Acute compartment syndrome (ACS) is an increase in tissue pressure within an osseofascial compartment above tissue perfusion pressure, resulting in diminished local circulation and eventual tissue necrosis.
Operative intervention can decrease the degree of permanent muscle and nerve injury in the initial stages of compartment syndrome.
Volkmann ischemic contracture is a delayed finding of compartment syndrome and represents a continuum of static muscle contractures secondary to fibrosis and neurologic injury.
ACS results from a nonelastic constrictive element, such as muscle fascia, casts, or tight dressings, which decreases venous outflow and arterial inflow in the setting of bleeding or muscle swelling.
Elevated intracompartmental pressure, when left untreated, results in a decrease in arterial perfusion to a level that is not compatible with tissue viability (Figure 51.1).
Continued cellular anoxia leads to activation of apoptosis via upregulated lysosomal pathways.
Permanent dysfunction of muscle occurs after 4 to 12 hours of anoxia.
Mechanism of injury
External causes: extracompartmental compression by tight dressings or casts
Internal causes: bleeding or swelling from fractures, penetrating injuries, blunt soft tissue trauma or crush injuries, ischemia-reperfusion injuries, deep burns, animal/insect bites, intravenous fluid extravasation, infection, and bleeding secondary to coagulopathy
The incidence of compartment syndrome in pediatric upper extremity fractures is as low as 1%. Pediatric fractures most associated with forearm compartment syndrome are both bone forearm fractures and floating elbow injuries.
In adults, the most frequent upper extremity fractures correlated with compartment syndrome are both bone forearm fractures and distal radius fractures. Compartment syndrome is more commonly reported in males younger than 35 years, penetrating trauma, open fractures, and elbow dislocations.
Compartment syndrome of the hand is most strongly associated with intravenous injections.
A high index of suspicion must be present when there is pain out of proportion to injury.
Increasing analgesic demands must be closely monitored and may be the most reliable symptom of evolving compartment syndrome in children.
Loss of consciousness, altered mental status, diverting polytraumatic injuries, or regional anesthesia pose challenges in accurate diagnosis and may require objective tests such as compartment pressure measurements.
Compartment syndrome is a clinical diagnosis that may in certain circumstances be confirmed based on objective findings.
Consider the six P’s associated with ACS: pain, paresthesias, pallor, paralysis, pulselessness, and poikilothermia.
Unrelenting pain is the earliest and most sensitive finding.
Compartments will generally be tense on palpation, and passive stretch of the involved compartment will create intolerable discomfort.
Compartment pressure can be measured if physical examination findings are ambiguous. The patient should be supine, with the affected extremity at heart level.
An arterial line monitor or a handheld pressure-monitoring device (Stryker) may be used after appropriate calibration to avoid falsely elevated readings.
Threshold pressures include 30 to 40 mm Hg or within 30 mm Hg of diastolic blood pressure. In patients with bleeding disorders, diffuse thrombocytopenia, or cellulitis, obtaining pressure measurements may pose additional risk. See Table 51.1.
Radiographs of affected portion of upper extremity should be obtained to evaluate for fracture, foreign bodies, subcutaneous air, or other pathologies that may be contributing to the disease process.
ACS: tissue pressures increase within an osseofascial compartment, resulting in tissue ischemia.
Exertional compartment syndrome: transient tissue ischemia secondary to nonelastic fascial compartment unable to acclimate to
muscle amplification during increased activity. Patients report pain beginning as a slow ache within the first half-hour of beginning a specific activity until cessation and rest.
Neonatal compartment syndrome: newborns may have upper extremity swelling with distinctive skin lesions known as “sentinel lesions of neonatal compartment syndrome.”
TABLE 51.1 Myofascial Compartments of the Upper Extremity and Their Contents