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known objects exist as the consequences of directed operations, not because of conformity of thought or observation with something antecedent. We may, for reasons which Ihope will appear later, give the name intelligence to these directed operations. Using this term, we may say that the worth of any object that lays claim to being an object of knowledge is dependent upon the intelligence employed in reaching it. In saying this, we must bear in mind that intelligence means operations actually performed in the modification of condi- tions, including all the guidance that is given by means of ideas, both direct and symbolic.

it is only away of saying that the value of any cognitive conclusion depends upon the method by which it is reached, so that the perfecting of method, the perfecting of intelligence, is the thing of su- preme value. If we judge the work of ascientific inquirer by what he does and not by his speech when he talks about his work (when he is likely to talk in terms of traditional notions that have become habitual) we shall have little difficulty, I think, in accepting the idea that he determines the cognitive claims of anything presented to him on the basis of the method by which it is reached. The import of this doctrine is simple. It becomes complicated, however, the moment we contrast it with the doctrines which have dominated thought. For these all rest on the notion that areality in Being indepen- dently of the operations of inquiry is the standard and meas- ure of anything said to be known. Viewed in this connection, the conception just advanced involves hardly less than arevo- lutionary transformation of many of our most cherished con- victions. The essential difference is that between amind which beholds or grasps objects from outside the world of things, physical and social, and one which is aparticipant, interacting

Heisen- berg's principle of indeterminancy. The basic philosophy of the Newtonian system of the universe is closely connected with what is termed the principle of canonic conjugates. The fun- damental principle of the mechanical philosophy of nature is that it is possible to determine exactly (in principle if not in actual practice) both the position and the velocity of any body. Knowing this for each particle which enters into any change, as amotion, it is possible to calculate mathematically, that is exactly, just what will happen. The laws or physical equations that express the relations of the particles and bodies under different conditions are then assumed to be a"govern- ing" framework of nature to which all particular phenomena conform. Knowing volumes and momenta in aparticular case we can by the aid of fixed laws predict the subsequent course of events.

a- place's well-known saying that were there aknowledge (in mechanical terms) of the state of the universe at any one time its whole future could be predicted or deduced

critics had attacked the Newtonian scheme on the basis of alogical flaw in it. It first postulates that the position and velocity of any particle can be determined in isolation from all others. Then it postulates that there is a complete and continuous interaction of all these particles with one another. Logically, the two postulates nullify each other. But as long as the principles involved gave satisfactory results this objection was brushed aside or ignored. Heisenberg's prin- ciple compels arecognition of the fact that interaction prevents an accurate measurement of velocity and position for any body,

he change for the un- derlying philosophy and logic of science is, however, very great. In relation to the metaphysics of the Newtonian system it is hardly less than revolutionary. What is known is seen to be aproduct in which the act of observation plays aneces- sary role. Knowing is seen to be aparticipant in what is finally known. Moreover, the metaphysics of existence as something fixed and therefore capable of literally exact mathematical description and prediction is undermined. Knowing is, for philosophical theory, acase of specially directed activity in- stead of something isolated from practice. The quest for cer- tainty by means of exact possession in mind of immutable reality is exchanged for search for security by means of active control of the changing course of events. Intelligence in op- eration, another name for method, becomes the thing most worth winning.

The principle of indeterminancy thus presents itself as the final step in the dislodgment of the old spectator theory of knowledge. It marks the acknowledgment, within scientific procedure itself, of the fact that knowing is one kind of inter-

If we persist in the tradi- tional conception, according to which the thing to be known is something which exists prior to and wholly apart from the act of knowing, then discovery of the fact that the act of observa- tion, necessary in existential knowing, modifies that pre- existent something, is proof that the act of knowing gets in its own way, frustrating its own intent. If knowing is aform of doing and is to be judged like other modes by its eventual issue, this tragic conclusion is not forced upon us. Fundamen- tally, the issue is raised whether philosophy is willing to sur- render atheory of mind and its organs of knowing which originated when the practice of knowing was in its infancy.

In technical statement, laws on the new basis are formulae for the 'prediction of the 'probability of an observable occur- rence. They are designations of relations sufficiently stable to allow of the occurrence of forecasts of individualized situa- tions for every observed phenomenon is individual within limits of specified probability, not aprobability of error, but of probability of actual occurrence.

like all generalizations which go beyond the range of possible as well as of actual experience, aprice was paid for the sublime and inspiring ideal of areign of uni- versal and exact law: the sacrifice of the individual to the general, of the concrete to the relational. Spinoza's magnifi- cently sweeping dictum that "the order and connection of ideas is the order and connection of things" was in effect, although not avowedly as it was with Spinoza, the current measure of the intelligibility of nature. And auniverse whose essential characteristic is fixed order and connection has no place for unique and individual existences, no place for novelty and genuine change and growth. It is, in the words of William James, ablock universe. The fact that in detailed content it is athoroughly mechanistic world is, one may say, amere incident attending the fact that it is afixed and closed world.

the child who expressed surprise at the fact that rivers or bodies of water are always located conveniently near great cities. Suppose every one had had engrained in his mind the notion that cities, like rivers, are works of nature. Suppose it was then suddenly ascertained that cities were man made and were located near bodies of water in order that the activities of men in industry and com- merce might be better carried on and human purposes and needs be better served. We can imagine that the discovery would bring with it ashock. It would be upsetting because

rom the stand- point of traditional notions, it appears that nature, intrin- sically, is Irrational. But the quality of irrationality is imputed only because of conflict with aprior definition of ration- ality. Abandon completely the notion that nature ought to conform to acertain definition, and nature intrinsically is neither rational nor irrational. Apart from the use made of it in knowing, it exists in adimension irrelevant to either attribution, just as rivers inherently are neither located near cities nor are opposed to such location. Nature is intelligible and understand^/*?. There are operations by means of which it becomes an object of knowledge, and is turned to human purposes, just as rivers provide conditions which may be utilized to promote human activities and to satisfy human need.

The doctrine that nature is inherently rational was acostly one. It entailed the idea that reason in man is an outside spec- tator of arationality already complete in itself. It deprived reason in man of an active and creative office; its business was simply to copy, to re-present symbolically, to view agiven rational structure. Ability to make atranscript of this structure in mathematical formulas gives great delight to those who have the required ability. But it does nothing; it makes no difference in nature. In effect, it limits thought in man to retraversing in cognition apattern fixed and complete in itself. The doctrine was both an effect of the traditional separation between knowledge and action and afactor in perpetuating it. It relegated practical making and doing to asecondary and relatively irrational realm.

There is thus involved more than averbal shift if we say that the new scientific development effects an exchange of reason for intelligence. In saying this, "reason" has the tech- nical meaning given to it in classic philosophic tradition, the nous of the Greeks, the mtellectus of the scholastics. In this meaning, it designates both an inherent immutable order of nature, superempirical in character, and the organ of mind by which this universal order is grasped. In both respects, reason is with respect to changing things the ultimate fixed standard the law physical phenomena obey, the norm human action should obey. For the marks of "reason" in its traditional sense are necessity, universality, superiority to change, domination of the occurrence and the understanding of change.

