending muscle weakness involving the respiratory muscles. (See "Manifestations of multiple sclerosis in adults" and "Guillain-Barré syndrome in adults: Pathogenesis, clinical features, and diagnosis" and "Clinical features of amyotrophic later

#### Annotation 7607347973388

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Sepsis – Severe sepsis often causes respiratory compromise secondary to tachypnea and respiratory muscle fatigue, which may stem from underlying pneumonia, compensation for metabolic acidosis, or some other process.

UpToDate
neumonia, interstitial fibrosis, and others can lead to hypercapnic respiratory failure from hypoventilation, increased dead space, decreased respiratory drive, and respiratory muscle fatigue. •<span>Sepsis – Severe sepsis often causes respiratory compromise secondary to tachypnea and respiratory muscle fatigue, which may stem from underlying pneumonia, compensation for metabolic acidosis, or some other process. Intubation and mechanical ventilation can support the increased work of breathing and are often performed as part of the resuscitation for the anticipated clinical course. (See "Evaluat

#### Annotation 7607349021964

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Primary pulmonary disease – COPD, asthma, pneumonia, interstitial fibrosis, and others can lead to hypercapnic respiratory failure from hypoventilation, increased dead space, decreased respiratory drive, and respiratory muscle fatigue.

UpToDate
nd treatment of the adult patient with acute hypercapnic respiratory failure".) The following disease processes can lead to inadequate respiratory effort and often require ventilatory support: •<span>Primary pulmonary disease – COPD, asthma, pneumonia, interstitial fibrosis, and others can lead to hypercapnic respiratory failure from hypoventilation, increased dead space, decreased respiratory drive, and respiratory muscle fatigue. •Sepsis – Severe sepsis often causes respiratory compromise secondary to tachypnea and respiratory muscle fatigue, which may stem from underlying pneumonia, compensation for metabolic a

#### Annotation 7607350332684

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Stridor — Stridor occurs when there is airway obstruction. Inspiratory stridor suggests obstruction above the vocal cords (eg, foreign body, epiglottitis, angioedema). Expiratory stridor or mixed inspiratory and expiratory stridor suggests obstruction below the vocal cords (eg, croup, bacterial tracheitis, foreign body).

UpToDate
tilation. However, there are many processes where targeted intervention may improve respiratory distress and avoid mechanical ventilation, which are presented below based on signs and symptoms: <span>Stridor — Stridor occurs when there is airway obstruction. Inspiratory stridor suggests obstruction above the vocal cords (eg, foreign body, epiglottitis, angioedema). Expiratory stridor or mixed inspiratory and expiratory stridor suggests obstruction below the vocal cords (eg, croup, bacterial tracheitis, foreign body). Patients with signs of upper airway obstruction may need emergency airway management, although angioedema from anaphylaxis often improves with medical therapy (eg, epinephrine, antihist

#### Annotation 7607351381260

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Angioedema – Angioedema can cause significant swelling of the lips, tongue, posterior pharynx, and most dangerously the larynx; this can occur over minutes to hours and may cause severe dyspnea. Etiologies include idiopathic, allergic (ie, anaphylaxis), medication-related (eg, nonsteroidal antiinflammatory drug [NSAID], angiotensin-converting enzyme [ACE] inhibitor, angiotensin receptor blocker), and complement-related (eg, C1-esterase inhibitor deficiency or a nonfunctional allele). Patients who receive IV tissue plasminogen activator (tPA) for acute ischemic stroke are also at risk for developing angioedema, which tends to be hemilingual and contralateral to the ischemic hemisphere [7].

UpToDate
r endotracheal intubation with an attempt to push the foreign body into a major bronchus can be attempted. Management is discussed in detail elsewhere. (See "Airway foreign bodies in adults".) ●<span>Angioedema – Angioedema can cause significant swelling of the lips, tongue, posterior pharynx, and most dangerously the larynx; this can occur over minutes to hours and may cause severe dyspnea. Etiologies include idiopathic, allergic (ie, anaphylaxis), medication-related (eg, nonsteroidal antiinflammatory drug [NSAID], angiotensin-converting enzyme [ACE] inhibitor, angiotensin receptor blocker), and complement-related (eg, C1-esterase inhibitor deficiency or a nonfunctional allele). Patients who receive IV tissue plasminogen activator (tPA) for acute ischemic stroke are also at risk for developing angioedema, which tends to be hemilingual and contralateral to the ischemic hemisphere [7]. C1 inhibitors and bradykinin B2-receptor antagonists are targeted therapies for hereditary angioedema and reviewed separately. (See "Hereditary angioedema: Acute treatment of angioedema

#### Annotation 7607352429836

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Anaphylaxis – Anaphylaxis may cause severe swelling of the upper airway and tongue, and possibly airway occlusion. Bronchospasm may also be prominent. Symptoms and signs, which are often triggered by foods, insect bites, and various medications, develop over minutes to hours and may include skin and mucosal findings (eg, hives, flushing, oropharyngeal swelling), respiratory compromise (eg, wheezing, stridor, hypoxia), cardiovascular compromise (eg, hypotension, tachycardia, syncope), and gastrointestinal complaints (eg, abdominal pain, vomiting, and diarrhea).

UpToDate
eted therapies for hereditary angioedema and reviewed separately. (See "Hereditary angioedema: Acute treatment of angioedema attacks" and "An overview of angioedema: Pathogenesis and causes".) ●<span>Anaphylaxis – Anaphylaxis may cause severe swelling of the upper airway and tongue, and possibly airway occlusion. Bronchospasm may also be prominent. Symptoms and signs, which are often triggered by foods, insect bites, and various medications, develop over minutes to hours and may include skin and mucosal findings (eg, hives, flushing, oropharyngeal swelling), respiratory compromise (eg, wheezing, stridor, hypoxia), cardiovascular compromise (eg, hypotension, tachycardia, syncope), and gastrointestinal complaints (eg, abdominal pain, vomiting, and diarrhea). Intramuscular or IV epinephrine often improves symptoms if given promptly after the onset of symptoms. Since anaphylaxis has a variable course, preparations for endotracheal intubation

#### Annotation 7607353478412

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Organophosphate poisoning – Acute toxicity from organophosphorus agents presents with manifestations of cholinergic excess (bradycardia, salivation, lacrimation, vomiting, diarrhea, bronchorrhea, miosis) and should be recognizable on rapid examination. Management typically involves endotracheal intubation and empiric antidotal therapy with atropine, pralidoxime, and benzodiazepines.

UpToDate
e prior to mechanical ventilation often corrects hypoxia. (See "COVID-19: Respiratory care of the nonintubated hypoxemic adult (supplemental oxygen, noninvasive ventilation, and intubation)".) ●<span>Organophosphate poisoning – Acute toxicity from organophosphorus agents presents with manifestations of cholinergic excess (bradycardia, salivation, lacrimation, vomiting, diarrhea, bronchorrhea, miosis) and should be recognizable on rapid examination. Management typically involves endotracheal intubation and empiric antidotal therapy with atropine, pralidoxime, and benzodiazepines. (See "Organophosphate and carbamate poisoning".) Hypoxia with clear lungs — Causes with targeted interventions include: ●Pulmonary embolism (PE) – The initial approach to patients with

#### Annotation 7607354526988

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Pneumothorax – Any simple pneumothorax can develop into a life-threatening tension pneumothorax. Patients in extremis with a suggestive history and examination findings consistent with a tension pneumothorax (eg, hypotension, distended neck veins, unilateral diminished or absent breath sounds) should be treated with immediate needle decompression followed by a tube or catheter thoracostomy.

UpToDate
detail elsewhere. (See "Anaphylaxis: Emergency treatment".) Unilateral diminished breath sounds — Diminished breath sounds can be caused by anything that prevents air from entering the lungs. ●<span>Pneumothorax – Any simple pneumothorax can develop into a life-threatening tension pneumothorax. Patients in extremis with a suggestive history and examination findings consistent with a tension pneumothorax (eg, hypotension, distended neck veins, unilateral diminished or absent breath sounds) should be treated with immediate needle decompression followed by a tube or catheter thoracostomy. (See "Thoracostomy tubes and catheters: Placement techniques and complications".) ●Pleural effusion, hemothorax – Respiratory distress from a large pleural effusion or hemothorax can be

#### Annotation 7607355575564

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Methemoglobinemia – This abnormal hemoglobin variant can present with dyspnea, cyanosis, and an artifactual pulse oximetry reading of 85 to 88 percent that does not improve with supplemental oxygen. The diagnosis is confirmed by methemoglobin blood gas measurement (either arterial or venous) and treated with methylene blue.

