Session IX - Basic Science
Comparison of Three Methods for Measuring Intracompartmental Pressures in Compartment Syndrome: A Clinical and Laboratory Study
Purpose: The importance of the early and accurate diagnosis of acute compartment syndrome is well recognized. Intracompartmental pressure measurement may be a valuable tool to aid in making this diagnosis. Several methods and devices exist for measuring intracompartmental pressures, although the accuracy of these methods has not been well demonstrated. The purpose of this study is to determine the accuracy of several methods for measuring intracompartmental pressures in a clinical and laboratory setting.
Methods: Clinical Analysis: IRB approval was obtained for this study. Between July 2003 and December 2004, traumatized limbs in which compartment syndrome was suspected underwent intracompartmental pressure testing using 3 methods: (1) a solid-state intracompartment catheter device (STIC, Stryker, Kalamazoo, MI); ( 2) an electronic transducer-tipped catheter (ETTC, Synthes, Paoli, PA); and (3) an 18-g IV needle attached to an arterial line transducer and CVP monitor system (MWT, our modification of Whitesides' technique). All measurements were obtained by the senior author and testing was performed within a 1-cm diameter area in a predetermined randomized order. Fasciotomies were performed based on clinical diagnosis supported with intracompartmental pressure data. Intracompartmental pressure measurements obtained using these methods were compared. "Minor" and""major" discrepancies between measurements for each compartment using the 3 methods were defined as 6 to 10 mm Hg and >10 mm Hg, respectively. Laboratory Analysis: STIC, ETTC, and MWT were tested and compared using a thick plastic sheathed homogeneous gel "compartment" model. Pressures within the compartment model were increased using a perforated compressive platform weighted in 8-lb increments from 8 to 40 lbs. Eight trials were performed for STIC, ETTC, and MWT at each magnitude of pressure. A comparison of clinical and laboratory data collected using these methods was performed using repeated measures ANOVA and intraclass correlation coefficients (Excel, Microsoft Corp).
Results: Clinical Analysis: 35 muscle compartments were tested with all 3 methods in 22 limbs of 20 patients. 16 operations were performed to release intracompartmental pressure. There were 10 (9.5%) major deviations (2 STIC, 4 ETTC, and 4 MWT) and 17 (16%) minor deviations (6 STIC, 6 ETTC and 5 MWT) between the measurements obtained using the 3 testing methods. Treatment would have changed in 2 cases (6%) if treatment decisions had been based solely on these erroneous measures. The absolute mean difference between measures was 6.7 mm Hg (range, 0 to 46 mm Hg). Intraclass correlation coefficients for the 3 methods demonstrated excellent agreement, with ICCs ranging from 0.76 to 0.87. Laboratory Analysis: No statistical difference was seen between the values obtained using STIC, ETTC, and MWT using the "compartment" model. The absolute mean differences between the methods were 1.4 to 1.6 mm Hg (range, 0 to 6mm Hg) throughout the range of incremental compartment pressures. STIC, ETTC, and MWT demonstrated excellent agreement for the assessment of intracompartmental pressures (ICC 0.96-0.97).
Discussion/Significance: We have demonstrated that STIC, ETTC, and MWT are similarly accurate and reproducible in measuring intracompartmental pressures, both clinically and in a laboratory model. However, erroneous pressure measurements were seen in 27% of injured limbs when these methods were used clinically. These problems were not seen in the laboratory using the gel-filled compartment model, and it appears likely that the heterogeneous anatomy contained within the muscle compartments of an injured limb is a factor in this difference. Although pressure measurement may be a valuable adjunct in the evaluation of compartment syndrome, these findings strongly suggest that compartment pressure measurement should not be used as the primary determinant for or against fasciotomy. We recommend that careful physical examination and the global clinical picture remain the cornerstones to early diagnosis and expedient treatment.