ABSITE CRITICAL CARE EXAM 2024- 2025, Exams of Nursing

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ABSITE CRITICAL CARE EXAM 2024-

2025 WITH ACTUAL CORRECT

QUESTIONS AND VERIFIED

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All of the following are potent cardiac inotrope except

• Digoxin.
• Dopamine.
• Amrinone.
• Norepinephrine.

Digoxin. (Digoxin is only a minimally effective cardiac inotrope. In fact, its usefulness in congestive heart failure may be due to factors other than its very mild inotropic effect. It certainly has no role as an inotrope in the acutely failing heart. )

Hypoxic pulmonary vasoconstriction is worsened by

acidosis

Three days following completion debridement for Fournier's gangrene, a patient remains septic, requiring vasopressor therapy. Corticosteroid therapy should be considered because:

Relative adrenal insufficiency is suspected. (A high index of suspicion should be maintained for relative adrenal insufficiency in septic patients who are vasopressor dependent.)

increased oxygen delivery with exercise

• Improved ventilation-perfusion matching.
• Increased extraction ratio.

• Decreased functional residual capacity.
• Rightward shift of the oxyhemoglobin dissociation curve. (With exercise, metabolically active tissues result in increased temperature, 2-3 DPG levels and Pco, shifting the oxyhemoglobin dissociation curve to the right thereby facilitating off-loading of oxygen. Cardiac output rather than ventilation is the limiting factor in oxygen delivery to tissues. Increased oxygen extraction from hemoglobin therefore occurs until anaerobic threshold occurs. Transit time through the alveolar-capillary unit is decreased with exercise, thereby increasing the amount of blood (hemoglobin) exposed to the alveolus for gas exchange. Chemoreceptor stimulation affects sympathetic output to increase cardiac output and arterial pressure, which by minimizing zone one improves V̇/Q̇ matching. With exercise, afferents from joints, tendons, and peripheral chemoreceptors influence the respiratory center increasing minute ventilation by increasing both the rate and depth of breathing. This latter occurrence minimizes FRC, thereby making more alveoli available for respiration.)

pulmonary blood flow

• Pulmonary vascular resistance is lowest at end-tidal volume.
• Hypoxia causes pulmonary vasoconstriction.
• Hypercapnia causes pulmonary vasoconstriction.
• Pulmonary vascular resistance is equally distributed among the arteries, capillaries, and veins.
• Passive dispensability and recruitment of the pulmonary capillary bed is responsible for constant, low pressures with increasing cardiac output. (Hypercapnia and hypoxia, as well as other humoral factors, cause pulmonary vasoconstriction. Unlike the systemic vascular bed where varying organ demands require different degrees of perfusion, which is accomplished by variably regulating resistances, the pulmonary vascular resistance is evenly distributed. This is accomplished through a highly compliant circuit with relatively meager smooth muscle resistance that is passively responsive to changes in pressure and flow, distending open vessels and recruiting closed ones. Distended alveoli compress and stretch surrounding pulmonary capillaries thereby increasing resistance in accordance with Poiseuille Law; therefore, the least such distension of alveoli occurs at functional residual capacity or end-tidal volume.)

irreversible shock

In the setting of "damage control" laparotomy, not only should ostomies not be matured, but it is even acceptable to leave packing inside the abdomen if it has effectively obtained hemostasis. (In the setting of "damage control" surgery, patients are dangerously close to the threshold of irreversible shock. They are coagulopathic, hypothermic, and acidotic. Consequently, surgery should be terminated as soon as active sources of exsanguination are controlled. The patient should be returned to the intensive care unit for rewarming and correction of their other metabolic derangements. Should they survive long enough to complete resuscitation, they are then returned to the operating room for definitive treatment of their injuries. )

Chronic anticoagulation is required for patients with

Mechanical valves. (All mechanical valves require full anticoagulation with warfarin. Some have tried to utilize

mechanical valves without full anticoagulation, but with an unacceptably high embolization and thrombosis risk. )

polymorphonuclear cells (PMNs)

• PMNs are nonspecific in their host defense functions.
• Experimental evidence has demonstrated that blocking the interaction of PMN and endothelial adhesion molecules reduces organ injury.
• They migrate through the endothelial barrier by a process called diapedesis.

Anaerobic glycolysis occurs as a result of

Inadequate oxygen delivery to the cell

Which of the following mediators are likely to dominate the anti-inflammatory late stages of injury?

Interleukin-10 (IL-10). (IL-10 is an anti-inflammatory mediator produced by the host in an attempt to bring the organism back to homeostasis after surviving the early stages of injury. It acts to inhibit the release of a host of proinflammatory mediators, and infusion of IL-10 has been shown to improve survival in septic animals. Its potential role in causing late incidents of MOF and sepsis through relative immunosuppression by overproduction is being investigated. )

Class I hemorrhage

loss of 0-15%

**- In the absence of complications, only minimal tachycardia is seen.

• Usually, no changes in BP, pulse pressure, or respiratory rate occur.
• A delay in capillary refill of longer than 3 seconds corresponds to a volume loss of approximately 10%.**

Class II hemorrhage

loss of 15-30%

**- Clinical symptoms include tachycardia (rate >100 beats per minute), tachypnea, decrease in pulse pressure, cool clammy skin, delayed capillary refill, and slight anxiety.

• The decrease in pulse pressure is a result of increased catecholamine levels, which causes an increase in peripheral vascular resistance and a subsequent increase in the diastolic BP.**

Class III hemorrhage

loss of 30-40%

**- By this point, patients usually have marked tachypnea and tachycardia, decreased systolic BP, oliguria, and significant changes in mental status, such as confusion or agitation.

• In patients without other injuries or fluid losses, 30-40% is the smallest amount of blood loss that consistently causes a decrease in systolic BP.
• Most of these patients require blood transfusions, but the decision to administer blood should be based on the initial response to fluids.**

Class IV hemorrhage

loss of >40%

**- Symptoms include the following: marked tachycardia, decreased systolic BP, narrowed pulse pressure (or immeasurable diastolic pressure), markedly decreased (or no) urinary output, depressed mental status (or loss of consciousness), and cold and pale skin.