The change does not mean that nature has lost intelligi- bility. It rather signifies that we are in position to realize that the term intelligible is to be understood literally. It expresses apotentiality rather than an actuality. Nature is capable of being understood. But the possibility is realized not by amind thinking about it from without but by operations conducted from within, operations which give it new relations summed up in production of anew individual object. Nature has intel- ligible order as its possession in the degree in which we by our own overt operations realize potentialities contained in it. The change from intrinsic rationality in the traditional sense to an intelligibility to be realized by human action places responsibility upon human beings. The devotion we show to the ideal of intelligence determines the extent in which the actual order of nature is congenial to mind.

rtificial simplifica- tion or abstraction is anecessary 'precondition of securing ability to deal with affairs which are complex, in which there are many more variables and where strict isolation destroys the special characteristics of the subject-matter. This statement conveys the important distinction which exists between physical and social and moral objects. The distinction is one of methods of operation not of kinds of reality.

what is meant by "physical" in distinction from other adjectives that are prefixed to subject-matter is precisely an abstraction of alimited range of conditions and relations out of atotal complex. The same principle applies to mathematical objects. The use of symbols designating possible operations makes possible agreater degree of exactness and intellectual organization. There is no disparagement of ab- straction involved. Abstraction is simply an instance of the economy and efficiency involved in all intelligent practice: Deal first with matters that can be effectively handled, and then use the results to go on to cope with more complex affairs. Objection comes in, and comes in with warranted force, when the results of an abstractive operation are given astanding which belongs only to the total situation from which they have been selected. All specialization breeds afamiliarity which tends to create an illusion. Material dealt with by specialized abstractive processes comes to have apsychological independence and completion which is converted hyposta- tized into objective independence and self-sufficiency.

In arriving at statements which hold for all possible experiencers and observers under all possible varying indi- vidual circumstances we arrive at that which is most remote from any one concrete experience. In this sense, the abstrac- tions of mathematics and physics represent the common de- nominators in all things experienceable. Taken by themselves they seem to present aca$ut mortuum. Erected into complete statements of reality as such, they become hallucinatory obses- sions. But in practice, there is always an accompanying reverse movement. These generalized findings are employed to enrich the meanings of individualized experiences, and to afford, within limits of probability, an increased control of them. It is in this sense that all reflective knowledge as such is instrumental. The beginning and the end is the things of gross everyday experience. But apart from knowledge the things of our ordinary experience are fragmentary, casual, unregulated by purpose, full of frustrations and barriers. In the language previously used, they are problematic, obstructive, and chal- lenges to thought. By ignoring for atime their concrete and qualitative fullness, by making abstractions and generalizations, we ascertain certain basic relations upon which occurrence of the things experienced depend. We treat them as mere events,

There is no kind of inquiry which has amonopoly of the honorable title of knowledge. The engineer, the artist, the historian, the man of affairs attain knowledge in the degree they employ methods that enable them to solve the problems which develop in the subject-matter they are concerned with. As philosophy framed upon the pattern of experimental in- quiry does away with all wholesale skepticism, so it eliminates all invidious monopolies of the idea of science. By their fruits we shall know them.

he marking off of certain conclusions as alone truly science, whether mathematical or physical, is an historical incident. It sprang originally from man's desire for acertainty and peace which he could not attain practically in the absence of the arts of management and direction of natural conditions. When modern physical inquiry began, it had ahard time to get ahearing, or even to be permitted to carry on. The temp- tation was practically irresistible to treat it as an exclusive and esoteric undertaking. Moreover, as it progressed, it required more and more specialized technical preparation. The motive of defense from social attack and the motive of glorification

of aspecialized calling conspired together. All the eulogistic connotations that gather about "truth" were called into play. Thus "science," meaning physical knowledge, became a kind of sanctuary. Areligious atmosphere, not to say an idola- trous one, was created. "Science" was set apart jits findings were supposed to have aprivileged relation to the real. In fact, the painter may know colors as well as the physicist} the poet may know stars, rain and clouds as well as the meteorolo- gist jthe statesman, educator and dramatist may know human nature as truly as the professional psychologist} the farmer may know soils and plants as truly as the botanist and min- erologist. For the criterion of knowledge lies in the method used to secure consequences and not in metaphysical concep- tions of the nature of the real. Nevertheless in the end think- ers in all lines are dependent upon the mathematician and the physical inquirer for perfecting of the tools employed in their respective callings. That "knowledge" has many meanings follows from the operational definition of conceptions. There are as many con- ceptions of knowledge as there are distinctive operations by which problematic situations are resolved.

Many definitions of mind and thinking have been given. Iknow of but one that goes to the heart of the matter: response to the doubtful as such. No inanimate thing reacts to things as problematic. Its behavior to other things is capable of description in terms of what is determinately there. Under given conditions, it just reacts or does not react. Its reactions merely enstate anew set of conditions, in which reactions con- tinue without regard to the nature of their outcome. It makes no difference, so to say, to astone what are the results of its interactions with other things. It enjoys the advantage that it makes no difference how it reacts, even if the effect is its own pulverization. It requires no argument to show that the case is different with aliving organism. To live signifies that a connected continuity of acts is effected in which preceding ones prepare the conditions under which later ones occur. There is achain of cause and effects, of course, in what happens with inanimate things. But for living creatures, the chain has a particular cumulative continuity, or else death ensues.

This conception of the mental brings to unity various modes of response jemotional, volitional and intellectual. It is usual to say that there is no fundamental difference among these activities that they are all different phases or aspects of a common action of mind. But Iknow of but one way of making this assertion good: that in which they are seen to be distinctive modes of response to the uncertain. The emotional aspect of responsive behavior is its immediate quality. When we are con- fronted with the precarious, an ebb and flow of emotion marks adisturbance of the even tenor of existence. Emotions are conditioned by the indeterminateness of present situations with respect to their issue. Fear and hope, joy and sorrow, aversion and desire, as perturbations, are qualities of adivided response. They involve concern, solicitude, for what the present situation may become. "Care" signifies two quite different things: fret, worry and anxiety, and cherishing attention to that in whose potentialities we are interested. These two meanings represent different poles of reactive behavior to apresent hav- ing afuture which is ambiguous.

thinking is the actual transition from the problematic to the secure, as far as that is intentionally guided. There is no separate "mind" gifted in and of itself with afaculty of thought jsuch acon- ception of thought ends in postulating the mystery of apower outside of nature and yet able to intervene within it. Thinking is objectively discoverable as that mode of serial responsive behavior to aproblematic situation in which transition to the relatively settled and clear is effected.

The concrete pathologies of belief, its failures and perver- sions, whether of defect or excess, spring from failure to ob- serve and adhere to the principle that knowledge is the com- pleted resolution of the inherently indeterminate or doubtful. The commonest fallacy is to suppose that since the state of doubt is accompanied by afeeling of uncertainty, knowledge arises when this feeling gives way to one of assurance. Think- ing then ceases to be an effort to effect change in the objective situation and is replaced by various devices which generate a change in feeling or "consciousness." Tendency to premature judgment, jumping at conclusions, excessive love of simplicity, making over of evidence to suit desire, taking the familiar for the clear, etc., all spring from confusing the feeling of certi- tude with acertified situation. Thought hastens toward the settled and is only too likely to force the pace. The natural man dislikes the dis-ease which accompanies the doubtful and is ready to take almost any means to end it. Uncertainty is got rid of by fair means or foul. Long exposure to danger breeds an overpowering love of security. Love for security, translated into adesire not to be disturbed and unsettled, leads to dogmatism, to acceptance of beliefs upon authority, to in-

Here is where ordinary thinking and thinking that is scrupu- lous diverge from each other. The natural man is impatient with doubt and suspense: he impatiently hurries to be shut of it. Adisciplined mind takes delight in the problematic, and cherishes it until away out is found that approves itself upon examination. The questionable becomes an active questioning, asearch jdesire for the emotion of certitude gives place to quest for the objects by which the obscure and unsettled may be developed into the stable and clear. The scientific attitude may almost be defined as that which is capable of enjoying the doubtful jscientific method is, in one aspect, atechnique for making aproductive use of doubt by converting it into operations of definite inquiry.

