Compartment syndrome is diagnosed on the trend, not on a pulse

The classic teaching lists pallor, paralysis and pulselessness, and by the time those appear the muscle is already lost. The findings that matter come earlier and are less dramatic: pain disproportionate to the injury, pain that is escalating rather than settling, pain on passive stretch of the muscles in the compartment, and an analgesic requirement that keeps climbing despite adequate doses.

So the diagnosis lives in the trend on the observation chart rather than in a single examination. A patient whose morphine requirement is rising over four hours after a tibial fracture has a compartment problem until proven otherwise, and the examination is repeated rather than recorded once. Distal pulses are typically present throughout, so their presence is not reassurance; a plaster or dressing that is circumferential comes off before anything else is decided.

Where the patient cannot report pain — obtunded, intubated, under regional block, a young child — the clinical signs are unavailable and compartment pressure measurement is the only way to look. A regional block placed for analgesia after a high-risk injury should be a documented decision precisely because it removes the main monitoring signal.

• Track the analgesic requirement over time — a rising demand despite adequate doses is the earliest usable sign
• Test pain on passive stretch of the compartment muscles, and repeat the examination rather than documenting it once
• Do not use the presence of distal pulses as reassurance; they are usually preserved
• Release circumferential plaster and dressings before deciding anything else
• Measure compartment pressures where the patient cannot report pain — obtunded, intubated, blocked, or a young child

Why it matters

Waiting for the classic signs means waiting until the decision no longer matters.

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