Basic Surgery (100q).1

1.

In “catabolic” surgical patients, which of the following changes in body composition do not occur?

A.

Lean body mass increases.
B.

Total body water increases.
C.

Adipose tissue decreases.
D.

Body weight decreases.

Correct Answer
A. Lean body mass increases.

Explanation
Lean body mass represents the body compartment that contains protein. Because critical illness stimulates proteolysis and increased excretion of body nitrogen, this compartment is consistently reduced, not increased. The change in body composition is associated with a loss of body weight, an increase in total body water, and a decrease in body fat.

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2.

The characteristic changes that follow a major operation or moderate to severe injury do not include the following:

A.

Hypermetabolism.
B.

Fever
C.

Tachypnea
D.

Hyperphagia
E.

Negative nitrogen balance.

Correct Answer
D. HyperpHagia

Explanation
The characteristic metabolic response to injury includes hypermetabolism, fever, accelerated gluconeogenesis, and increased proteolysis (creating a negative nitrogen balance). Food intake is generally impossible because of abdominal injury or ileus. With time, food intake increases, but the patient generally experiences anorexia, not hyperphagia.

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3.

Shock can best be defined as:

A.

Hypotension
B.

Hypoperfusion of tissues.
C.

Hypoxemia
D.

All of the above.

Correct Answer
B. Hypoperfusion of tissues.

Explanation
Shock, no matter what the cause, is a syndrome associated with tissue hypoperfusion. Tissue hypoperfusion leads to tissue hypoxia, which may or may not be due to hypoxemia. Hypotension is a late sign of shock and, therefore, is not a good clinical indicator of the presence of tissue hypoperfusion.

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4.

Which of the following statements regarding cytokines is incorrect?

A.

Cytokines act directly on target cells and may potentiate the actions of one another.
B.

Interleukin 1 (IL-1) is a major proinflammatory mediator with multiple effects, including regulation of skeletal muscle proteolysis in patients with sepsis or significant injury.
C.

Platelet-activating factor (PAF) is a major cytokine that results in platelet aggregation, bronchoconstriction, and increased vascular permeability.
D.

Tumor necrosis factor alpha (TNF-a), despite its short plasma half-life, appears to be a principal mediator in the evolution of sepsis and the multiple organ dysfunction syndrome because of its multiple actions and the secondary cascades that it stimulates

Correct Answer
C. Platelet-activating factor (PAF) is a major cytokine that results in platelet aggregation, bronchoconstriction, and increased vascular permeability.

Explanation
Cytokines are soluble peptide molecules that are synthesized and secreted by a number of cell types in response to injury, inflammation, and infection. Cytokines, which include the interleukins, tumor necrosis factor, colony-stimulating factors, and the interferons, comprise only one category of inflammatory mediators involved in the host response. Endotoxin, complement fragments, eicosanoids, kinins, nitric oxide, oxidants, and PAF are noncytokine mediators that also have important roles in the systemic inflammatory response. IL-1 and TNF-a, like other cytokines, have multiple effects on target cells and potentiate the actions of other mediators to produce an amplified inflammatory response. TNF-a is thought to play a central role in the stress response, particularly in response to endotoxemia.

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5.

All of the following are true about neurogenic shock except:

A.

There is a decrease in systemic vascular resistance and an increase in venous capacitance.
B.

Tachycardia or bradycardia may be observed, along with hypotension.
C.

The use of an alpha agonist such as phenylephrine is the mainstay of treatment
D.

Severe head injury, spinal cord injury, and high spinal anesthesia may all cause neurogenic shock.

Correct Answer
C. The use of an alpHa agonist such as pHenylepHrine is the mainstay of treatment

Explanation
Neurogenic shock occurs when severe head injury, spinal cord injury, or pharmacologic sympathetic blockade leads to sympathetic denervation and loss of vasomotor tone. Both arteriolar and venous vessels dilate, causing reduced systemic vascular resistance and a great increase in venous capacitance. The patient's extremities appear warm and dry, in contrast to those of a patient in cardiogenic or hypovolemic shock. Tachycardia is frequently observed, though the classic description of neurogenic shock includes bradycardia and hypotension. Volume administration to fill the expanded intravascular compartment is the mainstay of treatment. The use of alpha-adrenergic agonist is infrequently necessary to treat neurogenic shock.

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6.

All of the following may be useful in the treatment of cardiogenic shock except:

A.

Dobutamine
B.

Sodium nitroprusside.
C.

Pneumatic antishock garment.
D.

Intra-aortic balloon pump

Correct Answer
C. Pneumatic antishock garment.

Explanation
Cardiogenic shock occurs when the heart fails to generate adequate cardiac output to maintain tissue perfusion. Intrinsic causes such as myocardial dysfunction secondary to coronary artery disease, or extrinsic causes such as pulmonary embolism, tension pneumothorax, and pericardial tamponade, may produce cardiogenic shock. Principles of treatment of cardiogenic shock are aimed at optimizing preload, cardiac contractility, and afterload. Preload is usually adequate or high in cardiogenic shock. Dobutamine is a useful inotropic agent, particularly when filling pressures are high, because of its mild vasodilatory effect, as well as its effect to enhance cardiac contractility. Afterload-reducing agents, such as sodium nitroprusside, may be beneficial in cardiogenic shock in the setting of elevated filling pressures, low cardiac output, and elevated systemic vascular resistance. Cardiac output may improve with use of afterload-reducing agents by decreasing myocardial wall tension and optimizing the myocardial oxygen supply-demand ratio. The intra-aortic balloon pump (IABP), by providing diastolic augmentation, reducing left ventricular afterload, and reducing myocardial oxygen consumption, is sometimes useful in the treatment of cardiogenic shock. The IABP is especially useful in low–cardiac output postcardiotomy patients, in patients awaiting revascularization, and in patients with acute myocardial infarction complicated by mitral insufficiency or ventricular septal defect. The pneumatic antishock garment (PASG), which causes an increase in systemic vascular resistance, is contraindicated in cardiogenic shock.

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7.

Which of the following statements about head injury and concomitant hyponatremia are true?

A.

There are no primary alterations in cardiovascular signs
B.

Signs of increased intracranial pressure may be masked by the hyponatremia.
C.

Oliguric renal failure is an unlikely complication
D.

Rapid correction of the hyponatremia may prevent central pontine injury
E.

This patient is best treated by restriction of water intake.

Correct Answer
A. There are no primary alterations in cardiovascular signs

Explanation
Acute symptomatic hyponatremia is characterized by central nervous system signs of increased intracranial pressure. Changes in blood pressure and pulse are secondary to increased intracranial pressure. In the absence of hypovolemia, asymptomatic patients may be treated by restriction of water intake; however, in such patients, hyponatremia should be partially corrected by parenteral sodium administration. Rapid correction, particularly to hypernatremia, may lead to central pontine myelinolysis. Oliguric renal failure may rapidly develop in severe hyponatremia

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8.

Which of the following statements about extracellular fluid are true?

A.

The total extracellular fluid volume represents 40% of the body weight.
B.

The plasma volume constitutes one fourth of the total extracellular fluid volume
C.

Potassium is the principal cation in extracellular fluid.
D.

The protein content of the plasma produces a lower concentration of cations than in the interstitial fluid
E.

The interstitial fluid equilibrates slowly with the other body compartments.

Correct Answer
B. The plasma volume constitutes one fourth of the total extracellular fluid volume

Explanation
The total extracellular fluid volume represents 20% of body weight. The plasma volume is approximately 5% of body weight. Sodium is the principal cation. The Gibbs-Donan equilibrium equation explains the higher total concentration of cations in plasma. Except for joint fluid and cerebrospinal fluid, the majority of the interstitial fluid exists as a rapidly equilibrating component.

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9.

1. Which of the following statements are true of a patient with hyperglycemia and hyponatremia?

A.

The sodium concentration must be corrected by 5 mEq. per 100 mg. per 100 ml. elevation in blood glucose.
B.

With normal renal function, this patient is likely to be volume overloaded.
C.

Proper fluid therapy would be unlikely to include potassium administration
D.

Insulin administration will increase the potassium content of cells.
E.

Early in treatment adequate urine output is a reliable measure of adequate volume resuscitation.

Correct Answer
D. Insulin administration will increase the potassium content of cells.

