Nearly 200,000 people are affected with a compartment syndrome each year in the United States.1 Although there are many causes, the clinical pathway in the development of this syndrome is the same.
Muscle groups in the body are surrounded by fascial sheaths that enclose the muscles within a defined space or compartment. When an injury occurs to the muscles within a compartment, swelling ensues. Because the tight fascial sheaths allow little room for expansion, the pressure within the compartment begins to increase. Eventually, blood flow is compromised and irreversible muscle injury follows. One must suspect a compartment syndrome early to prevent contracture deformities (i.e., Volkmann’s ischemic contractures) that result from ensuing muscle and nerve necrosis.
The most common locations for compartment syndrome are the forearm and leg.1 Other sites that have been implicated include the hand, shoulder, back, buttocks, thigh, abdomen, and foot. A discussion specific to each of these muscle compartments is included elsewhere in the text.
In approximately 70% of cases, compartment syndrome develops after a fracture and half of those are caused by tibia fractures.2 Other commonly associated fractures include the tibia, humeral shaft, forearm bones, and supracondylar fractures in children.3,4 Other causes of acute compartment syndrome include crush injury, constrictive dressings/casts, seizures, intravenous infiltration, snakebites, infection, prolonged immobilization, burns, acute arterial occlusion or injury, and exertion.2,5 A venous tourniquet can produce compartment syndrome in as little as 90 minutes if it is accidentally left in place.6 Patients with a coagulopathy (i.e., Coumadin, hemophilia) are at increased risk and may develop compartment syndrome after minimal trauma.
The diagnosis of compartment syndrome is primarily a clinical one. Patients will exhibit pain out of proportion to the underlying injury, sensory symptoms, and muscle weakness. Pain is the earliest and most consistent sign. It is usually persistent and not relieved by immobilization. It is critical that the emergency physician recognizes this condition by its early features, and before other signs and symptoms develop, to prevent permanent injury.
Pain that is aggravated by passive stretching is the most reliable sign of compartment syndrome.2 Diminished sensation is the second most sensitive examination finding for compartment syndrome. Sensory examination of the nerves coursing through the affected compartments will reveal diminished two-point discrimination or light touch. Both of these tests are more sensitive than pinprick. Palpation of the compartment will disclose tenderness and “tenseness” over the ischemic segments. The distal pulses and capillary filling may be entirely normal in a patient with significant muscle ischemia and, therefore, these findings should not be used to rule out the existence of a compartment syndrome.
To summarize, disproportionate pain is the earliest symptom, whereas pain with passive stretching of the involved muscles is the most sensitive sign of compartment syndrome. Paresthesias or hypesthesias in nerves traversing the compartment are also important signs of a developing compartment syndrome. Orthopedic consultation should be obtained as soon as compartment syndrome is a consideration.
Compartment Pressure Measurement
The decision to perform a fasciotomy is based on a combination of clinical findings, as previously outlined, and measurement of elevated compartment pressures. If one suspects a compartment syndrome, frequent reexamination in the hospital and measurement of compartment pressures must be carried out. Compartment pressures are most commonly performed using the commercially developed Stryker STIC device (Fig. 4–1 and Videos 4–1 and 4–2).2,7,8
Video 4-1: Stryker preparation and zeroing.
Video 4-2: Stryker pressure measurement.
Stryker STIC device for measuring compartment pressure. (Reprinted with permission from Reichman EF, Simon RR. Emergency Medicine Procedures. New York, NY: McGraw-Hill; 2004.)
If this device is unavailable, a backup technique, such as the infusion technique, can be performed with materials readily found in most emergency departments.8 The necessary equipment include (1) a blood pressure manometer, (2) 20-mL syringe, (3) three-way stopcock, (4) 18-gauge needle, (5) normal saline, and (6) two intravenous extension tubes.
The apparatus is set up such that the syringe and two extension tubes are attached to the ports of the three-way stopcock (Fig. 4–2). The plunger of the syringe is opened to the 15-mL mark. One extension tube is connected to the blood pressure device, whereas the other is connected to the 18-gauge needle. Saline is drawn up through the needle to fill one-half of the tubing and the stopcock is closed off so the saline will not be lost. The needle is then sterilely inserted into the muscle of the compartment to be measured. At this time, the stopcock is turned such that the syringe is opened to both extension tubes. As the syringe plunger is slowly depressed, the manometer reading will begin to rise. When the meniscus of the saline within the extension tubing is first noted to move, the pressure read from the manometer is the compartment pressure.8
Infusion technique for measuring compartment pressure.
Erroneous pressure readings can result in several situations. For this device to read accurately, the top of the column of saline must be placed at the same level as the tip of the needle. If the pressure is read while saline is being injected into the muscle, a falsely elevated reading will be obtained.8
Normal compartment pressures are below 10 mm Hg. At pressures >20 mm Hg, capillary blood flow within the compartment may be compromised. Traditional teaching had been to perform fasciotomy at pressures >30 mm Hg. However, in experimental studies, it has been shown that patients with higher diastolic blood pressures have a reduced likelihood of ischemic necrosis because of higher perfusion pressures. For this reason, many authors now recommend fasciotomy when the compartment pressure reaches a point that is 20 mm Hg below the mean arterial pressure or 30 mm Hg below the diastolic pressure.2,5
Measurements should be made in all of the compartments of the extremity in question. Multiple measurements within a single compartment may be necessary as evidence suggests that pressures at different locations within the same compartment are not uniform. Distances as short as 5 cm result in significantly different pressure readings that will alter clinical decision making. The highest pressure recorded should be used.2,8,9 Also given that the highest compartment pressures are often found after 12 to 36 hours, multiple measurements over time may be necessary.5
Several noninvasive methods of measuring compartment pressures are under investigation. Promising technology includes ultrasound with a pulsed phase-locked loop, laser Doppler flowmetry, and near-infrared spectroscopy.2,10,11
To summarize, compartment syndrome is a challenging diagnosis to make. Compartment pressure measurement is an adjunct to clinical examination. Controversy exists over cutoffs of compartment pressure that require immediate fasciotomy. The patient with an equivocal examination and indeterminate compartment measurements requires at a minimum prompt orthopedic consultation and clinical observation with serial examinations.
The treatment of compartment syndrome requires immediate fasciotomy. Delays may result in irreversible damage to muscles and nerves. In general, nerves and muscles can tolerate up to 4 hours of total ischemia. After 8 hours, damage is irreversible.8 However, there is evidence that pediatric patients may still have reasonably good outcomes despite delayed presentations.12
In addition to arranging for fasciotomy, the emergency physician must remove all circular constrictive dressings and splints and relieve flexion if the elbow and forearm are involved. The affected limb should be placed at the level of the heart to avoid reduction in arterial flow and increase in compartment pressure due to dependent edema. Hypotension must be avoided and treated aggressively.2,5 In partially reduced supracondylar fractures, skeletal traction is recommended. If relief is not obtained within 30 minutes, then surgery is indicated. One must not “watch and wait,” as the goal is to restore circulation before irreparable damage ensues. Rhabdomyolysis may complicate compartment syndrome, and adequate hydration to maintain urinary output is essential. See Chapter 1 for further discussion of rhabdomyolysis.