Osmol gap as a surrogate marker for serum propylene glycol concentrations in patients receiving lorazepam for sedation.

Study Objectives: To correlate serum propylene glycol concentration with osmol gap, serum lactate concentration, and amount of propylene glycol administered to mechanically ventilated patients receiving continuous infusions of lorazepam (80% propylene glycol by weight), and to characterize the prevalence of hyperosmolality and range of serum propylene glycol concentrations in this patient population.

Design: Prospective, controlled, observational study.

Setting: Adult surgical and cardiothoracic intensive care units (ICUs) of a 1200-bed, urban, tertiary care, teaching hospital.