If it is objected that such an examination itself involves mind and its organs, the rejoinder is that the theory we have advanced is self-applying. Its only "assumption" is that something is done, done in the ordinary external sense of that word, and that this doing has consequences. We define mind and its organs in terms of this doing and its results, just as we define or frame ideas of stars, acids, and digestive tissues in terms of their behavior. If it be urged that we do not know whether the re- sults of the directed operations are really knowledge or not, the answer is the objection assumes that we have some kind

hile traditional theories regard mind as an intruder from without into the natural development, or evolution, of organic structures, or else in the interest of natural continuity feel compelled to deny that mental behavior has any differential features, the theory that organic responses have mental quality in the degree in which they deal with the uncertain recognizes both continuity and difference. It can, in principle if not as yet in detail, give agenetic account of the development of mental and intellectual processes. There is neither asudden jump from the merely organic to the intellectual, nor is there complete assimilation of the latter to primitive modes of the former.

According to this doctrine, we are doubtful, puzzled, con- fused, undecided jobjects are complete, assured, fixed. It is not easy to reconcile this notion with the fact that in order to relieve our doubt, to "make up" our minds, we have to modify in some way, in imaginative or overt experimentation, the situation in which uncertainty is experienced.

there are few if any cases of trouble into which apersonal factor of desire or aversion does not enter as a productive cause. But the idea that this causal factor can be changed by purely direct means, by an exercise of "will" or "thought" is illusory. Achange of desire and purpose can it- self be effected only indirectly, by achange in one's actual relation to environment. This change implies definite acts.

The occurrence of problematic and unsettled situations is due to the charac- teristic union of the discrete or individual and the continuous or relational.

There are situations in which self-enclosed, discrete, indi- vidualized characters dominate. They constitute the subject- matter of esthetic experience} and every experience is esthetic in as far as it is final or arouses no search for some other ex- perience. When this complete quality is conspicuous the experi- ence is denominated esthetic

ll experienced objects have adouble status. They are individualized, consummatory, whether in the way of enjoyment or of suffering. They are also involved in a continuity of interactions and changes, and hence are causes and potential means of later experiences. Because of this dual capacity, they become problematic. Immediately and directly they are just what they are} but as transitions to and possi- bilities of later experiences they are uncertain. There is a divided response} part of the organic activity is directed to them for what they immediately are, and part to them as transitive means of other experienced objects. We react to them both as finalities and in preparatory ways, and the two reactions do not harmonize. This two-fold character of experienced objects is the source of their problematic character.

"tertiary"qualities (as they have been happily termed by Mr. Santayana), those which, in psychological analysis, we call affectional and emotional, are as much products of the doings of nature as are color, sound, pressure, perceived size and distance.

If existence were either com- pletely necessary or completely contingent, there would be neither comedy nor tragedy in life, nor need of the will to live. The significance of morals and politics, of the arts both technical and fine, of religion and of science itself as inquiry and discovery, all have their source and meaning in the union in Nature of the settled and the unsettled, the stable and the hazardous. Apart from this union, there are no such things as "ends," either as consummations or as those ends-in-view we call purposes. There is only ablock universe, either something ended and admitting of no change, or else apredestined march of events. There is no such thing as fulfillment where there is no risk of failure, and no defeat where there is no promise of possible achievement. Any philosophy that in its quest for certainty ignores the reality of the uncertain in the ongoing processes of nature denies the conditions out of which it arises. The attempt to include all that is doubtful within the fixed grasp of that which is theoretically certain is committed to insincerity and evasion, and in consequence will have the stigmata of internal contradiction. Every such philosophy is marked at some point by adivision of its subject-matter into the truly real and the merely apparent, asubject and an object, aphysical and a mental, an ideal and an actual, that have nothing to do with one another, save in some mode which is so mysterious as to create an insoluble problem. Action is the means by which aproblematic situation is re- solved. Such is the net outcome of the method of science. There is nothing extraordinary about this conclusion. Interac- tion is auniversal trait of natural existence. "Action" is the name given to one mode of this interaction, namely, that named from the standpoint of an organism.

The distinction once made between theory and practice has meaning as adistinction between two kinds of action: blind and intelligent. Intelligence is aquality of some acts, those which are directed} and directed action is an achievement not an original endowment. The history of human progress is the story of the transformation of acts which, like the interactions of inanimate things, take place unknowingly to actions qualified by understanding of what they are about} from actions con- trolled by external conditions to actions having guidance through their intent: their insight into their own conse- quences. Instruction, information, knowledge, is the only way in which this property of intelligence comes to qualify acts originally blind

telligent action is purposive action; if it is anatural oc- currence, coming into being under complex but specifiable con- ditions of organic and social interaction, then purpose like in- telligence is within nature jit is a"category" having objective standing and validity. It has this status in adirect way through the place and operation of human art within the natural scene j for distinctively human conduct can be interpreted and under- stood only in terms of purpose. Purpose is the dominant cate- gory of anything truly denominated history, whether in its enacting or in the writing of it, since action which is distinctively human is marked by intent.

We are free in the degree* in which we act knowing what we are about. The identification of freedom with "freedom of will" locates contingency in the wrong place. Contingency of will would mean that uncertainty was uncer- tainly dealt with jit would be aresort to chance for adecision. The business of "will" is to be resolute; that is, to resolve, under the guidance of thought, the indeterminateness of un- certain situations. Choice wavers and is brought to ahead arbitrarily only when circumstances compel action and yet we have no intelligent clew as to how to act. The doctrine of "free-will" is adesperate attempt to es- cape from the consequences of the doctrine of fixed and im- mutable objective Being. With dissipation of that dogma, the need for such ameasure of desperation vanishes.

It is not claimed, therefore, that there is no philosophical problem of the relation of physical science to the things of ordinary experience. It is asserted that the problem in the -form in which it has chiefly occupied modern philosophy is an artifi- cial one, due to the continued assumption of premises formed in an earlier period of history and now having no relevancy to the state of physical inquiry. Clearing the ground of this unreal problem, however, only imposes upon philosophy the consid- eration of aproblem which is urgently practical, growing out of the conditions of contemporary life. What revisions and sur- renders of current beliefs about authoritative ends and values are demanded by the method and conclusions of natural science? What possibilities of controlled transformation of the content of present belief and practice in human institutions and associ

Formal analogy suggests that we regard our direct and original experience of things liked and enjoyed as only 'possi- bilities of values to be achieved jthat enjoyment becomes a value when we discover the relations upon which its presence depends. Such acausal and operational definition gives only a conception of avalue, not avalue itself. But the utilization of the conception in action results in an object having secure and significant value.

future in which the thing will continue to serve} it will do. It asserts aconsequence the thing will actively institute; it will do. That it is satisfying is the content of aproposition of fact; that it is satisfactory is ajudgment, an estimate, an appraisal. It denotes an attitude to be taken, that of striving to perpetuate and to make secure.

ithout the introduction of operational thinking, we oscillate between atheory that, in order to saye the objec- tivity of judgments of values, isolates them from experience and nature, and atheory that, in order to save their concrete and human significance, reduces them to mere statements about our own feelings.

