Compartment Syndrome

In a nutshell

Acute compartment syndrome is pressure inside a closed fascial compartment outrunning capillary perfusion, so the tissue dies while the pulse survives. Release constriction, call the senior orthopaedic surgeon, and decompress immediately once diagnosed.

Classic presentation

Six hours after a tibial shaft fracture a young man needs escalating morphine, screams when you passively extend his toes, and has a tense calf with easily palpable pulses.

Key points

• 1A diastolic minus compartment pressure difference below 30 mmHg indicates increased risk; an absolute pressure above 40 mmHg should prompt consideration of urgent decompression. Neither replaces clinical judgement.
• 2Two seniority bars, and they differ. Inconclusive signs go to a senior surgeon who can decide; the pressure-based call and delayed presentation are consultant-grade.
• 3A nerve block, epidural or reduced consciousness makes the pain score unusable. BOASt then wants invasive monitoring, or review by staff trained in both blocks and compartment syndrome.
• 4Training every member of the trauma pathway, and keeping a pressure monitor available, are hospital-level standards. This is not only a personal competence.
• 5Chronic exertional compartment syndrome is a different disease: predictable exercise-related pain that settles with rest. It is explicitly outside this standard.
• 6There is no creatine kinase (CK) cut-off for this diagnosis in any UK national guideline. CK tracks muscle damage; it does not decide whether to operate.

Exam traps

Illustrations

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Key sources

1. British Orthopaedic Association Standard for Trauma (BOASt): Diagnosis and Management of Compartment Syndrome of the Extremities (Revised July 2025. Background (key clinical findings are pain out of proportion to the associated injury and pain on passive movement of the muscles of the involved compartments); Exclusions (chronic exertional compartment syndrome); standard 1 (training, standardised recording using the RCN chart, guidance where assessment is not possible, capability to measure intracompartmental pressure); standard 2 (limb injuries, extremity surgery, or any prolonged procedure that may cause hypoperfusion); standard 3 (what each assessment records); standard 4 (dose and rate of analgesics, particularly opiates); standard 5 (hourly assessment with findings whether present or not, an interpretation and a rationale); standard 6 with footnote ** (regional anaesthesia: joint decision making, documented consent, agreed monitoring policy); standard 7 (circumferential dressings released to expose the skin, the limb elevated, re-evaluation within 30 minutes); standard 8 (hourly examination, pressure measurement with concurrent blood pressure, senior surgical review); standard 9 (immediate surgical decompression, NCEPOD 1); standard 10 (open decompression of all involved compartments, debridement, documentation, two-incision four-compartment lower limb fasciotomy); standard 11 (plastic surgeon within 24 hours, re-exploration within 72 hours); standard 12 (delayed presentation, two consultants, non-operative option with renal assessment and protection); standard 13 (no consensus for foot compartment syndrome); footnote *** (a difference of less than 30 mmHg between diastolic and compartment pressure indicates increased risk, the consultant orthopaedic surgeon decides, and urgent decompression should be considered above an absolute 40 mmHg))Published 1 Jul 2014 | Updated 1 Jul 2025
2. Royal College of Nursing: Acute Limb Compartment Syndrome Observation Chart (September 2016, publication code 005457, footnoted by BOASt standard 1b as the example standardised recording tool. Patients at risk: tibial, forearm or high-energy distal radius fractures; orthopaedic injury or intervention with known coagulopathy or anticoagulation; crush injuries; high impact trauma including open fractures; also newly applied traction, a restrictive cast or a tight circumferential bandage. Monitor hourly for the first 24 hours, 4-hourly from 24 to 48 hours, reverting to hourly if suspicion arises. Pain out of proportion and pain on passive movement are the key clinical findings, and the primary symptom is pain on passive extension. Changes in pulse, sensation and skin colour are late symptoms of neurovascular compromise and should not be relied upon to diagnose compartment syndrome. Escalate immediately at a total pain score of 5 or above, an individual pain parameter score of 3, or a clinical concern. Delta pressure equals diastolic blood pressure minus intracompartmental pressure reading; escalate a reading greater than 40 or a delta of 29 or less. Patients who have had a nerve block or epidural, or who are unconscious, cannot use the pain section)Published 1 Sept 2016
3. UK Kidney Association, Clinical Practice Guideline: Treatment of Acute Hyperkalaemia in Adults (Final version October 2023. Severity bands (mild 5.5 to 5.9, moderate 6.0 to 6.4, severe 6.5 mmol/L or more); guidelines 16.2a and 16.2b (calcium is indicated in the presence of ECG changes) with Appendix 3A (calcium gluconate 10%, 30 mL over 10 minutes); guidelines 16.3.1 to 16.3.3 (10 units soluble insulin in 25 g glucose, and 10% glucose at 50 mL/hour for 5 hours where pre-treatment glucose is below 7.0 mmol/L); urgent 12-lead ECG at a serum potassium of 6.0 mmol/L or more and continuous cardiac monitoring at 6.5 mmol/L or more)Published 19 Dec 2023
4. NICE NG37: Fractures (complex): assessment and management (Published 17 February 2016, last updated 23 November 2022; the 2022 update revised only the negative-pressure wound therapy recommendation, so the compartment-syndrome material is unchanged 2016 text. Compartment syndrome after tibial fracture: maintain awareness for 48 hours after injury or fixation by regularly assessing and recording clinical symptoms and signs in hospital, considering continuous compartment pressure monitoring where symptoms and signs cannot be readily identified, and advising people how to self-monitor after they leave hospital)Published 17 Feb 2016 | Updated 23 Nov 2022
5. BNF: Morphine (Indications and dose, acute pain, adult, by slow intravenous injection: initially 5 mg every 4 hours, use reduced dose in frail and elderly patients, adjusted according to response)
6. BNF: Paracetamol (Indications and dose, mild to moderate pain, adult: by mouth 0.5 to 1 g every 4 to 6 hours, maximum 4 g per day; by intravenous infusion at a body-weight of 51 kg and above, 1 g every 4 to 6 hours given over 15 minutes, maximum 4 g per day)
7. National Confidential Enquiry into Patient Outcome and Death (NCEPOD): Classification of Intervention (In effect since December 2004. Category 1, Immediate: immediate life, limb or organ-saving intervention, resuscitation simultaneous with intervention, normally within minutes of the decision to operate; target location the next available operating theatre, breaking into existing lists if required. NCEPOD recommends the consultant who will perform the intervention assigns the category at the time of the decision to operate)