on 04-Sep-2017 (Mon)

Características Básicas. Los servicios que TCP proporciona para la comunicación entre aplicaciones, pueden caracterizarse en los cuatro puntos siguientes: - Cuando dos aplicaciones transfieren grandes cantidades de datos, podemos pensar en esos datos como secuencias de octetos. El módulo TCP del nodo destino entrega las secuencias de octetos que recibe a la capa superior, tal y como la capa superior del nodo origen se la entregó a TCP. - Circuito virtual: TCP proporciona un servicio de comunicación orientado a la conexión. De esta forma TCP suministra un servicio fiable de transporte de datos de extremo a extremo. Entre otros servicios, TCP proporciona el establecimiento de la conexión, la transferencia de información y la desconexión. - Buffers de datos. Las aplicaciones transfieren sus datos en forma de cadenas de octetos al módulo TCP. Este agrupa o divide las cadenas de octetos recibidas en función del tamaño del paquete que puede transmitir. Para hacer más eficiente la transmisión y reducir el tráfico en la red, es necesario que el módulo TCP disponga de buffers donde acumular la información. Obviamente estos buffers pueden retrasar la transmisión de determinada información. Cuando es necesario realizar la transmisión inmediata de algunos datos, puede solicitarse a TCP que transmita dicha información (push), aún cuando su tamaño sea menor que el que proporciona mayor rendimiento. - Conexión full-duplex: |TCP/IP permite que las conexiones establecidas entre dos nodos sean concurrentes o simultáneas en ambos sentidos. Las aplicaciones ven este servicio como dos canales de transmisión (uno de entrada y otro de salida), sin interacción aparente.

Código: Especifica el propósito y el contenido del segmento. Los seis bits de este campo tienen el siguiente significado cuando su valor es 1: • URG: Puntero datos urgentes válido. • ACK: Número de confirmación válido. • PSH: Solicitud de push. • RST: Reinicialización de la conexión. • SYN: Sincronización de números de secuencia. • FIN : El emisor ha enviado todos los datos.

His adversary, al-Farazdaq, also used obscenity as a lampooning tool. He is crying on the dungheaps of the abandoned campsites, while his mother, on the tips of the slaves' penises, is going up and down.

They brought l:fiqqa, 31 having stuffed her perineum, while a hireling, saddler of beasts, was singing to make the she-ass go. She stopped to scold me but I said to her, 'On your knees, 185 l:fiqqa, you and your collected works (i.e. lampoons on me) will be underneath!' And I bared my prick to her. She cowered, just as a she-ass in heat cowers. She found someone with a hard-on, who had changed into easy clothes; and someone who does scandalous things will change into easy clothes. And I left your mother, Jarir, as if she were, kneeling, for the people a well-trodden road. The penis-knobs of the infatuated ones on her arse

were like travellers coming to the wells of (the villages of) al-Nibaj and Thaytal. I::Iiqqa, I have never heard about a man with two testicles who got pregnant, except al-Maragha's son (i.e. Jarir). He drank the sperm and in his belly there grew an uncircumcised woman whose clitoris is itching at the end.

Positioning allows the best exposure of surgical site and the least compromise in both physiological functions and mechanical stresses in joints and other body parts

A Lawyer focused on nerve injuries

Potential for corneal abrasion is always present when mask ventilating patients.

Aortocaval Syndrome • Pressure of baby and uterus decreases blood return hence hypotension

Aortocaval Syndrome • Pressure of baby and uterus decreases blood return hence hypotension • Put a wedge under mom’s right hip

Aortocaval Syndrome starts at 18-24 weeks

Keep hanging badges away from the patients face when hand ventilating

Treatment of Corneal Abrasions • Patch • Topical Numbing • Topical Antibiotics • Fluorscein Eye Stain/Wood Lamp • Sew there eyes shut • Optho Consult

Sunderland Classification system divides nerve injuries into five categories

First-degree injury is A reversible local conduction block at the site of the injury. This injury does not require surgical intervention and usually will recover within a matter hours to a few weeks

A second-degree injury is a loss of continuity of the axons or electrical wires within the nerve. If 2nd degree is confirmed through pre-operative nerve testing, surgical intervention is usually not required

Third-degree injury: There is damage to the axons and their supporting structures within the nerve. In this case, recovery is variable.

Third-degree injury: There is damage to the axons and their supporting structures within the nerve. In this case, recovery is variable. Intra-operative nerve conduction studies are often able to help predict outcome and need for simple cleaning of the nerve (neurolysis) or a more extensive repair with grafting.