Judgments about values are judg- ments about the conditions and the results of experienced ob- jects; judgments about that which should regulate the forma- tion of our desires^ affections and enjoyments.

judgment of the value of an object to be experienced is instrumental to appreciation of it when it is realized. But the notion that every object that happens to satisfy has an equal claim with every other to be avalue is like supposing that every object of perception has the same cognitive force as every other. There is no knowledge without perception} but objects perceived are known only when they are determined as consequences of connective op- erations. There is no value except where there is satisfaction, but there have to be certain conditions fulfilled to transform a satisfaction into avalue.

Amoral law, like alaw in physics, is not something to swear by and stick to at all hazards; it is a formula of the way to respond when specified conditions pre- sent themselves. Its soundness and pertinence are tested by what happens when it is acted upon. Its claim or authority rests finally upon the imperativeness of the situation that has to be dealt with, not upon its own intrinsic nature as any tool achieves dignity in the measure of needs served by it.

PostGIS 3.4.0dev Manual (whole document)

Pulmonary embolism in patients with severe COPD exacerbation (September 2023)

Pulmonary embolism (PE) is an important potential trigger for COPD exacerbation. In a recent multicenter study, 1580 patients with COPD who were admitted to the hospital with acute worsening of respiratory symptoms were all screened for PE with computed tomography pulmonary angiogram within 48 hours of admission [1]. PE was identified in 266 (17 percent), with 166 patients (11 percent) having PE involving the main or lobar pulmonary arteries. Purulent sputum production decreased the odds of PE by 60 percent. We suggest obtaining imaging for PE in patients requiring admission for COPD exacerbation who do not have evidence of other triggers (eg, infection or heart failure).

The Global Initiative for Chronic Obstructive Lung Disease (GOLD), a report produced by the National Heart, Lung, and Blood Institute (NHLBI) and the World Health Organization (WHO), defines an exacerbation of chronic obstructive pulmonary disease (COPD) as "an event characterized by dyspnea and/or cough and sputum that worsens over ≤14 days, which may be accompanied by tachypnea and/or tachycardia, and is often associated with increased local and systemic inflammation caused by airway infection, pollution, or other insult to the airways" [1,2]. This generally includes an acute change in one or more of the following cardinal symptoms:

● Cough increases in frequency and severity

● Sputum production increases in volume and/or changes character

● Dyspnea increases

The clinical manifestations and evaluation of patients with exacerbations of COPD are discussed in detail here. A table to assist with emergency management of severe acute exacerbations of COPD is provided (table 1).

Pseudomonas infection risk factors: Broad spectrum antibiotic use in the past 3 months; chronic colonization or previous isolation of Pseudomonas aeruginosa from sputum (particularly in past 12 months); very severe underlying COPD (FE_V1 <30% predicted); chronic systemic glucocorticoid use.

Among patients with COPD, the frequency of exacerbation varies with the severity of disease, and some patients have more frequent exacerbations than others independent of other measures of disease severity [1,3].

In a separate survey of more than 1000 patients, 21 percent of those who reported a COPD exacerbation required hospitalization [7].

Risk factors — According to observational studies, the risk of developing an exacerbation of COPD correlates with the following features [8-13]:

● Advanced age

● Productive cough

● Longer duration of COPD

● History of antibiotic therapy

● COPD-related hospitalization within the previous year

● Chronic mucous hypersecretion

● Peripheral blood eosinophil count >0.3⁴ x 10⁹ cells/L (340 cells/microL)

● Theophylline therapy

● Presence of one or more comorbidities (eg, ischemic heart disease, heart failure, or diabetes mellitus)

The Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines suggest using primarily history of exacerbations, history of hospitalization for exacerbation, and symptoms to assess the exacerbation risk [1].

Worsening airflow obstruction remains associated with an increasing prevalence of exacerbations, hospitalization, and death [16]. It is used as a component of the BODE index, a prognostic tool that can also be used to assess therapeutic response to medications, pulmonary rehabilitation therapy, and other interventions [17].

A similar observation was made in a case-control study that assessed the presence of GERD symptoms and frequency of COPD exacerbations in 80 patients with COPD. The presence of GERD symptoms was associated with an increased risk of COPD exacerbations (RR 6.55, 95% CI 1.86-23.11) [18]. However, in an observational study of 638 patients with stable COPD, therapy with proton pump inhibitors did not decrease the risk for severe exacerbations [20].

Gastroesophageal reflux disease (GERD) may be an additional risk factor for COPD exacerbations [18,19].

Left ventricular diastolic dysfunction at baseline is associated with a higher frequency of hospitalization for COPD exacerbation [21]. Diastolic dysfunction is common in patients with COPD, likely due to both comorbid vascular mechanisms (eg, hypertension, coronary artery disease, systemic inflammation) as well as metabolic and structural consequences of COPD (eg, lung hyperinflation, chronic hypoxia, and hypercapnia) [22,23]. Many of these contributing factors worsen during an exacerbation and may lead to diastolic decompensation, followed by pulmonary congestion and bronchial hyper-reactivity [24]. High heart rates, whether due to breathlessness, anxiety, or atrial arrhythmias, further exacerbate this pathophysiology.

Secondary pulmonary hypertension may be an additional risk factor for COPD exacerbations, possibly as an indicator of disease severity. In a follow-up to the ECLIPSE study, chest computed tomography scans were used to compute the ratio of the diameter of the pulmonary artery to the diameter of the aorta (PA:A ratio) [25]. In the study, a PA:A ratio greater than 1 was an independent risk factor for a future severe exacerbation (OR 3.44, 95% CI 2.78-4.25). Notably, a PA:A ratio >1 suggests the presence of pulmonary hypertension, although it does not clarify the cause of pulmonary hypertension (eg, hypoxemia due to COPD or other lung disease, left heart failure, sleep apnea). The clinical usefulness of this observation in terms of treatment decisions is unclear.

Triggers — Respiratory infections, most commonly viral (eg, rhinovirus) or bacterial, are estimated to trigger approximately 70 percent of COPD exacerbations (table 2) [1,26]; atypical bacteria are a relatively uncommon cause [27,28]. The remaining 30 percent are due to environmental pollution, pulmonary embolism, or have an unknown etiology [1,29-31].

COPD exacerbations have been associated with exposure to poor outdoor air quality, such as higher levels of ozone, carbon monoxide, particulate matter (up to 10 microns), and nitrogen dioxide [32,33]. Increased ambient levels of fine particulate matter (≤2.5 microns, aka PM_2.5) are associated with an increase in hospitalization and mortality in COPD [34]. In a trial of 116 patients with COPD and exposure to poor air quality at home (PM_2.5 >10 mcg/m³), use of indoor air filters versus sham air filters resulted in a dose-dependent improvement in respiratory symptoms and risk of moderate exacerbations [35].

As dyspnea and cough are nonspecific symptoms, COPD exacerbations of unknown etiology may be triggered or caused by other medical conditions, such as myocardial ischemia, heart failure, aspiration, or pulmonary embolism [1,36].

