What are the symptoms and diagnosis of compartment syndrome?

Identifying Compartment Syndrome

Diagnose compartment syndrome clinically based on pain out of proportion to injury combined with pain on passive muscle stretch—these two findings together give a 68% positive predictive value, and direct compartment pressure measurement should only be used when clinical diagnosis remains uncertain, particularly in obtunded or uncooperative patients. 1

Clinical Presentation: The "6 Ps" Framework

The earliest and most reliable warning signs are:

• Pain out of proportion to injury is the single most important early indicator of acute compartment syndrome (ACS), though it alone provides only 25% diagnostic accuracy 1
• Pain on passive stretch of the affected muscle compartment is considered by many the most sensitive early sign; when combined with severe pain, diagnostic accuracy increases to 68% 1
• Pressure/tension manifests as increasing firmness of the compartment as intracompartmental pressure rises 1
• Paresthesia (numbness, tingling) results from nerve ischemia 2, 1
• Paresis (motor weakness) is a late sign indicating significant tissue damage; when pain, pain on stretch, and paralysis are all present, positive predictive value reaches 93%, but irreversible muscle ischemia may have already occurred 1
• Pulselessness, pallor, and decreased temperature are late signs indicating severe tissue damage and arterial occlusion—waiting for these signs leads to irreversible damage and is too late for meaningful intervention 2, 1, 3

Critical Diagnostic Pitfalls

Never rely on palpation alone—it has only 54% sensitivity and 76% specificity in children and is unreliable in isolation 4, 1

Never wait for late signs (pulselessness, pallor, paralysis)—these indicate irreversible damage has already occurred 1, 3

Clinical signs alone have low sensitivity and positive predictive value but high specificity and negative predictive value—meaning the absence of clinical signs is more accurate in excluding compartment syndrome than their presence is in making the diagnosis 4

When to Measure Compartment Pressure

Measure intracompartmental pressure only when:

• Clinical diagnosis remains uncertain despite evaluation 1
• Patient is obtunded, confused, sedated, or uncooperative and cannot report pain 1, 3
• Patient is a young child who cannot reliably communicate symptoms 1

Pressure Measurement Thresholds

Use these criteria for fasciotomy indication:

• Compartment pressure ≥30 mmHg in normotensive patients with positive clinical findings 2, 1
• Compartment pressure ≥20 mmHg in hypotensive patients 2
• Differential pressure ≤30 mmHg (diastolic blood pressure minus compartment pressure)—this is the most recognized cut-off in current practice 1

Technical Considerations for Pressure Measurement

• Use side-ported needles or slit catheters rather than 18-gauge needles, which can overestimate pressure by up to 18 mmHg and lead to unnecessary fasciotomies 4
• Traditional needle manometry, multiparameter monitors, or dedicated transducer-tipped monitors are all acceptable 1
• Never rely solely on pressure measurements without clinical correlation—combining both is essential 4

High-Risk Populations Requiring Vigilant Monitoring

• Young men under 35 years with tibial fractures 1
• Tibial shaft fractures specifically 1
• Crush injuries or high-energy trauma 2, 1
• Vascular injuries or burns 1
• Patients on anticoagulation 1
• Motorcyclists with lower-extremity injuries 5

Timing and Monitoring Strategy

Most cases develop within the first 24 hours, but compartment syndrome can occur up to 65 hours post-injury 3

Implement this monitoring protocol:

• Repetitive clinical assessment every 30 minutes to 1 hour during the first 24 hours in high-risk patients 3
• Evaluate for the "four P's" (pain, paresthesia, paresis, pressure/tension) at each assessment 3
• Extended surveillance beyond 24 hours for crush injuries, hemorrhagic injuries, reperfusion of ischemic lesions, or hypotension 3
• Continuous compartment pressure monitoring may be considered in high-risk, obtunded patients, though evidence shows it provides little advantage over serial clinical examination in alert, cooperative patients 4, 1

Immediate Management Algorithm

When compartment syndrome is suspected:

1. Remove all constricting dressings, casts, or splints immediately 1
2. Position the limb at heart level (not elevated, as elevation decreases perfusion pressure) 2, 1
3. Arrange urgent surgical consultation for fasciotomy without delay 1
4. Measure compartment pressures only if diagnosis remains in doubt 1
5. Never order imaging studies that delay surgical intervention—plain X-rays are frequently normal and CT/ultrasound have no established role in acute diagnosis 1

Special Diagnostic Challenges

In sedated or obtunded patients, direct compartment pressure measurement becomes critical since clinical signs cannot be reliably elicited 1, 3

Recognize that no single sign or investigation is guaranteed to diagnose or exclude compartment syndrome—maintain high clinical suspicion despite normal pressure readings if clinical signs are concerning 4

Compartment syndrome can occur with soft tissue injuries alone, even without fractures 1