• This amount of hemorrhage is immediately life threatening.**

lung volumes and pulmonary function testing

• Quantitative perfusion scans utilize radiolabeled albumin to act as a surrogate for functioning (ventilated) lung. Insofar as its relative distribution relies on perfusion, this presupposes that ventilation matches perfusion and that hypoxic, nonventilated lung restricts perfusion by means of HPV.
• The ratio FEV:FVC is usually normal in restrictive disease, although the individual lung volumes are reduced and compliance curves are shifted to the right.
• MMFR reflects the volume of flow within the second and third quarters of the first second of forced expiration when the effects of transpleural pressure and obstructive flow dynamics are maximal within compromised airways. It is the most sensitive indicator of obstructive parenchymal disease.
• The RER is the proportion of oxygen consumption to the production of carbon dioxide at the cellular level during aerobic respiration. At anaerobic threshold during stress testing, oxygen consumption is maximized and carbon dioxide production continues to increase via the anaerobic glycolytic pathway such that the RER markedly increases.

mandatory minute volume-controlled ventilation

It requires greater than calculated tidal volume delivery. (Because volume delivery is preset, excess volume above that calculated as necessary for the individual must be delivered to account for the circuitry dead space. Also because the volume is preset, it is not dependent on thoracic or pulmonary compliance or airway pressures for complete delivery. Pressure controlled ventilation uses airway pressure limits to cease delivery of tidal volume when certain peak airway pressures are met as a means of minimizing barotrauma. Because volume- controlled ventilation has no such limits, high tidal volumes may persistently raise mean airway pressures contributing to barotrauma. Other permutations of volume-controlled ventilation rely on patient effort and participation, therefore are usually associated with the development of lower airway pressures than MMV. )

regarding lateral decubitus, one-lung ventilation during anesthesia for thoracotomy

• Compliance is decreased.
• Physiologic shunting is increased.
• Intravenous anesthetics are preferred to inhalation anesthetics.
• Functional residual capacity is decreased. (With upside lung collapse, no increase in dead-space ventilation occurs but there is a substantial increase in physiological shunting of nonventilated, perfused lung. This is partially offset by hypoxic pulmonary vasoconstriction which is nullified with inhalation anesthetics. With anesthesia and lateral decubitus positioning paralysis of the diaphragm and its subsequent upward displacement, mediastinal shifting downward by gravity and restriction of chest wall movement of the downside lung result in marked decrease in FRC and downside lung and chest wall compliance. )

Use of epinephrine in most shock states is limited by all of the following side effects

• Act as a potent renal artery vasoconstrictor.
• Increase plasma glucose, lactate, and free fatty acids.
• Cause peripheral vasodilatation at low levels.
• Increase cardiac oxygen consumption.
• Cause arrhythmias.

Flow-volume loops are qualitatively useful in differentiating restrictive from obstructive lung disease.

• Bronchospastic pulmonary disease results in a concave effort-independent limb of the expiratory flow loop.
• Effort-independent expiratory airflow does not depend on a transpulmonary pressure gradient for continued exhalation.
• Fixed obstruction of large airways is characterized by a truncated inspiratory and expiratory flow loop.
• Intrathoracic variable obstruction is characterized by a truncated expiratory flow loop. (Tracheomalacia represents a form of intrathoracic variable obstruction where the inspiratory flow loop is normal as a result of negative transpleural pressure, which allows the nonsupported trachea to remain open; truncation of the expiratory flow loop occurs when positive transpleural pressure collapses the nonsupported trachea. Smooth muscle contraction of small airways acutely diminishes the effort-independent flow achievable by passive elastic recoil of the lung at equal pressure point resulting in a concavity of expiratory flow loop. Fixed obstructions of the airway, as with stricture or tumor, limit both mid-inspiratory and expiratory flow, in accordance with Poiseuille Law, as transpleural pressure increases.)

therapies for cardiogenic shock

The use of thrombolytic agents in the setting of acute myocardial infarction shows a clear benefit when given within 12 hours of the onset of symptoms.

Factors which could increase coronary blood flow

Bradycardia. (Bradycardia increases the time that the heart is in diastole, thereby increasing the time for coronary perfusion to occur)

Aortic valvular stenosis in adults

Is associated with a short life expectancy once symptoms are evident (less than a 50% 2-year survival.)

oxygen molecules within an alveolar-capillary unit

Net diffusion of oxygen and carbon dioxide through the alveolar-capillary barrier is proportionately equivalent. (Although carbon dioxide is substantially more diffusible through the alveolar-capillary barrier than oxygen, a higher initial diffusion gradient exists for oxygen, which by combining with hemoglobin is able to maintain this gradient advantage such that approximately equivalent amounts of oxygen and carbon dioxide are eventually exchanged. Chemical binding with hemoglobin takes oxygen out of

solution such that its partial pressure is reduced and the gradient for diffusion is increased. Oxygen transport is perfusion limited in that once hemoglobin is fully saturated, continued exposure to the alveolus as a result of increase in transit time results in no further net uptake by hemoglobin. Among other factors, the oxyhemoglobin dissociation curve is shifted to the right with increases in temperature, decreasing Hgb's affinity for oxygen and facilitating off-loading. Increasing partial pressure of a particular gas within the alveolus diminishes the partial pressures of other gases within that alveolus; therefore increased carbon dioxide concentrations within the alveolus limits available oxygen for diffusion.)

A 47-year old male has recently undergone CT-guided percutaneous drainage of an intra-abdominal abscess secondary to diverticulitis. Post drainage the patient becomes septic. All of the following concerning administration of activated protein C are correct

• Activated protein C inhibits factor Va.
• Activated protein C inhibits neutrophil-endothelial adhesion.
• Activated protein C inhibits plasminogen activator inhibitor-1.

normal pericardium

It may serve as a barrier to infection. (Serving as a barrier to infection may be the evolutionary advantage gained by animals that had a strong pericardium. It may also serve as a barrier to the spread of tumor, which is why intrapericardial resection for a pneumonectomy may offer an advantage in terms of resection.)

Sources of error in calculating cardiac output using thermodilution techniques

• Inaccurate measurement of the amount of indicator injected.
• Variability in speed of injection.
• Variability in location of the position of the pulmonary artery catheter. (It is not necessary to accurately measure the indicator temperature when using thermodilution techniques. The sensor at the tip of the PA catheter can detect the passage of the fluid bolus as it is at a temperature other than that of the blood. )

acid-base regulation within the body

• Bicarbonate ion is increased in respiratory acidosis.
• Volume contraction metabolic alkalosis is a result of bicarbonate retention by the kidney.
• Alveolar ventilation primarily influences the direction of equilibrium of the bicarbonate buffer system.
• Correction of metabolic alkalosis involves both volume expansion and potassium replacement. (The bicarbonate buffer system is substantially enhanced by the buffering capacity of hemoglobin; specifically the histidine residue accepts the H created by dissociation, leaving the bicarbonate ion to combine with fixed acid. The alveolar concentration of carbon dioxide is the rate limiting step in the availability of bicarbonate ions to buffer fixed acids. Increased minute ventilation lowers alveolar partial pressure of carbon dioxide and thus plasma partial pressure, shifting the bicarbonate buffer equation to the left allowing for dissociation and creation of bicarbonate. With loss of sodium through diuresis, vomiting or diarrhea, volume contraction induces the renin-aldosterone system to retain Na at the expense of H and K associated with Cl; bicarbonate is retained for electrical neutrality leading to a metabolic alkalosis. Volume replacement to inhibit the rennin-aldosterone system and K

replacement to cause exchange of intracellular H to buffer bicarbonate is necessary to reverse this. With respiratory acidosis, bicarbonate ion is increased due to hemoglobin-histidine buffering of the dissociated H.)

acquired mitral stenosis

The left ventricular myocardium is usually not dilated (because the left ventricle is underfilled as a result of the valvular abnormality)

Proper use of a pulmonary artery catheter

Estimation of LVEDP with pulmonary catheter wedge pressure.