Explanation
Each 100-mg. per 100 ml. elevation in blood glucose causes a fall in serum sodium concentration of approximately 2 mEq. per liter. Excess serum glucose acts as an osmotic diuretic, producing increased urine flow, which can lead to volume depletion. Insulin therapy and the correction of the patient's associated acidosis produce movement of potassium ions into the intracellular compartment.

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10.

Which of the following is/are not associated with increased likelihood of infection after major elective surgery?

A.

Age over 70 years.
B.

Chronic malnutrition.
C.

Controlled diabetes mellitus.
D.

Long-term steroid use.
E.

Infection at a remote body site.

Correct Answer
C. Controlled diabetes mellitus.

Explanation
Controlled diabetes mellitus has been shown repeatedly not to be associated with increased likelihood of incisional infection provided one avoids operations on body parts that may be ischemic or neuropathic. Uncontrolled diabetes mellitus, such as ketoacidosis, is associated with a dramatic increase in surgical infection. The other parameters noted—age over 70, chronic malnutrition, regular steroid use, and an infection at a remote body site—are well-recognized adverse predictive factors and are identified in tables within the chapter.

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11.

Which of the following are not determinants of a postoperative cardiac complication?

A.

Myocardial infarct 4 months previously.
B.

Clinical evidence of congestive heart failure in a patient with 8.5 gm. per dl. hemoglobin.
C.

Premature atrial or ventricular contractions on electrocardiogram
D.

A harsh aortic systolic murmur.
E.

Age over 70 years.

Correct Answer
B. Clinical evidence of congestive heart failure in a patient with 8.5 gm. per dl. hemoglobin.

Explanation
Clinical evidence of congestive heart failure in a patient with 8.5 gm. per dl. hemoglobin concentration is a misleading sign. Evidence of congestive failure is ordinarily a major risk factor, but in this particular patient the anemia lends itself to correction by preoperative transfusion with packed red blood cells, and often it is found that congestive failure and the associated increased risks disappear when the hemoglobin concentration is returned to the 12 gm. per dl. or higher ratio. All other factors are overt signs of increased likelihood of a postoperative cardiac event, the most ominous being a myocardial infarction 4 months preoperatively or the presence of a harsh aortic systolic murmur suggesting the presence of aortic stenosis. Age over 70 years and the presence of premature atrial or ventricular contractions on the electrocardiogram are less strong determinants of a postoperative cardiac complication.

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12.

Which of the following statements regarding whole blood transfusion is/are correct?

A.

Whole blood is the most commonly used red cell preparation for transfusion in the United States.
B.

Whole blood is effective in the replacement of acute blood loss.
C.

Most blood banks in the United States have large supplies of whole blood available.
D.

The use of whole blood produces higher rates of disease transmission than the use of individual component therapies

Correct Answer
B. Whole blood is effective in the replacement of acute blood loss.

Explanation
Whole blood is effective as a replacement fluid for acute blood loss because it provides both volume and oxygen-carrying capacity (red blood cells). It is rarely used in the United States nowadays, and most blood banks do not provide whole blood transfusions. It is significantly more efficient to separate donated blood into its components. In this manner, the red blood cell mass can be used to provide oxygen-carrying capacity, the plasma can be used for factor replacement, and the platelets and white cells can be used for patients deficient in these components. The use of whole blood to replace acute blood loss is associated with lower disease transmission rates than the use of packed red blood cells, fresh frozen plasma, and platelets, each from a different donor.

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13.

In patients receiving massive blood transfusion for acute blood loss, which of the following is/are correct?

A.

Packed red blood cells and crystalloid solution should be infused to restore oxygen-carrying capacity and intravascular volume.
B.

Two units of FFP should be given with every 5 units of packed red blood cells in most cases
C.

A “six pack” of platelets should be administered with every 10 units of packed red blood cells in most cases.
D.

One to two ampules of sodium bicarbonate should be administered with every 5 units of packed red blood cells to avoid acidosis.
E.

One ampule of calcium chloride should be administered with every 5 units of packed red blood cells to avoid hypocalcemia.

Correct Answer
A. Packed red blood cells and crystalloid solution should be infused to restore oxygen-carrying capacity and intravascular volume.

Explanation
Patients who are suffering from acute blood loss require crystalloid resuscitation as the initial maneuver to restore intravascular volume and re-establish vital signs. If 2 to 3 liters of crystalloid solution is inadequate to restore intravascular volume status, packed red blood cells should be infused as soon as possible. There is no role for “prophylactic infusion” of FFP, platelets, bicarbonate, or calcium to patients receiving massive blood transfusion. If specific indications exist patients should receive these supplemental components. In particular, patients who have abnormal coagulation tests and have ongoing bleeding should receive FFP. Patients who have depressed platelet counts along with clinical evidence of oozing (microvascular bleeding) benefit from platelet infusion. Sodium bicarbonate is not necessary, since most patients who receive blood transfusion ultimately develop alkalosis from the citrate contained in stored red blood cells. The use of calcium chloride is usually unnecessary unless the patient has depressed liver function, ongoing prolonged shock associated with hypothermia, or, rarely, when the infusion of blood proceeds at a rate exceeding 1 to 2 units every 5 minutes.

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14.

The evaluation of a patient scheduled for elective surgery should always include the following as tests of hemostasis and coagulation:

A.

History and physical examination.
B.

Complete blood count (CBC), including platelet count
C.

Prothrombin time (PT) and activated partial thromboplastin time (APTT).
D.

Studies of platelet aggregation with adenosine diphosphate (ADP) and epinephrine

Correct Answer
A. History and pHysical examination.

Explanation
The evaluation of most patients scheduled for elective surgery who do not have a history of significant bleeding disorders is somewhat controversial. An adequate history and physical examination screen out most patients with bleeding problems. For patients who are scheduled to undergo a major surgical procedure, it is advisable to obtain a CBC and platelet count, as well as a PT and APTT level. This detects a large number of bleeding disorders but does not rule out all possible causes of perioperative bleeding. Studies of platelet aggregation are indicated only for patients who are suspected of having qualitative defects of platelet function (e.g., von Willebrand's disease).

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15.

The most common cause of fatal transfusion reactions is:

A.

An allergic reaction.
B.

An anaphylactoid reaction.
C.

A clerical error.
D.

An acute bacterial infection transmitted in blood.

Correct Answer
C. A clerical error.

Explanation
The most common cause of fatalities related to transfusion reactions result from ABO-incompatible transfusion related to clerical error. Most such reactions occur if a type O person receives type A red cells owing to a clerical error that occurs either at the time the blood sample was drawn, during processing in the laboratory, or at the time a unit is administered. The importance of extremely careful labeling, transfer, and handling of specimens and of cross-matched blood products cannot be overemphasized. Allergic and other reactions are common but rarely fatal. The transmission of bacterial organisms (e.g., Staphylococcus aureus) has been reported especially with platelet concentrates maintained at or near room temperature. Fortunately, such reactions are rare.

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16.

A modified amino acid solution with increased equimolar branched-chain amino acids and decreased aromatic amino acids has been proposed for patients with hepatic insufficiency. Which of the following statements is/are true?

A.

This formulation is proposed for the use of patients with fulminant hepatitis
B.

Nitrogen balance is achieved in such patients with amounts of 40 gm. of amino acids per 24 hours.
C.

The use of 80 to 100 gm. of such solutions is associated with hepatic encephalopathy
D.

In some studies of surgical patients, improvements in mortality have been reported.

Correct Answer
D. In some studies of surgical patients, improvements in mortality have been reported.

Explanation
The use of modified amino acid solutions is based on the false neurotransmitter hypothesis of the cause of hepatic coma. According to this hypothesis, the imbalance between aromatic and branched-chain amino acids in the plasma results in abnormally high levels of the toxic aromatic amino acids in the brain, thus provoking hepatic encephalopathy. The use of modified amino acid mixtures, with glucose as the calorie base, has been associated in a number of studies with improvement in encephalopathy. Meta-analysis has concluded that the use of such solutions is indicated as therapy for hepatic encephalopathy but has been proposed only for hepatic encephalopathy complicating acute exacerbation of chronic liver disease. Although there are a few anecdotal reports of beneficial effects on hepatic encephalopathy of acute fulminant hepatitis, the use of such a solution has not been advocated, but such a modified solution is tolerated better than standard amino acid mixtures in patients requiring TPN. In some studies, particularly in complicated surgical cases, the use of a high–branched-chain, low–aromatic amino acid solution has been associated with lower mortality. These statements are true only for studies in which the modified solutions are given with hypertonic glucose as a calorie base. Studies in which lipid was the principal calorie source have not revealed such improvements in mortality. In recent studies, giving an aromatic amino acid–deficient, branched-chain amino acid–enriched solution to patients about to undergo resection of the liver has proved particularly efficacious in a group of patients with cirrhosis, decreasing morbidity and showing a trend toward decreased mortality.

