This prospective clinical study investigates the relationship between intra-compartmental pressure and soft tissue oxygenation (StO2) measured non-invasively by near-infrared spectroscopy (NIRS) in patients at risk of acute compartment syndrome.

Patients (over 13 years) with fractures of the tibial diaphysis or high-energy fractures of the forearm or distal radius, or patients with soft tissue injury were recruited. Non-invasive and invasive monitoring was carried out pre and post operatively. The ‘Delta P’ value (DP) was calculated as the compartment pressure subtracted from the diastolic blood pressure. The threshold for fasciotomy was a DP < 30mmHg. Non-invasive tissue saturation measurements and pressure measurements were taken from the same compartment (anterior tibial or volar forearm). StO2 values were simultaneously recorded from the contralateral (uninjured) limb at the same anatomical site. All patients had the difference between the StO2 value on the injured and uninjured sides calculated (‘StO2 difference’).

42 patients with tibial diaphyseal fractures, 2 patients with forearm fractures and one case with thigh swelling were recruited to the study. The mean age was 40 years (SD 17 years). 11 patients underwent a four-compartment lower leg fasciotomy determined by a DP < 30mmHg. Patients who required a fasciotomy had an ‘StO2 difference’ that was 20% lower (p = 0. 002) compared to those who did not develop acute compartment syndrome. This suggests that patients who require a fasciotomy have reduced StO2 values on their injured legs compared to the contralateral (uninjured) side.

We have observed that non-invasive StO2 measurements for patients over 13 years at risk of acute compartment syndrome, correlates with the requirement for a fasciotomy as defined by P < 30mmHg. We are optimistic that near-infrared spectroscopy (NIRS) will be a reliable new non-invasive technique for detection of an acute compartment syndrome.