INTRAMUSCULAR DEOXYGENATION DURING EXERCISE IN PATIENTS WHO HAVE CHRONIC ANTERIOR COMPARTMENT SYNDROME OF THE LEG

Currently, the definitive diagnosis of chronic compartment syndrome is based on invasive measurements of intracompartmental pressure. We mea sured the intramuscular pressure and the relative oxygenation in the a nterior compartment of the leg in eighteen patients who were suspected of having chronic compartment syndrome as well as in ten control subj ects before, during, and after exercise, Chronic compartment syndrome was considered to be present if the intramuscular pressure was at leas t fifteen millimeters of mercury (2.00 kilopascals) before exercise, a t least thirty millimeters of mercury (4.00 kilopascals) one minute af ter exercise, or at least twenty millimeters of mercury (2.67 kilopasc als) five minutes after exercise. Changes in relative oxygenation were measured with use of the non-invasive method of near-infrared spectro scopy. In all patients and subjects, there was rapid relative deoxygen ation after the initiation of exercise, the level of oxygenation remai ned relatively stable during continued exercise, and there was reoxyge nation to a level that exceeded the pre-exercise resting level after t he cessation of exercise, During exercise, maximum relative deoxygenat ion in the patients who had chronic compartment syndrome (mean relativ e deoxygenation [and standard error], -290 +/- 39 millivolts) was sign ificantly greater than that in the patients who did not have chronic c ompartment syndrome (-190 +/- 10 millivolts) and that in the control s ubjects (-179 +/- 14 millivolts) (p < 0.05 for both comparisons). In a ddition, the interval between the cessation of exercise and the recove ry of the pre-exercise resting level of oxygenation was significantly longer for the patients who had chronic compartment syndrome (184 +/- 54 seconds) than for the patients who did not have chronic compartment syndrome (39 +/- 19 seconds) and the control subjects (33 +/- 10 seco nds) (p < 0.05 for both comparisons), CLINICAL RELEVANCE: Patients who had chronic anterior compartment syndrome of the leg had greater rela tive deoxygenation during exercise as well as delayed reoxygenation af ter exercise; these findings support an ischemic etiology for chronic compartment syndrome. Near-infrared spectroscopy may be useful as a no n-invasive diagnostic tool for the evaluation of patients suspected of having chronic anterior compartment syndrome of the leg.