A life-threatening double gap metabolic acidosis

Abstract

Double gap metabolic acidosis represents the high anion gap metabolic acidosis combined with raised serum osmolal gap due to retention of unmeasured osmole with accompanied metabolite. We describe a 62-year-old man diagnosed with community-acquired pneumonia undergoing continuous sedation in the context of asynchronous mechanical ventilation. High anion gap metabolic acidosis coupled with high plasma osmolal gap was noted with resultant severe bradyarrhythmia. d-Lactic acidosis and high serum concentration of propylene glycol (PG) eventually established the diagnosis of lorazepam-induced PG intoxication. Discontinuation of lorazepam followed by emergent long-extended hemodialysis effectively resolved the metabolic derangement without further recurrence. Serum osmolal gap is a sensitive and convenient surrogate for both early bedside detection and monitoring the therapeutic efficacy. Therefore, PG intoxication must be considered in the differential diagnosis of double gap metabolic acidosis. Early recognition with prompt hemodialysis intervention can avoid a life-threatening catastrophe.