During the course of splenectomy for trauma, a patient`s systolic blood pressure drops acutely from 120 mm Hg to 70 mm Hg and the left hemidiaphragm appears to bulge into the abdomen. The most likely cause is

left tension pneumothorax

In aortic dissection, key principles in the initial preoperative care include

• Establishing the diagnosis with certainty using aortography, echocardiography, or CT scanning.
• Controlling blood pressure with vasodilators.
• Controlling pain using narcotics and sedatives. (The top priority is to repair the intra pericardial part of the aorta. Often, peripheral ischemia will go away once the flow is redirected in the upper aorta. If these ischemic areas are not treated adequately, then supplemental procedures can be undertaken after the ascending aorta is repaired. Complications of the dissection in the ascending portion of the aorta will kill the patient in the short term.)

the classic three-bottle water seal drainage system for chest tubes

The level of immersion of the central tube of the third bottle regulates intrapleural pressure. (The central tube of the third bottle equilibrates atmospheric pressure with the unregulated negative pressure applied by a wall suction to determine intrapleural pressure by the amount of immersion below the water surface. Because the water seal occurs at the second bottle, its purpose being solely that, pleural drainage to the first bottle does not affect the intrapleural pressure. This three-bottle system is a closed system such that massive air leaks that cannot be expeditiously evacuated to the wall suction because of insufficient negative pressure as the result of inadequate depth of the central pressure regulating tube of the third bottle will accumulate within the pleural space as a progressive, and potentially a tension, pneumothorax.)

Early adaptations to high altitude that optimize oxygen delivery include

• An increase in auto-PEEP.
• Hypoxia-induced bronchiolar constriction.
• Hypoxemic regulation of peripheral arterial chemoreceptors.
• Optimization of zone one ventilation-perfusion matching.

In treating low cardiac output after cardiac surgery, all of the following are commonly used treatment modalities

• Volume administration.
• Vasodilators.
• Catecholamines.
• Pacing.

Continuous positive airway pressure (CPAP) is least effective

• Obstructive sleep apnea.
• Pulmonary edema.
• Atelectasis.
• Obesity hypoventilation syndrome. (Continuous positive airway pressure decreases functional residual capacity and recruits more collapsed alveoli for ventilation as well as placing more lung parenchyma on the steep portion of the compliance curve, making ventilation easier. Therefore it is effective in atelectasis and obesity where zone three is suboptimal. It is also effective in stenting open the pharynx, which has a tendency to collapse from atony and extrinsic fatty compression with obstructive sleep apnea. The increased alveolar pressure tends to oppose the hydrostatic forces of the interstitium with pulmonary edema, making this an effective therapeutic modality. However, emphysematous lung already has substantially increased lung volumes and hyperinflation on the plateau of the compliance curve making CPAP much less effective under these circumstances. )

Following resuscitation of a patient in septic shock secondary to urosepsis, base deficit and serum lactate remain abnormally high. Considerations for further management should be

• Reassessment of hemoglobin concentration.
• Placement of a pulmonary artery catheter.
• Further fluid resuscitation with crystalloid solution.
• Optimization of DO.

emphysema

• Increased minute ventilation.
• Increased airway resistance.
• Early (increased) closing volume.
• Adverse length-tension relationship of diaphragm.
• Decreased chest wall compliance. (Destruction of alveoli and septae results in increased diameter of coalesced alveoli. This causes lower intra-alveolar pressure in accordance with the Law of Laplace such that earlier closure of terminal bronchioles by transpleural pressure occurs at higher volumes. The diaphragm is forced downward with hyperinflation, decreasing the curvature and, thereby, increasing its length. The result is an adverse effect in its length-tension relationship. Airway resistance is inversely proportional to the fourth power of the radius of terminal bronchioles and to their overall cross-sectional area. Destruction of these terminal bronchioles and early collapse of the remaining increases airway resistance. Minute ventilation as well as inspiratory flow rate must be increased in order to overcome auto-PEEP created by early closing volume before passive airflow can occur. With air trapping, there is increased residual volume and functional residual capacity that decreases chest wall compliance.)

pericardial tamponade

It causes a loss of ventricular compliance.

Compliance of the lung is defined as

Volume produced by a unit pressure change

Significant diffusion block at the alveolar-capillary membrane may be assessed by using either the diffusing capacity for carbon monoxide or exercise arterial blood gases. Considering this, which one of the following is true?

Desaturation with exercise is a result of increased physiologic shunting. (Because hemoglobin is normally saturated with oxygen within the first 0.25 seconds of transit time through the alveolar-capillary unit, hypoxemia occurring after exercise suggests alveolar-capillary block in that decreased transit time of blood through the alveolus eliminates the reserve required for equilibration and results in physiological shunting of incompletely saturated hemoglobin. Carbon monoxide binds with hemoglobin but, unlike oxygen, it does so irreversibly such that its partial pressure gradient remains constant. Its diffusion coefficient is also lower than that of oxygen such that its gradient for diffusion remains constant and reflective of physical restrictions to its diffusion. Therefore it is said to be diffusion limited. )

You are consulted on a patient in the ICU who suffers from chronic alcoholism. The patient presents to the emergency room with shortness of breath and guaiac positive stool. The patient's BP is 75 mm Hg, cardiac index is 1.8 L/min/m, and pcwp is 28 mm Hg. This patient's diagnosis is most consistent with:

Cardiogenic shock. (Shortness of breath secondary to pulmonary edema, low cardiac index, and elevated pcwp are all consistent with cardiogenic shock.)

A newborn infant is noted to have persistent cyanosis and a systolic heart murmur. Administration of 100% inspired oxygen does not reverse the cyanosis. Which one of the following diagnoses is most likely to be incorrect?

• Hypoplastic left heart syndrome.
• Isolated ventricular septal defect.
• Truncus arteriosus.
• Tricuspid atresia.
• Tetralogy of Fallot.

Isolated ventricular septal defect.

pericardial tamponade

It is associated with a "paradoxical pulse." (Which is an increased difference between peak-to-peak systolic pressures with inspiration and expiration.)

A 20-year old man has suffered a gunshot wound to the abdomen. At laparotomy, the patient is found to have a grade IV liver injury with 2.5 L blood loss. The patient is coagulopathic with a temperature of 32.5°C. All of the following should be immediate management considerations:

• Correction of acidosis.
• Administration of fresh frozen plasma and platelets.
• Damage control procedure.
• Patient rewarming. (Until adequate blood and blood products are administered, recombinant factor VII is not indicated. Furthermore, to date, administration of recombinant factor VII has failed to show survival benefit in this patient population.)

EKG evidence of pericarditis

ST-segment elevation in all leads.

The most accurate modality for diagnosis of an abdominal aortic aneurysm

Computed tomography. (Computed tomography is one of the best ways of diagnosing abdominal aortic aneurysms. It can also accurately measure the size, and, with a fair degree of accuracy, tell whether the aneurysm has leaked or not.)