Although the frequency of pulmonary embolism among patients hospitalized with an exacerbation of COPD varies across studies [38-41], a systematic review prior to this multicenter study showed a similar pooled prevalence of 23 percent when all patients were evaluated by CTPA within 48 hours of hospital admission (seven studies, 999 patients) [42]. An important limitation of these studies is their inability to determine whether the pulmonary embolism is the cause of the COPD exacerbation, a result of the COPD exacerbation, or a mere bystander.

The clinical manifestations of exacerbations of COPD range from a mild increase in dyspnea, cough that is productive or nonproductive to respiratory failure with acute respiratory acidosis and/or hypoxemia.

Medical history — By definition, patients present with the acute onset or worsening of respiratory symptoms, such as dyspnea, cough, and/or sputum production, over several hours to days [1,43]. These symptoms should be characterized further in terms of the following features:

● Time course of the symptoms

● Comparison to baseline level of symptoms

● Severity of respiratory compromise (eg, dyspnea at rest, dyspnea climbing stairs, dyspnea severity using a visual analog [1-10] scale)

● Delineation of sputum characteristics (eg, amount, color, purulence, blood)

● Use of home oxygen now or in the past

Associated features that might suggest an alternate diagnosis or comorbidity include:

● Constitutional symptoms (eg, fever, chills, night sweats)

● Chest pain, chest pressure, peripheral edema, or palpitations

● Risk factors for coronary disease

● Risk factors for thromboembolic disease

● Upper respiratory symptoms that might suggest a viral respiratory infection or exposure to anyone with influenza

Patients should be asked if they currently smoke cigarettes or use vaping products. The past history of exacerbations should be ascertained: number of prior exacerbations, courses of systemic glucocorticoids, antibiotic therapy in the preceding three months, prior exacerbations requiring hospitalization or ventilatory support, and response to therapy of previous exacerbations.

Attention should also be paid to other physical findings, such as fever, hypotension, bibasilar fine crackles and peripheral edema, which might suggest a comorbidity or alternate diagnosis.

We do not use procalcitonin or C-reactive protein to determine the need for antibiotics in COPD exacerbations, as study results do not clearly and consistently demonstrate that either assay adds value to clinical judgment alone. (See "Evaluation for infection in exacerbations of chronic obstructive pulmonary disease", section on 'Procalcitonin and C-reactive protein'.)

In one multicenter study of nearly 1600 patients hospitalized for COPD exacerbation who were assessed with CT pulmonary angiogram, the rates of pulmonary embolism based on low, moderate, or high probability Wells criteria scores were 7, 38, and 74 percent, respectively [37].

Purulent sputum production decreased the odds of venous thromboembolism by approximately 60 percent.

Given this prevalence rate, we suggest obtaining imaging for pulmonary embolism (typically CT pulmonary angiogram) in patients with severe symptoms who do not have evidence of other triggers (eg, infection or heart failure).

Risk factors for infection with Pseudomonas aeruginosa in patients with acute COPD exacerbations

Chronic colonization or previous isolation of Pseudomonas aeruginosa from sputum (particularly in the past 12 months)

Very severe COPD (FEV1 <30% predicted)

Bronchiectasis on chest imaging

Broad-spectrum antibiotic use within the past 3 months

Chronic systemic glucocorticoid use

Sputum Gram stain and culture are not obtained for most exacerbations of COPD. However, sputum Gram stain and culture can be useful in patients at risk for a poor outcome or increased risk of infection with Pseudomonas (table 3 and table 4).

Influenza testing is appropriate during influenza season or in patients with features of influenza (eg, acute onset of fever, myalgias, coryza during an influenza outbreak).

Respiratory virus panel in selected patients – The majority of COPD exacerbations are caused by viral infections, predominantly adenovirus. While not necessary in most patients, PCR diagnostic panels can detect multiple respiratory viruses simultaneously (eg, influenza, adenovirus, parainfluenza virus, respiratory syncytial virus, human metapneumovirus, coronavirus, and rhinovirus). These studies are more frequently obtained in patients with community-acquired pneumonia, and the exact indications for their use in COPD exacerbations are not clear.

Severity of exacerbation — The classification of exacerbation severity proposed by an international commission and adopted by the Global Initiative for Chronic Obstructive Lung Disease (GOLD) is based on symptoms, vital signs, and arterial blood gas (ABG) and c-reactive protein values (if obtained) (figure 1) [1,17]:

● Mild – Dyspnea <5 on a visual analog (1-10) scale (VAS); respiratory rate <24 breaths per minute; heart rate <95 beats per minute; resting SaO2 ≥92 percent breathing ambient air or the patient's usual oxygen prescription and change in saturation ≤3 percent from baseline (if known); CRP<10 mg/L (if obtained). Treatment with short-acting bronchodilators is often sufficient for mild exacerbations.

● Moderate – Three out of five of the following: Dyspnea ≥5 on VAS; respiratory rate ≥24 breaths per minute, heart rate ≥95 beats per minute; resting SaO2 <92 percent breathing ambient air or the patient's usual oxygen prescription and/or change in saturation >3 percent from baseline (if known); CRP ≥10 mg/L (if obtained). Treatment of moderate exacerbations generally includes short-acting bronchodilators plus antibiotics and/or oral glucocorticoids.

● Severe – Meets moderate criteria combined with hypercapnia and acidosis on ABG (PaCO2 >45 mmHg and pH <7.35). Treatment of severe exacerbations includes short-acting bronchodilators, antibiotics, and oral or intravenous glucocorticoids. Severe exacerbations may be associated with respiratory failure and require noninvasive or invasive ventilation.

Patients with COPD who present to the hospital with acute worsening of dyspnea should be evaluated for potential alternative diagnoses, such as heart failure, cardiac arrhythmia, pneumonia, pulmonary embolism, and pneumothorax [1,44,45].

A chest radiograph will differentiate among several of these possibilities (eg, heart failure, pneumonia, pneumothorax); a clear chest radiograph may be a clue to pulmonary embolism, especially when dyspnea and hypoxemia are more prominent than cough or sputum production.

The importance of considering these alternate diagnoses was illustrated in an autopsy study of 43 patients with COPD who died within 24 hours of admission for a COPD exacerbation [44]. The primary causes of death were heart failure, pneumonia, pulmonary thromboembolism, and COPD in 37, 28, 21, and 14 percent, respectively.

Cardiac arrhythmias – Cardiac arrhythmias, such as atrial fibrillation, are frequent in patients with COPD, and may be a trigger or consequence of COPD exacerbation [1]. A bedside electrocardiogram can be diagnostic.

Pneumothorax – COPD is a risk factor for pneumothorax. Worsening dyspnea can be due to either a COPD exacerbation or pneumothorax, but acute pleuritic chest pain would be more suggestive of pneumothorax while increased volume of sputum and sputum purulence would suggest a COPD exacerbation.

Pulmonary embolism – The sudden onset of symptoms such as dyspnea, pleuritic chest pain, tachypnea, and cough may be caused by a pulmonary embolism. The suspicion for pulmonary embolism rises in the absence of purulent sputum production, history of an upper respiratory infection, or pneumothorax [36-42,46,47].

Examination of the language of dyspnea suggests that this symptom represents a number of qualitatively distinct sensations, and that the words utilized by patients to describe their breathing discomfort may provide insight into the underlying pathophysiology of the disease.

Dyspnea is a term used to characterize a subjective experience of breathing discomfort that is comprised of qualitatively distinct sensations that vary in intensity. The experience derives from interactions among multiple physiological, psychological, social, and environmental factors, and may induce secondary physiological and behavioral responses.

