Compartment syndrome

Surgical approach

Goal: urgent decompression of all involved muscle compartments to restore perfusion and prevent irreversible neuromuscular injury
- Time-critical: irreversible muscle/nerve injury can occur within hours; do not delay for imaging if clinical suspicion is high
Procedure: fasciotomy (limb dependent)
- Leg: typically 2-incision, 4-compartment fasciotomy (anterior, lateral, superficial posterior, deep posterior)
- Forearm: volar (often extended) ± dorsal fasciotomy; consider carpal tunnel release if median nerve compromise
- Hand/foot: multiple compartment releases as indicated
Wound management: leave wounds open; temporary dressings/negative pressure therapy; planned re-look and delayed closure/skin graft
- Re-look commonly at 24–48 h to assess viability and further debridement
If established necrosis/sepsis: debridement; in extreme cases amputation
- Consider source control and critical care involvement early

Anaesthetic management

Type of anaesthesia
- Usually GA (time-critical, painful, may be unstable; need full access and repeated examinations post-op)
- Regional: not first-line if it risks masking evolving pain/neurology; may be considered selectively with senior agreement and robust monitoring (e.g., single-shot peripheral nerve block avoided by many; catheter techniques controversial)
Airway
- ETT commonly preferred (urgent surgery, potential aspiration risk, need for controlled ventilation, possible metabolic derangement/hyperkalaemia, potential for prolonged surgery/re-look)
- SGA may be acceptable for short, stable cases with low aspiration risk, but less common
Duration
- Typically 1–2 h for single-limb fasciotomy; longer if multiple compartments/limbs, debridement, vascular repair, or complex trauma
How painful
- Very painful pre-op; post-op pain significant (large open wounds) but may improve after decompression; requires multimodal analgesia and often opioids/PCA
Key intra-op priorities
- Treat as potential reperfusion/rhabdomyolysis case: anticipate hyperkalaemia, acidosis, myoglobinuria, AKI; have calcium/insulin-dextrose/bicarbonate available
- IV access: at least 2 large-bore cannulae; consider arterial line if significant trauma, expected metabolic derangement, or frequent blood gases/electrolytes
- Bloods: VBG/ABG, K+, lactate, CK, U&E, FBC, coagulation; group & save/crossmatch depending on mechanism and expected bleeding
- Fluids: balanced crystalloid; avoid hypovolaemia; aim urine output (often targeted higher if rhabdomyolysis) with senior guidance; consider urinary catheter
- Tourniquet: if used, document time; anticipate tourniquet release effects (acidosis/hyperkalaemia/hypotension)
- Temperature and pressure area care; limb positioning to avoid further compromise
Post-op destination
- HDU/ICU if significant rhabdomyolysis, metabolic derangement, AKI risk, polytrauma, sepsis, or ongoing bleeding
- Ongoing monitoring: pain, neurovascular status, renal function, electrolytes, CK, urine colour/output; plan for re-look surgery

Definition and pathophysiology

Compartment syndrome: raised pressure within a closed osteofascial compartment causing reduced capillary perfusion and tissue ischaemia
Perfusion pressure concept: tissue perfusion depends on arterial inflow minus compartment pressure; as compartment pressure rises, microcirculatory flow falls
- Delta pressure (ΔP) = diastolic BP − compartment pressure; low ΔP implies poor perfusion
Vicious cycle: ischaemia → capillary leak/oedema → further pressure rise → worsening ischaemia
Time course: nerve dysfunction can occur early; muscle necrosis can occur within hours if untreated

Aetiology and risk factors

Trauma (commonest): fractures (esp. tibial shaft), crush injury, high-energy soft tissue injury
Reperfusion: after vascular injury/repair, prolonged limb ischaemia, revascularisation
Iatrogenic/external compression: tight casts/bandages, prolonged limb compression (e.g., intoxication/immobility), lithotomy position, tourniquet-related issues
Bleeding into compartment: anticoagulation/bleeding diathesis, haemophilia, post-operative bleeding
Burns/circumferential eschar (may require escharotomy rather than fasciotomy depending on level of constriction)

Clinical features (diagnosis is primarily clinical)

Pain out of proportion to injury and escalating analgesic requirement
Pain on passive stretch of muscles within the compartment
Tense, swollen compartment; firm “wood-like” feel
Neurological symptoms: paraesthesia, numbness; later weakness/paralysis
Vascular signs (late/unreliable): pallor, pulselessness; pulses can be present until late
Important caveat: diagnosis is difficult in obtunded/intubated patients, children, and those with regional anaesthesia or heavy opioid sedation