A hemodynamic characteristic of cardiac tamponade

Decreased pulmonary venous return.

ventilation-perfusion relationships

• Zone one is worse perfused than zones two or three.
• Hypovolemia and positive pressure ventilation diminishes zone three.
• Zone three alveoli are more compliant than zones one or two.
• Hypoxic pulmonary vasoconstriction augments ventilation-perfusion matching.
• Regional perfusion is determined predominantly by gravity. (Gravity and pulmonary artery pressure, acting in opposite manner, determine the extent of zone one, which is characterized by larger, less-well ventilated, less compliant, nonperfused alveoli. The opposite characteristics transition downward through zone two to zone three alveoli. At low PA pressures, gravity dominates and zone one is larger. Hypovolemia causes low PA pressure and positive pressure ventilation increases alveolar pressure, both of which tend to increase zone one and decrease the other two zones. In instances where alveoli are not ventilated, as with atelectasis or consolidation, hypoxic pulmonary vasoconstriction reflexively occurs to limit perfusion to these areas and augment V̇/Q̇ matching. )

A previously healthy 24-year old man fell 20 ft from a balcony in the French Quarter, landing on his back. On arrival to the emergency room, he states that he cannot move his arms or legs. On physical examination, his blood pressure is 70/35 mmHg, his heart rate is 58 bpm, his arms and legs are warm and pink, and he smells strongly of alcohol. After infusion of 2 L of crystalloid, his blood pressure is still only 80/40 mm Hg. The only finding on his trauma series is a C6-7 subluxation. The most important next step in his management is:

Investigations designed to detect intra-abdominal injury. (The force imparted by a 20 ft fall onto one's back is significant enough to cause intra-abdominal injuries in addition to a neck subluxation. Refractory hypotension in this setting demands an immediate workup for sources of hemorrhage.)

Which of the following determines arterial oxygen content

Arterial oxygen saturation of Hgb, Hgb, and partial pressure of O dissolved in plasma.

Congenital heart disease with abnormal shunting is associated with a significant risk during surgical operations of any kind for all of the following reasons

• Emboli.
• Arterial desaturation.
• Endocarditis. (Congenital heart disease does not usually cause lethal ventricular arrhythmias. All of the other conditions in this list are associated with congenital heart disease and do increase the risk of operation.)

Pressure and/or flow are decreased by an arterial stenosis that

Reduces diameter by 50%. (An arterial stenosis that on arteriography appears to decrease the diameter by at least 50% decreases the cross-sectional area by 75% is a flow-limiting lesion. )

Which of the following are not appropriate interventions for decreasing the incidence of the systemic inflammatory response (SIRS) and multiple organ failure (MOF)?

• Early fixation of long bone fractures.
• Infusion of anti-TNF-α antibody.
• Early enteral feeding.
• Decreased ventilatory tidal volumes.

Infusion of anti-TNF-α antibody. (Given the role which TNF-α has been shown to play in SIRS and MOF, blocking its actions by an antibody seems intuitively attractive. Further, animal studies gave hope that this modality would improve outcomes from these conditions. Sadly, studies in humans have not borne this out. Other trials with anti-IL-1 and antiendotoxin also failed to show a therapeutic benefit.)

The induction of general anesthesia in a patient with cardiac tamponade

Can interfere with a peripheral vasoconstriction and produce hypotension. (General anesthesia causes peripheral vasodilatation instead of constriction and hypotension may result. The slope will actually worsen if systemic vascular resistance is decreased.)

Measurement of cardiac output using the Fick principle requires

• Arterial oxygen content.
• Mixed venous oxygen content.
• Oxygen consumption.

All are potential causes of cardiogenic shock except:

• Myocardial infarction.
• Pericardial tamponade.
• Tension pneumothorax.
• Cardiac arrhythmias.
• Excessive preload.

Excessive preload. (Excessive preload is typically not a cause of cardiogenic shock, but is a result of cardiogenic shock.)

A 60-year-old man has an arterial PO of 60 mm Hg when the calculated alveolar PO is 94 mm Hg. This difference is most commonly due to

a ventilation-perfusion mismatch

oxygen delivery and consumption

• Under normal circumstances, approximately 20% to 30% of the oxygen delivered to the capillary bed is extracted by the tissues.
• In conditions of decreased delivery of oxygen, tissues are capable of extracting up to 50% to 60% of the oxygen content in the capillary blood.
• When cellular oxygen supply does not meet demand, anaerobic respiration results. (The variables in the equation for the delivery of oxygen are cardiac output, hemoglobin level, oxygen saturation of hemoglobin, and the partial pressure of oxygen dissolved in blood. Increases in the first three variables all yield significant increases in the total amount of oxygen carried by blood. The partial pressure of oxygen is multiplied by a factor of 0.003, however, and therefore has a miniscule contribution to the total oxygen content.)

Dopamine at doses of 5 to 10 μg/kg/min

has a largely inotropic action profile (Dopamine has a dose-dependent action profile. At 3 to 5 μg/kg/min, its actions are largely to increase renal blood flow. At doses of 5 to 10 μg/kg/min, it largely acts to stimulate myocardial β receptors and has an inotropic effect. At doses greater than 10 μg/kg/min, it stimulates α receptors and has a chronotropic effect.)

As oxygen delivery increases on the flat horizontal portion of the oxygen consumption-delivery curve

Oxygen consumption remains the same (On the flat horizontal portion of the oxygen consumption-delivery curve, oxygen delivery meets cellular demand of oxygen; as oxygen delivery increases, oxygen consumption remains the same.)

Most disorganized ventricular arrhythmias (frequent PVCs, ventricular fibrillation) are caused by

Metabolic derangements. (Most disorganized ventricular arrhythmias are caused by some sort of metabolic derangement such as ischemia or magnesium or potassium deficiencies. These abnormalities are not well treated by antiarrhythmic medications.)

The best management for a patient with a posterior knee dislocation

Arteriogram. (The patient may have fairly normal pulses and still have an intimal injury of the popliteal artery that is similar to the intimal disruption that can be seen in aortic isthmus injury.)

the possible etiologies of multiorgan failure

• Anticytokine antibodies have shown therapeutic promise in animal studies.
• Evidence has shown that intestinal mucosa is made permeable by sepsis.
• The "two-hit" hypothesis postulates that after mounting an appropriate response to some physiologic insult, the patient is left with a primed immune system which manifests an exaggerated immune response to a second challenge.
• The early stages after injury actually appear to consist of an immediate proinflammatory state as the organism tries to address the physiologic insult. When properly modulated, this is an appropriate function. When overexpressed, this proinflammatory state leads to the systemic inflammatory response syndrome. Later, anti-inflammatory and immunosuppressive mechanisms are brought into play to bring the organism back to homeostasis. If overmanifested, they can lead to a relative generalized immunosuppression and late incidents of sepsis or multiorgan failure.

compensatory mechanisms in shock

Antidiuretic hormone causes the reabsorption of free water by the kidney and has vasoconstrictive properties. (Antidiuretic hormone is released from the posterior pituitary where it stimulates free water retention by the kidney and acts as a powerful vasoconstrictor.)