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17.

In the nutritional support of patients with cancer, which of the following statements is/are true?

A.

Nutritional support benefits the patient's lean body mass but does not enable the tumor to grow
B.

In experimental animals, the growth of implanted tumors is directly proportional to the amount of calories and protein supplied.
C.

Prospective randomized trials of nutritional support utilizing chemotherapy and radiation therapy have revealed benefits to patients receiving total parenteral nutrition
D.

Studies of nutritional support for patients with cancer about to undergo surgery revealed decreased morbidity and mortality, especially morbidity from sepsis.

Correct Answer
B. In experimental animals, the growth of implanted tumors is directly proportional to the amount of calories and protein supplied.

Explanation
The problem with the patient with cancer is a very vexing one. Clearly, one of the metabolic effects of cancer, cachexia, affects patients in the last quartile of their disease and makes such patients intolerant of chemotherapy, radiation therapy, and, in many cases, operative procedures. Total parenteral nutrition (TPN) has been proposed as a means of reversing cachexia and enabling patients to better tolerate surgery, chemotherapy, and radiation therapy. In experimental animals, it is clear that the provision of calories and protein, especially in excessive amounts, is associated with the more rapid growth of tumors and decreased survival, especially in the group that is overfed in the extreme. There is also evidence suggesting that overfeeding, or at least TPN, may result in increased growth (or at least change cell kinetics) in patients who are overnourished with TPN. Of the randomized prospective trials that have been carried out, no trial utilizing chemotherapy or radiation therapy has revealed a survival advantage for patients receiving TPN. Indeed, in Shamberger's study, there is a suggestion that the tumor-free interval following treatment of lymphoma may be shorter in patients receiving TPN. In patients undergoing surgery, however, especially those who are severely malnourished (as recently revealed in the VA study) or in patients with major procedures such as esophagogastrectomy (as in Muller's study), evidence suggests that TPN is beneficial. In a late follow-up in Muller's study, there was no apparent increase in recurrence, and the survival rate was the same, despite much higher mortality in the non-TPN group. This suggests that any improved survival following operation may have been offset by an increased late recurrence rate, although it is difficult to reach this conclusion. In summary, for patients with cancer TPN probably nourishes the tumor as well as the host. Nonetheless, in severely malnourished patients provision of TPN from 5 to 10 days preoperatively may increase survival and decrease morbidity. Overfeeding must be avoided. Future studies will undoubtedly reveal that there are certain nutrients that tumors require, which probably should be best avoided.

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18.

Glucose overload results in increased CO 2 production. Which of the following statements are true?

A.

In patients with respiratory insufficiency, administration of glucose as a principal calorie source is contraindicated
B.

In patients with pulmonary infection and sepsis, calorie support should consist of 95% fat and 5% glucose.
C.

In Askanazi's study, increased CO 2 production and difficulty in weaning was associated only with pronounced overfeeding.
D.

CO 2 production should be measured in most patients who are supported by respirators in intensive care units and are receiving nutritional support

Correct Answer
C. In Askanazi's study, increased CO 2 production and difficulty in weaning was associated only with pronounced overfeeding.

Explanation
Few papers have excited as much interest as that by Askanazi, Kinney, and co-workers, which demonstrated that glucose calories given to patients with severe respiratory impairment may result in difficulty in weaning from a respirator. Subsequent research has suggested, however, that this occurs only with severe overfeeding, when the respiratory quotient is greater than 1 and calories are excessive. If one examines the conditions under which Askanazi's patients were studied, these were a group of septic, depleted patients who were taken from almost no nutritional support to a caloric supply of 2.25 times their caloric requirement, most of the calories consisting of glucose. Suffice it to say that, in patients with impaired respiratory function, one should measure VCO2 and, when VCO2 is significantly elevated and appears to interfere with weaning, decrease the amount of glucose calories and increase the amount of fat. If one measures or estimates calorie requirements and does not overfeed, lipid can be utilized for 25% of the caloric requirement and glucose for the remainder, without much fear of excessive CO 2 production.

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19.

Which of the following statements about the presence of gallstones in diabetes patients is/are correct?

A.

Gallstones occur with the same frequency in diabetes patients as in the healthy population.
B.

The presence of gallstones, regardless of the presence of symptoms, is an indication for cholecystectomy in a diabetes patient.
C.

Diabetes patients with gallstones and chronic biliary pain should be managed nonoperatively with chemical dissolution and/or lithotripsy because of severe complicating medical conditions and a high operative risk.
D.

The presence of diabetes and gallstones places the patient at high risk for pancreatic cancer.
E.

Diabetes patients with symptomatic gallstones should have prompt elective cholecystectomy, to avoid the complications of acute cholecystitis and gallbladder necrosis.

Correct Answer
E. Diabetes patients with symptomatic gallstones should have prompt elective cholecystectomy, to avoid the complications of acute cholecystitis and gallbladder necrosis.

Explanation
Gallstones have been found to be very prevalent in patients with type II (non–insulin-dependent) diabetes mellitus, perhaps related to the dyslipoproteinemia in such patients. Although the complications of acute cholecystitis (infection, sepsis, gangrene of the gallbladder) are more common in diabetics, a decision-analysis study has shown that prophylactic cholecystectomy cannot be justified since the risk of morbidity and/or mortality from the cholecystectomy procedure is as great as that of complications or death from acute cholecystitis. Patients who become symptomatic should be promptly prepared and should undergo elective cholecystectomy, because an emergency operation in these patients with comorbid conditions, especially coronary artery disease, has substantial added mortality associated with it. There is no causal relationship between diabetes and pancreatic cancer.

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20.

Intensive insulin therapy:

A.

Prevents the aggressive development of atherosclerosis in diabetic patients
B.

Is not associated with unawareness of hypoglycemia.
C.

Improves peripheral neuropathy
D.

Improves established retinopathy and nephropathy
E.

Is indicated in all patients with non–insulin-dependent diabetes mellitus (NIDDM).

Correct Answer
C. Improves peripHeral neuropathy

Explanation
Intensive insulin therapy is indicated in patients with IDDM who can actively participate in their own management and the attainment of the goals set for their blood glucose and glycosylated hemoglobin (HgA1 c) levels. Because the main complication of intensive therapy is iatrogenic hypoglycemia, this mode of treatment is not indicated for patients with NIDDM, who often have coexisting medical conditions such as coronary artery disease and who tolerate hypoglycemia poorly. There is little or no evidence that macrovascular disease is affected by intensive insulin therapy, and the added weight gain and hyperinsulinemia associated with the therapy may worsen atherosclerosis. Unawareness of hypoglycemia is directly related to a recent hypoglycemia episode, so patients treated intensively are often unaware of the problem. Intensive therapy does not improve established retinopathy or nephropathy but slows or prevents progression of these complications; however, better glucose control may improve peripheral neuropathy.

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21.

What is the major determinant in an individual patient's risk for perioperative complications?

A.

The surgical procedure.
B.

The length of the surgical procedure.
C.

The anesthetic technique (e.g., general, regional).
D.

The length of anesthesia.
E.

All of the above.

Correct Answer
A. The surgical procedure.

Explanation
The planned surgical procedure is the major determining factor in assessing an individual patient's risk for perioperative complications and in deciding which anesthetic technique will be most appropriate. Good communication between the surgeon and the anesthesiologist is vital, as the surgeon knows better than anyone else the extent of the operation and the length of time it will require.

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22.

Advantages of epidural analgesia include:

A.

Earlier mobilization after surgery.
B.

Earlier return of bowel function.
C.

Shorter hospitalizations.
D.

Decreased stress response to surgery.
E.

All of the above

Correct Answer
E. All of the above

Explanation
Epidural analgesia include excellent pain relief, decreased sedation with more rapid recovery to presurgical levels of consciousness, earlier mobilization after surgery with increased ability to co-operate with respiratory therapy and physical therapy. Following vascular surgery epidural analgesia may also improve graft flow through mild sympathetic blockade. Earlier return of bowel function, decreased stress response, shorter hospitalizations, and decreased morbidity have all been associated with epidural analgesia.

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23.

Factors that decrease collagen synthesis include all of the following except:

A.

