Definitions

compartment pressure

Compartment syndrome

Compartment syndrome is an acute medical problem following injury, surgery or in most cases repetitive and extensive muscle use, in which increased pressure (usually caused by inflammation) within a confined space (fascial compartment) in the body impairs blood supply. Without prompt treatment, it may lead to nerve damage and muscle death. This condition is most commonly seen in the anterior compartment and posterior compartment of the leg.

Causes

Because the connective tissue that defines the compartment does not stretch, a small amount of bleeding into the compartment, or swelling of the muscles within the compartment can cause the pressure to rise greatly. Common causes of compartment syndrome include tibial or forearm fractures, ischemic-reperfusion following injury, hemorrhage, vascular puncture, intravenous drug injection, casts, prolonged limb compression, crush injuries and burns. Another possible cause can be from the use of creatine monohydrate. Past use of creatine has been known to cause this condition.

When compartment syndrome is caused by repetitive heavy use of the muscles, as in a cyclist, it is known as chronic compartment syndrome (CCS). This is usually not an emergency, but the loss of circulation can cause temporary or permanent damage to nearby nerves and muscle.

Pathophysiology

Any condition that results in an increase in compartment contents or reduction in a compartment’s volume could lead to the development of an acute compartment syndrome. When pressure is elevated capillary blood flow is compromised. Edema of the soft tissue within the compartment further raises the intra-compartment pressure, which compromised venous and lymphatic drainage of the injured area. Pressure, if further increased in a reinforcing vicious cycle, can compromise arteriole perfusion, leading to further tissue ischemia.

The normal mean interstitial tissue pressure is near zero mmHg in non-contracting muscle. If this pressure becomes elevated to 30 mmHg or more, small vessels in the tissue become compressed, which leads to reduced nutrient blood flow i.e., ischemia and pain. Of particular importance is the difference between compartment pressure and diastolic blood pressure; where diastolic blood pressure exceeds compartment pressure by less than 30mmHg it is considered an emergency.

Untreated compartment syndrome mediated ischemia of the muscles and nerves lead to eventual irreversible damage and death of the tissues within the compartment.

Symptoms and signs

The 6 "Ps"—pain out of proportion to what is expected, paresthesias, passive stretch pain, pulselessness, paralysis, and pressure on passive extension of the compartment—are said to be useful in recognition of compartment syndrome. Of these only the first two are reliable in the latter stages of compartment syndrome.

  • Pain is often reported early and almost universally. The description is usually of deep, constant, and poorly localized and is sometimes described as out of proportion with the injury. The pain is aggravated by stretching the muscle group within the compartment and is not relieved by analgesia up to and including morphine
  • Paresthesia (alterated sensation e.g. "pins & needles") in the cutaneous nerves of the affected compartment is another typical sign.
  • Paralysis of the limb is usually a late finding. The compartment may feel very tense and firm as well (pressure).
  • Note that a lack of pulse rarely occurs in patients, as pressures that cause compartment syndrome are often well below arterial pressures and pulse is only affected if the relevant artery is contained within the affected compartment.

Action to take

If you are a patient outside of hospital
Return to the emergency department immediately, or nearest hospital.

If you are a physician
Remove any cast or bandage around the limb immediately - all layers should be clear down to skin
Contact a senior orthopaedic or vascular surgeon

Diagnosis

CCS can be tested for by gauging the pressure within the muscle compartments. If the pressure is sufficiently high, a fasciotomy may be required. Various recommendations of the intracompartmental pressure are used with some sources quoting >30mmHg as an indication for fasciotomy while others suggest a >30mmHg difference between intracompartmental pressure and diastolic blood pressure. This latter measure may be more sensible in the light of recent advances in permissive hypotension which allow patients to be kept hypotensive in resuscitation.

Treatment

Acute compartment syndrome is a medical emergency requiring immediate surgical treatment known as a fasciotomy to allow the pressure to return to normal.

Subacute compartment syndrome, while not quite as much of an emergency, usually requires urgent surgical treatment similar to acute compartment syndrome.

Chronic compartment syndrome in the lower leg can be treated conservatively or surgically. Conservative treatment includes rest, anti-inflammatories, elevation of the limb and manual decompression. In cases where symptoms persist the condition should be treated by a surgical procedure, subcutaneous fasciotomy or open fasciectomy. Without treatment chronic compartment syndrome can develop into the acute syndrome. A possible complication of surgical intervention for chronic compartment syndrome can be chronic venous insufficiency.

Hyperbaric oxygen therapy has been shown to be a useful adjunctive therapy to crush injury, compartment syndrome, and other acute traumatic ischemias by improving wound healing and reducing repetitive surgery.

Complications

Failure to relieve the pressure can result in necrosis of tissue in that compartment, since capillary perfusion will fall leading to increasing hypoxia of those tissues. If left untreated, acute compartment syndrome can lead to more severe conditions including rhabdomyolysis and kidney failure.

See also

References

External links

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