UpToDate
(See "Emergency ultrasound in adults with abdominal and thoracic trauma", section on 'Pericardial and limited cardiac examination' and "Cardiac tamponade" and "Emergency pericardiocentesis".) ●<span>Methemoglobinemia – This abnormal hemoglobin variant can present with dyspnea, cyanosis, and an artifactual pulse oximetry reading of 85 to 88 percent that does not improve with supplemental oxygen. The diagnosis is confirmed by methemoglobin blood gas measurement (either arterial or venous) and treated with methylene blue. (See "Methemoglobinemia".) Wheezing — Wheezing suggests obstruction below the level of the trachea and is found with asthma, anaphylaxis, a foreign body in a mainstem bronchus, or a fix

#### Annotation 7607356624140

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Cardiac tamponade – Cardiac tamponade can be caused by trauma, malignancy, uremia, drugs, or infection and can present with acute dyspnea. The classic triad of hypotension, distended neck veins, and muffled heart tones suggest the diagnosis but are often absent.

UpToDate
tment, prognosis, and follow-up of acute pulmonary embolism in adults" and "Approach to thrombolytic (fibrinolytic) therapy in acute pulmonary embolism: Patient selection and administration".) ●<span>Cardiac tamponade – Cardiac tamponade can be caused by trauma, malignancy, uremia, drugs, or infection and can present with acute dyspnea. The classic triad of hypotension, distended neck veins, and muffled heart tones suggest the diagnosis but are often absent. The ECG generally shows sinus tachycardia and low voltage and only rarely reveals electrical alternans. Bedside cardiac ultrasound can identify pericardial effusion and often diagnose t

#### Annotation 7607357672716

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Pulmonary embolism (PE) – The initial approach to patients with suspected massive PE should focus upon stabilizing the patient while clinical evaluation and definitive diagnostic testing are ongoing. Anticoagulation should be initiated even prior to confirming the diagnosis if risk-benefit regarding suspicion of PE and risk of bleeding appear favorable.

UpToDate
piric antidotal therapy with atropine, pralidoxime, and benzodiazepines. (See "Organophosphate and carbamate poisoning".) Hypoxia with clear lungs — Causes with targeted interventions include: ●<span>Pulmonary embolism (PE) – The initial approach to patients with suspected massive PE should focus upon stabilizing the patient while clinical evaluation and definitive diagnostic testing are ongoing. Anticoagulation should be initiated even prior to confirming the diagnosis if risk-benefit regarding suspicion of PE and risk of bleeding appear favorable. Computed tomography pulmonary angiography (CTAP) is the first-choice diagnostic test and can discover alternate causes of hypoxia [8]. In the patient too unstable to travel to radiology

#### Annotation 7607358721292

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup In patients who fail to improve with standard COPD treatment, re-evaluate for a PE, which may be responsible for up to 25 percent of apparent "COPD exacerbations."

UpToDate
infection. Respiratory distress from a COPD exacerbation typically improves quickly with NIV in addition to medications (eg, beta adrenergic agonists, muscarinic antagonists, glucocorticoids). <span>In patients who fail to improve with standard COPD treatment, re-evaluate for a PE, which may be responsible for up to 25 percent of apparent "COPD exacerbations." (See "COPD exacerbations: Management" and "Noninvasive ventilation in adults with acute respiratory failure: Benefits and contraindications".) ●Asthma – Asthma exacerbations generally p

#### Annotation 7607359769868

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Acute coronary syndrome (ACS) – Older adults and patients with diabetes who have a myocardial infarction may present with dyspnea as their sole symptom.

UpToDate
ment" and "Airway management in acute severe asthma for emergency medicine and critical care".) ECG changes, tachycardia, or associated chest pain — Causes with targeted interventions include: ●<span>Acute coronary syndrome (ACS) – Older adults and patients with diabetes who have a myocardial infarction may present with dyspnea as their sole symptom. An ECG showing ST-elevation myocardial infarction requires rapid reperfusion therapy (eg, percutaneous coronary intervention, fibrinolysis). (See "Diagnosis of acute myocardial infarcti

#### Annotation 7607360818444

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Cardiac arrhythmia – Cardiac rhythm abnormalities, such as atrial flutter, atrial fibrillation, and tachyarrhythmias (eg, supraventricular tachycardia [SVT] and ventricular tachycardia) can result in dyspnea. Such abnormalities may stem from underlying disease, including myocardial ischemia or cardiac decompensation due to the elevated heart rate or uncoordinated contractions.The subjective feeling of dyspnea often improves with slowing down the rate of a tachycardic rhythm.

UpToDate
n therapy (eg, percutaneous coronary intervention, fibrinolysis). (See "Diagnosis of acute myocardial infarction" and "Overview of the acute management of ST-elevation myocardial infarction".) ●<span>Cardiac arrhythmia – Cardiac rhythm abnormalities, such as atrial flutter, atrial fibrillation, and tachyarrhythmias (eg, supraventricular tachycardia [SVT] and ventricular tachycardia) can result in dyspnea. Such abnormalities may stem from underlying disease, including myocardial ischemia or cardiac decompensation due to the elevated heart rate or uncoordinated contractions. The subjective feeling of dyspnea often improves with slowing down the rate of a tachycardic rhythm. (See "Overview of the acute management of tachyarrhythmias" and "Atrial fibrillation: Overview and management of new-onset atrial fibrillation" and "Atrioventricular nodal reentrant tac

#### Annotation 7607361867020

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Fever – Fever can be associated with an infection, hypersensitivity pneumonitis, aspiration pneumonitis, PE, or poisoning (eg, aspirin overdose can cause hyperthermia and tachypnea).

UpToDate
tructures, or abdomen can lead to dyspnea. Acute symptoms may not manifest until a day or longer following trauma. (See "Initial evaluation and management of blunt thoracic trauma in adults".) ●<span>Fever – Fever can be associated with an infection, hypersensitivity pneumonitis, aspiration pneumonitis, PE, or poisoning (eg, aspirin overdose can cause hyperthermia and tachypnea). (See "Salicylate (aspirin) poisoning: Clinical manifestations and evaluation".) ●Paroxysmal nocturnal dyspnea (PND) – Keep in mind that PND is not specific for ADHF. Patients with COPD

#### Annotation 7607362915596

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Paroxysmal nocturnal dyspnea (PND) – Keep in mind that PND is not specific for ADHF. Patients with COPD may present with a similar history.

UpToDate
eumonitis, aspiration pneumonitis, PE, or poisoning (eg, aspirin overdose can cause hyperthermia and tachypnea). (See "Salicylate (aspirin) poisoning: Clinical manifestations and evaluation".) ●<span>Paroxysmal nocturnal dyspnea (PND) – Keep in mind that PND is not specific for ADHF. Patients with COPD may present with a similar history. ●Hemoptysis – Hemoptysis is associated with a number of conditions, including PE, severe valvular disease (eg, mitral stenosis), tuberculosis, malignancy, bronchitis, pneumonia, pulmona

#### Annotation 7607363964172

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup ough and sputum – Purulent sputum suggests bronchitis or pneumonia, and pink frothy sputum suggests ADHF. A nonproductive cough is a nonspecific symptom and may be associated with asthma, heart failure, respiratory infection, or PE.

UpToDate
culosis, malignancy, bronchitis, pneumonia, pulmonary contusion, and the effects of anticoagulants (eg, alveolar hemorrhage). (See "Evaluation and management of life-threatening hemoptysis".) ●C<span>ough and sputum – Purulent sputum suggests bronchitis or pneumonia, and pink frothy sputum suggests ADHF. A nonproductive cough is a nonspecific symptom and may be associated with asthma, heart failure, respiratory infection, or PE. ●Medications – A medication list provides information about chronic or acute illness. Ask about recent dosing changes, new medications, and adherence (in a nonjudgmental manner). Oral c

#### Annotation 7607365012748

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Acute respiratory distress syndrome (ARDS) can occur following overdose of various drugs (eg, aspirin, cocaine, opioids, phenothiazines, and tricyclic antidepressants).

