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ABS Surgical Critical Care study materials
ABS Surgical Critical Care study resources

ABS Surgical Critical Care practice questions

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Question 1Biology of critical illness and support of organ system function

In a patient with septic shock, which hemodynamic pattern is most characteristic of the distributive phase before fluid resuscitation?

  1. High systemic vascular resistance with low cardiac output
  2. Elevated pulmonary capillary wedge pressure with reduced ejection fraction
  3. Fixed cardiac output with a wide arteriovenous oxygen difference
  4. Low systemic vascular resistance with normal or high cardiac output Correct answer.

Explanation

Distributive shock from sepsis is defined by pathologic vasodilation, so systemic vascular resistance falls and cardiac output is typically normal or elevated in the early resuscitated phase. The other patterns describe cardiogenic or hypovolemic physiology.

Question 2Biology of critical illness and support of organ system function

Which acid-base disturbance is most consistent with prolonged severe vomiting?

  1. Respiratory alkalosis with hypoxemia
  2. High anion gap metabolic acidosis
  3. Metabolic acidosis with hyperkalemia
  4. Metabolic alkalosis with hypokalemia Correct answer.

Explanation

Vomiting removes gastric hydrochloric acid and causes volume and chloride depletion, generating a chloride-responsive metabolic alkalosis; renal potassium wasting produces hypokalemia. The other patterns do not follow gastric acid loss.

Question 3Biology of critical illness and support of organ system function

A patient in the ICU has a serum sodium of 118 mmol/L after several days of poor intake and free water excess. Which initial correction strategy is safest?

  1. Slow correction with a rise of no more than about 8 to 10 mmol/L in 24 hours Correct answer.
  2. Withholding all sodium until symptoms resolve
  3. Free water restriction alone with no monitoring of sodium
  4. Rapid correction to 135 mmol/L within 6 hours

Explanation

Severe hyponatremia must be corrected gradually because overly rapid rises risk osmotic demyelination. A limit of roughly 8 to 10 mmol/L per 24 hours is standard, with faster initial correction reserved for active seizures.

Question 4Biology of critical illness and support of organ system function

Which finding best distinguishes acute respiratory distress syndrome from cardiogenic pulmonary edema at the bedside?

  1. Presence of frothy pink sputum
  2. Normal or low pulmonary capillary wedge pressure with refractory hypoxemia Correct answer.
  3. Bilateral infiltrates on chest radiograph
  4. Elevated brain natriuretic peptide level

Explanation

ARDS is a noncardiogenic permeability edema, so filling pressures are typically normal or low and hypoxemia is refractory to supplemental oxygen. Cardiogenic edema is driven by elevated hydrostatic pressure.

Question 5Biology of critical illness and support of organ system function

Which mechanism is the principal cause of hypoxemia in early acute respiratory distress syndrome?

  1. Intrapulmonary shunt from flooded alveoli Correct answer.
  2. Diffusion block from thickened pleura
  3. Hypoventilation from sedation
  4. Reduced inspired oxygen fraction

Explanation

Alveoli filled with proteinaceous edema fluid are perfused but not ventilated, creating true right-to-left shunt that is poorly responsive to supplemental oxygen. Hypoventilation and low inspired oxygen are not the primary lesions.

Question 6Biology of critical illness and support of organ system function

A ventilated patient with severe ARDS has a plateau pressure of 34 cm H2O and a tidal volume of 6 mL/kg predicted body weight. Which adjustment best follows lung-protective principles?

  1. Increase positive end-expiratory pressure without limit
  2. Reduce tidal volume and accept permissive hypercapnia to lower plateau pressure Correct answer.
  3. Increase tidal volume to improve carbon dioxide clearance
  4. Switch to pressure support ventilation at the same pressures

Explanation

Lung-protective ventilation targets plateau pressure at or below about 30 cm H2O to limit barotrauma, so tidal volume should be reduced with tolerance of hypercapnia. Raising volume or unbounded PEEP worsens alveolar stress.

Question 7Biology of critical illness and support of organ system function

Which parameter is the most reliable bedside indicator of adequate oxygen delivery relative to consumption in a critically ill patient?

  1. Respiratory rate
  2. Urine specific gravity
  3. Arterial oxygen saturation alone
  4. Central venous oxygen saturation with lactate trend Correct answer.

