How do you measure compartment pressure in a patient suspected of having compartment syndrome?

Compartment Pressure Measurement in Suspected Compartment Syndrome

Measure compartment pressure using needle manometry (traditional needle technique, arterial line transducer systems, or dedicated transducer-tipped catheters) inserted directly into the suspected compartment, but only when clinical diagnosis remains uncertain—particularly in obtunded, confused, or uncooperative patients who cannot reliably report pain. 1, 2

When to Measure Compartment Pressure

• Measure pressure when the diagnosis is in doubt, not as a routine screening tool in alert patients who can report symptoms 1, 2
• Obtunded or sedated patients who cannot communicate pain require pressure measurement as clinical examination is unreliable 1, 2
• Confused or uncooperative patients where clinical signs cannot be reliably elicited warrant direct pressure measurement 1
• Do not delay fasciotomy to obtain pressure measurements if clinical diagnosis is clear based on pain out of proportion and pain with passive stretch 2

Available Measurement Techniques

Three primary methods exist for measuring intracompartmental pressure, though they show only satisfactory agreement (intraclass correlation 0.83) with mean differences of 8.3 mmHg between methods 3:

• Traditional needle manometry using an 18-gauge needle connected to an arterial line transducer and pressure monitor 1
• Multiparameter monitors typically used for arterial blood pressure monitoring 1
• Dedicated transducer-tipped intracompartmental pressure monitors (e.g., Stryker device, used by 63% of surgeons) 1, 4

Critical Technical Considerations

• Avoid 18-gauge needles alone, as they may overestimate compartment pressure by up to 18 mmHg compared to slit catheters or side-ported needles 1, 5
• Measure all relevant compartments in the affected limb, not just one compartment 1
• Position measurements within 5 cm of the fracture site where pressures are typically highest 6

Single vs. Continuous Monitoring

• Single measurements are adequate in alert, cooperative patients who can undergo serial clinical examination 1
• Continuous pressure monitoring should be considered in high-risk, obtunded patients where serial examination is impossible 1, 2
• Continuous monitoring combined with differential pressure threshold achieves 94% sensitivity and 98% specificity in tibial shaft fractures 1
• There is little evidence that continuous monitoring reduces missed cases compared to serial examination in alert patients 1

Pressure Thresholds for Intervention

The differential pressure threshold is the most recognized cut-off currently used, not absolute pressure alone 1, 2:

• Fasciotomy is indicated when differential pressure (diastolic BP minus compartment pressure) is ≤30 mmHg in patients with other signs or symptoms of compartment syndrome 1, 2
• Some guidelines use a narrower threshold of 10-30 mmHg differential 1
• Absolute compartment pressure ≥30 mmHg was traditionally used but leads to 29% fasciotomy rate after tibial surgery when used in isolation without clinical signs 1, 2
• Higher absolute thresholds up to 45 mmHg have been suggested but also over-diagnose when taken alone 1

Why Differential Pressure Matters

• Tissue perfusion depends on both diastolic blood pressure and compartment pressure 1
• Hypertensive patients tolerate higher compartment pressures without ischemia compared to hypotensive patients 1
• Hypotensive patients develop ischemia at lower absolute compartment pressures 1

Critical Pitfalls to Avoid

• Never rely on pressure measurements alone without clinical context—even differential pressure thresholds miss some cases of compartment syndrome 1
• Do not use pressure measurement as a substitute for clinical judgment in alert patients with classic symptoms 2
• Interpret single pressure readings cautiously, as measurements can vary by 8-51 mmHg depending on technique and location 3
• Do not delay surgical consultation to obtain pressure measurements if clinical diagnosis is evident 2
• Recognize that 27% of measurements show major differences (>10 mmHg) between methods, so clinical findings must guide treatment decisions 3

Clinical Context is Paramount

• Pressure measurement is the gold standard adjunctive test only when combined with clinical features suggesting compartment syndrome 1
• Clinical signs alone have low positive predictive value (25% for severe pain alone, 68% for pain plus pain on passive stretch) but high negative predictive value 1, 2
• The absence of clinical signs is more accurate in excluding compartment syndrome than their presence is in confirming it 1
• Use objective scoring charts (e.g., UK Royal College of Nursing chart) to maintain heightened awareness among healthcare staff 1, 5