UpToDate
d hemorrhagic alveolitis (ie, "crack lung") or pneumothorax. E-cigarettes and other vaping products have been associated with "E-cigarette or vaping product use-associated lung injury (EVALI)." <span>Acute respiratory distress syndrome (ARDS) can occur following overdose of various drugs (eg, aspirin, cocaine, opioids, phenothiazines, and tricyclic antidepressants). (See "Overview of pulmonary disease in people who inject drugs" and "E-cigarette or vaping product use-associated lung injury (EVALI)" and "Pulmonary complications of cocaine use" and "

#### Annotation 7607366061324

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Psychogenic causes of acute dyspnea are diagnoses of exclusion in the ED; organic causes must be thoroughly considered first. Nevertheless, among patients younger than age 40 with no medical conditions, psychogenic dyspnea (eg, anxiety, panic attack) may be the cause in a sizable minority of patients [9,10].

UpToDate
on 'Drugs and alcohol'.) ●Psychiatric conditions – Ask about existing psychiatric diagnoses, history of panic attacks, and history of similar episodes that may have had unrevealing evaluations. <span>Psychogenic causes of acute dyspnea are diagnoses of exclusion in the ED; organic causes must be thoroughly considered first. Nevertheless, among patients younger than age 40 with no medical conditions, psychogenic dyspnea (eg, anxiety, panic attack) may be the cause in a sizable minority of patients [9,10]. ●Pregnancy – A number of physiologic changes occur during pregnancy that affect respiratory function, including an increase in minute ventilation, a decrease in functional residual capa

#### Annotation 7607367109900

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Physical examination — Perform a more thorough physical examination after the initial rapid screen and any necessary stabilization is completed. Important signs are discussed below and in the accompanying table (table 4).

UpToDate
d diagnosis" and "Eclampsia" and "Amniotic fluid embolism" and "Peripartum cardiomyopathy: Etiology, clinical manifestations, and diagnosis" and "Management of heart failure during pregnancy".) <span>Physical examination — Perform a more thorough physical examination after the initial rapid screen and any necessary stabilization is completed. Important signs are discussed below and in the accompanying table (table 4). An unremarkable pulmonary and cardiac examination does not rule out significant disease. As examples, the sensitivity and specificity of the pulmonary examination are limited for making

#### Annotation 7607368158476

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup An unremarkable pulmonary and cardiac examination does not rule out significant disease. As examples, the sensitivity and specificity of the pulmonary examination are limited for making the diagnosis of pneumonia or ADHF [11-15].

UpToDate
rm a more thorough physical examination after the initial rapid screen and any necessary stabilization is completed. Important signs are discussed below and in the accompanying table (table 4). <span>An unremarkable pulmonary and cardiac examination does not rule out significant disease. As examples, the sensitivity and specificity of the pulmonary examination are limited for making the diagnosis of pneumonia or ADHF [11-15]. ●Respiratory rate – Patients with serious underlying disease may have a fast, normal, or slow respiratory rate. As an example, patients with PE may have a respiratory rate in the normal

#### Annotation 7607369207052

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Respiratory rate – Patients with serious underlying disease may have a fast, normal, or slow respiratory rate. As an example, patients with PE may have a respiratory rate in the normal range. Measurements of the respiratory rate obtained during triage may not be accurate [16,17].

UpToDate
examination does not rule out significant disease. As examples, the sensitivity and specificity of the pulmonary examination are limited for making the diagnosis of pneumonia or ADHF [11-15]. ●<span>Respiratory rate – Patients with serious underlying disease may have a fast, normal, or slow respiratory rate. As an example, patients with PE may have a respiratory rate in the normal range. Measurements of the respiratory rate obtained during triage may not be accurate [16,17]. ●Pulse oximetry – Pulse oximetry provides crucial information about arterial oxygenation and should be checked upon presentation to the ED in all patients complaining of dyspnea. Examin

#### Annotation 7607370255628

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Pulse oximetry – Pulse oximetry provides crucial information about arterial oxygenation and should be checked upon presentation to the ED in all patients complaining of dyspnea. Examining the waveform, if feasible, can help ensure accuracy since many conditions can cause erroneous readings (table 5). Standard pulse oximeters are not accurate in the setting of hypothermia, shock, carbon monoxide poisoning, and methemoglobinemia. Pulse oximetry may miss hypoxia, especially in patients with darkly pigmented skin [18].

UpToDate
slow respiratory rate. As an example, patients with PE may have a respiratory rate in the normal range. Measurements of the respiratory rate obtained during triage may not be accurate [16,17]. ●<span>Pulse oximetry – Pulse oximetry provides crucial information about arterial oxygenation and should be checked upon presentation to the ED in all patients complaining of dyspnea. Examining the waveform, if feasible, can help ensure accuracy since many conditions can cause erroneous readings (table 5). Standard pulse oximeters are not accurate in the setting of hypothermia, shock, carbon monoxide poisoning, and methemoglobinemia. Pulse oximetry may miss hypoxia, especially in patients with darkly pigmented skin [18]. (See "Pulse oximetry".) In general, healthy individuals demonstrate an oxygen saturation (SpO2) of 95 percent or greater. Older adults and patients with obesity or who smoke heavily oft

#### Annotation 7607371304204

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup In general, healthy individuals demonstrate an oxygen saturation (SpO2) of 95 percent or greater. Older adults and patients with obesity or who smoke heavily often maintain saturation between 92 and 95 percent, while patients with severe chronic lung disease may have baseline saturation below 92 percent. In the setting of acute dyspnea, saturations that are lower than expected or lower than a patient's known baseline should be investigated and explained.

UpToDate
setting of hypothermia, shock, carbon monoxide poisoning, and methemoglobinemia. Pulse oximetry may miss hypoxia, especially in patients with darkly pigmented skin [18]. (See "Pulse oximetry".) <span>In general, healthy individuals demonstrate an oxygen saturation (SpO2) of 95 percent or greater. Older adults and patients with obesity or who smoke heavily often maintain saturation between 92 and 95 percent, while patients with severe chronic lung disease may have baseline saturation below 92 percent. In the setting of acute dyspnea, saturations that are lower than expected or lower than a patient's known baseline should be investigated and explained. In a patient who complains of dyspnea on exertion, especially who is not hypoxic at rest, obtaining pulse oximetry while ambulating often provides useful data that can inform further te

#### Annotation 7607372352780

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup In a patient who complains of dyspnea on exertion, especially who is not hypoxic at rest, obtaining pulse oximetry while ambulating often provides useful data that can inform further testing and disposition. Worsening oxygen desaturation with ambulation can often change an anticipated discharge to an admission.

UpToDate
ve baseline saturation below 92 percent. In the setting of acute dyspnea, saturations that are lower than expected or lower than a patient's known baseline should be investigated and explained. <span>In a patient who complains of dyspnea on exertion, especially who is not hypoxic at rest, obtaining pulse oximetry while ambulating often provides useful data that can inform further testing and disposition. Worsening oxygen desaturation with ambulation can often change an anticipated discharge to an admission. ●Breath sounds during audible and lung auscultation •Stridor is a sign of airway obstruction. Inspiratory stridor suggests obstruction above the vocal cords (eg, foreign body, epiglotti

#### Annotation 7607373401356

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Jugular venous distension – Elevated jugular venous pressure may be present with ADHF, tension pneumothorax, cardiac tamponade, or any other cause of elevated intrathoracic pressure that prevents right heart filling. It can be assessed by observing the veins of the neck (movie 2) or examining hepatojugular reflux.

UpToDate
and fourth (S4) heart sounds'.) •Muffled or distant heart sounds – Quieter heart sounds occur with pericardial effusions but must be interpreted in the context of the overall clinical setting. •<span>Jugular venous distension – Elevated jugular venous pressure may be present with ADHF, tension pneumothorax, cardiac tamponade, or any other cause of elevated intrathoracic pressure that prevents right heart filling. It can be assessed by observing the veins of the neck (movie 2) or examining hepatojugular reflux. (See "Examination of the jugular venous pulse", section on 'How to examine the jugular venous pulse'.) •Pulsus paradoxus – Pulsus paradoxus can occur when right heart function is compro

#### Annotation 7607374449932

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup A number of conditions such as peritonitis, ruptured viscous, or bowel obstruction can cause severe pain that affects respiration and may manifest as acute shortness of breath, although this is generally not the patient's primary complaint [19]. (See "Evaluation of the adult with nontraumatic abdominal or flank pain in the emergency department".)