Explanation

Mixed or central venous oxygen saturation reflects the balance between oxygen delivery and consumption, and a falling lactate indicates improving tissue perfusion. Saturation alone does not capture delivery or consumption.

Question 8Biology of critical illness and support of organ system function

Which change in renal physiology is most characteristic of early prerenal azotemia?

  1. Elevated urinary sodium with muddy brown casts
  2. Fractional excretion of sodium above 2 percent with dilute urine
  3. Fixed urine osmolality equal to plasma
  4. Fractional excretion of sodium below 1 percent with concentrated urine Correct answer.

Explanation

In prerenal states the tubules remain intact and avidly reabsorb sodium and water, producing a low fractional excretion of sodium and concentrated urine. Intrinsic injury impairs reabsorption and raises urinary sodium.

Question 9Biology of critical illness and support of organ system function

A patient with septic shock has a rising creatinine and oliguria despite adequate mean arterial pressure. Which intervention most directly addresses the underlying renal insult in this setting?

  1. Immediate hemodialysis regardless of metabolic status
  2. Dopamine infusion at renal-dose range
  3. Restoration of renal perfusion and treatment of the septic source Correct answer.
  4. High-dose loop diuretic to increase urine output

Explanation

Septic acute kidney injury is driven by altered perfusion and inflammation, so restoring hemodynamics and controlling the infection source addresses the cause. Diuretics and renal-dose dopamine do not improve outcomes and may cause harm.

Question 10Biology of critical illness and support of organ system function

Which electrolyte abnormality most directly predisposes to prolonged QT interval and torsades de pointes?

  1. Hypernatremia
  2. Hyperphosphatemia
  3. Hypocalcemia
  4. Hypomagnesemia Correct answer.

Explanation

Magnesium deficiency impairs repolarization and prolongs the QT interval, predisposing to torsades de pointes. Repletion of magnesium is required even when serum levels are borderline.

Question 11Biology of critical illness and support of organ system function

A patient with acute decompensated heart failure is hypotensive with cold extremities and a high lactate. Which profile best describes this presentation?

  1. Cold and dry with normal cardiac output
  2. Warm and dry with low filling pressures
  3. Warm and wet with high cardiac output
  4. Cold and wet with elevated filling pressures and low cardiac output Correct answer.

Explanation

Low-output cardiogenic shock produces cool extremities and congestion with elevated filling pressures and lactate elevation from hypoperfusion. The warm profiles fit distributive or compensated states.

Question 12Biology of critical illness and support of organ system function

Which physiologic effect explains why norepinephrine is first-line in septic shock?

  1. Direct increase in myocardial contractility through phosphodiesterase inhibition
  2. Selective beta-2 agonism causing bronchodilation
  3. Blockade of histamine receptors reducing capillary leak
  4. Alpha-1 mediated vasoconstriction that raises systemic vascular resistance Correct answer.

Explanation

Norepinephrine restores vascular tone primarily through alpha-1 vasoconstriction, raising mean arterial pressure in vasodilatory shock, with modest beta-1 inotropy. It is not a phosphodiesterase inhibitor or antihistamine.

Question 13Biology of critical illness and support of organ system function

A patient receiving high-dose vasopressors remains hypotensive with a normal central venous pressure. Which additional assessment best guides fluid responsiveness?

  1. Single measurement of central venous pressure
  2. Urine output over the prior hour
  3. Passive leg raise producing a rise in cardiac output Correct answer.
  4. Serum lactate level alone

Explanation

Dynamic measures such as a passive leg raise or stroke volume variation predict fluid responsiveness better than static pressures. Central venous pressure alone correlates poorly with volume status.

Question 14Biology of critical illness and support of organ system function

Which coagulation abnormality is most typical of early disseminated intravascular coagulation?

  1. Prolonged prothrombin time with low fibrinogen and elevated D-dimer Correct answer.
  2. Isolated thrombocytosis with normal fibrinogen
  3. Isolated prolongation of bleeding time with normal platelet count
  4. Elevated factor VIII with shortened partial thromboplastin time

Explanation

DIC consumes clotting factors and platelets while generating fibrin degradation products, so prothrombin time lengthens, fibrinogen falls, and D-dimer rises. Platelet counts typically fall rather than rise.

Question 15Biology of critical illness and support of organ system function

Which nutritional strategy is best supported in the first week for a hemodynamically stable critically ill patient who cannot eat?

