USMLE Prep - Medical Reference Library

Acute Compartment Syndrome — Clinical Diagnosis and Fasciotomy Timing

System: Orthopedics • Reviewed: Sep 1, 2025 • Step 1Step 2Step 3

Synopsis:

Emergent limb‑threatening condition recognized by severe pain out of proportion, pain with passive stretch, tense compartments, paresthesias, and evolving motor deficits. When exam is equivocal, measure pressures; a delta‑pressure (diastolic minus intracompartment) ≤30 mmHg supports diagnosis. Remove constrictive dressings, keep limb at heart level, and perform prompt fasciotomy—ideally within 6 hours of ischemia.

Key Points

  • Confirm diagnosis early with highest‑yield tests (and do not let testing delay time‑critical therapy).
  • Use explicit hemodynamic, respiratory, and neurologic targets to guide escalation.
  • Document disposition criteria, follow‑up, and patient education before discharge.

Algorithm

  1. Primary survey and neurovascular check (5 P’s; pulses may be present).
  2. Remove casts/dressings; keep limb at heart level (not elevated).
  3. Assess pain with passive stretch and escalating analgesic requirement.
  4. If exam unreliable → measure compartment pressures in all compartments.
  5. ΔP ≤30 mmHg or progressive neuro deficit → notify ortho emergently.
  6. Resuscitate, correct coagulopathy, and consent for fasciotomy.
  7. Urgent 4‑compartment fasciotomy (e.g., leg: anterior/lateral & superficial/deep posterior).
  8. Intra‑op debridement of non‑viable tissue; leave wounds open with vessel loop/NPWT.
  9. ICU/step‑down monitoring: CK, electrolytes, urine output (target ≥0.5–1 mL/kg/h).
  10. Second‑look debridement at 24–48 h; plan staged closure/skin grafting.
  11. Address precipitant (reperfusion, fracture fixation, anticoagulation issues).
  12. Rehab planning and complication surveillance (infection, contracture, neuropathy).

Clinical Synopsis & Reasoning

Emergent limb‑threatening condition recognized by severe pain out of proportion, pain with passive stretch, tense compartments, paresthesias, and evolving motor deficits. When exam is equivocal, measure pressures; a delta‑pressure (diastolic minus intracompartment) ≤30 mmHg supports diagnosis. Remove constrictive dressings, keep limb at heart level, and perform prompt fasciotomy—ideally within 6 hours of ischemia.


Treatment Strategy & Disposition

Stabilize ABCs. Initiate guideline‑concordant first‑line therapy with precise dosing and continuous monitoring. Escalate to advanced or procedural interventions when predefined failure criteria are met. Define ICU, step‑down, and ward disposition triggers explicitly, and arrange specialty consultation early.


Epidemiology / Risk Factors

  • Risk varies by comorbidity and precipitating factors

Investigations

TestRole / RationaleTypical FindingsNotes
CBCAnemia/leukocytosisContext‑specificTrend response
BMPElectrolytes/renalDerangements commonRenal dosing/monitoring
Condition‑specific imagingPer topicDiagnostic hallmarkDo not delay with red flags
Compartment pressureDiagnostic confirmation when exam unclearΔP ≤30 mmHgSerial checks in obtunded patients
Creatine kinase/urinalysisRhabdomyolysis detectionCK↑, myoglobinuriaManage hyperkalemia/AKI risk

Pharmacology

MedicationMechanismOnsetRole in TherapyLimitations
Analgesia (multimodal)Opioid/non‑opioidImmediatePain control pre‑opAvoid masking progression
Crystalloid resuscitationVolume expansionImmediateOptimize perfusionAvoid overload
Tetanus prophylaxisImmunizationHoursWound managementPer immunization status

Prognosis / Complications

  • Outcome depends on timeliness of diagnosis and definitive therapy

Patient Education / Counseling

  • Explain red flags, adherence, and the follow‑up plan; provide written instructions.

References

  1. See bibliography — Link