Investigations and diagnostic thresholds

Do not delay decompression for tests if strong clinical suspicion
Compartment pressure measurement (adjunct): useful when exam is unreliable or diagnosis uncertain
- Common thresholds used: absolute pressure ~30–40 mmHg OR ΔP (DBP − compartment pressure) ≤ 30 mmHg
- Interpret in clinical context; hypotension reduces ΔP and increases risk at lower absolute pressures
Bloods/urine for complications: CK (rhabdomyolysis), K+, creatinine, acid–base; urine dip for blood with few/no RBCs suggests myoglobin

Immediate management (pre-op / ED / ward)

Call for senior help early: orthopaedics/vascular + anaesthetics; treat as time-critical emergency
Remove external constriction: split casts/bandages down to skin; remove tight dressings
Limb position: keep at heart level (avoid elevation that reduces arterial inflow; avoid dependent position that increases oedema)
Analgesia: titrated IV opioids; avoid masking progression with excessive sedation; frequent reassessment
Resuscitation: correct hypotension/hypovolaemia to maintain perfusion pressure; treat sepsis/bleeding as appropriate
Prepare for theatre: NBM status assumed; aspiration prophylaxis if indicated; consent and documentation of neurovascular status

Anaesthetic considerations: peri-operative risks and strategies

Reperfusion/rhabdomyolysis risks: hyperkalaemia, metabolic acidosis, arrhythmias, myoglobinuric AKI, DIC (severe crush)
Monitoring: ECG for peaked T waves/arrhythmias; consider arterial line for serial gases and BP in high-risk cases
Induction: RSI if trauma/full stomach; avoid hypotension (preserve ΔP); consider ketamine/etomidate depending on physiology and local practice
Muscle relaxant choice: if significant crush/rhabdomyolysis/hyperkalaemia risk, avoid suxamethonium; use rocuronium with sugammadex availability as appropriate
Fluids and renal protection: maintain euvolaemia; balanced crystalloid; manage hyperkalaemia promptly; consider ICU-led strategies for rhabdomyolysis (targets vary)
Analgesia: multimodal (paracetamol ± NSAID if renal function/bleeding risk acceptable); opioids; consider wound infiltration; regional techniques only with clear plan not to obscure assessment
Antibiotics: per local trauma/open fracture guidance; tetanus status if relevant

Complications and outcomes

Local: muscle necrosis, nerve injury, contractures (Volkmann’s ischaemic contracture in forearm), chronic pain, infection, delayed healing
Systemic: rhabdomyolysis → hyperkalaemia, acidosis, AKI; sepsis; multi-organ failure (severe crush)
Medico-legal: missed/delayed diagnosis is a common cause of litigation; meticulous documentation and repeated examinations are essential

You are called to ED: a patient with a tibial shaft fracture has escalating pain despite opioids. How do you assess for compartment syndrome and what are your immediate actions?

Structure: recognise time-critical diagnosis, clinical features, immediate measures, escalation and theatre.

Assess: pain out of proportion, pain on passive stretch, tense compartment, sensory change; document neurovascular status; note that pulses may remain present
Immediate actions: call orthopaedics urgently; remove/split cast and dressings to skin; keep limb at heart level; resuscitate to avoid hypotension; provide titrated analgesia with frequent reassessment
Prepare for urgent fasciotomy: treat as full stomach; plan GA/RSI if indicated; arrange bloods (U&E/K+/CK/ABG), IV access, and consider arterial line if high risk

What is the role of compartment pressure monitoring? Include commonly used thresholds and limitations.

Pressure measurement is an adjunct when clinical assessment is uncertain or unreliable.

Indications: obtunded/intubated patient, equivocal signs, multiple injuries, inability to assess pain reliably
Thresholds: absolute pressure ~30–40 mmHg OR ΔP (DBP − compartment pressure) ≤ 30 mmHg
Limitations: technique/placement errors; single readings may miss evolving syndrome; hypotension reduces ΔP so “safe” absolute pressures may still be dangerous
If high clinical suspicion: do not delay fasciotomy for measurements

Discuss the anaesthetic implications of fasciotomy for compartment syndrome, including metabolic complications and monitoring.

Key issue: reperfusion/rhabdomyolysis physiology and time-critical surgery.