  1. Prolonged fasting until bowel sounds return
  2. High-dose glutamine supplementation
  3. Immediate full-calorie parenteral nutrition on day one
  4. Early enteral nutrition with gradual advancement toward goal Correct answer.

Explanation

Early enteral feeding within 24 to 48 hours supports gut integrity and is preferred over parenteral nutrition when the gut works. Full-calorie feeding too early and routine glutamine have not shown benefit and may cause harm.

Question 16Biology of critical illness and support of organ system function

Which statement best describes the stress response to critical illness regarding glucose metabolism?

  1. Counterregulatory hormones increase hepatic gluconeogenesis and insulin resistance Correct answer.
  2. Inflammatory mediators improve insulin sensitivity
  3. Cortisol suppresses hepatic glucose output
  4. Insulin secretion is uniformly increased with enhanced peripheral uptake

Explanation

Cortisol, catecholamines, and glucagon rise in critical illness, driving gluconeogenesis and insulin resistance, producing stress hyperglycemia. Inflammatory mediators worsen rather than improve insulin sensitivity.

Question 17Biology of critical illness and support of organ system function

A patient with septic shock has refractory hypotension despite fluids and norepinephrine. Which intervention is most appropriate next according to current guidance?

  1. Add vasopressin to reduce catecholamine requirements Correct answer.
  2. Start a beta-blocker to control tachycardia
  3. Begin renal replacement therapy for blood pressure control
  4. Give a large bolus of hydroxyethyl starch

Explanation

Vasopressin is added as a second vasopressor in catecholamine-refractory septic shock to reduce adrenergic dose requirements. Beta-blockade, starch, and dialysis are not indicated for refractory hypotension.

Question 18Biology of critical illness and support of organ system function

Which finding on arterial blood gas most suggests a primary respiratory alkalosis rather than metabolic acidosis with respiratory compensation?

  1. Low partial pressure of carbon dioxide with a low bicarbonate
  2. Low bicarbonate with a low partial pressure of carbon dioxide
  3. Low partial pressure of carbon dioxide with a normal or high bicarbonate Correct answer.
  4. High partial pressure of carbon dioxide with a high bicarbonate

Explanation

In a primary respiratory alkalosis, carbon dioxide falls and bicarbonate is normal acutely or rises with renal compensation. A low bicarbonate with low carbon dioxide reflects metabolic acidosis with respiratory compensation.

Question 19Biology of critical illness and support of organ system function

Which mechanism best explains hypoxemia in a patient with a large right-to-left intracardiac shunt?

  1. Diffusion limitation across the alveolar membrane
  2. Deoxygenated blood bypassing ventilated lung Correct answer.
  3. Ventilation-perfusion mismatch that responds well to oxygen
  4. Alveolar hypoventilation

Explanation

In a true shunt, deoxygenated blood enters the systemic circulation without contacting ventilated alveoli, so hypoxemia is poorly responsive to supplemental oxygen. Hypoventilation and diffusion limitation behave differently.

Question 20Biology of critical illness and support of organ system function

Which of the following is the most appropriate initial fluid choice for resuscitation of a patient with septic shock and no contraindication?

  1. Five percent dextrose in water
  2. Hypertonic saline
  3. Albumin as the first-line fluid
  4. Balanced crystalloid Correct answer.

Explanation

Balanced crystalloids are recommended for initial resuscitation in sepsis because they avoid the hyperchloremic acidosis associated with large volumes of normal saline. Hypertonic saline and dextrose are not resuscitation fluids.

Question 21Biology of critical illness and support of organ system function

A patient with acute pancreatitis develops hypocalcemia and tetany. Which mechanism best explains the low calcium?

  1. Increased intestinal calcium absorption
  2. Saponification of peripancreatic fat binding calcium Correct answer.
  3. Elevated parathyroid hormone secretion
  4. Increased renal calcium reabsorption

Explanation

Pancreatic lipases release fatty acids that bind calcium in a process of fat saponification, lowering serum calcium in severe pancreatitis. Parathyroid hormone rises in response to hypocalcemia rather than causing it.

Question 22Biology of critical illness and support of organ system function

Which physiologic change of normal aging most affects the dosing of renally cleared drugs in critically ill elderly patients?