Protein depletion.
B.

Infection
C.

Anemia
D.

Advanced age.
E.

Hypoxia

Correct Answer
C. Anemia

Explanation
Collagen synthesis, an integral part of wound healing, is affected by many local and systemic factors. Protein depletion impairs fibroplasia. Hypoproteinemia leads to diminution of fibroblast proliferation, proteoglycan and collagen synthesis, angiogenesis, and wound remodeling. Although anemia was once believed to be a significant cause of wound disruption, studies have shown that, in the absence of malnutrition or hypovolemia, anemia with a hematocrit greater than 15% does not interfere with wound healing. In contrast, molecular oxygen is critical for collagen synthesis because it is one of the factors required for the hydroxylation of lysine and proline. Also, hypoxia favors wound infection. The role of age in collagen synthesis is not clear, but the incidence of wound failure and incisional hernias is greater in patients older than 60. Fibroplasia occurs at a slower rate in older animals. Perhaps more than any other factor, wound infection is associated with the risk of wound failure.

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24.

Which of the following statement(s) is/are true concerning the cell function of phagocytosis?

A.

Phagocytosis is a mechanistically distinct process of endocytosis performed by special cells to take up larger particles such as bacteria or erythrocytes
B.

Lymphocytes are the primary blood cell involved with this process
C.

The process involves a coating of the cytoplasmic surface known as clathrin
D.

Phagocytosis is performed only by white blood cells and tissue macrophages

Correct Answer
A. pHagocytosis is a mechanistically distinct process of endocytosis performed by special cells to take up larger particles such as bacteria or erythrocytes

Explanation
Phagocytosis is a specialized form of endocytosis by which large particles are internalized by specialized cells primarily macrophages and neutrophils. To be phagocytosed, particles must bind to the surface of the phagocytic cell, usually as the result of specific antibody coating the particle. The phagocytic cell then extends pseudopods which engulf the particle. This event is followed by membrane fusion and a pinching off. As opposed to endocytosis, this process does not involve the membrane protein, clathrin, but rather actin. A physiologically relevant site of phagocytosis is the thyroid gland, where thyroid follicular cells phagocytose and digest thyroglobulin from the lumen of the thyroid follicle, thereby releasing the thyroid hormones, thyroxine triiodothyronine.

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25.

A striking feature of living cells is a marked difference between the composition of the cytosol and the extracellular milieu. Which of the following statement(s) concerning the mechanisms of maintenance of these differences is/are true?

A.

The cell membrane is able to maintain a 10,000 fold gradient between the extracellular concentration of ionized calcium and the intracellular concentration
B.

The key to these differences is the fact that the plasma membrane is normally impermeable to sodium, potassium and calcium
C.

The selectivity of biologic membranes is highly consistent and seldom changes
D.

The selectivity of cell membranes relates only to ions and not organic compounds

Correct Answer
A. The cell membrane is able to maintain a 10,000 fold gradient between the extracellular concentration of ionized calcium and the intracellular concentration

Explanation
The survival of the cell requires that cytosolic composition be maintained within narrow limits, despite the constant influx of nutrients and the simultaneous outflow of waste. A familiar example of the distribution of ions across the cell membrane is that of sodium and potassium. Cells are typically rich in potassium and contain very little sodium. Despite the fact that they are constantly bathed by fluid that is precisely the opposite composition. Even more impressive is the distribution of ionized calcium. The extracellular concentration of this ion is typically of the order of 10–3M, whereas that of cytosol is typically 10–7M, a 10,000-fold gradient. Such nonequilibrium ion distributions are even more remarkable in light of the fact that the plasma membrane is, to varying degrees, leaky to ions such as sodium, potassium and calcium. The plasma membrane is leaky to a variety of substances, but it exhibits an astonishing ability to discriminate or select one substance over another. This selectivity relates to not only ions but also for organic compounds such as glucose. Finally, the selectivity of biologic membranes can be altered drastically as a result of regulatory or signaling processes that occur within the cell.

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26.

Which of the following statement(s) is/are true concerning DNA?

A.

DNA is contained only in the nucleus of the cell
B.

DNA strands are encoded by the sequence of four bases—adenine, guanine, cytosine and uridine
C.

The basic unit of information of DNA is the intron, a sequence of three bases
D.

There are an infinite number of possible codons

Correct Answer
A. DNA is contained only in the nucleus of the cell

Explanation
The genetic blueprint of an organism is carried in the nucleus of every cell, encoded by the sequence of four bases—adenine, guanine, cytosine and thymine, which together make up two long chains bound together by hydrogen bonds to form a DNA double helix. A gene is a segment of DNA that is transcribed into a corresponding RNA molecule that either codes for a protein or forms a structural RNA molecule. Genes are commonly between 10,000 and 100,000 base pairs in length and include, in addition to the coding sequence, flanking regions and intervening sequences, termed introns. Introns are removed from the primary RNA transcript by a process called splicing. The basic unit of information is the codon, a sequence of three bases or triplet. The four nucleotide bases arranged as triplets lead to 64 possible codons. Sixty-one of these code for amino acids and three are termination signals called stop codons.

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27.

An important step in protein synthesis is transcription. Which of the following statement(s) is/are true concerning this process?

A.

The first step in gene transcription involves separating the double helix of DNA by an enzyme known as DNA polymerase
B.

The initial product of DNA transcription is called heterogeneous nuclear RNA which codes directly for proteins
C.

After processing is complete, the mRNA is exported from the nucleus to the cytoplasm
D.

Only one protein can be produced from an initial mRNA strand

Correct Answer
C. After processing is complete, the mRNA is exported from the nucleus to the cytoplasm

Explanation
Transcription of a gene begins at an initiation site associated with a specific DNA sequence, termed a promoter region. After binding to DNA, the RNA polymerase opens up a short region of the double helix to expose the nucleotides. Once the two strands of DNA are separated, the strand containing the promoter acts as a template to which ribonucleoside triphosphates base pair by hydrogen bonds. The initial products of transcription are known as heterogeneous nuclear RNA because of their large size variation. These primary transcripts are then processed to form mRNA. RNA splicing accounts for mature RNA being much shorter than nuclear RNA. Moreover, alternative splicing can lead to the production of different mRNA molecules and in some cases different proteins from the same gene. mRNA is exported from the nucleus only after processing is complete.

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28.

Which of the following statement(s) is/are true concerning nutritional support of the injured patient?

A.

The goal of nutritional support is maintenance of body cell mass and limitation of weight loss to less than 25% of preinjury weight
B.

Under-nutrition may compromise the patient’s available defense mechanisms
C.

Nutritional support is an immediate priority for the trauma patient
D.

Fifty percent of non-nitrogen caloric requirements should be provided in the form of fat

Correct Answer
B. Under-nutrition may compromise the patient’s available defense mechanisms

Explanation
Metabolic response to injury results in increased energy expenditure. If energy intake is less than expenditure, oxidation of body fat stores and erosion of lean body mass will occur with resultant loss of weight. When weight loss exceeds 10–15% of body weight, the complications of malnutrition interact with disease processes, with increased morbidity and mortality rates. The goal of nutritional support is maintenance of body cell mass and limitation of weight loss to less than 10% preinjury. The major impact of nutritional support in the trauma patient is to aid host defense. Under-nutrition may compromise the available host defense mechanism and may thus increase the likelihood of invasive sepsis, multiple organ system failure, and death. Resuscitation, oxygenation and arrest of hemorrhage are immediate priorities for survival. Nutritional support is an essential part of the metabolic care of the critically ill patient and should be instituted after resuscitation before significant weight loss occurs. The nutritional requirements of a trauma patient can be determined by determining basal metabolic rate with appropriate increases based on extent of injury and hospital activity. After initial determination of nitrogen requirements, caloric requirements should be distributed at a ratio of 70% as glucose and 30% as fat.

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29.

Which of the following statement(s) is/are true concerning the indications and administration of nutritional support to cancer patients?

A.

Preoperative nutritional support should be provided to all patients with cancer
B.

To be effective, preoperative nutrition must be given for at least two weeks preoperatively
C.

Parenteral nutrition is the preferred route of feeding for all cancer patients
D.

Standard total parenteral nutrition solutions maintain integrity of the small bowel
E.

