Differential DiagnosisDifferential Diagnosis

Wide-Complex PEA Causes

Resuscitation differential that separates metabolic etiologies from toxicologic causes in wide-complex PEA arrest.

Query: How do I distinguish metabolic from toxic causes of wide-complex PEA?

Summary

Distinguishing metabolic causes (e.g., hyperkalemia) from drug-induced, clinically significant concentration causes (such as sodium channel blocker toxicity) in wide‐complex PEA relies on context, history, ECG nuances, and laboratory data. In metabolic disturbances like hyperkalemia, you often see a history of renal dysfunction or acidosis with associated ECG findings (peaked T waves progressing to widening) and lab confirmation, whereas in sodium channel blocker toxicity you may have a history suggestive of overdose, markedly prolonged QRS duration sometimes with a rightward axis, and a pattern that improves with sodium bicarbonate administration ^1^2.

At-a-glance

FeatureMetabolic (e.g. Hyperkalemia)Drug Toxicity (Sodium Channel Blocker Overdose)
Clinical HistoryOften patients with renal failure, acidosis, or known electrolyte disturbancesHistory of ingestion/overdose or exposure to sodium channel blockers
ECG CharacteristicsGradual QRS widening with preceding peaked T waves; may show other hyperkalemic featuresMarkedly widened QRS with potential rightward axis deviation; sometimes very pronounced widening
Laboratory EvaluationElevated serum potassium corroborates the diagnosisDrug levels (if available) and supportive toxicology consistent with overdose
Treatment ApproachCalcium administration (e.g., calcium gluconate), insulin-dextrose, and measures to shift potassium intracellularlySodium bicarbonate is central for reversing sodium channel blockade; supportive care tailored to toxin
Contextual CluesOccur in a metabolic crisis scenarioToxicological exposure context with corresponding clinical findings