  1. Reduced lean body mass and declining glomerular filtration Correct answer.
  2. Increased glomerular filtration rate
  3. Enhanced hepatic first-pass metabolism
  4. Increased total body water

Explanation

Aging reduces lean body mass and glomerular filtration, so renally cleared drugs accumulate and loading doses may need adjustment for body composition. Filtration declines rather than rises, and total body water tends to fall.

Question 23Biology of critical illness and support of organ system function

Which finding most suggests that a patient with acute respiratory failure will benefit from noninvasive positive pressure ventilation rather than immediate intubation?

  1. Refractory hypoxemia with multiorgan failure
  2. Copious secretions with an unprotected airway
  3. Hemodynamic instability with a rising lactate
  4. Hypercapnic respiratory failure from a chronic obstructive pulmonary disease exacerbation with preserved mental status Correct answer.

Explanation

Noninvasive ventilation reduces intubation and mortality in hypercapnic exacerbations of chronic obstructive pulmonary disease when the airway is protected and the patient is cooperative. Refractory hypoxemia, inability to protect the airway, and instability are contraindications.

Question 24Biology of critical illness and support of organ system function

Which mechanism underlies the lactic acidosis associated with prolonged hypoperfusion?

  1. Reduced lactate clearance by the liver as the only mechanism
  2. Impaired renal excretion as the sole cause
  3. Anaerobic metabolism producing lactate when oxygen delivery falls below demand Correct answer.
  4. Excess lactate production from increased oxidative phosphorylation

Explanation

When oxygen delivery cannot meet demand, cells shift to anaerobic glycolysis and generate lactate, though impaired clearance also contributes. Increased oxidative phosphorylation would reduce rather than raise lactate.

Question 25Biology of critical illness and support of organ system function

A patient with severe traumatic brain injury has an intracranial pressure of 25 mm Hg. Which physiologic principle best guides therapy?

  1. Keep the head of bed flat to promote venous drainage
  2. Maintain cerebral perfusion pressure by supporting mean arterial pressure while controlling intracranial pressure Correct answer.
  3. Hyperventilate to a carbon dioxide of 20 mm Hg continuously
  4. Restrict sodium to reduce cerebral edema

Explanation

Cerebral perfusion pressure equals mean arterial pressure minus intracranial pressure, so therapy supports arterial pressure while lowering intracranial pressure through positioning and osmotic therapy. Prolonged severe hypocapnia risks ischemia.

Question 26Biology of critical illness and support of organ system function

In a healthy adult at rest, which factor most directly determines the oxygen content of arterial blood?

  1. Serum bicarbonate and arterial pH
  2. Cardiac output and systemic vascular resistance
  3. Hemoglobin concentration and arterial oxygen saturation Correct answer.
  4. Arterial partial pressure of oxygen alone

Explanation

Arterial oxygen content is dominated by the hemoglobin-bound fraction, computed as roughly 1.34 times hemoglobin times saturation, with a small dissolved component from PaO2. Saturation and hemoglobin therefore drive content far more than PaO2 by itself.

Question 27Biology of critical illness and support of organ system function

A patient has a mixed venous oxygen saturation of 50% with normal arterial saturation. Which interpretation is most consistent with this value?

  1. There is a large right-to-left shunt at the pulmonary level
  2. Oxygen consumption has fallen below normal baseline
  3. Oxygen delivery is inadequate relative to tissue oxygen consumption Correct answer.
  4. The patient has carbon monoxide poisoning

Explanation

Mixed venous saturation reflects the balance of oxygen delivery and consumption; a low value means tissues are extracting a greater fraction of delivered oxygen. This pattern suggests delivery is insufficient for demand or consumption is elevated.

Question 28Biology of critical illness and support of organ system function

Which acid-base disturbance is most characteristic of prolonged vomiting with loss of gastric contents?

  1. Metabolic alkalosis with hypochloremia Correct answer.
  2. High anion gap metabolic acidosis
  3. Metabolic acidosis with hyperchloremia
  4. Respiratory acidosis with hypercapnia

Explanation

Loss of hydrochloric acid and volume depletion generate a hypochloremic metabolic alkalosis with volume contraction maintaining the alkalosis. The kidney conserves chloride and excretes bicarbonate poorly in this setting.

Question 29Biology of critical illness and support of organ system function

A patient with severe acute kidney injury has a serum potassium of 7.2 mmol/L with peaked T waves on ECG. Which intervention most rapidly stabilizes the myocardium?