None of the above

Correct Answer
E. None of the above

Explanation
The role of nutritional support in the cancer patient remains an important component of overall therapy. Preoperative nutritional support should be given only to those patients who do not require an emergency operation and who have severe weight loss (> 15% of pre-illness body weight) and a serum albumen < 2.9 mg%. Preoperative nutrition (enteral or parenteral) should not be given for longer than 7 to 10 days. Enteral nutrition is always the preferred route of feeding cancer patients if the GI tract is functional. There are several benefits of using the bowel lumen for nutrient delivery. The trophic effects of enteral feeding on small bowel mucosa have been well described. The integrity of the mucosal lining is maintained and it may provide an effective barrier to intraluminal enteric organisms which might otherwise translocate into the systemic circulation. Atrophic changes may be seen in the intestinal epithelium after several days of bowel rest; this atrophy is not reversed by currently available total parenteral nutrition solutions.

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30.

Which of the following statement(s) concerning intravenous nutritional support is/are true?

A.

Concentrations of glucose no higher than 5% should be used to avoid peripheral vein sclerosis
B.

A major disadvantage of the peripheral technique is limited caloric delivery
C.

If total parenteral nutrition is required, access to the superior vena cava via the external jugular vein is the most suitable site
D.

Venous thrombosis is an uncommon complication for long-term central vein catheterization

Correct Answer
B. A major disadvantage of the peripHeral technique is limited caloric delivery

Explanation
Although peripheral access can be used for intravenous nutrition, the major disadvantage of this technique is limited caloric delivery to meet catabolic demands within tolerated fluid limits. Infusion of glucose (up to 10%), amino acid solutions, and fat emulsions can be administered peripherally but these solutions must be nearly isotonic to avoid peripheral vein sclerosis. The preferred method of access for total parenteral nutrition is into the superior vena cava by cutaneous cannulation of the subclavian vein. Alternative sites include the internal and external jugular vein but the catheter exiting from the neck region makes it more difficult to secure and maintain a sterile dressing. Complications from long-term central venous catheterization include venous thrombosis and venous catheter-related infection. Thrombosis of central vessels is a complication which is often overlooked. The clinical suspicion of subclavian vein thrombosis is only about 3%, whereas studies that use phlebography or radionucleotide venography indicate the incidence is as high as 35%.

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31.

Which of the following statement(s) is/are true concerning the role of glutamine in total parenteral nutrition?

A.

Glutamine is an essential amino acid
B.

Glutamine appears to be of primary benefit in critical illness
C.

Glutamine is included in most standard TPN solutions
D.

Glutamine is the primary energy source for intestinal mucosal cells of the small bowel and colon

Correct Answer
B. Glutamine appears to be of primary benefit in critical illness

Explanation
Glutamine is the most studied gut-specific nutrient. Glutamine has been classified as a nonessential or nutritionally dispensable amino acid since glutamine can be synthesized in adequate quantities from other amino acids and precursors. Glutamine is not included in most nutritional formulas and has been eliminated from TPN solutions because of its relative instability and short half life compared to other amino acids. With few exceptions, glutamine is present in oral enteral diets but only at relatively low levels characteristic of the concentration in most animal and plant stores (about 7% of total amino acids). Several recent studies, however, have demonstrated that glutamine may be an essential amino acid during critical illness, particularly as it relates to supporting the metabolic requirements of the intestinal mucosa. These studies demonstrate that dietary glutamine is not required during states of health but appears to be beneficial when glutamine depletion is severe and/or when intestinal mucosa is damaged by insults such as chemotherapy or radiation therapy. The addition of glutamine to enteral diet reduces the incidence of gut translocation but these improvements are dependent upon the amount of supplemental glutamine and the type of insult studied. Glutamine-enriched TPN partially attenuates villous atrophy that develops during parenteral nutrition. The use of intravenous glutamine in patients appears to be safe and effective in its ability to maintain muscle glutamine stores and improve nitrogen balance. In contrast to glutamine, short chain fatty acids are primary energy source for colonocytes.

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32.

Which of the following statements concerning perioperative nutrition is true concerning the above-described patient?

A.

Since the patient’s weight had been stable with no preoperative nutritional deficit, 5% dextrose intravenous solutions are adequate for the initial postoperative source of nutrition
B.

Preoperative immunologic status should be determined including total peripheral lymphocyte count and delayed hypersensitivity reaction to determine skin-test response to common antigens
C.

Routine postoperative fluid administration with intravenous 5% glucose solutions can provide the calories to meet basal energy requirements
D.

A jejunal feeding catheter should be placed at the time of surgery for postoperative enteral feeding

Correct Answer
A. Since the patient’s weight had been stable with no preoperative nutritional deficit, 5% dextrose intravenous solutions are adequate for the initial postoperative source of nutrition

Explanation
Most patients undergoing elective operations are adequately nourished. Unless the patient has suffered significant preoperative malnutrition, characterized by weight loss greater than 10–15%, or has major intraoperative or postoperative complications, solutions containing 5% dextrose may be administered for five to seven days before initiation of enteral nutrition, with no detrimental effect on outcome. The usual postoperative surgical patient is given intravenous glucose at 125 cc/hour receives about 500 kcal/day, far less than the actual number of kcal needed to meet energy requirements. The increased cost of feedings and potential complications associated with intravenous nutrition cannot be justified. Although the use of jejunal feedings in the postoperative period may be useful in some patients, especially those undergoing extensive gastrointestinal surgery, this technique would not appear indicated in the patient described above.

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33.

Which of the following statement(s) is/are true concerning the clinical management of an open wound?

A.

A wet-to-dry dressing is the most optimal form of wound management
B.

A moist occlusive dressing promotes epithelialization and reduces pain
C.

The protein rich plasma exudate covering the open wound facilitates healing
D.

Irrigation of the wound disrupts epithelialization therefore inhibiting the healing process

Correct Answer
B. A moist occlusive dressing promotes epithelialization and reduces pain

Explanation
Epithelialization is more rapid under moist conditions than dry conditions. Without dressings, a superficial wound, or one with minimal devitalized tissue forms a scab or crust, meaning that the blood and serum will coagulate, dry, and form a protective moisture barrier over the open wound. If a wound is kept moist with an occlusive dressing, then epithelial migration is optimized. In addition, the pain of an open wound is dramatically reduced under an occlusive dressing. The traditional wet-to-dry dressing if truly left to dry, simply produces desiccation and necrosis of the surface layer of the wound which delays epithelialization. Although wet-to-dry dressings can be effective for debridement of wound exudate, they are generally less desirable than a moist healing environment combined with effective cleaning of the wound (i.e. water irrigation). Any open wound will leak plasma. With more inflammation, the plasma capillary permeability is further increased. This exudate of serum proteins and inflammatory cells serves as a rich culture medium. This, in turn, will continue to cycle bacterial proliferation and lead to further exudate formation. The net result of this cycle is delayed or absent wound healing. In addition, the edema that results from capillary dysfunction, increases the distance for diffusion from oxygen and nutrient sources to their metabolic targets.

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34.

Which of the following statement(s) is/are correct concerning the management of an open wound?

A.

Frequent surgical debridement is usually necessary
B.

Water irrigation can effectively debride most wounds
C.

Hydrogen peroxide is particularly useful in the management of open wounds
D.

A number of the newer dressing products have clearly been shown to promote wound healing compared to simple moist occlusive dressing

Correct Answer
B. Water irrigation can effectively debride most wounds

Explanation
Although there are numerous dressing products commercially available at present, no treatment has been demonstrated to improve healing beyond that of standard treatment which adheres to basic principles. In the absence of large amounts of necrotic tissue, wound debridement does not need to be accomplished surgically. Simple water irrigation either with whirlpool or by water from a hand held shower spray can generate enough power to effectively debride most wounds. Frequent moist dressing changes can accomplish this as well, and in some cases, occlusive absorptive dressings can generate enough tissue proteases to effectively degrade proteins which the absorptive dressings remove. Deeper portions of a wound may accumulate exudate and bacteria. In such cases, water irrigation may be particularly useful. Commonly used agents such as hydrogen peroxide actually may be harmful to normal tissue and are weak oxidants and do a poor job of debriding. Enzymatic debriding agents can be effective when used properly. Most of the newer dressing products have been designed to be more absorptive and achieve moist healing without infection from excess exudate. However, it must be emphasized that as long as moist healing is achieved, there has been no evidence that one product is better than another.

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35.

Which of the following statement(s) is/are true concerning the role of antibiotics in wound care?

A.

Systemic antibiotics are indicated for all open wounds
B.

Bacterial resistance can occur with systemic but not topical antibiotics
C.

