Review Question - QID 216658

Leg Compartment Syndrome Studies Compartment pressure measurements QID: 216658 (OBQ15.111.1)

QID 216658 (Type "216658" in App Search)

You are called to evaluate a 45-year-old male in the ED who was in a motor vehicle accident prior to arrival. EMS reported a prolonged extrication and GCS of 6 on scene, which required a field intubation. He has obvious deformity and crepitus of his left leg, with radiographs seen in Figure A. The ED physician reports an increase in soft tissue swelling and firmness of the leg. You decide to measure the patient's compartments given clinical concern for compartment syndrome. Which of the following is true of intracompartmental pressure measurements?

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Interobserver reliability is poor

51%

733/1438

Should be obtained remote to the zone of injury

16%

224/1438

Should always be obtained to objectively confirm clinical suspicion for compartment syndrome

81/1438

Have high specificity for diagnosis of compartment syndrome when absolute pressures exceed 20 mmHg

10%

150/1438

Threshold for fasciotomy remains similar intraoperatively

17%

239/1438

Select Answer to see Preferred Response

Intracompartmental pressure monitoring has poor interobserver reliability, which has created narrow indications for its use in diagnosis of compartment syndrome.

In most cases, compartment syndrome can be diagnosed clinically. However, it is important to obtain objective information when the patient cannot purposefully participate in the examination. Intracompartmental pressure monitoring can be useful in these cases to determine if fasciotomies are indicated. A difference in diastolic blood pressure (DBP) and compartment pressure <30 mmHg (Delta P) has been thought to represent a sensitive and specific measurement for diagnosis of compartment syndrome. Absolute compartment pressures >30 mmHg are be less useful, however, as it has been shown some patients tolerate these pressures without symptoms. To further complicate factors, anesthesia can lower the diastolic pressure, making intraoperative decisions more difficult on whether to perform fasciotomy after fracture fixation. In addition, some have pointed out issues with interobserver reliability and poor technique when measuring compartment pressures.

McQueen et al. prospectively reviewed 116 patients with tibia fractures that had continuous monitoring of their anterior compartment for 24 hours. They found that using an absolute pressure of 30 mmHg would have resulted in 50 patients (43%) treated with unnecessary fasciotomies. They conclude using a differential pressure (Delta P) of 30 mmHg is a more reliable indicator of compartment syndrome.

Large et al. reviewed interobserver reliability in compartment pressure measurements among 38 physicians. They note that only 31% of the measurements were performed using the correct technique and 30% of measurements had catastrophic errors made. They concluded that even when measurements were obtained with proper technique, there was a high rate of inaccuracy which only increased in cases were technique was poor.

Figure A shows a closed comminuted tibial shaft fracture.

Incorrect Answers:
Answer 2: Compartment measurements should be obtained at the level of the fracture site, ideally within 5 cm.
Answer 3: Compartment measurements are not necessary in cases of clinically confirmed compartment syndrome and should not impede fasciotomy in awake and alert patients.
Answer 4: Absolute pressure measurements >30 mmHg have been previously described in the diagnosis of compartment syndrome but his has recently been challenged with several authors unacceptably high rates of false positive diagnoses.
Answer 5: Anesthesia intraoperatively lowers DBP but does not affect compartment pressure, causing the Delta P to be falsely lower. Therefore, preoperative DBP should be used when measuring compartment pressures intraoperatively.