Pressure Methods - Ruling Out
Moderate evidence supports the use of repeated/continuous intracompartmental pressure monitoring and a threshold of diastolic blood pressure minus intracompartmental pressure >30 mmHg to assist in ruling out acute compartment syndrome.
Management of Acute Compartment Syndrome
This guideline was produced in collaboration with METRC, with funding provided by the US Department of Defense. Endorsed by: ACS, AOFAS, and SOMOS

Rationale

There are 2 moderate quality studies (McQueen 2013, Janzing 2001) and 3 low quality studies (Sangwan 2003, Mubarak 1978, Dickson 2003) evaluating the sensitivity and specificity of compartment pressure monitoring for diagnosing ACS. Variability in defining ACS, the type and duration of compartment pressure monitoring (single reading vs. continuous vs. intermittent), and the threshold for fasciotomy complicate interpretation of these studies. However, in all of the studies where a differential pressure of 30 mmHg was used as a cutoff (diastolic blood pressure-ICP or mean arterial pressure- ICP), pressure monitoring showed good sensitivity and/or specificity, indicating that, when combined with clinical symptoms, pressure monitoring can be useful in ruling out compartment syndrome. There was not adequate evidence to support a single absolute pressure cutoff to diagnose ACS.

One moderate strength study (McQueen 2013) examined the sensitivity of continuous compartment pressure monitoring with a threshold for fasciotomy of DBP-ICP <30 for >2 consecutive hours. This study also attempted to quantify false positives and false negatives based on intraoperative findings and clinical sequelae, which lends the study practical strength. While this study found DBP-ICP < 30 to have high sensitivity and specificity, another moderate quality study (Janzing 2001) found this threshold to have poorer specificity, indicating that using DBP-ICP < 30 to diagnose compartment syndrome will result in unnecessary fasciotomies (false positives). The three lower quality studies (Sangwan 2003, Murbarak 1978, Dickson 2003) showed that using DBP-ICP < 30 to diagnose compartment syndrome had good specificity, but were variable in their findings as to the sensitivity of the test.

The findings of another low quality study looking at continuous pressure monitoring vs. no pressure monitoring for tibia fractures (McQueen 1996) supports the fact that few compartment syndromes will be missed using DBP-ICP<30 as a cutoff for diagnosing ACS.

POSSIBLE HARMS OF IMPLEMENTATION

Using a threshold of DBP-ICP <30 to diagnose compartment syndrome might lead to overtreatment
(fasciotomies for patients without true compartment syndrome). Relying on a single pressure reading as
opposed to serial or continuous compartment readings is not a reliable way to diagnose compartment
syndrome and may result in missed compartment syndrome. Relying solely on pressure readings should
be avoided: clinical suspicion and clinical exam must factor into diagnosis as well.

FUTURE RESEARCH

Further studies examining the sensitivity and specificity of pressure measuring methods, techniques and
thresholds vs. reference standards that take into account false negatives and false positives would be
beneficial.