An indication for systemic antibiotic administration is a granulation tissue bacterial count in excess of greater than 105 organisms/gram of tissue on quantitative analysis
D.

Silver sulfadiazine is useful only for the management of burns

Correct Answer
C. An indication for systemic antibiotic administration is a granulation tissue bacterial count in excess of greater than 105 organisms/gram of tissue on quantitative analysis

Explanation
The role of antibiotics in wound care is controversial. All open wounds are colonized with bacteria. Only when surrounding tissue is invaded (cellulitis) are systemic antibiotics clearly indicated. Antibiotics may also be useful in other situations such as when granulation tissue has a high bacterial count (> 105 organisms/gram tissue), or in the case of reduced resistance to bacteria such as in a diabetic foot ulcer. The routine use of systemic antibiotics for chronic wounds should be avoided to reduce the development of resistant bacterial strains within the wound. Topical ointments are frequently used and can be useful. The topical vehicle may help keep the wound moist and the bacterial count in the wound may be lowered as the result. However, as with most antibiotics, resistant organisms quickly emerge. Silver sulfadiazine, frequently used for burn care, is also useful for chronic wounds. Its broad spectrum of activity, lack of relevant drug-resistant plasmids in bacteria, and its low cost make it a good choice.

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36.

Scar formation is part of the normal healing process following injury. Which of the following tissues has the ability to heal without scar formation?

A.

Liver
B.

Skin
C.

Bone
D.

Muscle

Correct Answer
C. Bone

Explanation
Every tissue in the body undergoes reparative processes after injury. Bone has the unique ability to heal without scar and liver has the potential to regenerate parenchyma, the only organ that has maintained that ability in the adult human. Although liver does regenerate, it often heals with scar (cirrhosis) as well. With these exceptions, all other mature human tissues heal with scar.

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37.

Which of the following factors have been demonstrated to promote wound healing in normal individuals?

A.

Vitamin A supplementation
B.

Vitamin C supplementation
C.

Vitamin E application to the wound
D.

Zinc supplementation
E.

None of the above

Correct Answer
E. None of the above

Explanation
Several important systemic factors or conditions influence wound healing. Interestingly, there are no known systemic conditions that lead to enhanced or more rapid wound healing. Overall nutrition as well as adequate vitamins play an important role in wound healing. Vitamin A is involved in the stimulation of fibroplasia, collagen cross-linking, and epithelialization. Although there is no conclusive evidence in humans, vitamin A may be useful clinically for steroid-dependent patients who have problematic wounds or who are undergoing extensive surgical procedures. Vitamin C is a necessary cofactor in hydroxylization of lysine and proline in collagen synthesis and cross-linkage. The utility of vitamin C supplementation in patients who otherwise take in a normal diet has not been established. Vitamin E is applied to wounds and incisions empirically by many patients. The evidence to support this practice is entirely anecdotal. In fact, large doses of vitamin E have been found to inhibit wound healing. Zinc and copper are also important cofactors for many enzyme systems that are important to wound healing. Deficiency states are seen with parenteral nutrition but are rare and readily recognized and treated with supplements. Overall, vitamin and mineral deficiency states are extremely rare in the absence of parenteral nutrition or other extreme dietary restrictions. There is no evidence to support the concept that supranormal provision of these factors enhance wound healing in normal patients.

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38.

Which of the following statement(s) is/are true concerning excessive scarring processes?

A.

Keloids occur randomly regardless of gender or race
B.

Hypertrophic scars and keloid are histologically different
C.

Keloids tend to develop early and hypertrophic scars late after the surgical injury
D.

Simple reexcision and closure of a hypertrophic scar can be useful in certain situations such as a wound closed by secondary intention

Correct Answer
D. Simple reexcision and closure of a hypertropHic scar can be useful in certain situations such as a wound closed by secondary intention

Explanation
True keloids are uncommon and occur predominantly in dark skinned people with a genetic predisposition for keloid formation. In most cases, the gene appears to be transmitted as an autosomal dominant pattern. The primary difference between a keloid and a hypertrophic scar is that a keloid extends beyond the boundary of the original tissue injury. It behaves as a tumor and extends into or invades the normal surrounding tissue creating a scar that is larger than the original wound. Histologically, keloids and hypertrophic scars are similar. Both contain an overabundance of collagen. Although the absolute number of fibroblasts is not increased, the production of collagen continually out paces the activity of collagenase, resulting in a scar of ever increasing dimensions. Hypertrophic scars respect the boundaries of the original injury and do not extend into normal unwounded tissue. There is less of a genetic predisposition, but hypertrophic scars also occur more frequently in Orientals and the Black population. They are often seen on the upper torso and across flexor surfaces. Some improvement in a keloid can be obtained with excision followed by intra-lesional steroid injection. However, the resulting scar is unpredictable and potentially worse. Reexcision and closure should, however, be considered for hypertrophic scars, if the condition of closure can be improved. This is especially pertinent for wounds that originally healed by secondary intention or that are complicated by infection. Keloids typically develop several months after the injury and rarely, if ever, subside. Hypertrophic scars usually develop within the first month after wounding and often subside gradually.

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39.

Which of the following statement(s) is/are true concerning the vascular response to injury?

A.

Vasoconstriction is an early event in the response to injury
B.

Vasodilatation is a detrimental response to injury with normal body processes working to avoid this process
C.

Vascular permeability is maintained to prevent further cellular injury
D.

Histamine, prostaglandin E2 (PGE2) and prostacyclin (PGI2) are important mediators of local vasoconstriction

Correct Answer
A. Vasoconstriction is an early event in the response to injury

Explanation
After wounding, there is transient vasoconstriction mediated by catecholamines, thromboxane, and prostaglandin F2 (PGF2a). This period of vasoconstriction lasts for only five to ten minutes. Once a clot has been formed and active bleeding has stopped, vasodilatation occurs in an around the wound. Vasodilatation increases local blood flow to the wounded area, supplying the cells and substrate necessary for further wound repair. The vascular endothelial cells also deform, increasing vascular permeability. The vasodilatation and increased endothelial permeability is mediated by histamine, PGE2, and prostacyclin as well as growth factor VEGF (vascular endothelial cell growth factor). These vasodilatory substances are released by injured endothelial cells and mast cells and enhance the egress of cells and substrate into the wound and tissue.

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40.

Bleeding complications are frequently associated with fibrinolytic therapy. Which of the following statement(s) concerning complications of fibrinolytic therapy is/are true?

A.

Careful monitoring of prothrombin time and aPTT time are necessary to avoid bleeding complications
B.

A level of serum fibrinogen less than 100 mg/dl is associated with an increased risk of bleeding
C.

Recent (less than 10 days) major surgery is a contraindication to systemic but not regional fibrinolytic therapy
D.

A patient with a cerebrovascular event occurring less than two months ago can be treated with fibrinolytic therapy if head CT scan is normal

Correct Answer
B. A level of serum fibrinogen less than 100 mg/dl is associated with an increased risk of bleeding

Explanation
Fibrinolytic therapy induces a hemostatic defect through a combination of factors. Hypofibrinogenemia and fibrin degradation products inhibit fibrin polymerization and, in combination with a decrease in the clotting factors V and VIII, prolong the ability of blood to clot. However, coagulation tests in general do not correlate well with bleeding complications. A level of fibrinogen less than 100 mg/dl is associated with an increased risk of bleeding. Absolute contraindications to thrombolytic therapy include active internal bleeding, recent (less than 2 months) cerebral vascular accident, and documented left heart thrombosis. Recent (less than 10 days) major surgery, obstetric delivery, organ biopsy, or major trauma is considered a major relative contraindication to either regional or systemic thrombolytic therapy.

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41.

Which of the following statements regarding IL-1 are correct?

A.

While IL-1 and TNFa share many biologic effects, IL-1 appears to be more potent
B.

IL-1 expression is in part autoregulated
C.

IL-1 inhibits prostaglandin production
D.