UpToDate
ch to the difficult airway in adults for emergency medicine and critical care", section on 'Identifying the anatomically difficult airway'.) ●Abdominal distension, masses, or peritoneal signs – <span>A number of conditions such as peritonitis, ruptured viscous, or bowel obstruction can cause severe pain that affects respiration and may manifest as acute shortness of breath, although this is generally not the patient's primary complaint [19]. (See "Evaluation of the adult with nontraumatic abdominal or flank pain in the emergency department".) •Ascites secondary to malignancy or liver disease can distend the abdominal cavity, placing pressure on the diaphragm and thereby increasing the work of breathing [20]. In such cases, d

#### Annotation 7607375498508

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Ascites secondary to malignancy or liver disease can distend the abdominal cavity, placing pressure on the diaphragm and thereby increasing the work of breathing [20]. In such cases, dyspnea often improves after large-volume paracentesis. (See "Evaluation of adults with ascites".)

UpToDate
shortness of breath, although this is generally not the patient's primary complaint [19]. (See "Evaluation of the adult with nontraumatic abdominal or flank pain in the emergency department".) •<span>Ascites secondary to malignancy or liver disease can distend the abdominal cavity, placing pressure on the diaphragm and thereby increasing the work of breathing [20]. In such cases, dyspnea often improves after large-volume paracentesis. (See "Evaluation of adults with ascites".) •Obesity is a risk factor for obstructive sleep apnea and obesity hypoventilation syndrome, which can present with chronic dyspnea on exertion in addition to daytime hypersomnolence, hy

#### Annotation 7607376547084

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Obesity is a risk factor for obstructive sleep apnea and obesity hypoventilation syndrome, which can present with chronic dyspnea on exertion in addition to daytime hypersomnolence, hypoxemia, and hypercapnia. Additionally, increased abdominal pressure on the diaphragm can affect pulmonary function, and obesity has been associated with an increased risk of DVT and PE.

UpToDate
g pressure on the diaphragm and thereby increasing the work of breathing [20]. In such cases, dyspnea often improves after large-volume paracentesis. (See "Evaluation of adults with ascites".) •<span>Obesity is a risk factor for obstructive sleep apnea and obesity hypoventilation syndrome, which can present with chronic dyspnea on exertion in addition to daytime hypersomnolence, hypoxemia, and hypercapnia. Additionally, increased abdominal pressure on the diaphragm can affect pulmonary function, and obesity has been associated with an increased risk of DVT and PE. (See "Clinical manifestations and diagnosis of obesity hypoventilation syndrome" and "Overweight and obesity in adults: Health consequences", section on 'Respiratory system'.) ●Skin ins

#### Annotation 7607377595660

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Supplemental oxygen can be started at 2 liters per minute (LPM) via nasal cannula with a target oxygen saturation of 94 to 98 percent.

UpToDate
vital signs may not need supplemental oxygen and the above general measures (eg, young patients with no comorbidities and patients with typical exacerbations of chronic disease such as asthma). <span>Supplemental oxygen can be started at 2 liters per minute (LPM) via nasal cannula with a target oxygen saturation of 94 to 98 percent. Other oxygen delivery systems and targets are discussed elsewhere. (See "Evaluation and management of the nonventilated, hospitalized adult patient with acute hypoxemia", section on 'Ox

#### Annotation 7607378644236

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup COPD exacerbation – Do not withhold oxygen from patients with COPD, but lower the target saturation to 90 to 94 percent, with the understanding that this may reduce ventilatory drive and cause hypercarbia. However, failure to oxygenate the patient may have profoundly adverse consequences.

UpToDate
cute hypoxemia", section on 'Oxygen and respiratory support'.) Supplemental oxygen should be used cautiously in patients with COPD exacerbation or ACS, although this is not an exhaustive list. ●<span>COPD exacerbation – Do not withhold oxygen from patients with COPD, but lower the target saturation to 90 to 94 percent, with the understanding that this may reduce ventilatory drive and cause hypercarbia. However, failure to oxygenate the patient may have profoundly adverse consequences. If a clinician determines that a COPD patient requires endotracheal intubation, oxygen delivery should be maximized without regard to the target oxygen saturation or hypercarbia. (See "

#### Annotation 7607379692812

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup ACS – Excessive oxygen may be harmful in those with ACS. Administer oxygen for ACS only when the oxygen saturation is consistently below 94 percent.

UpToDate
target oxygen saturation or hypercarbia. (See "COPD exacerbations: Management" and "The evaluation, diagnosis, and treatment of the adult patient with acute hypercapnic respiratory failure".) ●<span>ACS – Excessive oxygen may be harmful in those with ACS. Administer oxygen for ACS only when the oxygen saturation is consistently below 94 percent. (See "Overview of the acute management of ST-elevation myocardial infarction", section on 'Therapies of unclear benefit'.) Often, response to supplemental oxygen and other therapies or

#### Annotation 7607380741388

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup An improvement in SpO2 immediately after the administration of low-flow oxygen indicates a ventilation-perfusion (V/Q) mismatch.

UpToDate
, response to supplemental oxygen and other therapies or provocative maneuvers (eg, obtaining pulse oximetry while ambulating) assists in diagnosis and disposition. The following are examples: ●<span>An improvement in SpO2 immediately after the administration of low-flow oxygen indicates a ventilation-perfusion (V/Q) mismatch. (See "Measures of oxygenation and mechanisms of hypoxemia", section on 'Ventilation-perfusion mismatch'.) ●Rapid improvement following treatment with bronchodilators strongly suggests b

#### Annotation 7607381789964

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Failure to improve with oxygen administration may indicate a right-to-left shunt or presence of methemoglobinemia.

UpToDate
es of oxygenation and mechanisms of hypoxemia", section on 'Ventilation-perfusion mismatch'.) ●Rapid improvement following treatment with bronchodilators strongly suggests bronchoconstriction. ●<span>Failure to improve with oxygen administration may indicate a right-to-left shunt or presence of methemoglobinemia. (See "Methemoglobinemia" and "Measures of oxygenation and mechanisms of hypoxemia", section on 'Right-to-left shunt'.) ●In a patient with HIV (especially CD4 counts < 200 cells/micro

#### Annotation 7607382838540

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup In a patient with HIV (especially CD4 counts < 200 cells/microL) who presents with fever, cough, and dyspnea progressing over days to weeks, a profound drop in SpO2 associated with ambulation is characteristic of Pneumocystis pneumonia.

UpToDate
tion may indicate a right-to-left shunt or presence of methemoglobinemia. (See "Methemoglobinemia" and "Measures of oxygenation and mechanisms of hypoxemia", section on 'Right-to-left shunt'.) ●<span>In a patient with HIV (especially CD4 counts < 200 cells/microL) who presents with fever, cough, and dyspnea progressing over days to weeks, a profound drop in SpO2 associated with ambulation is characteristic of Pneumocystis pneumonia. (See "Epidemiology, clinical presentation, and diagnosis of Pneumocystis pulmonary infection in patients with HIV".) Diagnostic testing Overview — Testing should be performed in the con

#### Annotation 7607383887116

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Metabolic acidosis — Tachypnea and dyspnea can occur from respiratory compensation for metabolic acidosis, which is suggested by a low bicarbonate concentration (often defined as <23 mEq/L) on the serum chemistries. Evaluation includes confirmation with a blood gas and testing for specific causes (table 9).A venous blood gas is generally sufficient (as compared with arterial blood gas) to confirm presence and assess degree of metabolic acidosis.

UpToDate
resent with valvular disease, echocardiogram can be helpful in patients with acute dyspnea after other nonvalvular etiologies have been excluded. (See "Valvular heart disease in older adults".) <span>Metabolic acidosis — Tachypnea and dyspnea can occur from respiratory compensation for metabolic acidosis, which is suggested by a low bicarbonate concentration (often defined as <23 mEq/L) on the serum chemistries. Evaluation includes confirmation with a blood gas and testing for specific causes (table 9). A venous blood gas is generally sufficient (as compared with arterial blood gas) to confirm presence and assess degree of metabolic acidosis. Laboratory evaluation for specific causes is discussed elsewhere. (See "Approach to the adult with metabolic acidosis", section on 'Evaluation'.) Asthma ●Peak flow and pulmonary functio

#### Annotation 7607384935692

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup D-dimer – This test is not part of the workup of every patient with chest pain or shortness of breath and depends upon the patient's pretest probability for PE. Patients with a negative Pulmonary Embolism Rule-out Criteria (PERC) score (table 7) (calculator 1) can be ruled out for PE without D-dimer testing. Patients at low or moderate risk for PE according to a validated scoring system (eg, modified Wells criteria for PE) (table 8) and a negative enzyme-linked immunosorbent assay (ELISA) D-dimer can be ruled out for PE without further testing (algorithm 2 and algorithm 3).

