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Normal compartment pressure is less than 8-10 mm Hg. 52,53
There is much confusion and disagreement in the literature as to how measured compartment pressures should be interpreted. We advocate a conservative approach, given that the ramifications for untreated compartment syndrome may be quite serious. One study demonstrated that recorded pressures vary with the depth of needle/catheter insertion. 54 Another study demonstrated that compartment pressure measurements in fractured limbs gave dramatically higher recordings when measured within 5 cm of the fracture site 55 . |
Absolute compartment pressure
Delta pressure
Delta MAP |
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One way in which compartment pressures may be interpreted is by merely looking at the absolute pressure measurement. An absolute pressure reading over 30 mm Hg is generally considered "abnormal", but controversy exists as to the level at which emergent fasciotomy should be performed. The most common recommendation is to perform fasciotomy whenever absolute pressure exceeds 30 mm Hg. 20,21,25,56 Others have shown that with close observation, fasciotomies may be reserved for absolute pressures exceeding 45 mm Hg. 3,48 Another investigator found that fasciotomy could be withheld for pressures less than 50 mm Hg provided that sensory and motor deficits were absent. 55
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Another way of interpreting compartment pressures is through the concept of "delta pressure". The degree of tissue perfusion has been shown to correlate with diastolic blood pressure, and when pressure within a compartment exceeds diastolic blood pressure, perfusion ceases. Therefore, many investigators advocate the use of "delta pressure" when considering fasciotomy. Delta pressure is defined as Diastolic Blood Pressure minus Compartment Pressure. Support for this interpretive method is shown by the observation that relative hypertension is protective againt the development of compartment syndromes. 57 Whitesides and others have therefore advocated use of a delta pressure between 10 and 30 mm Hg as a threshold for operative management. 37,48,58
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Similar to the concept of delta pressure, Hepenstall advocates the use of mean arterial pressure (MAP) as a reference for interpretation of compartment pressures. 59 He suggests a difference of less than 30 mm Hg between MAP and measured compartment pressure be used as a threshold for fasciotomy. Mars et al have suggested that compartment pressures in children be interpreted using this technique. 60 |
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