Dyspnea is considered acute when it develops over hours to days and chronic when it occurs for more than four to eight weeks

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Respiratory system dyspnea includes discomfort related to disorders of the central controller, the ventilatory pump, and the gas exchanger (table 1), while cardiovascular system dyspnea includes cardiac diseases (eg, acute ischemia, systolic dysfunction, valvular disorders, pericardial diseases), as well as anemia and deconditioning; the latter two lead to dyspnea via altered delivery and/or utilization of oxygen (figure 1).

The "respiratory controller" determines the rate and depth of breathing via efferent signals sent to the ventilatory muscles. Factors that stimulate the respiratory centers in the brainstem lead to increased ventilation and breathing discomfort in a variety of settings; these often are secondary to derangements in other parts of the system, such as hypoxia or hypercapnia due to ventilation/perfusion mismatching in the gas exchanger, or stimulation of pulmonary receptors as occurs with interstitial inflammation or edema.

In addition, drugs such as aspirin (at a toxic dose) or progesterone and conditions such as pregnancy or diabetic ketoacidosis can produce dyspnea through central effects independent of problems in the ventilatory pump or gas exchanger. Typically, dyspnea associated with stimulation of the respiratory controller is described as a sensation of "air hunger" or an "urge or need to breathe" [2-4].

To some degree, the breathing pattern may also reflect what are presumed to be attempts by the controller to reduce breathing discomfort. Thus, patients with severe airflow obstruction generally adapt a relatively slow, deep breathing pattern to minimize the pleural pressures needed to overcome airways resistance to generate adequate flow. Alternatively, patients with interstitial fibrosis or kyphoscoliosis and reduced lung or chest wall compliance have a characteristic rapid, shallow breathing pattern which minimizes the work needed to expand the thorax.

When the respiratory controller is stimulated (eg, by exercise), airflow obstruction may heighten the sensation of air hunger. The increase in respiratory rate during exercise in the setting of expiratory flow limitation can lead to exercise-induced air-trapping, a process known as dynamic hyperinflation.

For patients with restrictive lung disease, the adoption of breathing patterns with either an increase or decrease in tidal volume from their average resting tidal volume results in increased dyspnea [5]. Breathing with a rapid, shallow pattern, the patient experiences an increase in the ratio of dead space to tidal volume (since anatomic dead space is relatively fixed), which leads to a need for greater total ventilation (hence, the increase in respiratory rate); this adds to respiratory work-load and may contribute to the development of hypercapnia. In contrast, an increase in tidal volume requires a significant increase in respiratory work due to the stiffness of the lung. Since most patients with restrictive lung disease tend to use a rapid, shallow breathing pattern, we conclude that this pattern, relative to alternatives, must produce less dyspnea.

The most common derangements of the ventilatory pump result in a sense of increased "work of breathing" [6-10].

Neuromuscular weakness (eg, myasthenia gravis, Guillain-Barré syndrome) leads to a condition in which the patient must exert near maximal inspiratory effort to produce a normal negative pleural pressure [11].

When hyperinflation results in an end-inspiratory volume that approximates total lung capacity, patients often complain of an inability to get a deeper satisfying breath [ 9]. A sensation of chest tightness may also be present in patients in whom acute bronchoconstriction is the cause of airflow obstruction [6,7,12,13].

Most of the common cardiopulmonary disorders leading to dyspnea are associated with some derangement of the gas exchanger due either to destruction of the diffusing membrane (eg, emphysema, pulmonary fibrosis) or the addition of fluid or inflammatory material into the lungs such that ventilation to alveoli is reduced regionally. To a lesser degree, the distance for diffusion may also contribute in these conditions or in the greatly dilated pulmonary capillaries seen in some patients with hepatopulmonary syndrome.

Diseases affecting the gas exchanger are typically characterized by hypoxemia, either at rest or with exercise, and by chronic hypercapnia in more severe cases. These gas exchange abnormalities stimulate the respiratory centers in the brainstem and lead to a sensation of "air hunger" or an increased urge to breathe.

When heart failure causes an increase in pulmonary venous pressure, it can lead to dyspnea either by producing hypoxemia or by stimulating pulmonary vascular and/or interstitial receptors (eg, unmyelinated J-receptors, also called C-fibers).

Deconditioning – Individuals usually complain of respiratory discomfort when they engage in vigorous physical activity, even in the presence of a normal cardiovascular and respiratory system and normal hematocrit. More fit individuals experience less discomfort for any given workload; cardiovascular fitness is determined by the ability of the heart to increase maximal cardiac output and by the ability of the peripheral muscles to utilize oxygen efficiently for aerobic metabolism.

Dyspnea due to deconditioning is typically described as "heavy breathing" or a sense of "breathing more" [8], and with careful questioning, one can determine that the patient is actually limited by fatigue or leg discomfort rather than breathing discomfort.

While clinical history is often insufficient to make a secure diagnosis, it provides guidance in narrowing the diagnostic possibilities and selecting diagnostic tests. In one study of 85 patients presenting to a pulmonary unit with a complaint of chronic dyspnea, the initial impression of the etiology of dyspnea based upon the patient history alone was correct in 66 percent of cases [19].

The temporal pattern of breathlessness and association with certain triggers can provide important clues. Breathing discomfort arising over the course of minutes to hours is due to a relatively limited number of conditions (table 2).

Causes of acute dyspnea

Cardiovascular system

Acute myocardial ischemia

Heart failure

Cardiac tamponade

Respiratory system

Bronchospasm

Pulmonary embolism

Pneumothorax

Pulmonary infection - bronchitis, pneumonia

Upper airway obstruction - aspiration, anaphylaxis

Chronic exertional dyspnea and paroxysmal nocturnal dyspnea (PND) are both associated with heart failure, although nocturnal dyspnea is more specific to heart failure. Asthma is also associated with exertional and nocturnal dyspnea, but unlike PND does not usually improve with sitting or standing

Orthopnea, the development of or worsening of dyspnea in the supine position, is also associated with heart failure and increased pulmonary capillary pressure due to the increased venous return to the heart in this position. Central obesity, however, with a large protuberant abdomen, may also lead to orthopnea; increased intra-abdominal pressure associated with large abdominal girth impairs movement of the diaphragm during inhalation; in addition, intrapleural pressure increases, which may lead to narrowing or closure of small airways at the bases of the lungs, and can worsen gas exchange and hypoxemia. Finally, patients with inspiratory muscle weakness may also complain of orthopnea due to the increased work of breathing associated with moving the diaphragm against high intra-abdominal pressure.

Bendopnea, the worsening of dyspnea when leaning forward, is described in patients with decompensated heart failure [20] but may also be seen in patients with central obesity, particularly when the patient attempts to tie their shoes from the sitting position.

Dyspnea that is not exacerbated by exertion is more often due to a functional or perceptual problem than to cardiopulmonary disease.

Intermittent dyspnea – Intermittent dyspnea associated with cold air or animal dander exposure suggests asthma; work-related dyspnea may suggest occupational asthma; and dyspnea following upper respiratory infections may be due to asthma or chronic obstructive pulmonary disease (COPD).

In addition to asthma, intermittent symptoms that resolve completely between episodes can be seen with recurrent aspiration; recurrent pulmonary emboli and heart failure can also wax and wane, but generally are characterized by a baseline level of dysfunction. The presence of specific, reproducible inciting events such as exercise or cold air exposure is common with airways hyperreactivity.