UpToDate
regnant adult with suspected acute pulmonary embolism" and "Fat embolism syndrome" and "Acute chest syndrome (ACS) in sickle cell disease (adults and children)" and "Amniotic fluid embolism".) ●<span>D-dimer – This test is not part of the workup of every patient with chest pain or shortness of breath and depends upon the patient's pretest probability for PE. Patients with a negative Pulmonary Embolism Rule-out Criteria (PERC) score (table 7) (calculator 1) can be ruled out for PE without D-dimer testing. Patients at low or moderate risk for PE according to a validated scoring system (eg, modified Wells criteria for PE) (table 8) and a negative enzyme-linked immunosorbent assay (ELISA) D-dimer can be ruled out for PE without further testing (algorithm 2 and algorithm 3). It is not appropriate to use a D-dimer to screen patients at high risk for thromboembolic disease; they require a CT angiogram or ventilation perfusion (V/Q) scan (algorithm 4). (See "C

#### Annotation 7607385984268

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup BNP testing is not helpful when used indiscriminately in patients with acute, severe dyspnea, although it may be helpful in patients with a suspected cardiac origin [39].

UpToDate
y syndrome".) ●BNP – The measurement of BNP is helpful when the diagnosis of ADHF is in question. However, it can be elevated secondary to many causes of fluid overload, such as kidney failure. <span>BNP testing is not helpful when used indiscriminately in patients with acute, severe dyspnea, although it may be helpful in patients with a suspected cardiac origin [39]. In a metanalysis of ED patients with acute dyspnea of suspected cardiac origin (5 trials, 2513 patients), routine BNP testing decreased hospital length of stay by about one day, and the

#### Annotation 7607387032844

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup • Less than 100 pg/mL – Negative predictive value of over 90 percent for ADHF. • Between 100 pg/mL and 500 pg/mL – Cannot differentiate between ADHF and other causes of elevated BNP. Causes of a false-positive BNP (generally between 100 pg/mL and 500 pg/mL) include PE, fluid overload states (eg, renal failure, liver failure), critical illness, and other causes of right ventricular distension (eg, cor pulmonale, pulmonary hypertension). • Greater than 500 pg/mL – Positive predictive value over 90 percent for ADHF.

UpToDate
sed hospital length of stay by about one day, and there was a trend towards reduced admission rates [40]. BNP is interpreted as follows (see "Natriuretic peptide measurement in heart failure"): <span>•Less than 100 pg/mL – Negative predictive value of over 90 percent for ADHF. •Between 100 pg/mL and 500 pg/mL – Cannot differentiate between ADHF and other causes of elevated BNP. Causes of a false-positive BNP (generally between 100 pg/mL and 500 pg/mL) include PE, fluid overload states (eg, renal failure, liver failure), critical illness, and other causes of right ventricular distension (eg, cor pulmonale, pulmonary hypertension). •Greater than 500 pg/mL – Positive predictive value over 90 percent for ADHF. Infection — Pulmonary infections such as community-acquired pneumonia (CAP) can present with productive cough, fever, dyspnea, hypoxia, and pleuritic chest pain, although these are inse

#### Annotation 7607388081420

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Arterial blood gas – The role of arterial blood gas in the diagnosis and treatment of the acutely dyspneic patient is limited. The decision to perform tracheal intubation is based on clinical assessment and not on the arterial blood gas. Oxygenation is easily assessed using transcutaneous pulse oximetry. If there is any concern about pulse oximetry accuracy (table 5), we obtain an arterial blood gas. Acid-base status can be assessed using a venous blood gas and the serum bicarbonate. We do not routinely use arterial or venous blood gas for monitoring unless there is a discrepancy with pulse oximeter or capnography.

UpToDate
linical assessment and focused testing [21,22]. Arterial blood gas and chest multidetector computed tomography (MDCT) should not be performed routinely and reserved for specific circumstances. ●<span>Arterial blood gas – The role of arterial blood gas in the diagnosis and treatment of the acutely dyspneic patient is limited. The decision to perform tracheal intubation is based on clinical assessment and not on the arterial blood gas. Oxygenation is easily assessed using transcutaneous pulse oximetry. If there is any concern about pulse oximetry accuracy (table 5), we obtain an arterial blood gas. Acid-base status can be assessed using a venous blood gas and the serum bicarbonate. We do not routinely use arterial or venous blood gas for monitoring unless there is a discrepancy with pulse oximeter or capnography. (See "Arterial blood gases" and "Venous blood gases and other alternatives to arterial blood gases".) ●Chest MDCT – Even though chest MDCT will diagnose multiple problems, including mal

#### Annotation 7607389129996

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Chest MDCT – Even though chest MDCT will diagnose multiple problems, including malignancy, pneumonia, and pulmonary edema, it is most useful in dyspneic ED patients with trauma or concern for PE and when plain chest radiograph is inconclusive. MDCT does entail some risks, including contrast-induced nephropathy, allergic reaction to contrast, and radiation-related malignancy. MDCT should be performed when it is needed to establish an important diagnosis, even in patients with compromised kidney function since contrast-related kidney injury is relatively uncommon.

UpToDate
blood gas for monitoring unless there is a discrepancy with pulse oximeter or capnography. (See "Arterial blood gases" and "Venous blood gases and other alternatives to arterial blood gases".) ●<span>Chest MDCT – Even though chest MDCT will diagnose multiple problems, including malignancy, pneumonia, and pulmonary edema, it is most useful in dyspneic ED patients with trauma or concern for PE and when plain chest radiograph is inconclusive. MDCT does entail some risks, including contrast-induced nephropathy, allergic reaction to contrast, and radiation-related malignancy. MDCT should be performed when it is needed to establish an important diagnosis, even in patients with compromised kidney function since contrast-related kidney injury is relatively uncommon. (See "Prevention of contrast-induced acute kidney injury associated with computed tomography" and "Radiation dose and risk of malignancy from cardiovascular imaging".) Studies for almos

#### Annotation 7607390178572

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup ADHF – Signs of ADHF that may appear on a CXR include cardiomegaly, cephalization of blood vessels, interstitial edema (eg, "Kerley B" lines, peribronchial cuffing), vascular congestion (image 1), and pleural effusions.

UpToDate
est radiograph — A CXR is obtained for most ED patients with acute dyspnea (an exception being otherwise asymptomatic asthma patients who respond well to treatment). Diseases identified by CXR ●<span>ADHF – Signs of ADHF that may appear on a CXR include cardiomegaly, cephalization of blood vessels, interstitial edema (eg, "Kerley B" lines, peribronchial cuffing), vascular congestion (image 1), and pleural effusions. Radiographic findings can lag behind the clinical picture, and approximately 20 percent of patients admitted with ADHF have a nondiagnostic CXR [23]. ADHF and pneumonia can have a simil

#### Annotation 7607391227148

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Radiographic findings can lag behind the clinical picture, and approximately 20 percent of patients admitted with ADHF have a nondiagnostic CXR [ 23].

UpToDate
may appear on a CXR include cardiomegaly, cephalization of blood vessels, interstitial edema (eg, "Kerley B" lines, peribronchial cuffing), vascular congestion (image 1), and pleural effusions. <span>Radiographic findings can lag behind the clinical picture, and approximately 20 percent of patients admitted with ADHF have a nondiagnostic CXR [23]. ADHF and pneumonia can have a similar appearance on CXR, but ADHF is generally associated with hypertension (except in cardiogenic shock), often responds to aggressive early therapy, an

#### Annotation 7607392275724

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup ADHF is among the most common causes of acute respiratory failure among patients over 65 years of age.

UpToDate
ptoms range from mild dyspnea on exertion to severe pulmonary edema. Common findings include tachypnea, pulmonary crackles, jugular venous distension (movie 2), S3 gallop, and peripheral edema. <span>ADHF is among the most common causes of acute respiratory failure among patients over 65 years of age. (See "Examination of the jugular venous pulse", section on 'How to examine the jugular venous pulse' and "Approach to diagnosis and evaluation of acute decompensated heart failure in ad

#### Annotation 7607393324300

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Cardiomyopathy – The physiologic derangements associated with cardiomyopathy (primarily dilated cardiomyopathy) may result in pulmonary edema and manifest as dyspnea. CXR can appear similar to ADHF or just show cardiomegaly. Potential causes include cardiac ischemia, hypertension, alcohol abuse, cocaine abuse, and a number of systemic diseases (eg, sarcoidosis, systemic lupus erythematosus).