  1. Intravenous regular insulin with dextrose
  2. Intravenous calcium gluconate Correct answer.
  3. Intravenous sodium bicarbonate
  4. Oral sodium polystyrene sulfonate

Explanation

Calcium antagonizes the membrane effects of hyperkalemia at the cardiac membrane within minutes, protecting against arrhythmia while potassium is shifted or removed. It does not lower serum potassium itself.

Question 30Biology of critical illness and support of organ system function

Which mechanism best explains the hyperchloremic metabolic acidosis produced by large-volume infusion of 0.9% sodium chloride?

  1. Excess chloride relative to sodium reduces the strong ion difference Correct answer.
  2. Renal tubular bicarbonate reabsorption is stimulated
  3. Unmeasured anions such as ketones are generated
  4. Lactate accumulates because of impaired hepatic clearance

Explanation

Normal saline has equal sodium and chloride concentrations, and the high chloride load lowers the strong ion difference, producing a dilutional hyperchloremic acidosis. The kidney cannot excrete the chloride load quickly enough.

Question 31Biology of critical illness and support of organ system function

Which hemodynamic pattern is most typical of cardiogenic shock from acute left ventricular failure?

  1. High cardiac index with low filling pressures
  2. Normal cardiac index with low pulmonary artery occlusion pressure
  3. Low cardiac index with elevated filling pressures Correct answer.
  4. High cardiac index with low systemic vascular resistance

Explanation

Pump failure reduces stroke volume and cardiac index while elevated ventricular filling pressures reflect congestion. Systemic vascular resistance is typically high as a compensatory response.

Question 32Biology of critical illness and support of organ system function

A patient with septic shock has a mean arterial pressure of 60 mm Hg and a lactate that has risen from 2 to 5 mmol/L despite 30 mL/kg of crystalloid. Which next step is most consistent with current sepsis guidance?

  1. Begin dobutamine as the first vasoactive agent
  2. Start a norepinephrine infusion to target a mean arterial pressure of at least 65 mm Hg Correct answer.
  3. Place a pulmonary artery catheter to guide fluid therapy
  4. Give another 30 mL/kg bolus of crystalloid before any vasopressor

Explanation

When hypotension persists after initial fluid resuscitation, vasopressors are indicated to restore perfusion pressure, and norepinephrine is the recommended first agent. Additional fluid in the absence of preload responsiveness risks edema without improving perfusion.

Question 33Biology of critical illness and support of organ system function

Which change in respiratory mechanics most directly increases the work of breathing in a patient with acute lung injury?

  1. Reduced lung compliance requiring greater inspiratory pressure Correct answer.
  2. Increased functional residual capacity from hyperinflation
  3. Reduced physiologic dead space
  4. Increased pulmonary capillary wedge pressure

Explanation

Work of breathing rises when compliance falls because a larger pressure change is needed for each unit of volume delivered. Stiff lungs in acute lung injury therefore increase the effort required to breathe.

Question 34Biology of critical illness and support of organ system function

Which mechanism best explains hypoxemia that persists despite supplemental oxygen in a patient with pneumonia and dense alveolar consolidation?

  1. Diffusion limitation across a thickened membrane
  2. Reduced inspired oxygen fraction at altitude
  3. Hypoventilation from reduced respiratory drive
  4. Intrapulmonary shunting through unventilated lung units Correct answer.

Explanation

Blood perfusing consolidated, unventilated alveoli does not contact oxygen and returns to the left heart desaturated, forming a shunt that supplemental oxygen cannot fully correct. This is the classic intrapulmonary shunt physiology of consolidation.

Question 35Biology of critical illness and support of organ system function

Which statement best describes the effect of critical illness on the hypothalamic-pituitary-adrenal axis?

  1. Cortisol production is uniformly suppressed in all critically ill patients
  2. Cortisol levels may be elevated while relative adrenal insufficiency can still occur Correct answer.
  3. Mineralocorticoid deficiency is the dominant adrenal abnormality in sepsis
  4. Adrenal function is unaffected by severe illness

Explanation

Critical illness activates the axis and raises total cortisol, yet some patients have inadequate adrenal reserve relative to the stress level, termed critical illness related corticosteroid insufficiency. This can contribute to vasopressor dependence.

Question 36Biology of critical illness and support of organ system function

A patient with severe acute pancreatitis and a serum calcium of 1.6 mmol/L develops carpopedal spasm. Which mechanism best accounts for the hypocalcemia?