The rapidity with which symptoms develop during exercise can also provide useful diagnostic information. For example, patients who develop shortness of breath and wheezing after walking 50 to 100 feet often have acute elevations in pulmonary capillary wedge pressure (usually due to cardiac diastolic dysfunction) or pulmonary hypertension. In contrast, symptoms of exercise-induced asthma usually are precipitated by more intense activity, beginning three minutes into exercise, peaking within 10 to 15 minutes, and resolving by 60 minutes. (See "Exercise-induced bronchoconstriction".)

Respiratory muscle weakness generally leads to gradually progressive dyspnea, sometimes with an acute worsening at a time of illness, particularly a respiratory infection.

It is important to note that scales like the mMRC do not measure dyspnea directly; rather, they assess the intensity of exercise that provokes dyspnea and, indirectly, the degree of disability resulting from dyspnea. Routine assessment of dyspnea in hospitalized patients is feasible [27] and severity of dyspnea on admission to the hospital predicts increased mortality [28].

Associated symptoms such as cough, sputum production, nasal congestion, chest pain, peripheral edema, Raynaud phenomenon, joint swelling, and muscle weakness can help identify areas for further investigation.

While some clusters of phrases were common to a number of disease categories (eg, increased work or effort of breathing was found with COPD, asthma, and neuromuscular disease), each disease had a relatively unique set of clusters associated with it.

The sensation of "air hunger" has been associated with acute bronchoconstriction and hyperinflation in asthma and COPD, heart failure, pulmonary embolism, and restricted thoracic motion, as well as acute hypercapnia from any cause [3,4,32].

Acute bronchoconstriction leads to a series of sensations as the degree of obstruction worsens, from "chest tightness" to an increased "effort to breathe" to a sensation of "air hunger" [6-9,12,13]. The sensation of "tightness" appears to be independent of the work of breathing [33]. Attention to the use of verbal descriptors of dyspnea may help the clinician avoid underestimation of the severity of airflow limitation when objective measurements of lung function are not possible.

Report of "increased work of breathing" is associated with COPD, moderate to severe asthma, myopathy, and pulmonary fibrosis.

Patients with COPD and dynamic hyperinflation sometimes complain of a sensation of "unsatisfying breaths" or a sense that they "cannot get a deep breath" [9].

A sensation of rapid, shallow breathing may correspond to interstitial lung disease or reduced chest wall compliance.

Heart failure is also associated with a sensation of "suffocation" [6].

A sense of heavy breathing is typical of deconditioning.

The absence of cigarette smoking argues strongly against a diagnosis of COPD, unless the patient has a history of tuberculosis or use of biomass cooking fuels. In one study, a history of smoking cigarettes had a positive predictive value for COPD of 0.4; COPD is uncommon among patients who have never smoked or have smoked less than 10 pack years [42].

Physical examination — A complete physical examination is essential. In particular, the focus should be directed at the presence or absence of stridor, wheezing, crackles, tachycardia, arrhythmia, heart murmurs, gallop, peripheral edema, muscle weakness, dysphonia, and evidence of rheumatic disease. However, the absence of physical findings tends to have a greater negative predictive value, than the positive predictive value of any identified signs [19].

Clubbing is associated with several causes of dyspnea, including bronchiectasis, idiopathic pulmonary fibrosis, lung cancer, and pediatric cyanotic heart disease, but not asthma, COPD, or adult-onset hypoxemia.

Jugular venous distention indicates elevated R-sided filling pressures that suggest heart failure, valvular disease, or pulmonary hypertension.

Decreased or distant heart sounds may suggest a pericardial effusion but may also be due to obesity or hyperinflation from emphysema.

Abdominal rounding, the protruding of the central abdomen with diminished transverse diameter during exhalation, has been associated with acute heart failure [47].

Zur Verarbeitung der Datenworte beherrschen Prozessoren eine Menge von Maschinenbefehlen, die man Maschinenbefehlssatz nennt. Im Maschinenbefehlssatz sind Maschinenbefehle enthalten, um Datenworte z.B. zu addieren, zu multiplizieren oder bitweise logische Verknüpfungen zwischen Datenworten durchzuführen. Weil Maschinenbefehle nur aus Nullen und Ein- sen bestehen, was für Menschen wenig anschaulich ist, bezeichnet man sie mit einem Buch- stabenkürzel, dem Mnemonic. Für den Addierbefehl nimmt man beispielsweise häufig den Mnemonic ADD. Programme, die man unter Verwendung von Mnemonics darstellt, nennt man Assembler-Programme. Der Prozessor wird mit einem Takt betrieben, der die Dauer eines Verarbeitungsschrittes be- stimmt. Die Taktfrequenz ist einer von mehreren wesentlichen Faktoren, die die Rechenleis- tung oder Performance eines Computers bestimmen, also welche Rechenarbeit er in einer gewissen Zeitspanne erbringen kann. Ein weiterer Einflussfaktor sind Maßnahmen zur Paral- lelisierung der Abläufe, z.B. das Pipelining, so dass während eines Takts an mehreren Opera- tionen gleichzeitig gearbeitet wird. Bei vielen Prozessoren, den so genannten CISC-Prozessoren, steht hinter jedem Maschinen- befehl ein Mikroprogramm aus noch einfacheren Befehlen, den Mikrobefehlen. Es ist fest in den Prozessor einprogrammiert. In diesem Fall benötigt ein Maschinenbefehl mehrere Takte. RISC-Prozessoren dagegen führen idealerweise jeden Maschinenbefehl in nur einem Takt aus und besitzen keine Mikroprogrammierung. Für einen Programmierer sind Maschinenprogramme häufig auf einer zu niedrigen Ebene an- gesiedelt, um damit größere Anwendungen zu entwickeln. Für solche Zwecke eignen sich an- dere Programmiersprachen wie C, C++ oder Java besser. Manche Programmiersprachen sind Allzwecksprachen, andere sind auf bestimmte Einsatzbereiche zugeschnitten, z.B. auf Web- Anwendungen oder Simulationen.

Clues to the need for an urgent evaluation include heart rate >120 beats/minute, respiratory rate >30 breaths/minute, pulse oxygen saturation (SpO₂) <90 percent, use of accessory respiratory muscles, difficulty speaking in full sentences (which may be a sign of reduced vital capacity or very high drive to breathe), stridor, asymmetric breath sounds or percussion, diffuse crackles, diaphoresis, and cyanosis.

The five most common causes of chronic dyspnea are the following:

● Asthma (see 'Respiratory' above)

● Chronic obstructive pulmonary disease (COPD) (see 'Respiratory' above)

● Interstitial lung disease (see 'Respiratory' above)

● Myocardial dysfunction (see 'Cardiovascular' above)

● Obesity/deconditioning (see 'Cardiovascular' above)

24 bit = 24 b = 3 B = 3 Byte = 3 Bytes.

Üblicherweise verwendet man zur Angabe physikalischer Größen die so genannten SI-Ein- heiten (Système international d’unités), wie sie u.a. in der Norm ISO/IEC 80000-1 festgelegt sind. Darunter fallen Meter, Kilogramm, Sekunde, usw. Die Einheiten können mit SI-Präfixen wie Milli oder Kilo versehen werden, die Zehnerpotenzen darstellen.

...