UpToDate
(See "Examination of the jugular venous pulse", section on 'How to examine the jugular venous pulse' and "Approach to diagnosis and evaluation of acute decompensated heart failure in adults".) ●<span>Cardiomyopathy – The physiologic derangements associated with cardiomyopathy (primarily dilated cardiomyopathy) may result in pulmonary edema and manifest as dyspnea. CXR can appear similar to ADHF or just show cardiomegaly. Potential causes include cardiac ischemia, hypertension, alcohol abuse, cocaine abuse, and a number of systemic diseases (eg, sarcoidosis, systemic lupus erythematosus). (See "Causes of dilated cardiomyopathy".) ●High-output heart failure – High-output heart failure may be precipitated by a number of conditions, including severe anemia, pregnancy, berib

#### Annotation 7607394372876

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup High-output heart failure – High-output heart failure may be precipitated by a number of conditions, including severe anemia, pregnancy, beriberi (thiamine deficiency), and thyrotoxicosis. Signs include tachycardia, bounding pulses, a venous hum heard over the internal jugular veins, and carotid bruits.

UpToDate
clude cardiac ischemia, hypertension, alcohol abuse, cocaine abuse, and a number of systemic diseases (eg, sarcoidosis, systemic lupus erythematosus). (See "Causes of dilated cardiomyopathy".) ●<span>High-output heart failure – High-output heart failure may be precipitated by a number of conditions, including severe anemia, pregnancy, beriberi (thiamine deficiency), and thyrotoxicosis. Signs include tachycardia, bounding pulses, a venous hum heard over the internal jugular veins, and carotid bruits. An elevated troponin may be seen secondary to demand ischemia. (See "Causes and pathophysiology of high-output heart failure".) ●Pneumonia – Although an infiltrate on CXR is considered

#### Annotation 7607395421452

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Pneumonia – Although an infiltrate on CXR is considered the "gold standard" for diagnosing pneumonia (image 2), radiographs obtained early in the clinical course may be nondiagnostic [26]. Volume depletion may also lead to a negative initial CXR. Contrary to past teaching, the appearance of the CXR (lobar versus diffuse disease) does not accurately predict the nature of the pneumonia (eg, "typical" versus "atypical" organisms).

UpToDate
s hum heard over the internal jugular veins, and carotid bruits. An elevated troponin may be seen secondary to demand ischemia. (See "Causes and pathophysiology of high-output heart failure".) ●<span>Pneumonia – Although an infiltrate on CXR is considered the "gold standard" for diagnosing pneumonia (image 2), radiographs obtained early in the clinical course may be nondiagnostic [26]. Volume depletion may also lead to a negative initial CXR. Contrary to past teaching, the appearance of the CXR (lobar versus diffuse disease) does not accurately predict the nature of the pneumonia (eg, "typical" versus "atypical" organisms). Pneumonia and ADHF can have a similar appearance on CXR, but pneumonia is more often associated with a normal or low blood pressure, does not respond to early therapy, and is generally

#### Annotation 7607396470028

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Infection with COVID-19 can cause pneumonia. Common abnormal radiographic findings are consolidation and ground-glass opacities with bilateral, peripheral, and lower lung zone distributions. Lung involvement peaks in severity at 10 to 12 days after symptom onset.

UpToDate
sure, does not respond to early therapy, and is generally not associated with an elevation in BNP. (See "Clinical evaluation and diagnostic testing for community-acquired pneumonia in adults".) <span>Infection with COVID-19 can cause pneumonia. Common abnormal radiographic findings are consolidation and ground-glass opacities with bilateral, peripheral, and lower lung zone distributions. Lung involvement peaks in severity at 10 to 12 days after symptom onset. (See "COVID-19: Clinical features", section on 'Imaging findings' and "COVID-19: Diagnosis".) ●Noncardiogenic pulmonary edema (ARDS) – ARDS can complicate a wide range of conditions and

#### Annotation 7607397518604

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Noncardiogenic pulmonary edema (ARDS) – ARDS can complicate a wide range of conditions and is characterized by rapidly progressive dyspnea, hypoxia, and bilateral infiltrates on CXR. It can be difficult to distinguish from ADHF purely on clinical grounds; BNP and echocardiography can be helpful in differentiation. Potential causes of ARDS include sepsis, shock, severe trauma, toxic inhalations (eg, aspiration, thermal injury, anhydrous ammonia, chlorine), infections (eg, COVID-19, hantavirus, severe acute respiratory syndrome [SARS], dengue, Middle East respiratory syndrome), blood transfusion, and drug overdose (eg, cocaine, opioids, aspirin).

UpToDate
lung zone distributions. Lung involvement peaks in severity at 10 to 12 days after symptom onset. (See "COVID-19: Clinical features", section on 'Imaging findings' and "COVID-19: Diagnosis".) ●<span>Noncardiogenic pulmonary edema (ARDS) – ARDS can complicate a wide range of conditions and is characterized by rapidly progressive dyspnea, hypoxia, and bilateral infiltrates on CXR. It can be difficult to distinguish from ADHF purely on clinical grounds; BNP and echocardiography can be helpful in differentiation. Potential causes of ARDS include sepsis, shock, severe trauma, toxic inhalations (eg, aspiration, thermal injury, anhydrous ammonia, chlorine), infections (eg, COVID-19, hantavirus, severe acute respiratory syndrome [SARS], dengue, Middle East respiratory syndrome), blood transfusion, and drug overdose (eg, cocaine, opioids, aspirin). (See "Acute respiratory distress syndrome: Epidemiology, pathophysiology, pathology, and etiology in adults" and "Acute respiratory distress syndrome: Clinical features, diagnosis, and

#### Annotation 7607398567180

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup High-altitude pulmonary edema (HAPE) – HAPE is a form of noncardiogenic pulmonary edema that typically occurs between two to four days after rapid ascent to elevations over 2500 meters (8000 feet). Symptoms often begin with a nonproductive cough, dyspnea on exertion, and fatigue and may progress quickly to dyspnea at rest. Pulmonary symptoms are often accompanied by a headache and occasionally cerebral edema.

UpToDate
tory distress syndrome: Epidemiology, pathophysiology, pathology, and etiology in adults" and "Acute respiratory distress syndrome: Clinical features, diagnosis, and complications in adults".) ●<span>High-altitude pulmonary edema (HAPE) – HAPE is a form of noncardiogenic pulmonary edema that typically occurs between two to four days after rapid ascent to elevations over 2500 meters (8000 feet). Symptoms often begin with a nonproductive cough, dyspnea on exertion, and fatigue and may progress quickly to dyspnea at rest. Pulmonary symptoms are often accompanied by a headache and occasionally cerebral edema. (See "High-altitude pulmonary edema" and "Acute mountain sickness and high-altitude cerebral edema".) ●Pneumothorax – A pneumothorax sufficient to cause acute dyspnea is usually visible

#### Annotation 7607399615756

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Pneumothorax – A pneumothorax sufficient to cause acute dyspnea is usually visible on CXR (image 3 and image 4), while an additional expiratory view may be helpful [27]. In addition to trauma, vigorous coughing, and medical procedures (eg, central venous catheter placement, intubation, and barotrauma), a number of medical conditions (eg, COPD, cystic fibrosis, tuberculosis, Marfan syndrome, Pneumocystis pneumonia) increase the risk for developing a pneumothorax.

UpToDate
t. Pulmonary symptoms are often accompanied by a headache and occasionally cerebral edema. (See "High-altitude pulmonary edema" and "Acute mountain sickness and high-altitude cerebral edema".) ●<span>Pneumothorax – A pneumothorax sufficient to cause acute dyspnea is usually visible on CXR (image 3 and image 4), while an additional expiratory view may be helpful [27]. In addition to trauma, vigorous coughing, and medical procedures (eg, central venous catheter placement, intubation, and barotrauma), a number of medical conditions (eg, COPD, cystic fibrosis, tuberculosis, Marfan syndrome, Pneumocystis pneumonia) increase the risk for developing a pneumothorax. (See "Clinical presentation and diagnosis of pneumothorax" and "Pneumothorax in adults: Epidemiology and etiology" and "Initial evaluation and management of blunt thoracic trauma in adu

#### Annotation 7607400664332

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Pleural effusion, hemothorax – A moderate to large pleural effusion or hemothorax, which appear similar on CXR, can cause acute dyspnea. Common etiologies include infection, ascites, pancreatitis, cancer, heart failure, pneumonia, iatrogenic vessel transection, PE, and trauma. These are evaluated by cross-sectional imaging studies (eg, blood has high attenuation/Hounsfield units on CT) or by analysis of the pleural fluid.