  1. Reduced intestinal absorption from vitamin D excess
  2. Saponification of calcium in areas of fat necrosis Correct answer.
  3. Increased renal tubular calcium reabsorption
  4. Hyperparathyroidism driven by inflammation

Explanation

Pancreatic lipase releases fatty acids that bind calcium in areas of fat necrosis, lowering ionized calcium. This is a recognized cause of hypocalcemia in severe pancreatitis.

Question 37Biology of critical illness and support of organ system function

Which physiologic consequence of positive pressure ventilation most directly reduces venous return to the right heart?

  1. Reduced alveolar dead space
  2. Increased left ventricular afterload
  3. Increased intrathoracic pressure during inspiration Correct answer.
  4. Bronchodilation of small airways

Explanation

Positive pressure raises intrathoracic pressure, which reduces the pressure gradient for venous return to the right atrium and can lower preload. This effect is exaggerated with high tidal volumes or high positive end-expiratory pressure.

Question 38Biology of critical illness and support of organ system function

Which finding best supports a diagnosis of diabetes insipidus in a critically ill patient with polyuria?

  1. Low serum osmolality with concentrated urine
  2. High serum osmolality with inappropriately dilute urine Correct answer.
  3. Elevated urine sodium with low urine output
  4. High urine specific gravity with low serum sodium

Explanation

In diabetes insipidus, lack of antidiuretic hormone prevents water reabsorption, producing dilute urine despite rising serum osmolality. The urine is inappropriately dilute for the degree of hyperosmolality.

Question 39Biology of critical illness and support of organ system function

Which mechanism best explains the anemia of critical illness that develops over the first week in the intensive care unit?

  1. Blunted erythropoietin response with reduced red cell survival Correct answer.
  2. Iron overload from multiple transfusions
  3. Bone marrow failure from marrow fibrosis
  4. Acute hemolysis from mechanical ventilation

Explanation

Inflammatory mediators blunt erythropoietin production and response while red cell survival is shortened, producing a dilutional and hypoproliferative anemia. This is compounded by phlebotomy losses.

Question 40Biology of critical illness and support of organ system function

A patient with severe malnutrition is started on enteral feeding and develops weakness, confusion, and a fall in serum phosphate, potassium, and magnesium. Which process best explains this syndrome?

  1. Osmotic diuresis from hyperglycemia
  2. Acute adrenal crisis
  3. Sepsis-induced capillary leak
  4. Refeeding syndrome from an insulin surge driving intracellular shifts Correct answer.

Explanation

Reintroduction of carbohydrate stimulates insulin release, which drives phosphate, potassium, and magnesium into cells and can cause dangerous drops. Recognition requires checking electrolytes before and during refeeding in at-risk patients.

Question 41Physiologic responses to trauma, burns, and inflammation

In the initial resuscitation of a major burn, which intravenous fluid is preferred during the first 24 hours?

  1. Hypertonic saline (7.5%)
  2. Hydroxyethyl starch
  3. Lactated Ringer solution Correct answer.
  4. 5% dextrose in water

Explanation

Isotonic crystalloid, specifically Lactated Ringer solution, is the standard for burn resuscitation because it approximates extracellular composition and does not worsen the hypochloremic acidosis seen with large saline loads. Dextrose alone provides no volume and causes hyponatremia.

Question 42Physiologic responses to trauma, burns, and inflammation

Which formula estimates the initial 24-hour crystalloid requirement in an adult burn patient?

  1. Friedewald formula
  2. Parkland formula (4 mL/kg per % TBSA) Correct answer.
  3. Cockcroft-Gault equation
  4. Holliday-Segar method (4-2-1 rule)

Explanation

The Parkland formula uses 4 mL/kg body weight per percent total body surface area burned over 24 hours, with half given in the first 8 hours from the time of injury. The other formulas estimate maintenance fluids, LDL cholesterol, or creatinine clearance.

Question 43Physiologic responses to trauma, burns, and inflammation

A patient with 40% TBSA burns arrives 4 hours after injury. Using the Parkland formula, what is the most appropriate approach to fluid timing?

