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Difficulty: Very hardPreoperative and Postoperative Care

A 68-year-old man is evaluated in the surgical intensive care unit due to sudden clinical deterioration. He is currently on postoperative day 1 following an emergent open repair of a ruptured abdominal aortic aneurysm. During the surgery, he experienced significant hemorrhage and received 10 liters of crystalloid and 8 units of packed red blood cells. The patient remains mechanically ventilated and sedated. Over the past 4 hours, his total urine output has decreased to 15 mL. His temperature is 38.2°C (100.8°F), blood pressure is 86/50 mmHg, and heart rate is 118/min. Central venous pressure is measured at 22 mm Hg. The ventilator monitor reveals a sudden increase in peak inspiratory pressures from 24 cm H2O to 48 cm H2O, with a corresponding increase in plateau pressures from 20 cm H2O to 44 cm H2O. Physical examination shows a tense and massively distended abdomen. The surgical incision is dry and intact. Which of the following is the most appropriate next step in the management of this patient?

  1. Measurement of intravesical pressureAnswer
  2. B
    Intravenous administration of furosemide
  3. C
    Computed tomography of the abdomen and pelvis
  4. D
    Collection of blood cultures and initiation of antibiotics
  5. E
    Increase the positive end-expiratory pressure on the ventilator

Answer

The most appropriate next step is the measurement of intravesical pressure to confirm abdominal compartment syndrome.
The correct answer is the measurement of intravesical pressure. This patient's presentation is highly characteristic of Abdominal Compartment Syndrome (ACS). ACS is defined as intra-abdominal hypertension (intra-abdominal pressure > 20 mm Hg) associated with new-onset organ dysfunction. It frequently develops after major abdominal trauma or vascular catastrophes (like a ruptured abdominal aortic aneurysm) that require massive volume resuscitation, leading to profound bowel and retroperitoneal edema. The increased intra-abdominal pressure exerts mechanical effects on multiple organ systems: it pushes the diaphragm upward, reducing lung compliance and drastically increasing peak and plateau airway pressures on the ventilator. This transmitted intrathoracic pressure compresses the vena cava, reducing venous return (preload) and causing hypotension. Because the central venous pressure (CVP) measures the pressure within the thoracic vena cava, it is falsely elevated due to this extrinsic compression, rather than true intravascular volume overload. Furthermore, direct compression of the renal parenchyma and renal veins decreases the glomerular filtration rate, leading to severe oliguria. The gold standard for confirming ACS at the bedside before proceeding to definitive treatment (surgical decompression via reopening the laparotomy) is measuring the intra-abdominal pressure indirectly using a bladder catheter (intravesical pressure).

Step-by-Step Solution

1
Analyze the patient's fluid balance and clinical signs.
The patient received massive fluid resuscitation and now presents with oliguria, hypotension, and a tense abdomen.
Massive third-spacing of fluid leads to profound bowel edema, raising intra-abdominal pressure.
2
Interpret the cardiopulmonary parameters in the context of the physical exam.
High central venous pressure (CVP) and elevated peak/plateau airway pressures are noted despite systemic hypotension.
Elevated intra-abdominal pressure pushes the diaphragm cephalad. This transmits pressure to the thoracic cavity, falsely elevating the CVP (extrinsic compression of the vena cava) and increasing airway pressures (decreased chest wall compliance).
3
Determine the diagnostic test of choice for the suspected condition.
Measurement of intravesical (bladder) pressure is selected.
Intravesical pressure is the standard non-invasive surrogate for intra-abdominal pressure. A pressure >20 mm Hg with new organ dysfunction confirms Abdominal Compartment Syndrome (ACS), indicating the need for decompressive laparotomy.

Key Concept

Abdominal Compartment Syndrome typically occurs after massive fluid resuscitation, presenting with a tense abdomen, oliguria, hypotension, and increased airway pressures. The diagnostic next step is measuring intravesical pressure.
Estimated Time:2m 0s
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Topics

Preoperative and Postoperative Care

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