Objective: To evaluate the diagnostic performance of perfusion pressure (PP) thresholds for fasciotomy.
Design: Prospective observational study.
Setting: Seven Level-1 trauma centers.
Patients/participants: One hundred fifty adults with severe leg injuries and ≥2 hours of continuous PP data who had been enrolled in a multicenter observational trial designed to develop a clinical prediction rule for acute compartment syndrome (ACS).
Main outcome measurements: For each patient, a given PP criterion was positive if it was below the specified threshold for at least 2 consecutive hours. The diagnostic performance of PP thresholds between 10 and 30 mm Hg was determined using 2 reference standards for comparison: (1) the likelihood of ACS as determined by an expert panel who reviewed each patient's data portfolio or (2) whether the patient underwent fasciotomy.
Results: Using the likelihood of ACS as the diagnostic standard (ACS considered present if median likelihood ≥70%, absent if <30%), a PP threshold of 30 mm Hg had diagnostic sensitivity 0.83, specificity 0.53, positive predictive value 0.07, and negative predictive value 0.99. Results were insensitive to more strict likelihood categorizations and were similar for other PP thresholds between 10- and 25-mm Hg. Using fasciotomy as the reference standard, the same PP threshold had diagnostic sensitivity 0.50, specificity 0.50, positive predictive value 0.04, negative predictive value 0.96.
Conclusion: No value of PP from 10 to 30 mm Hg had acceptable diagnostic performance, regardless of which reference diagnostic standard was used. These data question current practice of diagnosing ACS based on PP and suggest the need for further research.
Level of evidence: Diagnostic Level I. See Instructions for Authors for a complete description of levels of evidence.