Expansion
The six Ps: pain, pallor, pulselessness, perishing cold, paraesthesia, paralysis
Expansion
The six Ps of acute limb ischaemia
- Pain
- Pallor
- Pulselessness
- Perishing cold
- Paraesthesia
- Paralysis
The order matters: the first four indicate ischaemia, while paraesthesia and paralysis indicate a threatened limb with impending irreversible damage, and demand immediate vascular referral rather than investigation.
Timescale: irreversible muscle damage begins at about 4 to 6 hours.
Compartment syndrome is the important mimic and is distinguished by:
- Pain out of proportion to the injury, and worse on passive stretch of the compartment muscles, which is the most sensitive sign
- A tense, swollen compartment
- Pulses are usually present, since compartment pressure rarely exceeds arterial pressure. Waiting for pulselessness is a classic and limb-losing error
It requires urgent fasciotomy, and the diagnosis is clinical.
Routine neurovascular assessment after any fracture or plaster application should document distal pulses, capillary refill, sensation and motor function, before and after any intervention, and be repeated.