Pulses Present and Pink Color. Unless there is a major arterial injury or disease, peripheral pulses are palpable and capillary refill is routinely present. Although compartment pressures are occasionally high enough to occlude a major artery, in more than 90% of patients the pulses are intact or can be confirmed with Doppler ultrasonography.

Differential Diagnosis

In patients with limb injuries and neurovascular deficits, the differential diagnosis is limited primarily to compartment syndrome, arterial injury, and nerve injury. Identification of the problem is important because the treatments differ: a compartment syndrome requires immediate decompression; an arterial injury requires immediate restoration of the circulation (either by repair of the artery or by removal of a thrombus); a nerve injury associated with a fracture or contusion (most commonly, neurapraxia) is usually treated with observation.

Compartment syndrome, arterial injury, and nerve injury frequently coexist, and the clinical findings overlap. Each condition may have associated motor and sensory deficit and pain. Arterial injury usually results in absent pulses, poor skin color, and decreased skin temperature, but a pseudoaneurysm and adequate collateral circulation may allow for a distal pulse. In contrast, in compartment syndrome, peripheral pulses are nearly always intact. Nerve injuries usually cause little pain, but the pain caused by antecedent trauma may be difficult to differentiate from ischemia pain. Diagnosis of neurapraxia is by exclusion of the other two entities. Doppler ultrasonography and arteriography are useful in diagnosing an arterial injury, and measurement of intracompartmental pressure may be used to detect or confirm compartment syndrome.

MEASUREMENT OF INTRACOMPARTMENTAL PRESSURE

Several techniques have been used to measure intracompartmental pressure (see Plate 7-15). The needle technique, first described in 1884, was popularized in the United States in the 1970s by Reneman and Whitesides. A variation of the needle technique employs continuous infusion of saline for long-term pressure monitoring.

The wick catheter does not require the injection of saline solution to measure equilibrium pressure. It was designed to prevent the catheter tip from being blocked by soft tissue and to maximize the surface area between the saline in the catheter and the fluids in the soft tissue. The fully automated, fluid-filled wick catheter system is connected to a pressure transducer and to a recording device for constant measurement of tissue pressure.

The slit catheter system is less likely to induce coagulation during long-term measurements, has a faster response time during exercise studies, and is more easily manufactured than the wick catheter.

Newer commercial devices have been developed; the most commonly used is the Stryker STIC Device. This device is small, portable, and easy to use and allows for repeat measurements in the same, or multiple, compartments easily.

Regardless of which device is chosen, it is important that it is zeroed and used properly. Studies of tibial fractures have shown a relationship between the distance from the fracture and the recorded pressure, so in the setting of a fracture the pressure measurements should be taken from within 5 cm of the fracture site. With or without an underlying fracture, multiple measurements can be taken and the highest recorded value considered.

INDICATIONS

The diagnosis of a compartment syndrome is now largely based on the clinical signs and symptoms. Invasive pressure measurements are still useful in situations in which the diagnosis cannot be made clinically or if confirmation is desired before surgical intervention:

Uncooperative or unreliable patients: interpretation of clinical findings may be difficult or not possible in adults with alcohol or drug intoxication. Frequently, children with fractures may be so frightened that careful neurologic evaluation is not possible.

Unresponsive patients: clinical evaluation of patients who are unconscious because of head injuries or drug overdose is not possible. The only reliable physical finding may be a swollen leg, making confirmation of the intracompartmental pressure mandatory.

Patients with associated neurovascular injury: it is often difficult to differentiate a nerve deficit associated with neurapraxia or with arterial injury from a compartment syndrome without measuring the intracompartmental pressure.