6 P's
Acute Limb Ischemia
Cold, pale, pulseless = OR within 6 hours.
For the FNP boards, an acutely cold and pulseless leg is a surgical emergency, and the 6 P's name every finding that should drive immediate vascular consultation. Pain (out of proportion to exam), Pallor (or mottled cyanosis), Pulselessness, Paresthesia, Paralysis, Poikilothermia (cold to touch). Window for limb salvage is roughly 6 hours from symptom onset. AANP exam vignettes use the 6 P's to test escalation — paralysis and pallor in a patient with atrial fibrillation is an embolic limb until proven otherwise, and the answer is anticoagulation, vascular surgery, and CT angiography, not Doppler in a week. Pain plus paresthesia alone still warrants same-day evaluation.
- PPainSudden, severe, out of proportion to exam.
- PPallorPale, mottled, or cyanotic skin distal to occlusion.
- PPulselessnessAbsent distal pulses (confirm with Doppler if weak).
- PParesthesiaNumbness, tingling — early sensory nerve ischemia.
- PParalysisLate sign. Motor nerves fail after sensory — muscle tissue is dying.
- PPoikilothermiaLimb assumes ambient temperature — cold to the touch.
Clinical Context
Sudden arterial occlusion from embolus (a-fib is the classic source) or in-situ thrombosis of atherosclerotic disease. Time from symptom onset to revascularization is critical — irreversible muscle damage begins at ~6 hours, complete limb loss by 12-24 hours.
Differs from chronic PAD, which is gradual and presents with intermittent claudication and skin changes over months. Paresthesia and paralysis are late findings — if you see those on exam, you''re already behind. The AANP loves asking you to distinguish acute vs. chronic limb ischemia and to recognize A-fib as the cardioembolic source.
Related Mnemonics
- 5 T's — Cyanotic Congenital Heart Defects
- CHA₂DS₂-VASc — Stroke Risk in Non-Valvular Atrial Fibrillation
- HAS-BLED — Bleeding Risk on Anticoagulation
- MR. PASS MVP — Systolic Murmurs
- MS ARD — Diastolic Murmurs
Sources
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