Eighteen hours into resuscitation for severe thermal injuries, a 42-year-old male patient … — USMLE Step 2 CK

Eighteen hours into resuscitation for severe thermal injuries, a $42$ -year-old male patient exhibits acute clinical deterioration in the intensive care unit. He initially presented following an industrial fire with full-thickness burns covering $55\%$ of his total body surface area, localized exclusively to his back and bilateral lower extremities. He was intubated upon arrival, and standard Parkland formula-based crystalloid infusion was initiated.

Current assessment reveals a precipitous drop in urine output to $10 \text{ mL/hr}$ . Vital signs show a temperature of $38.4^\circ\text{C}$ ( $101.1^\circ\text{F}$ ), blood pressure of $82/50 \text{ mm Hg}$ , and a heart rate of $135\text{/min}$ . The central venous pressure is elevated at $18 \text{ mm Hg}$ . The mechanical ventilator repeatedly triggers high-pressure alarms, with peak airway pressures rising acutely from $25 \text{ cm H}_2\text{O}$ to $48 \text{ cm H}_2\text{O}$ . On physical examination, the abdomen is tensely distended. Transducer measurement via the urinary catheter demonstrates an intravesical pressure of $34 \text{ mm Hg}$ . Which of the following is the most appropriate next step in management?

Decompressive laparotomyAnswer
B
Computed tomography of the abdomen and pelvis
C
Nasogastric tube insertion and continued observation
D
Administration of nebulized albuterol and intravenous corticosteroids
E
Initiation of broad-spectrum intravenous antibiotics

Answer

Decompressive laparotomy

The correct answer is decompressive laparotomy. This patient has developed secondary abdominal compartment syndrome (ACS), a known complication of the massive crystalloid resuscitation required for large surface area burns (burn shock resuscitation). The diagnosis is confirmed by an intra-abdominal pressure (measured via the bladder) greater than

20 \text{ mm Hg}

in the setting of new-onset organ failure. The upward displacement of the diaphragm causes high peak airway pressures, while compression of the inferior vena cava decreases venous return, leading to hypotension, elevated central venous pressure, and decreased renal perfusion (oliguria). The definitive, life-saving treatment for ACS with established multi-organ failure is immediate surgical decompression of the abdomen.

Step-by-Step Solution

Identify the complication of massive fluid resuscitation.

The patient has received massive crystalloid volumes for a 55% TBSA burn, leading to severe third-spacing and splanchnic edema.

Large-volume resuscitation causes capillary leak and fluid accumulation in the peritoneal and retroperitoneal spaces.

Interpret the clinical parameters.

Intravesical pressure is 34 mm Hg (normal < 5-7 mm Hg), indicating severe intra-abdominal hypertension (IAH).

Bladder pressure is the standard surrogate measurement for intra-abdominal pressure. Pressures > 20 mm Hg define abdominal compartment syndrome (ACS) if organ dysfunction is present.

Assess for organ dysfunction.

The patient has oliguria (renal), hypotension with elevated CVP (cardiovascular compression reducing venous return), and high peak airway pressures (pulmonary compression via upward diaphragmatic displacement).

The triad of IAH, respiratory compromise, and renal failure definitively establishes the diagnosis of ACS.

Determine the definitive intervention.

Decompressive laparotomy must be performed immediately.

When ACS causes refractory multi-organ failure, surgical opening of the abdominal fascia is required to release the pressure and restore organ perfusion.

Key Concept

Secondary abdominal compartment syndrome is a life-threatening complication of massive burn fluid resuscitation, diagnosed by intravesical pressures > 20 mm Hg with new organ dysfunction, and treated definitively with decompressive laparotomy.

Estimated Time:1m 30s

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