Abstract
Background
Overlooked compartment syndrome represents a devastating complication for the patient. Invasive compartment pressure measurement continues to be the gold standard. However, repeated measurements in uncertain cases may be difficult to achieve. We developed a new, noninvasive method to assess tissue firmness by pressure related ultrasound.
Methods
Decreased tissue elasticity by means of rising compartment pressures was mimicked by infusion of saline directly into the anterior tibial compartment of 6 human specimens post mortem. A pressure transducer (Codman) monitored the pressure of the anterior tibial compartment. A second transducer was located in a saline filled ultrasound probe head to allow a simultaneous recording of the probe pressure provoked by the user. The ultrasound images were generated at 5 and 100mmHg probe pressures to detect the tissue deformity by B-mode ultrasound. The fascial displacement was measured before and after compression (d). Subsequently, increments of 5mmHg pressure increases were used to generate a standard curve (0–80mmHg), thus mimicking rising compartment pressures. The intra-observer reliability was tested using 10 subsequent measurements. A correlation was determined between d and the simulated intacompartmental pressure (ICP) in the compartment. The Pearson correlation coefficient (r) was calculated. The reliability determined by the kappa value and a regression analysis was performed.
Results
With rising compartmental pressure, a concordant consistent correlation between d and ICP occurred. The Pearson coefficient was significant at r=0.979 and the intra-observer value kappa (k) showed a statistically good reliability (k10=0.73 and k70=0.79). Within a pressure ranging from 5–35mmHg there was an almost linear behavior, with decreasing elasticity and tissue movement in case of raising ICP.
Conclusions
Pressure related ultrasound emphasized as a reliable tool to determine the correlation between the measured compartmental displacement and the raising intracompartmental pressures. This may help to improve the clinical assessment of the compartment elasticity by the physician. Further studies are required to investigate whether the good correlation also applies for the clinical scenario. However, this new method may be useful to monitor trends in the compartment pressures and may help to avoid delayed decision of fasciotomy.