  1. Give the entire calculated 24-hour volume over the next 24 hours
  2. Give the full first-8-hour half immediately as a bolus
  3. Give half the calculated volume over the next 4 hours, then the remainder over 20 hours Correct answer.
  4. Delay fluids until urine output is measured

Explanation

The Parkland clock starts at the time of injury, so the first half is due within 8 hours of injury. If 4 hours have already elapsed, that half must be delivered over the remaining 4 hours. Resuscitation should never be delayed pending measurements.

Question 44Physiologic responses to trauma, burns, and inflammation

Which endpoint is the primary guide for titrating burn resuscitation fluid after the initial calculation?

  1. Serum lactate normalization within 1 hour
  2. Hematocrit maintenance above 40%
  3. Central venous pressure of 8-12 mm Hg
  4. Hourly urine output of 0.5-1.0 mL/kg per hour in adults Correct answer.

Explanation

Hourly urine output is the practical bedside endpoint, targeting roughly 0.5-1 mL/kg/h in adults (higher in children). CVP correlates poorly with volume responsiveness, and lactate and hematocrit are not used to drive hourly titration.

Question 45Physiologic responses to trauma, burns, and inflammation

A burn patient receiving large-volume crystalloid develops abdominal compartment syndrome. Which physiologic mechanism best explains this?

  1. Increased colloid oncotic pressure drawing fluid intravascularly
  2. Primary myocardial depression reducing splanchnic perfusion
  3. Capillary leak with visceral and abdominal wall edema plus reduced compliance Correct answer.
  4. Systemic vasodilation from inflammatory mediators

Explanation

Massive crystalloid resuscitation worsens capillary leak, producing bowel and abdominal wall edema that raises intra-abdominal pressure while reducing abdominal wall compliance. This combination lowers abdominal perfusion pressure and produces compartment syndrome.

Question 46Physiologic responses to trauma, burns, and inflammation

Which burn wound characteristic is most consistent with a full-thickness (third-degree) injury?

  1. Leathery, insensate, non-blanching skin Correct answer.
  2. Moist, painful, blanching erythema
  3. Superficial dry desquamation without pain
  4. Blistered, weeping, intensely painful skin

Explanation

Full-thickness burns destroy the dermis and its nerve endings, producing a leathery, insensate, non-blanching eschar. Partial-thickness burns remain painful and may blister or weep.

Question 47Physiologic responses to trauma, burns, and inflammation

Which patient meets criteria for transfer to a burn center?

  1. Partial-thickness burns of 3% TBSA on the forearm in a healthy adult
  2. Superficial partial burn of the knee in a child
  3. Superficial sunburn over 15% TBSA in an adult
  4. Full-thickness burns involving the hands Correct answer.

Explanation

Burns involving the hands, face, feet, genitalia, perineum, or major joints, and full-thickness burns of any size, warrant burn center referral. Small partial-thickness burns in otherwise healthy patients can be managed locally.

Question 48Physiologic responses to trauma, burns, and inflammation

In the first 24-48 hours after a major burn, which electrolyte abnormality is most characteristic?

  1. Hyperkalemia from cell lysis Correct answer.
  2. Hypokalemia from renal wasting
  3. Hypernatremia from free water loss
  4. Hypocalcemia from chelation

Explanation

Thermal injury causes cell membrane disruption and rhabdomyolysis, releasing intracellular potassium into the circulation, so hyperkalemia is common early. Later, potassium shifts intracellularly and hypokalemia may develop.

Question 49Physiologic responses to trauma, burns, and inflammation

A patient with circumferential full-thickness burns of the forearm develops progressive loss of radial pulse and paresthesias. What is the most appropriate immediate intervention?

  1. Fasciotomy of all forearm compartments
  2. Elevate the limb and reassess in 2 hours
  3. Mannitol infusion
  4. Escharotomy Correct answer.

Explanation

Circumferential full-thickness eschar acts as an unyielding band that impairs perfusion; escharotomy releases the constriction. Fasciotomy is reserved for compartment syndrome below the investing fascia, which is not the primary problem here.

Question 50Physiologic responses to trauma, burns, and inflammation

Which inhalation injury finding most strongly predicts the need for early intubation?

  1. Isolated cough without voice change
  2. Singed nasal hairs alone
  3. Mild conjunctival irritation
  4. Carbonaceous sputum with hoarseness and stridor Correct answer.

Explanation

Progressive airway edema is the major threat after inhalation injury, and hoarseness, stridor, carbonaceous sputum, or facial burns suggest impending obstruction. Early intubation before edema worsens is indicated when these signs are present.