A 71-year-old man with colon cancer is in the intensive care unit following a left hemicolectomy. His blood pressure is 72/38 mm Hg, pulse rate is 114/min, respiratory rate is 23/min, and oxygen saturation is 94% on 2 L of oxygen by nasal cannulae. A pulmonary artery catheter shows a central venous pressure of 8 cm H O, a pulmonary artery pressure of 22/8 mm Hg, a pulmonary artery wedge pressure of 6 mm Hg, and a cardiac output of 3.4 L/min. The next step in management should be the intravenous administration of

a fluid bolus

pulmonary artery catheters

Allow accurate approximation of left atrial pressure.

The magnitude of a left-to-right shunt in the presence of an ASD is determined by

Difference in compliance between left and right ventricles. (The blood will tend to fill the more compliant ventricle which will usually be the right, until chronic pulmonary hypertension yields right ventricular hypertrophy.)

Compared to conventional ventilation (endotracheal intubation), noninvasive ventilation (mask, continuous positive airway pressure) is

contraindicated in hemodynamically unstable patients

According to the American College of Chest Physicians/Society of Critical Care Medicine Consensus Conference, which of the following are not part of the diagnostic criteria for sepsis?

Hypotension defined as a systolic blood pressure less than 90 mm Hg. (Sepsis is defined as bacteriologic evidence of infection superimposed on a clinical picture of SIRS. According to the ACCP/SCCM, by definition these patients are hemodynamically stable. If they should

become hemodynamically unstable (defined as a systolic blood pressure <90 mm Hg), the name for the condition changes to "severe sepsis.")

SIRS

• Temperature greater than 38°C or less than 36°C.
• Heart rate greater than 90 bpm.
• Respiratory rate greater than 22 bpm
• White blood cell count greater than 12,000 or less than 4,000 and greater than 10% bands.

abdominal compartment syndrome

Once diagnosed, treatment consists of reopening the abdomen including doing so at the bedside if necessary. (The presence of an abdominal compartment syndrome requires decompression of the abdomen. If the patient is too unstable to be transported to the operating room, the abdomen should be promptly reopened at the bedside.)

carotid bruit

a marker for generalized atherosclerosis (In fact, studies have shown that a carotid bruit is a risk factor for coronary artery disease and future myocardial infarction.)

alveolar ventilation

The alveolar gas equation characterizes the potential for oxygen uptake and carbon dioxide removal. (Tachypnea at a given minute ventilation increases anatomic dead-space ventilation, not alveolar ventilation. Minute ventilation is the volume of gas that is inspired and expired at the nasopharynx and is different than that occurring at the alveolus by the anatomic dead-space volume. Although arterial Pco is proportional to alveolar ventilation, arterial Po is not as it may be affected by physiologic shunting, diffusion block, and so on. The RQ is constant under normal physiological conditions at ± 0.8; however, it may change substantially under conditions such as anaerobic metabolism, overfeeding, and so on. Because the alveolar gas equation characterizes the partial pressures of individual gases within the alveolus, which in turn determine the individual gradients for diffusion, the equation does characterize the potential for oxygen/carbon dioxide exchange. )

the following may constitute the physiological dead space of the respiratory system

• Emphysematous lung.
• Lung involved with a pulmonary embolus.
• Proximal two thirds subsegmental bronchi.
• Zone one alveoli. (The acinus, comprising the last seven generations of dividing subsegmental bronchi, is composed of respiratory bronchioles, alveolar ducts, and alveolar air sacs surrounded by the pulmonary capillary network and constitute the respiratory surface of the lung for gaseous exchange. All bronchi proximal to these constitute conducting airways not involved in gaseous exchange and, therefore, constitute anatomic dead space. Furthermore, nonperfused alveoli, such as may occur due to gravitational effects

with zone one alveoli and with certain pathologic conditions such as emphysema and PTE constitute alveolar dead space. Each of these contributes to the physiological dead space.)

the pericardial space

Allows access to all vessels entering and leaving the heart.

Which of the following tropic states of the heart best describes the compliance of the ventricle (i.e. the ability to accommodate blood return)?

Lusitropism. (This describes the tropic state of the heart relative to compliance, and is a measure of diastolic function.)

Most sustained ventricular arrhythmias are caused by:

Unequal conduction. (Most ventricular arrhythmias are caused by the unequal conduction and repolarization that occurs in areas of scar. Therefore, it is substrate-induced or anatomically based.)

Patients with tetralogy of Fallot

Have a dynamic obstruction to pulmonary outflow tract. (They do have a dynamic obstruction of pulmonary outflow which is somewhat similar to idiopathic hypertrophic subaortic stenosis on the left side of the heart. In the latter, positive inotrope can cause increased thickening of these muscles and thereby cause outflow tract obstruction.)

dopamine

• It frequently causes atrial arrhythmias at higher doses.
• It increases renal blood flow.
• It causes a release of norepinephrine.
• It directly stimulates α, β, and dopamine receptors.
• It is a precursor to norepinephrine.

The linear portion of the oxygen consumption-delivery curve represents the area of the curve where oxygen consumption

• Anaerobic metabolism occurs.
• Increases with increased oxygen delivery.
• Oxygen delivery is inadequate for oxygen demand at the cellular level.

the following suggest the presence of low cardiac index (<2.0 L/min/m)

• Persistent metabolic acidosis.
• Mixed venous oxygen saturation less than 50%.
• Low urinary output

Which of the following drugs is not a significant inotrope?

• Digoxin.
• Norepinephrine.

• Glucagon.
• Dopexamine.
• Amrinone.

Digoxin.

interstitial fluid flux across the alveolar-capillary membrane

The osmotic reflective coefficient in the Starling equation for capillary fluid exchange describes the relative permeability of the capillary wall to albumin. (The osmotic reflective coefficient does characterize the permeability of a capillary membrane to a particular protein; in this case, albumin in so far as it is the major oncotic protein of plasma. Transudated fluid into the interstitium is directed through interstitial and larger lymphatic channels directly to the systemic venous system, primarily the subclavian veins. The major oncotic force of the interstitium is hyaluronate, a proteoglycan, not albumin. The filtration coefficient of the Starling equation for capillary exchange describes the permeability of the capillary membrane—not the alveolar membrane—to fluid fluc as well as the unit area available for same. The compliance curve of the interstitium favors inhibition of early alveolar edema by resisting capillary hydrostatic forces initially, then absorbing and diverting large amounts of fluid subsequently before interstitial pressure exceeds that required for alveolar flooding.)

the intra-aortic balloon pump

It reduces cardiac afterload. (The most important effect of the intra-aortic balloon pump is that it reduces afterload. It is the only afterload reducing therapy which does not drop the diastolic pressure and thereby reduce the coronary perfusion pressure.)

the following factors directly influence cardiac output

• Preload.
• Afterload.
• Inotropic state of the heart.
• Compliance.

