Tests

1st tests to order

compartment pressure measurement

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Result
Test

Early diagnosis is essential and should be driven by a high index of suspicion based on the clinical history.[6]​ Compartment pressure measurement is indicated whenever the clinical exam is equivocal or the diagnosis is uncertain in a patient at risk.[8]​ Intracompartmental pressure monitoring may assist in diagnosing acute compartment syndrome but supporting studies show variability in the thresholds for fasciotomy, timing, and method of pressure monitoring.[6]​ Relying on pressure-based thresholds alone (without consideration of clinical suspicion and clinical exam findings) for diagnosing acute compartment syndrome may result in overtreatment with fasciotomy.[6][23][24]​ In one study of 64 patients, using a compartment pressure value of 30 mmHg as a threshold for fasciotomy led to a rate of fasciotomy of 29% after tibial surgery.[8][24]​ It is often helpful to obtain a baseline intracompartmental pressure in compartments that may be at risk, especially in a patient who cannot be examined in regular time intervals.

Without a dependable clinical exam (e.g., in the obtunded patient), repeated or continuous intracompartmental pressure measurements may be useful until acute compartment syndrome is diagnosed or ruled out.[6]​ Several pressure measurement devices are available for determining intracompartmental pressures. Single pressure values alone are not reliable for diagnosing compartment syndrome and may result in the diagnosis being missed.[6] All muscular compartments should be measured, not only the compartment thought to be at highest risk.[7] Below the knee, all four compartments should be checked, even though the anterior compartment has the highest risk of compartment syndrome.[7] Compartment pressure monitoring does not appear to provide useful information to guide decision making when considering fasciotomy in adults with evidence of irreversible intracompartmental (neuromuscular/vascular) damage.[6] Several pressure measurement devices are available for determining intracompartmental pressure: for example, arterial line transducer systems with side-port needles, slit catheters, and self-contained measuring systems.[8]

If specialized equipment is unavailable, a 16-gauge intravenous catheter connected to an arterial blood pressure (BP) transducer and monitor via saline-filled arterial line tubing can be used to measure compartment pressures.[25] An 18-gauge needle may overestimate compartment pressure by up to 18 mmHg when compared with a slit catheter or side-ported needle.[8][26]

The differential pressure (i.e., the difference between diastolic BP and measured compartment pressure: diastolic BP minus compartment pressure) may also be measured.[27]​ A threshold of diastolic BP minus intracompartmental pressure >30 mmHg (delta pressure) may assist in ruling out acute compartment syndrome.[6][27]​​[28]

Differential pressure within 20-30 mmHg of the diastolic pressure (delta pressure) is considered a strong indicator for fasciotomy.[18]​ However, care should be taken when using this criterion for patients who are receiving vasodilatory medications whose diastolic BP is low.

Result

variable; differential pressure within 20-30 mmHg of the diastolic pressure (delta pressure) is considered a strong indicator for fasciotomy

Tests to consider

serum creatine kinase

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Result
Test

Reflects muscle cell lysis and muscle necrosis.[18]

Result

elevated

urine myoglobin

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Result
Test

Reflects muscle cell lysis and muscle necrosis.​[18]​ Limited evidence supports the use of myoglobinuria in diagnosing acute compartment syndrome in patients with traumatic lower extremity injury.[6]

Result

elevated

troponin

Test
Result
Test

Reflects muscle cell lysis and muscle necrosis.[6][18]​​ Limited evidence supports the use of serum troponin in diagnosing acute compartment syndrome in patients with traumatic lower extremity injury.[6]

Result

elevated

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