Fourth-degree injury: In this case, there is damage to the axons and the surrounding tissues sufficient to create scarring that prevents nerve regeneration. Intra-operative electrical testing confirms that no electrical energy can be passed along the neural pathways in this injured nerve. Surgical intervention with nerve grafting is necessary to repair the damage.

Fifth-degree injury: These injuries are usually found in laceration or severe stretch injuries. The nerve is divided into two. The only way to repair a fifth-degree injury is through surgery.

What causes nerve injuries ? •Laceration •Focal contusion (Gunshot wounds) •Stretch/traction injury, Position related •Compression, possible position related •Hypotension •Misapplication of devices

• Drug injection injury • Electrical injury • Crnas • Prolonged flexion at elbow • Diabetes • Vitamin deficiencies • Alcoholism • Cancer • Hereditary Neuropathy

ngenital anomalies • Types of surgery, i.e. cardiac sternotomy • Prolonged Lithotomy, greater than 4 hours, i.e. Robotic • Body habitus • Obese • Body ‘folds’ • Increased pressure under folds • Non-obese • Lack of padding

Types of Nerve Injuries I. Pressure II. Friction III. Shearing forces

Pressure, friction, and shearing forces account for most problems and injuries due to faulty positioning of the surgical patient

Pressure • A mechanical force, can lead to obstruction of blood vessels, compression of nerves and soft tissue leads to inhibition of blood flow

Pressure • Tissues covering bony prominences are usually thin and easily damaged by pressure leading to tissue hypoxia

Pressure and rubbing are two external forces responsible for most injuries to bony prominences

Pathophysiology of Pressure •

When the patient is turned there is a hyperemic reaction: Vasodilation Release of blood elements into interstitial space Edema

Pathology of Pressure • End capillary pressure averages 32 mmHg

• This is the currently accepted external threshold pressure • Beyond this pressure small vessels collapse and thrombose • Occluded blood flow and oxygen deprivation occurs • Toxic metabolites then accumulate which leads to increased capillary permeability, edema, cell death, and pressure sore formation

Friction Injury to skin occurs when skin moves across coarse surfaces such as linen on the operating room table, transport litter, towels, or bath blankets used in positioning the patient.

Friction leads to: Abrasion, tearing, and inflammation

Operating room devices lead to injury: Safety belt Masks, straps Excessive rubbing on the skin by instruments

Friction is most commonly associated with superficial injuries manifesting as Blisters and abrasions

Shearing occurs when the skin remains stationary and the underlying tissue shifts

Shearing Forces In the operating room, shearing injuries can occur when an anesthetized patient is repositioned or when a body part is moved without repositioning the patients entire body

Sliding or dragging a patient or limb, without supporting all body parts leads to shearing

Transection • A cross section along a long axis. • Division by cutting across

New Role As CRNA •Guardian Angel

More Concerns and Considerations

• Patent airway • Optimal surgical exposure • Adequate respiratory excursion and air exchange • Adequate circulation • No excessive pressure to superficial nerves • Eyes protected from abrasions, pressure, fluids • Extremities supported • Head adequately supported • Minimal muscle strain or hyperextension • Anectine Myalgia’s or Nondepolarizer

The key issue in surgical patient positioning is prevention of injury

Planning and intervening ensures correct patient positioning

A first step is recognition of risk related events to vulnerable patient populations

You should be checking a patients position at least every 15 minutes, arms fall off bed, heads fall off pillow

Safety strap? Two needed for obese patient's

Pt too heavy for bed, each bed has a limit, some beds won’t move if pt is too heavy, find out the bed’s tolerance

Recommendations for Positioning of the Brachial Plexus •Limit arm abduction to 90 degrees or less •Axillary role placed for lateral position to minimize compression of humeral head into axilla •In prone position with arms above head, maintain abduction and anterior flexion of the arm to 90 degrees or less

After ulnar, brachial plexus is 2nd most common injury

Two fixation points, vertebrae, fascia of axilla

Two moveable points, clavicle and humeru

Nerve stretch from head turn opposite and arm abducted more than 90 degrees

Ulnar Neuropathy Anatomical Considerations Tubercle of the coronoid process is 1.5 times larger in men and boys Males are also more likely to have a thicker cubital tunnel retinaculum Females have a much thicker layer of subcutaneous fat between the skin and the ulnar nerve at the cubital tunnel and medial aspect of the coronoid process

Ulnar Nerve Damage Manifestations: ◦ Inability to abduct or oppose the fifth finger, diminish sensation over both surfaces of the fourth and fifth finger with resultant atrophy ◦ Claw Hand

A Simple, Quick, and Easy Test an Axillary Block To quickly assess the block, perform the “push-pull-pinch-pinch” test. This test can be done in less than a minute. It can identify “missed” nerves allowing time to formulate an alternative plan of anesthesia (i.e. supplementation or general anesthesia).

