Use of near-infrared spectroscopy to detect sustained hyperaemia following lower extremity trauma

Introduction: Patients who sustain lower extremity trauma are at highest risk for acute compartment syndrome (ACS) during the first 48 hours after surgical stabilization. Near-infrared spectroscopy (NIRS) may be a useful monitoring tool for ACS during this period; however, expected normal values have yet to be established. This study sought to evaluate whether the expected hyperaemic response is present 48 hours postoperatively, using NIRS. Materials and Methods: Participants consisted of 25 cases with acute unilateral lower extremity fractures. NIRS measurements for hemoglobin saturated with oxygen (rSO₂) were taken approximately 48 hours after surgical stabilization for each compartment bilaterally, using the contralateral (uninjured) leg as an internal control. Results: Mean rSO₂ values taken 48 hours from surgical stabilization from each compartment of the patients’ injured legs were significantly higher than the mean values of the contralateral legs (injured = 70, 68, 72, 70; contralateral = 55, 54, 57, 56 for anterior, lateral, deep posterior, and superficial posterior compartments, respectively; p < 0.0001 for all compartments). Conclusions: These results suggest that the hyperaemic response to injury remains present at 48 hours after surgical stabilization, and that NIRS values in an injured extremity should be expected to remain elevated throughout the window of concern for ACS. NIRS may be a valuable tool in monitoring leg injuries during this critical time period.