Compartment Syndrome
Compartment syndrome is a serious potential complication of extremity
trauma. It develops when pressure within an osseofascial muscle compartment rises
sufficiently to cause ischemia and subsequent necrosis.[189]
High-risk injuries include leg and forearm fractures, severe crush injuries, and
localized or prolonged external pressure on an extremity. Increased compartment
pressure may be due to increased compartment size from edema as a result of revascularization
of ischemic muscle or may be due to decreased compartment size from constrictive
dressings. Compartment syndrome is manifested by extreme pain unrelieved by analgesics,
paresthesias, loss of sensation, intact pulses, and tense swelling of the involved
region. Failure to recognize developing compartment syndrome has been theoretically
attributed to the use of epidural analgesia, but at least one case series suggested
that attentive clinical care could allow the benefits of epidural use without delaying
recognition of compartment syndrome.[190]
Paralysis
and loss of pulse are late signs. The clinical diagnosis is confirmed by measuring
a compartment pressure greater than 35 to 40 mm Hg, which is suggestive of impaired
capillary flow. Compartment syndrome will predictably lead to ischemia and necrosis
of the involved muscle, impairment of distal flow, and the need for amputation.
Fasciotomy to relieve elevated compartment pressure is thus a limb-saving procedure
that should be undertaken as soon as possible after the diagnosis is made.
Crush syndrome is the general manifestation of crush injury and
is caused by continuous prolonged pressure on one or more extremities[191]
;
it is commonly found in patients who have been trapped in one position for an extended
period. Muscle injury from ischemia causes myoglobinuria, which can lead to acute
renal failure and subsequent profound electrolyte disturbances. The most critical
treatment consists of crystalloid fluid resuscitation to maintain a urine output
of 1 to 2 mL/kg/hr; osmotic
diuresis with mannitol and alkalinization of urine with sodium bicarbonate to prevent
precipitation of myoglobin in the renal tubules have been shown to be beneficial.
[192]
Fasciotomy is avoided, but if necessary,
it
is followed by radical débridement of the injured muscle to prevent infection,
which is the major cause of morbidity and mortality. A creatine phosphokinase level
greater than 10,000 mg/dL, hemorrhagic shock, advanced age, and delay in fluid therapy
after the crush injury are risk factors for the development of rhabdomyolysis. These
patients may benefit from transfer to an institution that can perform continuous
renal replacement therapy.
