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Compartment syndrome
Pain out of proportion is the warning — pulselessness is far too late. Suspect it early in anyone at risk with escalating pain, act immediately by removing everything constrictive, and get an urgent orthopaedic decision. Fasciotomy saves the limb; waiting for "classic" signs loses it. Built for revision, not live patient decisions.
Settle them, and check the basics
minutes matterRed flags — what each should make you think
Pulses are usually present in compartment syndrome. Compartment pressure rises above capillary pressure long before it reaches arterial pressure, so a palpable pulse never excludes it. The "5 Ps" describe a limb that is already dying.
Immediate actions (BOAST)
- ✂Split everything to skin
- ↑Position and re-evaluate
- BPMaintain normotension
- O₂Oxygen
- ☎Urgent orthopaedic review
- 🔪Fasciotomy
Understand the patient
who · how to assessWho is at risk?
- Tibial shaft fractures (the commonest), forearm fractures, supracondylar fractures in children
- Crush injuries, prolonged lie / immobilisation, reperfusion after vascular repair
- Tight casts or dressings, burns (circumferential)
- IV/IO extravasation, drug injection, anticoagulation, bleeding disorders
- Young men with large muscle mass
Assessing it
- Pain out of proportion, escalating, poorly relieved by analgesia
- Pain on passive stretch of the muscles in the compartment (e.g. toe flexion/extension for the leg)
- Tense, "woody" compartment
- Late: paraesthesia, paralysis, pallor, pulselessness
Compartment pressure monitoring helps when clinical assessment is unreliable (unconscious, sedated, nerve block, children). A difference between diastolic BP and compartment pressure (ΔP) below 30 mmHg, or an absolute compartment pressure above 40 mmHg, should prompt consideration of urgent decompression (BOAST).
Work A–E — assess and act as you go
The diagnoses you must not miss
tap to open eachWhat points toward it, what would rule it in, and how to manage it.
At-risk injury with escalating pain, passive stretch pain, tense compartment.
Clinical diagnosis; compartment pressures if unreliable exam.
Release dressings to skin, maintain normotension, consultant orthopaedic decision, immediate fasciotomy of all affected compartments (leg: four compartments).
Crush or long lie, dark urine, very high CK, hyperkalaemia.
CK, U&E, K⁺, urine dip.
Aggressive IV fluids, treat hyperkalaemia, monitor renal function.
Absent pulses, pale cold limb after trauma.
ABPI, CT angiogram.
Vascular surgery emergency; fasciotomy often needed after revascularisation.
Investigate — what to order, when, and what it tells you
test with a question in mindClinical
Compartment pressure
Bloods
Don't delay for tests
Compartment syndrome is a clinical diagnosis. If the clinical picture fits, the treatment is fasciotomy; no imaging can make or exclude the diagnosis.
How the plan comes together
disposition · handovertheatre
Diagnosed: immediate fasciotomy. Inconclusive: hourly documented examination, consider pressure monitoring, senior decision-maker review.
Hand over: time of symptom onset, findings, pressures if measured, time decision made.
close observation
At-risk limb without signs: hourly neurovascular and pain observations documented, low threshold to review, clear escalation plan.
If the pain is out of proportion, think compartment syndrome. Split everything to skin, keep the limb level, and call a senior now. A palpable pulse doesn't exclude it. Nicely done getting here.
Clerking template
copy or downloadCompartment syndrome — documentation structure
A structure and prompt list to help you document and think systematically. It is not a completeness check and cannot guarantee nothing is missed — use your trust's own proforma, your seniors, and your clinical judgement.
Test yourself
active recallCover the answer, say it out loud, then reveal. Retrieval beats re-reading.
0 / 9 knownFrequently asked questions
quick answersWhat are the red flags for compartment syndrome?
- Pain out of proportion to the injury — think compartment syndrome
- Increasing analgesia requirement — think compartment syndrome
- Pain on passive stretch — think compartment syndrome
- Tense, swollen compartment — think compartment syndrome
- Paraesthesia, weakness — think late — act now
- Unconscious / sedated / regional block — think can't report pain — monitor pressures
What is the initial management of compartment syndrome?
- Split everything to skin — bandages, padding and casts along their full length
- Position and re-evaluate — BOAST: limb elevated and re-evaluated within 30 minutes; avoid excessive elevation — follow local guidance
- Maintain normotension — treat hypotension
- Oxygen — if hypoxic
- Urgent orthopaedic review — senior decision
- Fasciotomy — immediate surgical decompression once diagnosed (consultant decision)
Always alongside senior support and your local guideline.
What diagnoses must you not miss in compartment syndrome?
- Acute compartment syndrome — fasciotomy
- Rhabdomyolysis / reperfusion — crush · long lie
- Arterial injury (mimic) — pulseless, cold
Open each one in the must-not-miss section for what points toward it, how to rule it in, and how to manage it.
What investigations should a junior doctor order for compartment syndrome?
- Clinical — Serial documented examination — pain, stretch, compartments, neurology.
- Compartment pressure — ΔP (diastolic − compartment) below 30 mmHg, or absolute pressure above 40 mmHg.
- Bloods — CK, U&E, K⁺, clotting.
Admit or discharge: how is the plan decided for compartment syndrome?
- Theatre — Diagnosed: immediate fasciotomy. Inconclusive: hourly documented examination, consider pressure monitoring, senior decision-maker review.
- Close observation — At-risk limb without signs: hourly neurovascular and pain observations documented, low threshold to review, clear escalation plan.
Is there a clerking template for compartment syndrome?
Yes — there is a free clerking template for compartment syndrome on this page, structured as presenting complaint, red flags asked, history, examination (A–E), investigations, differentials, plan and escalation. You can copy it or download it as a Word document. Jump to the template.
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