Typical ECG findings

● Stage 1, seen in the first hours to days, is characterized by widespread ST elevation (typically concave up) with reciprocal ST depression in leads aVR and V1 (waveform 1). There is also frequently an atrial current of injury, reflected by elevation of the PR segment in lead aVR and depression of the PR segment in other limb leads and in the left chest leads, primarily V5 and V6. Thus, the PR and ST segments typically change in opposite directions. PR segment deviation, which is highly specific, though less sensitive, is frequently overlooked.

The TP segment is recommended as the baseline for comparison when measuring both PR and ST segment changes in acute pericarditis.

● Stage 2, typically seen in the first week, is characterized by normalization of the ST and PR segments.

● Stage 3 is characterized by the development of diffuse T-wave inversions, generally after the ST segments have become isoelectric. It is typically seen in the subacute phase, and its duration is not well documented and likely highly variable.

● Stage 4 is represented by normalization of the ECG. It can occur directly from stage 1 in self-limited cases or with prompt response to medical therapy.

1.2 Einheiten Wie erwähnt, sind grundlegende Einheiten in der Informatik das Bit und das Byte. Bei Grö- ßenangaben verwendet man nach IEC 60027-2 als Einheitenzeichen „bit“ für das Bit. Man findet aber auch gelegentlich ein „b“, wie es in IEEE 1541 festgelegt wurde. Für das Byte findet man nach IEC 60027-2 das Einheitenzeichen „B“. Es wird aber auch öfter in Form von „Byte“ oder „Bytes“ ausgeschrieben. Somit könnte man Angaben wie die folgen- den finden:

In patients with a clinically compatible syndrome, the demonstration of an infiltrate on chest imaging is generally sufficient to establish an initial working diagnosis and start empiric therapy. However, this combination of findings is ultimately nonspecific and is shared among many cardiopulmonary disorders. Thus, it is important to remain attentive to the possibility of an alternate diagnosis as a patient's course evolves.

For most patients with suspected CAP, we obtain posteroanterior and lateral chest radiographs. Radiographic findings consistent with the diagnosis of CAP include lobar consolidations (image 1A-B), interstitial infiltrates (image 2A-C), and/or cavitations (image 3). Although certain radiographic features suggest specific causes of pneumonia (eg, lobar consolidations suggest infection with typical bacterial pathogens), radiographic appearance alone cannot reliably differentiate among etiologies.

In selected cases, it is reasonable to make a clinical diagnosis without chest imaging in otherwise healthy patients with highly compatible syndromes (eg, acute onset, fever, cough, and signs of consolidation on physical examination) and lack of concern for other causes. However, clinical features alone have limited diagnostic accuracy, thus, we typically reserve this option for circumstances in which chest radiography cannot be easily obtained and the patient can be closely followed.

When CAP is suspected based on clinical features despite a negative chest radiograph, we obtain computed tomography (CT) of the chest in selected patients. These patients include immunocompromised patients, who may not mount strong inflammatory responses and thus have negative chest radiographs, as well as patients with known exposures to epidemic pathogens that cause pneumonia (eg, severe acute respiratory syndrome coronavirus 2, Legionella spp).

Obtaining a CT scan is also reasonable when CAP is suspected but the clinical presentation is atypical or the patient has possible alternative explanations for their syndrome (eg, chronic obstructive pulmonary disease exacerbation, pulmonary edema, atelectasis, etc).

Because there is no direct evidence to suggest that CT scanning improves outcomes for most patients and cost is high, we do not routinely obtain CT scans when evaluating patients for CAP.

In all cases, the initial diagnosis of CAP should be considered a working diagnosis. A substantial portion of patients initially diagnosed with CAP are ultimately found to have alternate diagnoses [4], therefore, findings that further support or refute the initial diagnoses should continue to be sought as the patient’s course progresses.

Classically, CAP is characterized by acute onset fever, cough (with or without sputum production), and shortness of breath [5-7]. In some cases, pleuritic chest pain may also be present

Less common symptoms include gastrointestinal complaints (eg, nausea, vomiting, diarrhea, abdominal pain), loss of appetite, and mental status changes.

Tachycardia, tachypnea, hypoxemia, or increased work of breathing may be present on physical examination. Crackles (rales) and rhonchi may be heard on chest auscultation, along with other signs of consolidation (eg, tactile fremitus, egophony, dullness to percussion).

As infection progresses, the dominant clinical picture may be of sepsis and/or respiratory distress.

In patients with advanced age or impaired immune systems, presenting symptoms can be subtle. For example, fever may be absent in older patients and mental status changes may be the sole presenting symptom [ 8,9].

In another study evaluating >28,000 adults presenting to primary care with an acute cough attributed to a lower respiratory tract infection, independent predictors of radiographic-confirmed pneumonia included fever, tachycardia, crackles on chest auscultation, and oxygen saturation <95 percent [7]. However, the positive predictive value (PPV) of all four variables combined was estimated to be only 67 percent.

One cohort study of >2800 adults with acute cough estimates the PPV of clinical judgement at 57 percent [11].

Similarly, there are no signs or symptoms that reliably distinguish among the many infectious causes of pneumonia (eg, viral versus bacterial or between different bacterial causes) [12]. However, the presence of certain features may raise the index of suspicion for particular pathogens (table 2).

CAP is a common working diagnosis and is on the differential diagnosis of patients presenting with respiratory tract infections, patients with cough and abnormal chest imaging, and patients with sepsis. Because CAP is common and its symptoms overlap with many other cardiopulmonary disorders, it is frequently overdiagnosed [4]. In one cohort study, approximately 17 percent of patients hospitalized with CAP were ultimately found to have a different diagnosis. The most common alternate diagnoses included heart failure, malignancy, and pulmonary infarct or fibrosis [4].

Acute bronchitis – Acute bronchitis is an infection that primarily involves the large airways (bronchi) but not the alveoli or pulmonary parenchyma. Prolonged cough, typically following an upper respiratory tract infection, is the most common symptom of acute bronchitis. In contrast to pneumonia, acute bronchitis is less likely to present with abnormal vital signs (pulse >100/minute, respiratory rate >24 breaths/minute, temperature >38°C [100.4°F], or oxygen saturation <95 percent) (figure 1). Mental status changes and/or other signs of systemic infection are typically absent. Signs of consolidation (rales, egophony, or tactile fremitus) should be absent on chest auscultation.

Influenza – Influenza is characterized by acute onset fever and cough, often accompanied by pronounced systemic symptoms including chills, rigors, myalgias, and/or arthralgias. Pneumonia complicates a minority of cases and may be primary (caused by influenza virus itself) or secondary, caused by bacterial respiratory pathogens (most often streptococci or Staphylococcus aureus).

Upper respiratory tract infection (URI) – URIs are commonly characterized by fever and cough, but in contrast to pneumonia lack signs of consolidation on chest auscultation. While the presence of rhinorrhea and pharyngitis favor the diagnosis URI over pneumonia, URIs sometimes precede or co-occur with CAP [11]

Exacerbations of chronic pulmonary diseases are frequently triggered by viral or bacterial infection or colonization of the respiratory tract mucosa. In most cases, infection does not extend beyond the mucosa, however, pneumonia can complicate these disorders. Higher fever, adventitious breath sounds on chest auscultation (eg, focal rales/crackles or rhonchi), and impaired oxygenation suggest pneumonia and generally indicate need for chest imaging.