6 P's — Compartment syndrome
Acute compartment syndrome recognition (post-trauma, post-tourniquet, prolonged positioning)
Mnemonic device
6 P's
Mapping
Pain
Out of proportion to injury; worse with passive stretch (most reliable early sign)
Pallor
Late finding — pale, cool extremity
Paresthesia
Numbness/tingling in nerve distribution; sensory deficit
Paralysis
Late — motor deficit, weakness, foot drop (peroneal)
Pulselessness
Very late — pulses often present until end-stage; do NOT wait for this
Poikilothermia
Cold extremity (perfusion mismatch with core)
Clinical note: Compartment pressure >30 mmHg (or ΔP <30, where ΔP = DBP − compartment pressure) → fasciotomy. Anesthesia red flag: regional block can MASK pain — be cautious in high-risk surgeries (tibia fracture, prolonged lithotomy). Document baseline neuro pre-block.