A Novel Non-invasive Method for the Detection of Elevated Intra-compartmental Pressures of the Leg

Summary

An ultrasound probe coupled with a pressure sensor is used to assess the intra-compartmental pressure of the leg by directly measuring the compartment fascia flattening pressure (CFFP). This non-invasive protocol will provide reliable assessment of the pressure inside the anterior muscular compartment of the lower leg.

Abstract

Acute Compartment Syndrome is a devastating consequence of musculoskeletal trauma. Currently the diagnosis is based on clinical signs and symptoms, and while adjuncts such as invasive intra-compartmental pressure measurements are often used to corroborate the physical exam findings, there remains no reliable objective test to aid in the decision to perform a decompressive fasciotomy. In a cadaver model of compartment syndrome, an ultrasound (US) based method has been shown to be a reliable measurement of increased intra-compartmental pressure. An absolute pressure of >100 mbar or a difference of 50 mbar in the CFFP between the legs can be considered pathologic. Using an ultrasound transducer, coupled with a pressure sensor, the pressure needed to flatten the superficial fascia of the anterior compartment of lower legs (Compartment Fascia Flattening Pressure [CFFP]) can be measured. The CFFP of the injured leg is compared to the CFFP of the uninjured leg. This US measured index can then serve as an adjunct to the physical exam in evaluating injured lower extremities and assessing the need for decompressive fasciotomy. The advantages of this protocol include: being a non-invasive method and an easily reproducible technique.

Introduction

The purpose of this novel protocol is to evaluate the intra-compartmental pressure of the leg in a non-invasive way by using an ultrasound transducer coupled with a pressure sensor. Compartment syndrome is a well-known complication in musculoskeletal trauma and is the result of elevated intra-compartmental pressures which compromise the perfusion of tissues leading to irreversible ischemic injury if not intervened upon. Its diagnosis is primarily based on clinical exam. Unfortunately, clinical exam alone has been shown to have poor sensitivity and specificity in the diagnosis of compartment syndrome¹. Invasive intra-compartmental pressure measu....

Protocol

This experimental protocol has been reviewed and approved by our hospital’s institutional review board (IRB) and follows all guidelines set forth by our institution’s human research ethics committee.

1. Identify the Fascia of the Anterior Compartment of the Leg

1. Identify a starting site for the ultrasound probe. Place the probe directly over the anterior compartment, just lateral to the tibial crest and one handbreadth distal to the tibial tubercle.
2. Identify the fascia as the bright, white strip just below the subcutaneous tissue on the ultrasound. Move the probe until the fascia is seen at the point where i....

Results

This technique has been used to measure 10 consecutive patients with injured legs without evidence of compartment syndrome and 3 patients with a clinical diagnosis of compartment syndrome necessitating decompressive fasciotomies. The average delta CFFP for patients without compartment syndrome was 10.7 ± 10.6 mbar compared to 157 ± 51.7 mbar for patients with compartment syndrome and single-tailed t-test identified the differences in pressures between the groups as being statistically significant (P < 0.02).

Discussion

This article demonstrates a novel, clinically applicable technique for the non-invasive measurement of intra-compartmental pressures in the leg using an ultrasound coupled with a pressure sensor. This technique only requires a hand-held ultrasound and a commercially available pressure sensing transducer. It is quick and easy to perform and is well tolerated by patients. The entire diagnostic procedure can be performed in under 5 min with no additional resources. The calculated delta CFFP may then be used in conjunction w.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Pressure sensor: Venous pressure measurement device	Vein press	VP 2014	A peripheral venous measuring device used in conjuction with an ultrasound to measure peripheral venous pressure.
Ultrasound probe: Vscan Extend R2 Dual Probe DICOM Base Package	GE Healthcare	H8038VP	Any ultrasound probe will be sufficent for this test. Using the narrow tranducer will function best when coupled to the pressure sensor