A normal inspiration is associated with all of the following

• Contraction of external intercostal muscles.
• Lower alveolar pressure.
• Less negative intrapleural pressure in the more apical pleural space.
• Decrease in airway resistance.
• Greater ventilation of zone three alveoli. (As the result of gravity, the transpulmonary pressure in the upper part of the hemithorax, corresponding to zone one of the lung, is more negative than that in the dependent portion of the hemithorax, corresponding to zone three of the lung. Therefore, zone one alveoli have a greater volume and are on the less steep portion of the compliance curve at functional residual capacity. With inspiration there will be a greater change in volume per unit change in transpulmonary pressure in zone three, resulting in proportionately greater ventilation of alveoli. Increasing transpulmonary pressure

gradient with inspiration increases alveolar volume and, according to the Law of Laplace, alveolar pressure decreases. Intrapleural pressure is decreased by the downward motion of the contracting diaphragm assisted by the external intercostal muscles' actions to upwardly rotate the ribs thereby increasing intrathoracic volume. Outward mechanical traction and the increasingly negative transpleural pressure gradient on alveoli and respiratory bronchioles increases their radii and decreases overall airway resistance proportional to the fourth power of their radii. )

All of the following clinical findings are common to both neurogenic and early septic shock except

Bradycardia. (Unopposed parasympathetic tone in neurogenic shock results in a concomitant bradycardia with heart rates often below 60 bpm. Young patient's easier compensation for bradycardia with appropriately increased ejection fraction explains in part the lower incidence of hypotension in this patient population. Partial answer. )

Therapeutic options for patients with ARDS

• Prone positioning.
• Hypoventilation.
• Decreased expiratory phase of ventilation.
• Decreased tidal volumes.
• NOT steroid administration! (Although once controversial, there is now substantive phase III trial evidence which refutes earlier studies that suggested low dose, chronic steroid administration was effective for the treatment of ARDS. Increased tidal volume ventilation has been shown to worsen the results of treatment of ARDS by virtue of the barotrauma caused by over distension of alveoli. Because gravity affects ventilation-perfusion matching, improvement in ventilation with ARDS has been shown to be effected by alternating supine and prone positioning. Auto-PEEP induced by decreasing expiratory time may minimize the barotrauma of tidal-recruitment (repetitive opening and closing of atelectatic alveoli with tidal ventilation) by maintaining some alveolar distension throughout the respiratory cycle. Very low tidal volumes and rates, even to the point of permissive hypercapnia, have been shown in several studies to decrease the barotrauma to the lungs and improve outcomes from ARDS. )

In a patient with an arterial PCO of 40 mm Hg

arterial PO indicates the degree of ventilation-perfusion mismatch

Side effects of nitroprusside

• Thiocyanate toxicity.
• Hypoxemia.
• A coronary steal phenomenon.

treatment of a patient in hypovolemic shock

• Airway concerns should always be addressed first in any patient in shock.
• Large-bore peripheral IVs are more efficient at volume infusion because they have a lower resistance to flow than a central line.
• If a patient in hypovolemic shock is still hypotensive after crystalloid boluses, blood should be

administered.

• Colloid solutions have not been shown to improve mortality.

Which catecholamine does not have mixed α and β effects?

Dobutamine (only a β effect)

pericardium

• Its ligamentous attachments maintain the heart's normal anatomical relationships regardless of the body's position.
• It contains cilia.
• It contains microvilli.

While making rounds in the ICU, a resident from another service approaches you with questions about his patient's pulmonary artery catheter values. The patient has a low cardiac index (CI), an elevated systemic vascular resistance (SVR), and a low pulmonary capillary wedge pressure (PCWP). Before he even begins telling you about the patient's history, you know that the patient is probably suffering from:

Hypovolemic shock. (Patients in hypovolemic shock first have a fall in their filling pressures. They attempt to compensate by elevating their SVR, but if the volume loss is significant enough the CI will drop.)

A young, obese woman develops the sudden onset of dyspnea and hypoxemia 2 days following surgery for a femur fracture. The pathophysiologic process involved is best described by

A diffusion abnormality exacerbated by increased dead-space ventilation. (The probable etiology in this scenario is pulmonary embolus. Pulmonary embolus, especially when large, eliminates perfusion of alveolar-capillary units effectively decreasing area for diffusion and increasing physiological dead space and shunting. Cardiac output and pulmonary artery pressures increase, which further result in diffusion abnormality by virtue of developing interstitial pulmonary edema. Reflex tachypnea increases dead space ventilation. Although pneumonia is a possibility, this is a little early in the course of events, especially for an otherwise healthy young woman. Spontaneous pneumothorax, although possible, is an unlikely scenario in this case. Ischemic-reperfusion inflammatory processes with associated diffusion defects, while possible later in the course of this event, are not the initial problem.)

transient ischemic attacks

They are most commonly caused by emboli. (Most (but not all) TIAs are caused by atheromatous emboli from the carotid bifurcation.)

the cytokine proinflammatory response

• TNF-α promotion of white blood cell adhesion to endothelium.
• IL-6 induction of T and B cell acute phase response.
• IL-1 induction of fever and hypotension.
• IL-8 recruitment of inflammatory cells to injury site. (IL-4 and IL-10 are anti-inflammatory cytokines that inhibit proinflammatory cytokines. Cytokine induced

hypotension is primarily stimulated by induction of nitric oxide synthetase mediated through the proinflammatory cytokines TNF-α and IL-1.)

with large bronchopleural fistulae

Atelectasis within the ipsilateral lung may occur. (With a large fistula, the inward elastic recoil of the lung may be unopposed by the lower airway pressure created by venting through the fistula resulting in collapse of alveoli and atelectasis. The outward recoil force of the chest wall may actually be decreased as the volume of the ipsilateral lung decreases with atelectasis. Intrapleural pressure is regulated by the depth of the atmospheric tube beneath the water of the third bottle with a three-bottle drainage system, or by the amount of wall suction applied with more modern contained drainage systems. With a large enough fistula this amount of suction may be inadequate or, with wall suction directly regulating intrapleural pressure, too high to prevent a pneumothorax without causing hypoxia as a result of increasing the airflow through the fistula at the expense of ventilating alveoli. High frequency jet ventilation provides adequate ventilation to patients with large fistulae by decreasing expiration time and increasing mean airway pressure and thus functional residual capacity. However, this may increase the air leak if tidal volumes aren't kept small. Balanced pleural drainage requires intubation of a patient with the purpose of equilibrating end tidal ventilator and intrapleural pressures in a positive-pressure ventilated patient, and is therefore not applicable to nonventilated patients.)

The distribution of vascular occlusive disease in diabetics

Is more frequent in the tibioperoneal circulation. (Diabetic patients have a significantly increased chance of having disease in the smaller vessels of the calf. They also have an increased propensity for generalized atherosclerotic disease.)

Compensatory mechanisms for hypovolemic shock

• Increased sympathetic activity.
• Increased heart rate.
• Increased cardiac contractility.
• Norepinephrine and epinephrine release.
• Increased peripheral vascular resistance.

Emphysematous bullous lung disease may contribute to hypoxemia by

• Hyperventilation.
• Diffusion block.
• Ventilation-perfusion mismatch.
• Restricted compliance.
• Physiological shunting. (Hyperinflation restricts thoracic compliance and elastic recoil of the lung. It also generates auto-PEEP that must be overcome by increasing minute ventilation and inspiratory flow to allow enough passive air flow and carbon dioxide elimination to provide adequate alveolar oxygen concentration.)

