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Difficulty: Very hardOrthopedic Surgery

A 28-year-old man is evaluated in the intensive care unit. He was involved in a high-speed motor vehicle collision 24 hours ago. His injuries include a severe traumatic brain injury and a closed, comminuted midshaft fracture of the right tibia. He is currently intubated, sedated, and unresponsive to commands. His vital signs include a blood pressure of 105/65 mm Hg105/65\text{ mm Hg} and a heart rate of 98/min98/\text{min}. The nursing staff reports that the patient's right lower leg has become increasingly firm over the past two hours. On physical examination, the right calf is tense, swollen, and non-compressible. The right dorsalis pedis and posterior tibial pulses are easily palpable, and capillary refill in the toes is less than 2 seconds. Which of the following is the most appropriate next step in the management of this patient's extremity?

  1. A
    Immediate four-compartment fasciotomy of the right lower leg
  2. B
    Duplex ultrasonography of the right lower extremity
  3. Measurement of right lower leg intracompartmental pressuresAnswer
  4. D
    Elevation of the right leg above the level of the heart and serial examination
  5. E
    CT angiography of the right lower extremity

Answer

Measurement of right lower leg intracompartmental pressures
Acute compartment syndrome (ACS) occurs when tissue pressure within a closed fascial space exceeds capillary perfusion pressure, leading to muscle and nerve ischemia. The earliest and most reliable clinical sign in an awake patient is pain out of proportion to the injury, which is exacerbated by passive stretch. Crucially, arterial pulses and capillary refill typically remain normal until very late in the clinical course. This occurs because compartment pressures (e.g., 30−40 mm Hg30-40\text{ mm Hg}) easily exceed capillary and venous pressures to cause ischemia, but they rarely exceed systolic arterial pressure (e.g., 105 mm Hg105\text{ mm Hg}). In a patient who is intubated, sedated, or otherwise unable to communicate, the clinical diagnosis cannot be reliably made. Therefore, the standard of care requires objective measurement of intracompartmental pressures (ICP) using a handheld manometer or arterial line setup. A delta pressure (diastolic blood pressure minus ICP) of less than 30 mm Hg30\text{ mm Hg} is diagnostic and serves as an absolute indication for emergency four-compartment fasciotomy.

Step-by-Step Solution

1
Assess the clinical presentation and physical exam findings.
The patient has a tense, non-compressible calf following a high-energy tibia fracture, but is intubated and unexaminable.
To recognize the high risk of acute compartment syndrome while acknowledging that classic symptoms like 'pain on passive stretch' cannot be assessed.
2
Evaluate the vascular status of the affected limb.
Pulses are easily palpable and capillary refill is normal.
To understand that normal pulses do not rule out compartment syndrome, as capillary perfusion is compromised long before systolic arterial inflow is occluded.
3
Determine the next best step for diagnosis based on the patient's neurological status.
Measurement of intracompartmental pressures is selected.
Because the patient cannot provide a reliable clinical exam, objective diagnostic data is mandatory before committing to a morbid surgical intervention like fasciotomy.

Key Concept

Diagnosis of acute compartment syndrome in unexaminable patients
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Topics

Orthopedic Surgery

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