Anaesthetic technique: usually GA; consider RSI; ETT preferred; avoid hypotension to preserve perfusion pressure
Monitoring: ECG, capnography, temperature; consider arterial line for serial gases/electrolytes in high-risk cases
Metabolic risks: hyperkalaemia, acidosis, arrhythmias; myoglobinuria → AKI; have calcium, insulin-dextrose, sodium bicarbonate available as per local protocols
Neuromuscular blockade: avoid suxamethonium if crush/rhabdomyolysis/hyperkalaemia risk; use non-depolariser (e.g., rocuronium)
Fluids/renal: balanced crystalloid; catheterise if significant risk; monitor urine output/colour; early ICU if deranged physiology

A patient has a dense peripheral nerve block for a tibial fracture. What are the concerns regarding compartment syndrome and how would you manage this situation?

Core issue: regional anaesthesia may obscure evolving pain and delay diagnosis; management is risk mitigation and vigilance.

Concern: pain is a key early symptom; dense sensory block may delay recognition; sedation/opioids can also mask symptoms
Mitigation: frequent documented neurovascular checks; maintain high suspicion; consider compartment pressure monitoring if exam unreliable; involve orthopaedics early
If concern persists: do not reassure based on analgesia; escalate urgently; definitive treatment is surgical decompression
Future practice: if high risk of compartment syndrome, many avoid dense long-acting blocks/catheters; if used, ensure shared plan, informed consent, and robust monitoring pathway

Explain why pulses can be present in compartment syndrome and why this is important clinically.

Compartment syndrome primarily compromises microcirculation/capillary perfusion before large-artery flow is lost
Therefore palpable pulses do not exclude compartment syndrome; relying on pulselessness risks late diagnosis

What complications might occur after decompression and reperfusion, and how would you detect and treat them peri-operatively?

Think: electrolyte/acid-base, renal, cardiac rhythm, bleeding, sepsis.

Hyperkalaemia: ECG changes (peaked T waves, widened QRS), arrhythmias; treat with IV calcium, insulin-dextrose, beta-agonist, consider bicarbonate if acidotic; consider dialysis if refractory
Metabolic acidosis: ABG/VBG; treat underlying cause, optimise perfusion/ventilation; bicarbonate selectively
Rhabdomyolysis/myoglobinuria: rising CK, dark urine; manage with fluids, avoid nephrotoxins, monitor U&E and urine output; early ICU/nephrology if AKI develops
Bleeding/coagulopathy: check Hb/coagulation; manage with blood products as indicated

Outline a peri-operative analgesic plan for fasciotomy wounds while maintaining the ability to monitor for ongoing ischaemia/compartment issues.

Multimodal baseline: paracetamol; NSAID only if renal function/bleeding risk acceptable; consider gabapentinoid only with caution (sedation)
Opioids: titrated IV opioids intra-op; post-op PCA often appropriate; avoid excessive sedation that impairs assessment
Regional/local: consider wound infiltration or carefully selected regional techniques only with explicit shared plan and monitoring; avoid dense long-acting blocks in high-risk evolving cases
Non-pharmacological: splintage, elevation to heart level, reassurance; plan for repeated debridements (analgesia strategy should anticipate re-looks)

An FRCA-style data interpretation: A post-fasciotomy patient becomes tachycardic with peaked T waves and a widening QRS. What is your differential and immediate management?

Most likely life-threatening cause is hyperkalaemia (reperfusion/rhabdomyolysis).

Differential: hyperkalaemia (most likely), severe acidosis, hypocalcaemia, myocardial ischaemia, drug effects
Immediate actions: call for help; ABC; high-flow oxygen; confirm rhythm; obtain urgent blood gas/electrolytes
Treat suspected hyperkalaemia immediately: IV calcium (membrane stabilisation), insulin-dextrose, nebulised salbutamol; consider bicarbonate if acidotic; stop K-containing fluids; prepare for dialysis if refractory
Continuous ECG monitoring; consider ICU transfer

List the key early clinical signs of compartment syndrome and the late signs.

Early: pain out of proportion, pain on passive stretch, tense compartment, paraesthesia
Late: weakness/paralysis, pallor, pulselessness (often very late), fixed sensory loss

What limb position is recommended while awaiting definitive management and why?

Heart level: avoids reducing arterial inflow (as with elevation) and avoids increasing oedema (as with dependency)

State the delta pressure definition used in compartment syndrome assessment.

ΔP = diastolic blood pressure − compartment pressure