Ask the patient to extend or “push” their forearm against light resistance. This tests the radial nerve.

Ask the patient to flex or “pull” the arm towards the nose against light resistance. This will test th e musculocutaneous nerve

A Simple, Quick, and Easy Test an Axillary Block To quickly assess the block, perform the “push-pull-pinch-pinch” test. This test can be done in less than a minute. It can identify “missed” nerves allowing time to formulate an alternative plan of anesthesia (i.e. supplementation or general anesthesia). Ask the patient to extend or “push” their forearm against light resistance. This tests the radial nerve. Ask the patient to flex or “pull” the arm towards the nose against light resistance. This will test th e musculocutaneous nerve.

Pinch the hypothenar aspect of the hand (i.e. small finger). This will test the ulnar nerve.

Pinch the thenar aspect of the hand (i.e. on the palmar surface of the hand). This will test the median nerve.

Radial Nerve Damage ◦ Manifested by: ◦ Wrist drop ◦ Inability to extend the metocarpals ◦ Weakness of abduction of the thumb

Ulnar Nerve Injury Etiology ◦ Complex Most common peripheral nerve injury ◦ 0.5% incidence in general population ◦ 35% incidence in cardiac surgical patient ◦ Why: ◦ Runs very superficial at the elbow ◦ Little tissue or fat to protect the nerve from external compression

Postural hypotension: Frequent complication of supine or head elevated position Treatment of choice includes: Fluids Vasopressors Avoid head up position until patient is CV stable

Prolonged compression of the hair follicles can occur causes ischemic changes to the blood vessels. Hypothermia and hypotension enhance the process Hair regrowth is usually complete within twelve weeks Generally occurs between the 3 rd and 28 th postoperative day Permanent hair loss can occur

Pressure Alopecia First week: Swelling Edema Crusting Ulceration

Permanent hair loss can occur Occipito-parietal pain and tenderness within 24 hours postop

Anti-Alopecia Recommendations • Reposition head every 30 minutes reduced the incidence of alopecia from 14% to 1% in a prospective study in cardiac surgical patients. • Remember that when you lift the head forward, your ETT is pushed forward and if the patient is light, they will gag, it can also change the position of your LMA, always consider listening with your stethoscope after a position change

Contoured Supine Position Commonly referred to as the ‘lawn chair’ position offers the patient an anatomically feasible position because of reduced lumbar sacral strain

So you have a nerve injury, now what? •Neurological consult •Nerve conduction and electromyographic studies •Nerve injuries sometimes take 18-21 days to manifest •Testing promptly can indicate whether the injury is old or new, acute or chronic •Recovery is slow •Deficits may be irreversible

Early neurology consultation EMG Determine level of lesion Sensory deficits are usually transient If longer than 5 days, refer to neurology for follow up No reliable treatment for peripheral nerve injury except supportive care Physical therapy is useful to prevent: Muscle atrophy Joint contractures Surgical decompression is used only when neuroma formation hampers recovery

Gather what you think you'll need, you get points for being independent and thoughtful • Blankets • Tape • Foam • Head pillow, Gummy pillow • Arm boards • Blue or green towels. • Prep for tape

• Arms straps • Axillary roll • Eye lube • Skin prep • Special arm holders • Pillows to elevate legs • To name but a few • No one remembers everything, write stuff down, have a flight plan

Initial Assessment •Comorbidities, diabetes, neuropathy, stroke, arthritis •Previous nerve injuries, stroke, trauma, surgery •Previous surgeries, wounds, chest tubes, vac dressings •ROM limitations/Any broken bones or dislocations

• Steroid skin/Super thin and friable • Anti coagulated, you can get a hematoma from just lying there • Labs, are they on Tpn, how is their nutrition • What nerve groups do I have to be worried about with the positioning •Pacemaker/AICD/, can I go prone? How long will the surgery be? •Accessed or nonaccessed Chemotherapy port •Old with no subcutaneous fat, skin tear waiting to happen

How would you attempt to decrease Peak • pressures during mechanical ventilation in the • paralyzed anesthetized patient? • Hint: deepen anesthetic, muscle relaxation, • decrease Vt and increase Rate, change I:E ratio • from 1:2 to 1:1.5. • Consider Pressure Control ventilation due to its • decelerating waveform

The supine or dorsal recumbent position should place the patients cervical, thoracic and lumbar vertebrae in a straight line. horizontal