UpToDate
al evaluation and management of blunt thoracic trauma in adults" and "Treatment of primary spontaneous pneumothorax in adults" and "Treatment of secondary spontaneous pneumothorax in adults".) ●<span>Pleural effusion, hemothorax – A moderate to large pleural effusion or hemothorax, which appear similar on CXR, can cause acute dyspnea. Common etiologies include infection, ascites, pancreatitis, cancer, heart failure, pneumonia, iatrogenic vessel transection, PE, and trauma. These are evaluated by cross-sectional imaging studies (eg, blood has high attenuation/Hounsfield units on CT) or by analysis of the pleural fluid. (See "Imaging of pleural effusions in adults" and "Pleural fluid analysis in adults with a pleural effusion".) ●COPD and asthma – Large lung volumes and a flattened diaphragm on CXR sug

#### Annotation 7607401712908

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Airway foreign body – Unilateral air trapping suggests a bronchial foreign body (image 6), but many organic foreign bodies are radiolucent and not evident on CXR [28]. Additionally, the absence of unilateral air trapping does not rule out a foreign body.

UpToDate
a in adults: Emergency department and inpatient management", section on 'Chest radiograph' and "Chronic obstructive pulmonary disease: Diagnosis and staging", section on 'Additional testing'.) ●<span>Airway foreign body – Unilateral air trapping suggests a bronchial foreign body (image 6), but many organic foreign bodies are radiolucent and not evident on CXR [28]. Additionally, the absence of unilateral air trapping does not rule out a foreign body. (See "Airway foreign bodies in adults", section on 'Imaging'.) ●Acute chest syndrome – This potentially life-threatening complication of sickle cell disease typically has new pulmonary

#### Annotation 7607402761484

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Acute chest syndrome – This potentially life-threatening complication of sickle cell disease typically has new pulmonary infiltrates on CXR. Patients generally complain of severe chest pain and acute dyspnea and have a fever. It is easily confused with pneumonia but should be considered in any patient with sickle cell disease.

UpToDate
e radiolucent and not evident on CXR [28]. Additionally, the absence of unilateral air trapping does not rule out a foreign body. (See "Airway foreign bodies in adults", section on 'Imaging'.) ●<span>Acute chest syndrome – This potentially life-threatening complication of sickle cell disease typically has new pulmonary infiltrates on CXR. Patients generally complain of severe chest pain and acute dyspnea and have a fever. It is easily confused with pneumonia but should be considered in any patient with sickle cell disease. (See "Overview of the clinical manifestations of sickle cell disease" and "Overview of the pulmonary complications of sickle cell disease".) ●Chest wall and direct pulmonary injury – Ri

#### Annotation 7607403810060

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup EVALI – Initially described in 2019, EVALI is caused by e-cigarette use, especially among males younger than 35 years of age. It is primarily associated with vaping tetrahydrocannabinol (THC) products and strongly correlated with the presence of vitamin E acetate in the formulations [29,30]. EVALI is characterized by shortness of breath, cough, chest pain, and gastrointestinal complaints and diffuse hazy or consolidative opacities on CXR.

UpToDate
oagulation can cause acute dyspnea. CXR can demonstrate diffuse opacities. (See "Evaluation of nonlife-threatening hemoptysis in adults", section on 'Chest imaging showing diffuse opacities'.) ●<span>EVALI – Initially described in 2019, EVALI is caused by e-cigarette use, especially among males younger than 35 years of age. It is primarily associated with vaping tetrahydrocannabinol (THC) products and strongly correlated with the presence of vitamin E acetate in the formulations [29,30]. EVALI is characterized by shortness of breath, cough, chest pain, and gastrointestinal complaints and diffuse hazy or consolidative opacities on CXR. (See "E-cigarette or vaping product use-associated lung injury (EVALI)".) ●Toxins and exposures – As examples, pneumonitis can result from ingestions of various agents such as hydrocarb

#### Annotation 7607404858636

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Lung cancer – Shortness of breath is a common symptom in patients with lung cancer at the time of diagnosis, occurring in approximately 25 percent of cases. Dyspnea may be due to extrinsic or intraluminal airway obstruction, obstructive pneumonitis or atelectasis, lymphangitic tumor spread, tumor emboli, pneumothorax, pleural effusion, or pericardial effusion with tamponade. (See "Clinical manifestations of lung cancer".)

UpToDate
of selected exposures" and "Acute hydrocarbon exposure: Clinical toxicity, evaluation, and diagnosis" and "Paraquat poisoning" and "Inhalation injury from heat, smoke, or chemical irritants".) ●<span>Lung cancer – Shortness of breath is a common symptom in patients with lung cancer at the time of diagnosis, occurring in approximately 25 percent of cases. Dyspnea may be due to extrinsic or intraluminal airway obstruction, obstructive pneumonitis or atelectasis, lymphangitic tumor spread, tumor emboli, pneumothorax, pleural effusion, or pericardial effusion with tamponade. (See "Clinical manifestations of lung cancer".) CXR findings that should raise the suspicion for lung cancer include new lesions larger than 3 cm, measurable growth in any nodule or mass, pleural nodularity, and asymmetric or signifi

#### Annotation 7607405907212

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup CXR findings that should raise the suspicion for lung cancer include new lesions larger than 3 cm, measurable growth in any nodule or mass, pleural nodularity, and asymmetric or significantly enlarged hilar or paratracheal nodes. Concerning but less specific findings include pleural effusions and nondependent or substantial atelectasis.

UpToDate
tive pneumonitis or atelectasis, lymphangitic tumor spread, tumor emboli, pneumothorax, pleural effusion, or pericardial effusion with tamponade. (See "Clinical manifestations of lung cancer".) <span>CXR findings that should raise the suspicion for lung cancer include new lesions larger than 3 cm, measurable growth in any nodule or mass, pleural nodularity, and asymmetric or significantly enlarged hilar or paratracheal nodes. Concerning but less specific findings include pleural effusions and nondependent or substantial atelectasis. (See "Overview of the initial evaluation, diagnosis, and staging of patients with suspected lung cancer", section on 'Initial evaluation'.) Electrocardiogram — An ECG with ST segment ch

#### Annotation 7607406955788

 #Demarche #Diagnosis #Diagnostique #Dyspnea-ED #Dyspnee-SAU #Emergency #SAU #Topo-Dyspnee #U2D #Urgences #Workup Electrocardiogram — An ECG with ST segment changes is strong evidence for cardiac ischemia; however, the initial ECG is normal in approximately 20 percent of patients subsequently diagnosed with a myocardial infarction, and only 33 percent of initial ECGs are diagnostic.

UpToDate
ffusions and nondependent or substantial atelectasis. (See "Overview of the initial evaluation, diagnosis, and staging of patients with suspected lung cancer", section on 'Initial evaluation'.) <span>Electrocardiogram — An ECG with ST segment changes is strong evidence for cardiac ischemia; however, the initial ECG is normal in approximately 20 percent of patients subsequently diagnosed with a myocardial infarction, and only 33 percent of initial ECGs are diagnostic. The ECG may also reveal signs of PE (right heart strain), pericardial effusion (diffuse low voltage (waveform 1), electrical alternans (waveform 2)), and other disease processes. Howeve

#### Annotation 7607408790796

 #Chest #Clinical #Cliniques #Diagnostic #Diagnostique #Douleur #Dyspnée #Embolie #Embolism #Emergency #Garjo #Manifestations #Pain #Pulmonaire #Pulmonary #Thoracique #U2D The PERC rule has eight criteria (table 4) (calculator 3): • Age <50 years • Heart rate <100 beats/minute • Oxyhemoglobin saturation ≥95 percent • No hemoptysis • No estrogen use • No prior DVT or PE • No unilateral leg swelling • No surgery/trauma requiring hospitalization within the prior four weeksIn patients with a low probability of PE who fulfill all eight criteria, the likelihood of PE is sufficiently low that further testing is not indicated.

