SLR - August 2014 - Nicole Byerley
The Estimated Sensitivity and Specificity of Compartment Pressure Monitoring for Acute Compartment Syndrome
Reference: McQueen MM, Duckworth AD, and Aitken SA. "The Estimated Sensitivity and Specificity of Compartment Pressure Monitoring for Acute Compartment Syndrome." The Journal of Bone & Joint Surgery 95.8 (2013): 673-677.
Reviewed By: Nicole Byerley PGY-2
Residency Program: Southern Arizona VA Health Care Systems
Podiatric Relevance: In dealing with acute trauma of the foot and ankle, it is important to understand the reliability of intra-compartment pressures in determining the diagnosis of an acute compartment syndrome and the patient’s need for intervention.
Methods: In a retrospective analysis of patients, 1184 patients (>12 years of age) were identified that sustained a tibial diaphyseal fracture over a 10 year period. From these, 205 patients were found to not be monitored with intra-compartment pressures and were excluded from the study. An additional 129 total patients were excluded (127 patients due to loss of follow up and two patients due to loss of limb not related to acute compartment syndrome). This allowed for 850 total patients included in the study.
The intra-compartmental pressure monitoring was performed in similar fashion. A slit catheter was inserted into the anterior compartment of the affected leg at time of admission. Pressures were measured for a period of at least 24 hours or until the intra-compartmental pressure was reducing steadily and the differential pressure (diastolic pressure minus intra-compartmental pressure) was steadily increasing. Diagnosis of acute compartment syndrome was made if the differential pressure was <30mmHG for more than two hours. The diagnosis was determined to be correct if fasciotomy resulted in escape of muscle with changes in muscle tissue characteristics/color. Acute compartment syndrome diagnosis was considered incorrect if fasciotomy could be primarily closed at 48 hours. The absence of acute compartment syndrome was determined by records displaying no neurological symptoms or contracture at long-term follow up.
The fasciotomies performed were all performed similarly with the decompression of all four compartments of the leg via two incisions.
Results: Fasciotomies were performed on 152 patients (17.9 percent) for acute compartment syndrome. Of these, 141 were determined to have a true compartment syndrome and six were determined to not have a compartment syndrome. Five patients had normal intra-compartmental pressures but with clinical symptoms, underwent fasciotomy; these patients all had operative findings consistent with acute compartment syndrome.
Fasciotomies were noteperformed on 698 patients (82.1 percent). Of these patients, 689 patients displayed no late sequelae of acute compartment syndrome at follow-up. Four of these patients that had normal intra-compartmental pressures and no fasciotomy developed late sequelae at follow-up. Five patients had abnormal differential pressures (patients all had low diastolic pressures) and given normal clinical findings, did not undergo fasciotomy; they developed no long-term sequelae at follow-up.
The estimated sensitivity of intra-compartmental pressure monitoring for a suspected acute compartment syndrome was 94% with an estimated specificity of 98 percent. The estimated positive predictive value was 93 percent and the negative predictive value was 99 percent.
Conclusions: A previous study cited in the article determines the sensitivity and specificity of diagnosing acute compartment syndrome based on clinical signs and symptoms. The data demonstrates that these indicators are not reliable unless three clinical symptoms are demonstrated, one being paralysis. However, once paralysis occurs, long-term sequelae are much more likely. However, intra-compartmental pressure measurement is demonstrated in this study to have a reliable sensitivity and specificity and a positive predicitive value that is similar to those of three symptoms without risking development of paralysis and long-term sequelae. It should be stated that sequential measurement of pressures are required for more accurate monitoring. This can reduce the delay to fasciotomy and the development of sequelae as the clinical symptoms/signs can lag behind the pressure changes. Monitoring over several hours also displays trends in pressures and provides more information in the need for fasciotomy. Doing so may lessen the likelihood to overtreat patients.