The results of exercise sufficient to cause intermittent claudication include

• Insufficient blood flow to muscles.
• Increased muscle blood flow.
• Decreased ankle pressure.
• Ankle brachial index less than 0.3.

Following endotracheal intubation, a central venous subclavian catheter has been placed in a patient. Shortly after insertion, his blood pressure drops to 70/40 mm Hg. The jugular veins are distended. The most likely diagnosis is

a tension pneumothorax

A 61-year old man with a long history of coronary artery disease presents to the emergency room with a history of sudden onset retrosternal chest pain, and bilateral crackles are audible on lung examination. EKGs show him to be having an inferior myocardial infarction. His blood pressure is 78/41 mm Hg, and his heart rate is 94 bpm. If a pulmonary artery catheter were placed, which of the following parameters would least likely be seen?

• Pulmonary capillary wedge pressure (PCWP) of 21.
• Systemic vascular resistance (SVR) of 300.
• Cardiac index (CI) of 1.9.
• Mixed venous oxygen saturation of 58%.

Systemic vascular resistance (SVR) of 300. (This patient appears to be in cardiogenic shock, and as such his SVR would be expected to be elevated in a compensatory effort to maintain perfusion. (Normal is approximately 900-1,200.) )

The rate of blood flow through a vessel varies inversely with

• Length of the stenosis in the vessel.
• Viscosity of the blood.
• Degree of stenosis of the vessel.

preload

• Disturbances of preload which result in shock are not usually amenable to treatment with vasopressors.
• In clinical terms, preload refers to the left ventricular end diastolic volume (LVEDV).
• The principle which allows a pulmonary artery catheter to work is dependent on the fact that the pulmonary circulation does not have valves. (A Starling curve plots left ventricular end diastolic volume (or preload) against cardiac output. As preload increases, so does the force of the myocardial contraction and therefore cardiac output. This mechanism is finite; however, at that point, the continued stretching of myocardial muscle fibers becomes excessive, they actually become less efficient and further increases in preload do not yield increases in cardiac output. At this point, signs of heart failure such as pulmonary edema appear and the Starling curve flattens out. )

factors that directly affect the diffusion of oxygen across the alveolar capillary barrier

• Solubility of the gas within the barrier.
• Surface area of membrane.

• Molecular weight of the gas.
• Alveolar concentration of the gas. (Although hemoglobin's capacity for reversibly binding with oxygen ultimately affects the partial pressure gradient for diffusion, this is an indirect effect and specific to oxygen and carbon monoxide. The diffusion of any gas across a barrier is dependent on the coefficient for diffusion of that particular barrier, which is proportional to the solubility and inversely proportional to the square root of the molecular weight of the gas. Diffusion of a gas is also directly proportional to its partial pressure difference across the barrier, which is determined by its alveolar concentration as well as the surface area available for diffusion.)

respiratory muscle function

• Shorter resting lengths decrease force-generating capacity for a given stimulus.
• Hypercapnia reduces respiratory muscle endurance.
• Hypoxia decreases muscle contraction.
• Force of contraction is dependent on the frequency of stimulation. (The "duty cycle" is that portion of the respiratory cycle during which contraction occurs and is inversely proportional to the adequacy of perfusion as contracting muscle compromises capillary vessels. As with all skeletal muscle, the greater the length of resting muscle (up to a point), the greater the potential for generating force in accordance with starling's hypothesis. Both hypoxia and hypercapnia reduce respiratory muscle endurance, whereas hypoxia also decreases the force of contraction of respiratory muscle. Force of contraction of respiratory muscle is proportional to rate of firing, the number of fibers stimulated, and the length of the muscle fiber stimulated.)

The spontaneous, rhythmic, involuntary cycle of alveolar ventilation is neurologically regulated by

• Carotid chemoreceptors response to hypoxemia.
• Pontine integration of peripheral afferents from the joints.
• Aortic chemoreceptor response to hypercapnia.
• Vagally mediated afferents from pulmonary vascular stretch receptors. (The ventrolateral medullary chemoreceptors are in contact with cerebrospinal fluid, not blood, and therefore cannot respond to hypoxemic changes. When increased ventilation is required, as with exercise, aortic and carotid body chemoreceptors cause this to occur by sensing changes in carbon dioxide partial pressure. Carotid body chemoreceptors also sense hypoxemia, which may supersede its response to hypercapnia if severe enough. Under certain acute pathologic conditions such as pulmonary embolus or congestive heart failure, vascular distension stimulates J-receptors that increase minute ventilation. Similarly, spindle cell receptors of the joints and tendons provide afferent input to the pneumotaxic center of the pons, with subsequent modulation of the apneustic center, to increase ventilation under conditions of increased activity.)

acquired aortic stenosis

It is associated with increased oxygen demand by the left ventricular myocardium. (An increased oxygen demand occurs not only because of the thickening of the myocardium, but also because of the high pressures that occur inside the left ventricular cavity during systole.)

septic shock

• It is possible for patients in septic shock to have decreased cardiac output, cool and clammy extremities, and oliguria.
• It is possible for patients in septic shock to have very high mixed venous oxygen saturations.
• It is possible for patients in septic shock to have increased cardiac output, warm and pink extremities, and brisk urine output. (The high mixed venous saturations sometimes seen in septic patients are not signs of efficient oxygen uptake and utilization. For unknown reasons, septic tissues have an impaired ability to utilize oxygen with which they are presented. The high venous saturations should not lead to a sense of complacency that oxygenation is adequate and aerobic metabolism is occurring in these patients.)

important determinants of cardiac output

• Heart rate (and rhythm).
• Contractility (inotropic state of the heart).
• Compliance (ventricular distensibility).
• Preload. (Hematocrit and hemoglobin do not affect cardiac output to any significant degree, although sometimes the cardiac output will rise somewhat in profound anemia.)

Subendocardial blood flow is affected by

• Diastolic pressure time index.
• Systolic pressure time index.
• Left ventricular end diastolic pressure.

Six hours following a laparotomy for a gunshot wound to the abdomen, you are called to the bedside for increasing abdominal distension and a decline in blood pressure. Indications for immediate reexploration include

• Recent onset of oliguria despite adequate fluid resuscitation.
• Suspected missed surgical bleeding.
• Elevated ventilator peak inspiratory pressures.
• Bladder pressures of 32 mm Hg.

pathophysiologic diffusion states - what is the mechanism of re-expansion pulmonary edema

Ischemic-reperfusion injury. (Although fluid overload is potentially an exacerbating component of postpneumonectomy pulmonary edema, the inciting cause for this and other similar pathologic situations such as re-expansion pulmonary edema, is likely ischemic-reperfusion injury possibly as a result of hypoxic pulmonary vasoconstriction. Chronic tobacco abuse results in the destruction of septae within acini with the subsequent coalescence of alveoli into air sacs that are without perfusion and result in physiologic dead space. This removal of large numbers of alveoli from respiratory units eliminates area for diffusion resulting in diffusion block. A significant component of pulmonary contusion is disruption of the integrity of the alveolar-capillary barrier such that administered albumin relocates to the interstitium or alveoli with adverse consequences on the Starling equation for capillary fluid exchange. Exercise decreases transit time through the respiratory unit thereby exposing more hemoglobin to the alveolus per unit

time, thereby increasing oxygen delivery. It has no effect on the rate of diffusion of oxygen through the alveolar-capillary barrier.)

