Compartment syndrome

Compartment syndrome
Classification and external resources
Foot, c. 2 weeks post surgery because of compartment syndrome
ICD-10	M62.2, T79.6
ICD-9	729.7, 958.9
DiseasesDB	3028
MedlinePlus	001224
eMedicine	emerg/739

Compartment syndrome is a medical term which refers to the compression of nerves, blood vessels and muscle inside a closed space (compartment) within the body. This leads to tissue death due to lack of oxygenation as the blood vessels are compressed by the raised pressure within the compartment. Compartment syndrome most commonly involves the forearm and lower leg. ^[1] It can be divided into acute, subacute or chronic compartment syndrome.

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.^[2][3] Another possible cause can be from the use of creatine monohydrate. A history of creatine use has been linked to this condition.^[4][5] Compartment syndrome can also occur following surgery in the Lloyd Davis lithotomy position, where the patient's legs are elevated for prolonged periods. As of February 2001, any surgery that is expected to take longer than six hours to complete must include Compartment Syndrome on its list of post-operative complications. The Lloyd Davis lithotomy position can cause extra pressure on the calves and on the pneumatic pressure Flowtron boots worn by the patient.

When compartment syndrome is caused by repetitive use of the muscles, as in a cyclist, it is known as chronic compartment syndrome (CCS).^[6][7] This is usually not an emergency, but the loss of circulation can cause temporary or permanent damage to nearby nerves and muscles.

Pathophysiology

Any condition that results in an increase in compartment contents or reduction in a compartment’s volume can 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 compromises 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 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, 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 30 mmHg it is considered an emergency.^{[citation needed]}

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

Symptoms and signs

There are classically 5 "Ps" associated with compartment syndrome — pain out of proportion to what is expected, paresthesia, pallor, paralysis, pulselessness; sometimes a 6th P, for polar/poikilothermia (i.e. cold) is added. Of these, only the first two are reliable in the diagnosis of compartment syndrome. ^[8][9] Paresthesia, however, is a late symptom.

• Pain is often reported early and almost universally. The description is usually of severe, 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). In some cases, some find that their feet and even legs fall asleep. This is because compartment syndrome prevents adequate blood flow to the rest of the leg.

• 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.

• Tense and swollen shiny skin, sometimes with obvious bruising of the skin.

• Congestion of the digits with prolonged capillary refill time.

Diagnosis

Compartment syndrome is a clinical diagnosis. However it can be tested for by gauging the pressure within the muscle compartments. If the pressure is sufficiently high, a fasciotomy will be required to relieve the pressure. Various recommendations of the intracompartmental pressure are used with some sources quoting >30 mmHg^[9] as an indication for fasciotomy while others suggest a <30 mmHg difference between intracompartmental pressure and diastolic blood pressure^[10]. 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. It is now relatively easy to measure compartment and subcutaneous pressures using the pressure transducer modules (with a simple intravenous catheter and needle) that are attached to most modern anaesthetic machines.

Treatment

Acute compartment syndrome is a medical emergency requiring immediate surgical treatment, known as a fasciotomy, to allow the pressure to return to normal.^[11]

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; some have even reported that acupuncture alleviates their symptoms. 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.^[12][13]

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. This can cause Volkmann's contracture in affected limbs. If left untreated, acute compartment syndrome can lead to more severe conditions including rhabdomyolysis and kidney failure.

See also

• Volkmann's contracture
• Armed Forces Institute of Regenerative Medicine ("committed to develop clinical therapies for [e.g.] Compartment syndrome")

References

External links

• Chronic Exertional Compartment Syndrome detailed at MayoClinic.com
• Duke Orthopedics compartment_syndrome
• 05-062a. at Merck Manual of Diagnosis and Therapy Home Edition
• Fasciotomy, Chronic Venous Insufficiency, and the Calf Muscle Pump
• Compartment syndrome
• Saphenous nerve injury after fasciotomy for compartment syndrome
• American Association of Orthopaedic Surgeons Compartment Syndrome