The ability of IL-1 to upregulate endothelial cell-neutrophil adhesion molecules is relatively limited

Correct Answer
B. IL-1 expression is in part autoregulated

Explanation
IL-1 and TNFa share many biologic properties. In addition, each potentiates the effects of the other one when given concurrently. Overall, IL-1 alone probably has weaker effects than TNFa with respect to the induction of shock; its role is likely to be important with respect to its marked potentiating abilities as it relates to TNFa. IL-1 expression is regulated by a host of factors including IL-2, granulocyte macrophage colony stimulating factor (GM-CSF), transforming growth factor b (TGF-b), TNFa, all of the interferons, and IL-1 itself. Other endogenous stimuli for IL-1 production include antigen-antibody complex, the Fc region of IgG, and C5a; other nonspecific exogenous stimuli include silica particles and UV irradiation.
One of the key proinflammatory features of IL-1-induced inflammation is the stimulation of arachadonic acid metabolism. IL-1 stimulates the release of pituitary stress hormones and increases the synthesis of collagenases, resulting in the destruction of cartilage, bone and other collagen-rich structures. IL-1 stimulates prostaglandin production.
One of the most important properties of IL-1 involves its interaction with the vascular endothelium. This includes the adherence of neutrophils, basophils, eosinophils, monocytes, and lymphocytes to the vascular endothelium via interaction between adhesion molecules on leukocytes and adhesion-receptor complex on the endothelial cells. By inducing the expression of ICAM-1, E-selectin, and VCAM-1 on endothelial cells, IL-1 provides a key step in the extravasation of leukocytes to sites of local inflammation and injury.

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42.

Which of the following statement(s) is/are true concerning the antibody response to an invading antigen?

A.

All antibodies are composed of one type of heavy and one type of light protein chain
B.

The carboxyl terminus of the heavy chain is the antigen binding site
C.

Antibody of the immunoglobulin G class is the initial antibody produced in response to an antigenic stimulus
D.

Immunoglobulins A, D, and E play an active role in the circulating humoral response

Correct Answer
A. All antibodies are composed of one type of heavy and one type of light protein chain

Explanation
Humoral defenses consist of antibody (immunoglobulin; Ig) and complement. All Ig classes (IgM, IgG, IgA, IgE, IgD) and IgG subclasses are composed of one type (M, G, A, E, D) of heavy and one type (K and g ) of light protein chains that consist of several domains both structurally and functionally. Each Ig molecule contains one or more units that consist of two heavy and two light chains linked by disulfide bonds. The amino terminus of both heavy and light chains contain several hypervariable regions that fold in three dimensions to produce the antigen-binding site. The carboxyl terminus of the heavy chains contain regions that activate complement and bind Fc receptors, by which direct adherence to polymorphonuclear leukocytes and macrophages take place after antigen binding occurs.
Initially, antibody of the IgM class is produced in response to an antigenic stimulus. A second exposure to the same antigen, or a cross-reactive antigen, leads to the so-called second set response, in which antibody of the IgG class with two binding sites is produced more rapidly and in larger quantity compared to the initial IgM primary response. Immunoglobulin of the IgA class is secreted by gut-associated lymphoid tissue and is combined with secretory components of protein to form a dimer termed secretory IgA. This antibody acts at a variety of epithelial sites to prevent microbial adherence and invasion. IgD and IgE exist in smaller amounts in the circulation and do not appear to play a major role as host defense components.

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43.

The use of antibiotics can be based on either the clinical course of a patient without the benefit of well-defined microbiologic data (empiric therapy), or targeted at specific identified pathogens once sensitivity reports are available (directed therapy). The following statement(s) is/are true concerning these therapies.

A.

The issue of toxic side effects of antibiotics is only important in dealing with emperic therapy
B.

Single agent therapy is generally inferior to specific multi-drug therapy (aminoglycoside plus an antianaerobic agent) for the treatment of secondary bacterial peritonitis due to appendicitis, diverticulitis, penetrating gastrointestinal injury, or anastomotic leak
C.

With the empiric use of antibiotics, a diligent search for the septic source should be undertaken and continued until identified
D.

In clinical situations in which polymicrobial infection is identified, specifically-directed treatment for the predominant organism is satisfactory

Correct Answer
C. With the empiric use of antibiotics, a diligent search for the septic source should be undertaken and continued until identified

Explanation
The use of empiric therapy without the benefit of well-defined microbiologic data is appropriate when there is sufficient clinical evidence to support the diagnosis such that it would be imprudent to withhold antimicrobial therapy. In this setting, however, a diligent search for the septic focus source should be undertaken and continued (cultures, radiographic procedures, etc.), and initial limits should be placed in the course of empiric therapy with continued reevaluation based on the clinical course of the patient. The choice of antibiotic agents should be based on the clinical situation and known activity patterns within the given institution. Single broad-spectrum agents, although suffering slightly from a lack of individual pathogen specificity, are useful in this setting in that they provide a broad coverage against several groups of pathogens and may avoid some of the toxic effects with specific combined modality regimens. Similarly, for directed therapy, single-agent therapy has been demonstrated to be equivalent to combined therapy and should be chosen in an attempt to select agents with appropriate sensitivities which retain suitable clinical efficacy but exhibit minimal toxicity. After review of cultural reports, many patients have demonstrated polymicrobial infection. Because experimental clinical evidence supports the concept of aerobic-anaerobic synergy, therapy should be directed against all potential components of the infection if the body site is such that these microorganisms may be present.

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44.

Cytokines are low-molecular-weight polypeptides exerting a wide variety of biologic effects at both local and systemic levels. Which of the following statement(s) is/are true concerning the production and actions of cytokines?

A.

Cytokines are produced solely by macrophages
B.

Cytokines act only on other cells within the same local environment
C.

Cytokines may have both protective and deleterious effects on the host
D.

Each specific cytokine is produced by a single cell type

Correct Answer
C. Cytokines may have both protective and deleterious effects on the host

Explanation
Macrophages, endothelial cells, lymphocytes, and other cells secrete a large number of different compounds, termed cytokines, that are most probably evolved for the purpose of local intercellular and intracellular signaling. Cytokines frequently are secreted after initial lymphocyte or macrophage activation, and may act on the secreting cell itself (autocrine activation) or on other cells within the same local environment (paracrine activation) to cause increased secretion of the same cytokine or other cytokines, respectively. Some cytokines are produced by several cell types, and most produce a wide array of effects. The duality of the effects of the cytokine component of host defenses, exerting both salutatory and deleterious effects on the host, has become increasingly evident.

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45.

The use of prophylactic antibiotics has become commonplace. Which of the following statement(s) is/are true concerning the prophylactic use of antibiotics?

A.

The appropriate use of prophylactic antibiotics must include the initiation of the agent prior to the surgical procedure
B.

Continuing the antibiotic into the postoperative period has led to improved results in antibiotic prophylaxis
C.

The prophylactic administration of broad-spectrum agents (third-generation cephalosporins) has been shown to be particularly advantageous
D.

The topical use of antimicrobial agents is of no advantage in the prophylactic setting

Correct Answer
A. The appropriate use of propHylactic antibiotics must include the initiation of the agent prior to the surgical procedure

Explanation
Intravenous administration of an antibiotic is clearly indicated for patients undergoing clean contaminated operations. These antibiotics should be administered prior to surgery to obtain adequate tissue levels at the time of potential contamination. However, there has been no added benefit demonstrated for the postoperative use of antibiotics with regard to prophylaxis. The choice of antibiotic is a complex issue which remains unresolved largely because both superficial and deep wound infections can occur as a result of either or both skin (superficial wound) flora (e.g., Staphylococcus aureus) and body site (deep wound) infection. For this reason, the administration of agents which possess activity directed against these expected agents is reasonable. Although administration of a first-generation cephalosporin is acceptable, second-generation cephalosporins or extended-spectrum penicillins with gram-positive and gram-negative activity and biliary tract excretion may be more suitable for patients undergoing gastrointestinal or biliary tract procedures. Similarly, the use of agents with additional anaerobic activity for patients undergoing gastrointestinal procedures involving the small bowel or colon should be considered. The administration of broad-spectrum agents such as third-generation cephalosporins for prophylaxis does not seem to provide additional benefit in comparison to the above-mentioned type antibiotics and may foster the development of resistant organisms within a given institution or superinfection within a given patient. There is evidence that in some cases the topical use of antimicrobial agents is equivalent to the administration of intravenous antimicrobial agent antibiotics.

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46.

New treatment modalities designed to modulate host defense mechanisms that have been demonstrated conclusively to be of benefit include:

A.

Gut decontamination
B.

Anti-LPS antibody
C.

Anti-TNF antibody
D.

Thymopentin
E.