UpToDate
signed to identify patients with a low clinical probability of PE in whom the risk of unnecessary testing outweighs the risk of PE [2,80-83] (see 'Low probability of pulmonary embolism' above). <span>The PERC rule has eight criteria (table 4) (calculator 3): •Age <50 years •Heart rate <100 beats/minute •Oxyhemoglobin saturation ≥95 percent •No hemoptysis •No estrogen use •No prior DVT or PE •No unilateral leg swelling •No surgery/trauma requiring hospitalization within the prior four weeks In patients with a low probability of PE who fulfill all eight criteria, the likelihood of PE is sufficiently low that further testing is not indicated. Best illustrating the value of PERC is a crossover cluster-randomized noninferiority trial of 1916 ED patients with a low gestalt clinical probability of PE (ie, 15 percent probability

#### Annotation 7607409839372

 Definition of Modulation Index of Amplitude Modulation The modulation index, also known as the modulation factor, is a measure of the extent to which the amplitude of a carrier signal is varied in accordance with a modulating signal in a modulation system. Recalling the definition of the amplitude modulation $$s_{HF}(t) = (A + \gamma s(t)) \cos(\omega_{c}t)$$, the modulation index is defined as: $$\displaystyle m = \frac{\max|\gamma s(t)|}{A} = \frac{\gamma\cdot\max|s(t)|}{A}$$

#### Annotation 7607410363660

 #Chest #Clinical #Cliniques #Diagnostic #Diagnostique #Douleur #Dyspnée #Embolie #Embolism #Emergency #Garjo #Manifestations #Pain #Pulmonaire #Pulmonary #Thoracique #U2D D-dimer levels rise with age such that using the traditional cutoff value of <500 ng/mL (fibrinogen equivalent units) results in reduced specificity of D-dimer testing in older patients (>50 years), a population in whom PE is common. Several studies report its use [2,63,99-104] with the most commonly used formula for age adjustment as: Age (if over 50 years) x 10 = cutoff value in ng/mL (fibrinogen equivalent units)

UpToDate
n patients with a low probability or low intermediate probability for PE. They should not be used in those with high-probability or intermediate-high-probability for PE. ●Age-adjusted D-dimer – <span>D-dimer levels rise with age such that using the traditional cutoff value of <500 ng/mL (fibrinogen equivalent units) results in reduced specificity of D-dimer testing in older patients (>50 years), a population in whom PE is common. Several studies report its use [2,63,99-104] with the most commonly used formula for age adjustment as: Age (if over 50 years) x 10 = cutoff value in ng/mL (fibrinogen equivalent units) One meta-analysis of six trials reported that in patients unlikely to have PE by the Wells criteria (score ≤4 (table 2) (calculator 1)), compared with a negative fixed level D-dimer, a

#### Annotation 7607411412236

 #Chest #Clinical #Cliniques #Diagnostic #Diagnostique #Douleur #Dyspnée #Embolie #Embolism #Emergency #Garjo #Manifestations #Pain #Pulmonaire #Pulmonary #Thoracique #U2D Approximately 10 percent of patients present with the symptoms of an infarcted lung, usually due to smaller, more peripheral emboli. Pleuritic pain is typical in this population due to inflammation of the pleura. Hemorrhage from the infarcted lung is also thought to be responsible for hemoptysis.

UpToDate
[9]. Dyspnea may be less frequent in older patients with no previous cardiopulmonary disease. Dyspnea is more likely to be present in patients who present with PE in the main or lobar vessels. <span>Approximately 10 percent of patients present with the symptoms of an infarcted lung, usually due to smaller, more peripheral emboli. Pleuritic pain is typical in this population due to inflammation of the pleura. Hemorrhage from the infarcted lung is also thought to be responsible for hemoptysis. (See "Epidemiology and pathogenesis of acute pulmonary embolism in adults", section on 'Pathogenesis and pathophysiology'.) Retrospective studies report syncope as the presenting sympto

#### Flashcard 7607414295820

Question
The modulation index, also known as the modulation factor, is a measure of the extent to which the amplitude of a carrier signal is varied in accordance with a modulating signal in a modulation system. Recalling the definition of the amplitude modulation $$s_{HF}(t) = (A + \gamma s(t)) \cos(\omega_{c}t)$$, the modulation index is defined as: [...]
$$\displaystyle m = \frac{\max|\gamma s(t)|}{A} = \frac{\gamma\cdot\max|s(t)|}{A}$$

status measured difficulty not learned 37% [default] 0

Definition of Modulation Index of Amplitude Modulation
ce with a modulating signal in a modulation system. Recalling the definition of the amplitude modulation $$s_{HF}(t) = (A + \gamma s(t)) \cos(\omega_{c}t)$$, the modulation index is defined as: <span>$$\displaystyle m = \frac{\max|\gamma s(t)|}{A} = \frac{\gamma\cdot\max|s(t)|}{A}$$ <span>

#### Flashcard 7607415868684

Question
The modulation index, also known as the modulation factor, is [...]. Recalling the definition of the amplitude modulation $$s_{HF}(t) = (A + \gamma s(t)) \cos(\omega_{c}t)$$, the modulation index is defined as: $$\displaystyle m = \frac{\max|\gamma s(t)|}{A} = \frac{\gamma\cdot\max|s(t)|}{A}$$
a measure of the extent to which the amplitude of a carrier signal is varied in accordance with a modulating signal in a modulation system

status measured difficulty not learned 37% [default] 0

Definition of Modulation Index of Amplitude Modulation

#### Flashcard 7607435005196

Question
There are three kinds of situations of modulation index of amplitude modulation: [...]

- Undermodulation occurs when $$m < 100\%$$.

- 100% modulation occurs when $$m = 100\%$$.

- Overmodulation occurs when $$m > 100\%$$, preventing envelope detection.

status measured difficulty not learned 37% [default] 0

Three situations of Modulation Index of Amplitude Modulation
There are three kinds of situations of modulation index of amplitude modulation: - Undermodulation occurs when $$m < 100\%$$. - 100% modulation occurs when $$m = 100\%$$. - Overmodulation occurs when $$m > 100\%$$, preventing envelope detection.

#### Annotation 7607438675212

 If however, you do have python installed but not  pip , then the best instructions for what to do next are on the python website.

Getting Started — SQLFluff 2.3.5 documentation
heir installation of python will come with pip (the python package manager) preinstalled. To confirm this you can type pip --version similar to python above. $pip --version pip 21.3.1 from ... <span>If however, you do have python installed but not pip, then the best instructions for what to do next are on the python website. Installing SQLFluff¶ Assuming that python and pip are already installed, then installing SQLFluff is straight forward.$ pip install sqlfluff You can confirm its installation by getting

#### Annotation 7607440772364

 Power of Amplitude Modulation Based on $$\displaystyle s_{HF}(t)=A\cos(\omega_{c}t)+ \frac{\gamma}{2}\cos\left((\omega_{c}-\omega_{i})t\right)+ \frac{\gamma}{2}\cos\left((\omega_{c}+\omega_{i})t\right)$$: - Power of carrier, based on Parseval's theorem: $$\displaystyle P_{\text {carrier }}=2\left(\frac{A}{2}\right)^2=\frac{A^2}{2}$$. - Power in sidebands, based on Parseval's theorem: $$\displaystyle P_{\text {sidebands }}=4\left(\frac{\gamma}{4}\right)^2=\frac{\gamma^2}{4}$$.

#### Flashcard 7607448898828

Question
Based on $$\displaystyle s_{HF}(t)=A\cos(\omega_{c}t)+ \frac{\gamma}{2}\cos\left((\omega_{c}-\omega_{i})t\right)+ \frac{\gamma}{2}\cos\left((\omega_{c}+\omega_{i})t\right)$$: [Power of carrier and Power of sidebands]
- Power of carrier, based on Parseval's theorem: $$\displaystyle P_{\text {carrier }}=2\left(\frac{A}{2}\right)^2=\frac{A^2}{2}$$.
- Power in sidebands, based on Parseval's theorem: $$\displaystyle P_{\text {sidebands }}=4\left(\frac{\gamma}{4}\right)^2=\frac{\gamma^2}{4}$$.
Based on $$\displaystyle s_{HF}(t)=A\cos(\omega_{c}t)+ \frac{\gamma}{2}\cos\left((\omega_{c}-\omega_{i})t\right)+ \frac{\gamma}{2}\cos\left((\omega_{c}+\omega_{i})t\right)$$: - Power of carrier, based on Parseval's theorem: $$\displaystyle P_{\text {carrier }}=2\left(\frac{A}{2}\right)^2=\frac{A^2}{2}$$. - Power in sidebands, based on Parseval's theorem: $$\displaystyle P_{\text {sidebands }}=4\left(\frac{\gamma}{4}\right)^2=\frac{\gamma^2}{4}$$.