Compartment Syndrome

SAMUEL E. GREENBERG, M.D.

Compartment Syndrome is a condition characterized by an elevation of the interstitial pressure within the closed confines of the skeletal muscle/fascia compartment. This pressure elevation is caused by trauma or excessive muscle activity resulting in excessive fluid or blood accumulation within this closed space and when the pressure exceeds the perfusion pressure, the tissue perfusion shuts down.

Ischemia and irreversible necrosis occurs, within 6 hrs., if not diagnosed quickly and treated by conservative means or surgical fasciotomy. A high index of suspicion is necessary and suggested by patient complaints which seem to outweigh the physical findings. Tissue pressure measurements confirm the presence of Compartment Syndrome.

The long muscles of the extremities are wrapped in sheaths of tissue called fascia. Also enclosed are the nerves and blood vessels, which serve these muscles. This fascia is fairly unyielding and sturdy, helping to give the muscle its linear characteristic and contributing to its strength. This community of muscle, nerves and blood vessels enclosed within a sturdy fascia wall is referred to as a Compartment.

Yet, because of this limited noncompliant fascia surrounding the muscle compartment, there is little opportunity for an elevation of the internal pressure, from such things as bleeding or edema, to be accommodated. When trauma, either from injury or from overuse occurs then the muscle may swell and the pressure in this Compartment becomes elevated.

Once the tissue pressure rises above the arterial perfusion pressure, the flow of oxygen and blood will cease and tissue hypoxia will ensue. Ischemia is followed by reperfusion, capillary leakage from the ischemic tissue, and this increase in tissue edema causes a decrease in tissue perfusion, by increasing tissue pressure, resulting in nerve and muscle damage. This, if not alleviated within 6 hrs. of onset, will result in necrosis of tissue, possible permanent tissue impairment, contractures, rhabdomyolysis, and even loss of limb, kidney failure and death.

The elevation of pressure in these muscle compartments along with the damage which develops, is referred to as COMPARTMENT SYNDROME.

Sometimes the syndrome is recurrent, as with exercise, but spontaneously abates with rest. Often it is irreversible, and must be attended to quickly.

Compartment Syndrome is found wherever there are compartments-hand, forearm, upper arms, abdomen, buttocks, and entire lower extremity

ETIOLOGY

Common causes of Compartment Syndrome are:

Long Bone fractures- especially fractures of the tibia, or the forearm. Also, after intramedullary nailing, in the thigh or upper arm. The presence of fracture blisters may encourage the formation of this syndrome.

Vascular injury - (inadvertent arterial puncture, extravagated caustic medication or contrast, repetitive juxtaposition venous sticks, etc.)

Crush Injuries
Vigorous muscular exercise-as by running, or from seizures or tetany.
Burns
Envenomation
Hemorrhage
Nephrotic Syndrome
Limb immobility under pressure-(Saturday Night Palsy).
High velocity injuries
Excessive external pressure as from Casts,external pressure suits ( MAST).. (These diminish the compartment size causing elevation of the pressure).

Certain operating room positioning of the patient, such as hip or knee flexion, leg elevation, compression bandaging, or prolonged use of a tourniquet can lead to this condition. All of these conditions, with the exception of increased external pressure, will cause increase fluid or blood to accumulate and an elevation of the internal pressure, putting the perfusion into that area at risk.

Individuals, who are on anticoagulations, are especially susceptible to internal bleeding with associated elevation of compartment pressure, when exposed to a simple venapuncture, inartfully done, or to a minor injury.

DIAGNOSIS

Since irreversible tissue damage can occur within 6 hours, it is incumbent for the Physician to maintain a high index of suspicion in situations where Compartment Syndrome is known to occur. Signs and symptoms often appear to be excessive when compared to the observed physical abnormality, but must be recognized before damage occurs. They are:

Pain- often severe, characterized as burning or tightness. This pain occurs even with rest.
Paresthesias-numbness and tingling
Strength- often diminished and almost paralyzed.
Flexibility of extremity parts- the earliest clues are often pain with active flexion, and, especially, pain with passive stretching movements.
Swelling- the area of the limb will become tense and hard. Comparing limb sized will help.
Chronic exertional compartment syndrome most often occurs in the anterior or the lateral lower extremity compartment.

LABORATORY DIAGNOSIS

The usual tests such as an SMA-16, and a CBC with differential are helpful towards indicating etiology. The interrogation of a dark urine, which is positive for blood, but reveals few red blood cells will direct one to checking a serum and urine myoglobin and CPK, to rule out muscle damage (rhabdomyolysis). A Prothombin time and a PTT are helpful. X-rays to check for bone damage and Ultrasound exam for venous competency to rule out DVT, or to assess accumulation of large quantities of fluid or blood are helpful.

But once suspected, Compartment Syndrome is best identified by measuring the tissue pressure, within the suspected compartment, by tonometers. It’s imperative to make sure that the tissue measured it within the right area and not in. If the intracompartmental pressure is greater than 30 mm of Hg., intervention is required. The capillary perfusion pressure is presumed to have been overwhelmed and for the capillaries to have shut down. Some authorities allow a compartment pressure o up to 70 mm of Hg, before recommending acute surgical fasciotomy.

A, supposedly more definitive measurement, is the delta p pressure. This is a measurement of the perfusion pressure as determined from the diastolic BP minus the Intracompartmental pressure. If the delta p pressure is less then 30 mm of Hg, a fasciotomy is indicated. This has been helpful in cases where the compartment pressure was as high as 40 mm of Hg, but if the delta p pressure was greater than 30 mm of Hg, the surgery was withheld with no loss of tissue. Conversely, if the compartment pressure was less than 30 mm of Hg and the delta p pressure was less than 30 mm of Hg, surgery was done and was felt to have been the right choice. Thallium stress testing, which is noninvasive, may be a more physiologic measurement.

TREATMENT

Fasciotomy has been the treatment of choice in this condition. Even the sequelae from prophylactic fasciotomy is less then the damage acquired from delay in treatment of Compartment Syndrome. Fasciotomy consists of . It carries the disadvantage of presenting an open wound, which is subject to infection, as well as prolonging the hospital stay of the patient.

Mannitol infusions, to try and osmotically lure the intracompartmental fluid back into the blood stream in order to lessen the intracompartmental pressure is receiving some recent recognition of success. Hyperbaric Oxygenation has, also, been recognized as a fairly successful remedy for this condition.