Compartment syndrome occurs when excessive pressure builds up inside an enclosed muscle space in the body. Compartment syndrome usually results from bleeding or swelling after an injury. The dangerously high pressure in compartment syndrome impedes the flow of blood to and from the affected tissues. It can be an emergency, requiring surgery to prevent permanent injury.
Groups of organs or muscles are organized into areas called compartments. Strong webs of connective tissue called fascia form the walls of these compartments.
After an injury, blood or edema (fluid resulting from inflammation or injury) may accumulate in the compartment. The tough walls of fascia cannot easily expand, and compartment pressure rises, preventing adequate blood flow to tissues inside the compartment. Severe tissue damage can result, with loss of body function or even death.
The legs, arms, and abdomen are most prone to developing compartment syndrome.
Acute compartment syndrome is the most common type of compartment syndrome. About three-quarters of the time, acute compartment syndrome is caused by a broken leg or arm. Acute compartment syndrome develops rapidly over hours or days.
Compartment syndrome can develop from the fracture itself, due to pressure from bleeding and edema. Or compartment syndrome may occur later, as a result of treatment for the fracture (such as surgery or casting).
Acute compartment syndrome can also occur after injuries without bone fractures, including:
- Crush injuries
- Overly tight bandaging
- Prolonged compression of a limb during a period of unconsciousness
- Surgery to blood vessels of an arm or leg
- A blood clot in a blood vessel in an arm or leg
- Extremely vigorous exercise, especially eccentric movements (extension under pressure)
Taking anabolic steroids can also contribute to developing compartment syndrome.
Another form of compartment syndrome, called chronic compartment syndrome, develops over days or weeks. Also called exertional compartment syndrome, it may be caused by regular, vigorous exercise. The lower leg, buttock, or thigh is usually involved.
Abdominal compartment syndrome almost always develops after a severe injury, surgery, or during critical illness. Some conditions associated with abdominal compartment syndrome include:
- Trauma, especially when it results in shock
- Abdominal surgery, particularly liver transplant
- Sepsis (an infection causing inflammation throughout the body)
- Severe ascites or abdominal bleeding
- Pelvic fracture
- Vigorous eccentric abdominal exercises (i.e. situps on a back extension machine in weight rooms)
Acute compartment syndrome usually develops over a few hours after a serious injury to an arm or leg. Some symptoms of acute compartment syndrome include:
- A new and persistent deep ache in an arm or leg
- Pain that seems greater than expected for the severity of the injury
- Numbness, pins-and-needles, or electricity-like pain in the limb
- Swelling, tightness and bruising
Symptoms of chronic compartment syndrome (exertional compartment syndrome) include worsening aching or cramping in the affected muscle (buttock, thigh, or lower leg) within a half-hour of starting exercise. Symptoms usually go away with rest, and muscle function remains normal. Exertional compartment syndrome can feel like shin splints and be confused with that condition.
Abdominal compartment syndrome usually develops in people who are hospitalized and critically ill on life support. They usually cannot describe their symptoms. Doctors or family may notice the abdominal compartment syndrome symptoms and signs:
- A tense, distended abdomen
- Wincing when the abdomen is pressed
- Urine output that slows down or stops
- Low blood pressure
A doctor may suspect compartment syndrome based on the type of injury, a person's description of symptoms, and a physical exam. Sometimes, the diagnosis of compartment syndrome is clear from these findings.
In many cases, a definite diagnosis of compartment syndrome requires direct measurement of pressures inside the body compartment. To do this, a doctor can insert a needle into the area of suspected compartment syndrome while an attached pressure monitor records the pressure. A plastic catheter can also be inserted to monitor the compartment pressure continuously.
In suspected abdominal compartment syndrome, a pressure monitor can be inserted into the bladder through a urinary catheter. High pressures in the bladder, when there are signs of abdominal compartment syndrome, strongly suggest the diagnosis.
Laboratory and imaging tests can support the diagnosis of compartment syndrome. But no single test other than a direct pressure measurement can make the abdominal compartment syndrome diagnosis.
Treatments for compartment syndrome focus on reducing the dangerous pressure in the body compartment. Dressings, casts, or splints that are constricting the affected body part must be removed.
Most people with acute compartment syndrome require immediate surgery to reduce the compartment pressure. A surgeon makes long incisions through the skin and the fascia layer underneath (fasciotomy), releasing excessive pressure.
Other supportive treatments include:
- Keeping the body part below the level of the heart (to improve blood flow into the compartment)
- Giving oxygen through the nose or mouth
- Giving fluids intravenously
- Taking pain medications
Chronic compartment syndrome can first be treated by avoiding the activity that caused it and with stretching and physical therapy exercises. Surgery is not as urgent in chronic or exertional compartment syndrome, but it may be required to relieve pressure.
Abdominal compartment syndrome treatments include life support measures like mechanical ventilation, medicines to support blood pressure (vasopressors), and kidney replacement therapies (such as dialysis). Surgery to open the abdomen in order to reduce the compartment syndrome pressures may be necessary. The best time to perform surgery in people with abdominal compartment syndrome is often not clear. Surgery for abdominal compartment syndrome may be lifesaving, but can also cause complications.