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Although the sequelae of untreated compartment syndromes have been recognized for more than 150 years, it is interesting to note how much controversy and confusion still persist when this diagnosis and its management are discussed. More than 25 years ago, Frederick A. Matsen III, MD, from Seattle defined a compartment syndrome as a condition in which increased pressure within a limited space compromises the circulation and function of the tissues within that space. Therefore, the four essential components of a compartment syndrome are a limiting envelope, increased tissue pressure, reduced tissue circulation, and abnormalities in neuromuscular function. The investing fascia around muscles and nerves in the compartments of extremities is, of course, the major limiting envelope; however, skin dressings, splints, or casts can act as limiting envelopes as well.

Compartment syndromes are caused by increased content or decreased volume of a musculofascial compartment. Increased content of a compartment is caused by edema of the contents, hemorrhage into the compartment, or increased size of the contents. Edema is the most common cause, and examples include ischemia and ischemia-reperfusion, obstruction of venous outflow, nonischemic edema, infiltration/injection, and a variety of unusual medical causes such as hypothyroidism or diabetes mellitus. Decreased volume of a compartment is related to the entities listed above (ie, dressings, splints, casts) as well as to air splints, pneumatic antishock garments, or even premature closure of a fasciotomy site.

Edema of the contents of a compartment is usually due to arterial occlusion, a low flow state, and near exsanguination, all conditions in which ischemia followed by reperfusion occurs. These all cause increased capillary permeability, movement of intravascular fluid into the interstitial space, secondary edema, and transformation of superoxide radicals to hydroxyl, carbon, and nitrogen free radicals. Increased edema in a musculofascial compartment increases local venous pressure and, therefore, decreases the arteriovenous gradient at the cellular level. When the decrease in arteriovenous gradient exceeds the compensation provided by autoregulation, decreased capillary flow to oxygen-sensitive tissues such as muscles and nerves causes the classical symptoms of a compartment syndrome. In general, muscles in a compartment of an extremity can survive without oxygenated flow and suffer no permanent change for 4 hours. In contrast, nerves in a compartment will start to suffer neuropraxia after 1 to 4 hours of ischemia.

The method of diagnosis of a compartment syndrome will depend on the clinical presentation of the patient. Unresponsive patients or those with a need for an emergency operation due to hemorrhage cannot undergo a formal history and comprehensive physical examination. Therefore, some surgeons will perform a fasciotomy on the extremity of such a patient based on whether or not the patient is considered to be at “high risk” for developing a compartment syndrome. Other surgeons will measure the compartment pressure or calculate the differential pressure.

If a formal history and physical examination can be obtained, disproportionate pain and well-known findings due to the compartment syndrome are usually present. The classical findings include: swelling of the extremity or compartment, pain with passive stretch of the muscles in the compartment, paresthesias and decreased 2-point discrimination in the distal sensory distribution of a nerve passing through the compartment, and weakness or paralysis of the muscles in the compartment. Distal arterial pulses are almost always present in the absence of a proximal arterial occlusion or injury.

If the patient cannot be examined or the physical examination is equivocal, it is appropriate to measure the compartment pressure. A variety of techniques including the older needle injection technique, wick catheter, slit catheter, 16-gauge needle attached to arterial tubing that is connected to a standard monitor, and a commercially available pressure monitor system have been used over the past 40 years. Most centers use the 16-gauge needle/arterial tubing/monitor or the commercially available system in the modern era. The greatest concern with choosing an absolute numerical value to prompt a fasciotomy is that there are several factors that may influence whether adverse sequelae will occur. Included among these are: compartment pressure, patient's blood pressure, time that elevated compartment pressure has been present, metabolic demands of muscles and nerves in the affected compartment, and, most importantly, individual susceptibility. For these reasons, the absolute pressure that prompts a fasciotomy has varied from 30 to 45 mm Hg over the past 40 years. For this reason, many surgeons have chosen to use the differential pressure described by Thomas E. Whitesides, Jr, from Emory University in 1975. The differential pressure is defined as the patient's diastolic blood pressure minus the compartment pressure measured in millimeters of mercury (mm Hg). Most centers use a range of less than 20 to 30 mm Hg to prompt a fasciotomy, and this range has been well validated in numerous studies over the past 15 years.

Near-infrared spectroscopy has been studied as a tool to diagnosis a compartment syndrome in laboratory and clinical settings as well. The decrease in tissue oxygenation that occurs when a compartment syndrome is present is the marker that is used. More clinical validation of this device will be needed before it can be considered a diagnostic equivalent to measurement of compartment pressure or differential pressure.

When a compartment syndrome is diagnosed in a high risk situation, on clinical examination, or using a measure of compartment or differential pressure, emergency (within 1 hour) fasciotomy is indicated. The complexity of this simple mandate increases if the patient has developed the rare secondary extremity compartment syndrome (SESC). This entity is seen as part of the postresuscitation systemic inflammatory response syndrome and is characterized by a diffuse capillary leak. Multiple compartments in multiple uninjured or injured extremities develop classical compartment syndromes. The need for fasciotomies in all compartments of three or more extremities in a single patient is not rare. Despite increased recognition of this syndrome, amputations due to delays in diagnosis and treatment still occur. As would be expected in patients with major systemic insults, the mortality rate has ranged from 35% to 70% in the 2 largest published series.

Although isolated patients with compartment syndromes respond to medical management, fasciotomy in the operating room is the preferred treatment. The compartments below the knee are the most commonly affected, and 4-compartment fasciotomy is performed through medial and lateral incisions. The anterior (quadriceps) and posterior (hamstrings) compartments of the thigh can be decompressed through a single lateral incision over the vastus lateralis muscle; fasciotomy of the medial (adductors) compartment is rarely necessary. The lateral (mobile wad) and superficial and deep volar compartments of the forearm can be decompressed using the volar-ulnar skin incision with further dissection between the flexor carpi ulnaris and flexor digitorum muscles. Fasciotomies of the foot and hand are required on occasion, and techniques for decompression are well described.

Closure of fasciotomy wounds after a period of elevation can be accomplished by delayed insertion of vertical mattress sutures in the skin. If tension is excessive, a “pie crust” incision in the adjacent skin may allow for primary closure to be completed. Insertion of “shoelace” elastic bands at the first operation and sequential tightening over time is another popular technique for delayed closure. Commercial devices to close the skin gap over fasciotomy sites are available as well. Vigorous attempts should be made to avoid the need for split-thickness skin grafts as coverage.

The long-term sequelae of fasciotomies include pain, cosmetic deformities, and muscle weakness in selected patients. Although the incidence is much higher than commonly appreciated, fasciotomies will continue to be performed for limb salvage in a variety of clinical situations.