The mode of mechanical ventilation by which tidal amount is variably determined by the degree of inspiratory effort

Pressure-support ventilation (PSV). (With PSV, tidal volume is pressure limited where inspiratory effort acts as a trigger to deliver variable tidal volume as determined by the amount of preset support, airway resistance, and patient effort. With assist-control ventilation, mandatory minute ventilation and synchronized intermittent mandatory ventilation, predetermined rate and tidal volume are programmed so that set minute ventilation is mandated whether determined solely by the machine or in part by the patient. CPAP is not a means of delivering tidal volume but rather of decreasing functional residual capacity.)

The pressure-volume curve of the pericardium states that:

Removal of a small amount of pericardial fluid may dramatically increase cardiac output. (As little as 10 mL of pericardial fluid removed may dramatically increase cardiac output.)

The likelihood of endocarditis is significantly increased with

Disruption of endocardium. (This condition is necessary for endocarditis to occur. Bacteremia must also be present of course, but bacteremia is a common condition, whereas endocarditis is not.)

A postsurgical patient you are managing has a history of congestive heart failure. Despite fluid resuscitation, the patient remains hypotensive with an elevated SVR. Management considerations should include:

• β-1 agonist infusion.
• Phosphodiesterase inhibitor infusion.
• Nitroprusside infusion.
• Fluid infusion following afterload reduction.

Sudden postoperative hypotension in a patient shortly after undergoing a pneumonectomy and partial resection of the pericardium can be due to all of the following except:

• Massive pulmonary vein tear.
• Cardiac herniation through the pericardium.
• Massive pulmonary artery stump leak.
• Acute myocardial infarction.
• Cardiac tamponade.

Cardiac tamponade. (If bleeding occurred around the heart, it would not produce tamponade because it would decompress into the pleural space at the site of pericardial resection.)

Factors that determine cardiac output

• Stroke work index.
• Afterload.

• Preload.
• Compliance. (All of these factors - preload, afterload, stroke volume, compliance, heart rate, and inotropic state of the heart - affect the cardiac output. )

Which equation accurately reflects the relationship between the content of oxygen in arterial blood (CaO), hemoglobin (Hgb), partial pressure of oxygen (PaO), and the arterial oxygen saturation (SaO)?

CaO= (1.34 × Hgb × SaO) + (0.003 × PaO). (The first portion of the equation describes the amount of oxygen carried by hemoglobin. The constant 1.34 signifies the amount of oxygen in milliliter that each gram of hemoglobin can carry when fully saturated. This is multiplied by the number of grams of hemoglobin present (Hgb) and the percentage of hemoglobin saturation (SaO). The other portion of the equation describes the amount of oxygen which can be carried dissolved in plasma. The solubility coefficient of oxygen in plasma is very small (0.003), and the partial pressure of the dissolved oxygen must be multiplied by this constant. This shows that the contribution of dissolved oxygen to the total oxygen content of blood is very minor.)

Immediate life-threatening consequences of myocardial infarction

• Complete atrioventricular nodal block.
• Ventricular septal rupture.
• Myocardial rupture. (Left ventricular aneurysm formation is a chronic condition and does not occur immediately after myocardial infarction. Furthermore, it is generally not life threatening except perhaps as a result of some of its complications. )

epinephrine's pulmonary effects

(via β-2 receptors) include bronchodilation and inhibition of mast cell degranulation.

ARDS

• ARDS is part of the SIRS response to certain inciting factors.
• ARDS is characterized by a change in the filtration coefficient of the Starling equation for fluid exchange.
• Is caused by the release of toxic cytokines, free radicals, and other inflammatory mediators.
• ARDS includes disseminated intravascular coagulopathy as part of the pathology. (Although volume overload may exacerbate the process once developed, it does not precipitate ARDS. ARDS appears to be part of the systemic inflammatory response (SIRS) to certain factors such as sepsis, trauma, extracorporeal perfusion, and so on. ARDS is a permeability pulmonary edema (as opposed to hydrostatic pulmonary edema), in which the release of toxic mediators affect not only alveolar-capillary membrane permeability, but also causes C-reactive protein mediated platelet aggregation of the microvasculature leading to DIC and multisystem organ failure. )

A noncompliant dialysis patient presents with a 3-day history of lethargy and fatigue. On physical examination he is found to have cold clammy skin, a thready pulse of 125, and respiratory variation in the blood pressure from 110/85 mm Hg on expiration to 90/70 mm Hg on inspiration. He has an audible

systolic murmur but no diastolic murmur. Which one of the following statements regarding this patient is correct:

An echocardiogram will likely demonstrate diastolic collapse of the right ventricle, and respiratory variation of flow in the ascending aorta. (The patient likely has developed uremic pericarditis from dialysis noncompliance, and has developed cardiac tamponade; the "murmur" is likely a pericardial friction rub and not a valvular abnormality. ACE- inhibitor therapy and hemodialysis with ultrafiltration of volume is contraindicated in tamponade and may worsen a low cardiac output state. A pulmonary embolism could cause some of the findings on physical examination that mimic tamponade, with the exception of a murmur or friction rub, and the history of dialysis noncompliance would cause one to suspect pericarditis instead of embolism. Acute aortic valve endocarditis causes a diastolic murmur and a low diastolic blood pressure. Diastolic collapse of the right ventricle and respiratory variation of blood flow in the aorta are common findings in tamponade.)

A patient with an anatomic dead space of 150 ml has a tidal volume of 500 ml, a respiratory rate of 20/min, and an arterial PCO of 45 mm Hg. Postoperatively, total physiologic dead space increases to 250 ml and tidal volume decreases to 450 ml/kg. To maintain the same arterial PCO , the patient`s respiratory rate must be

35/min (?)

How does anaerobic glycolysis impair cell function?

• Accumulation of lactic acid.
• Impaired ATP production.
• Accumulation of hydrogen ions.

A blood clot in the left iliac vein could reach the brain through a patent

foramen ovale

Following a gunshot wound to the abdomen, a patient is hypotensive with minimal urine output. An appropriate physiologic renal response includes which one of the following

• Renal arterial vasoconstriction.
• Sodium reabsorption by angiotensin II action on renal tubule.
• Water retention by ADH action on the distal nephron.
• Release of renin from the juxtaglomerular cells.

A 44-year-old woman collapses after removal of a nevus. Local anesthesia was used. Her blood pressure is 70/0 mm Hg, pulse rate is 42/min, and respiratory rate is 24/min. The most appropriate initial management is

the administration of atropine intravenously

During periods of anaerobic glycolysis