None of the above

Correct Answer
E. None of the above

Explanation
Selective gut decontamination involves the use of orally administered antibiotics that achieve a high intraluminal level directed against gram-negative aerobes and yeast, leaving the host anaerobic intestinal microflora relatively undisrupted. Although a reduction and alteration of the microorganisms responsible for infectious episodes have been demonstrated in certain groups of patients, a clear-cut impact on host mortality has not been shown. Because LPS may be responsible for toxicity both directly and through host mediator systems, the availability of agents to bind against this portion of the gram-negative bacteria to reduce mortality has been intensively examined. Unfortunately, large multicenter randomized trials provide no evidence of benefit for this treatment. Similarly, since many of the systemic manifestations of gram-negative bacteremia are mediated by cytokines, the effect of an anti-TNF antibody preparation is currently in clinical trial. No proven benefits have yet been identified. Finally, the use of immunostimulants to enhance the state of activation of host defenses has been proposed. Thymopentin is a peptide that contains active thymopoetin, a thymic molecule that acts to stimulate T-lymphocyte activity. Preliminary trials indicate that this agent ameliorates host septic response after major operations and trauma but conclusive evidence that concurrent reduction of infection-related mortality occurs is not available.

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47.

Which of the following statement(s) is/are true concerning the diagnosis and management of hypovolemic shock?

A.

A fall in hematocrit or hemoglobin always accompanies hemorrhagic shock
B.

The treatment of shock is generic regardless of the etiology
C.

Pharmacologic intervention to increase myocardial contractility in hypovolemic shock is an important part the early management
D.

Complications are less frequent after treatment of hemorrhagic shock than septic or traumatic shock

Correct Answer
D. Complications are less frequent after treatment of hemorrhagic shock than septic or traumatic shock

Explanation
Hypovolemic shock is readily diagnosed when there is an obvious source of volume loss and overt signs of hemodynamic instability and increased adrenergic output are present. After acute hemorrhage, hemoglobin and hematocrit values do not change until compensatory fluid shifts have occurred or exogenous fluid is administered. These values decrease once transcapillary refill, osmotic-induced shifts, or non-RBC volume resuscitation expands the blood volume. It is imperative that the distinction be made between hypovolemic and cardiogenic forms of shock, because appropriate therapy differs dramatically. Restoration of perfusion in hypovolemic shock requires reexpansion of circulating blood volume in conjunction with necessary interventions to control ongoing volume loss. Continued hemodynamic instability after fluid resuscitation implies that shock has not been reversed or that there is ongoing blood or volume loss. In severe, prolonged hypovolemia, ventricular contractile function may itself become depressed and require inotropic support to maintain ventricular performance, but in general, pharmacologic interventions directed toward increased contractility in situations of inadequate preload are ineffective, further complicate metabolic derangements, and are not indicated until adequate volume replacement has been completed. Complications are less frequent after treatment of hemorrhagic shock than in situations of septic or traumatic shock. In the later circumstances, the massive activation of inflammatory mediator response systems and consequences of their disseminated, indiscriminate cellular injury can be quite profound.

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48.

A 22-year-old man sustains a single stab wound to the left chest and presents to the emergency room with hypotension. Which of the following statement(s) is/are true concerning his diagnosis and management?

A.

The patient likely is suffering from hypovolemic shock and should respond quickly to fluid resuscitation
B.

Beck’s triad will likely be an obvious indication of compressive cardiogenic shock due to pericardial tamponade
C.

Echocardiography is the most sensitive noninvasive approach for diagnosis of pericardial tamponade
D.

The placement of bilateral chest tubes will likely resolve the problem

Correct Answer
C. EchocardiograpHy is the most sensitive noninvasive approach for diagnosis of pericardial tamponade

Explanation
Shock from cardiac compression occurs when external pressure on the heart impairs ventricular filling. Because ventricular filling is a function of venous return and myocardial compliance, any process that places pressure on the heart can cause compressive cardiogenic shock. Included among these are pericardial tamponade, tension pneumothorax, mediastinal hematoma, and positive pressure from mechanical ventilation. Any patient with hypotension after a wound in proximity of the heart should be considered to have compressive cardiogenic shock until proven otherwise. The classical clinical findings of pericardial tamponade include Beck’s triad of hypotension, neck vein distention and muffled heart sounds. Pulses paradoxus may be noted (this involves a decrease rather than the normal increase of systolic blood pressure with inspiration; values 10mmHg are significant). These findings, however, may be obscured in a noisy emergency room environment by positive pressure ventilation or by associated injuries. Placement of a CVP catheter confirms the elevation of right-sided filling pressure. If a pulmonary artery catheter has been placed, findings consistent with tamponade or other forms of cardiac compression are a trend toward equalization of chamber pressures as hypotension progresses. In the patient at risk, echocardiography is an extremely sensitive and noninvasive approach to demonstrate pericardial fluid and the need for operation. Pericardial tamponade must be relieved urgently and cardiac injuries require emergent sternotomy. Chest tube placement would not be appropriate as the sole treatment in this patient.

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49.

A 32-year-old man suffers a spinal cord injury with a resultant paraplegia in a motorcycle accident. He presents to the emergency room with hypotension. Which of the following statement(s) is/are true concerning his diagnosis and management?

A.

The low blood pressure can be assumed to be due to neurogenic shock
B.

The sole cause of hypotension is the loss of sympathetic input to the venous system
C.

Despite significant hypotension, secondary organ injury will be uncommon
D.

There is no role for pharmacologic intervention to maintain blood pressure

Correct Answer
C. Despite significant hypotension, secondary organ injury will be uncommon

Explanation
Neurogenic shock results from interruption of sympathetic vasomotor input and develops after spinal cord injury, spinal anesthesia, and severe head injury. Under normal conditions, baseline sympathetic activity establishes a degree of arteriolar and venous constriction. Ablation of this tone results in decreased systemic vascular resistance and a dramatic increase in venous capacity, causing hypotension due to relative hypovolemia. Arteriolar dilatation not only lowers the systemic vascular resistance but also allows previously unopened vascular beds to be perfused, greatly expanding venous capacity. Removal of sympathetic inputs to innervated portions of the venous system allows further venodilatation. Restoration of an effective, albeit expanded, intravascular volume may require extremely large volumes of resuscitation fluid to restore normal cardiac filling pressures. This will restore cardiac output and reverse hypotension. However, pharmacologic intervention with vasoactive drugs may be necessary and is preferable to excessive volume resuscitation. Post-shock sequelae are infrequent. Although there is significant hypotension with neurogenic shock, there is usually little if any hypoperfusion. Thus, activation of inflammatory cascade and subsequent organ injury rarely occur.
A major pitfall in the management of neurogenic shock arises when there is coexistent hemorrhage or ongoing volume loss that is not appreciated. This is not an unusual situation because cervical spine trauma causing paraplegia or severe head injury is frequently associated with multiple injuries. Thus, in trauma the initial response to neurogenic shock is large volume resuscitation regardless of the presumed etiology. If hemodynamic instability persists after initial trauma resuscitation, one must assume that the cause is not neurogenic and search for occult blood loss or cardiogenic causes of shock.

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50.

Which of the following statement(s) is/are true concerning septic shock?

A.

The clinical picture of gram negative septic shock is specifically different than shock associated with other infectious agents
B.

The circulatory derangements of septic shock precede the development of metabolic abnormalities
C.

Splanchnic vascular resistance falls in similar fashion to overall systemic vascular resistance
D.

Despite normal mechanisms of intrinsic expansion of the circulating blood volume, exogenous volume resuscitation is necessary

Correct Answer
D. Despite normal mechanisms of intrinsic expansion of the circulating blood volume, exogenous volume resuscitation is necessary

Explanation
The clinical findings in sepsis and septic shock represent the host response to infection. Gram-positive and gram-negative bacteria, viruses, fungi, rickettsiae, and protozoa have all been reported to produce a clinical picture of septic shock, but the overall response is independent of the specific type of invading organism. Septic shock develops as a consequence of the combination metabolic and circulatory derangements accompanying the systemic infection. It appears that the circulatory deficits are preceded by the metabolic abnormalities induced by infection. In fact, the circulatory changes in hyperdynamic sepsis appear to be an adaptive response to the underlying metabolic dysfunction. Cardiac output is high and systemic vascular resistance low in hyperdynamic septic shock. However, splanchnic vasoconstriction is pronounced even in the absence of systemic hypotension and even though systemic vascular resistance is reduced. Expansion of circulating blood volume can occur through either transcapillary refill or fluid resuscitation. Due to the ongoing inflammatory mediator-induced increases in capillary permeability and continued loss of intravascular volume, exogenous volume resuscitation must be provided to restore venous return and ventricular filling.

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