Vancomycin does not enhance hypotension under anesthesia.

The rapid administration of vancomycin is associated with flushing and hypotension, a consequence of histamine release. The manufacturer discourages administering vancomycin to anesthetized patients, stating that vancomycin aggravates the hypotensive effects of anesthetics. To test this, we randomly assigned 36 adults (ASA classes I through III) to one of two groups: preinduction (Preind, n = 19) and postinduction (Postind, n = 17). Both groups received two different infusions: vancomycin (1 g/250 mL normal saline) and saline (250 mL normal saline) over 30-60 min. The Preind group received vancomycin before anesthesia was induced and saline was administered immediately after anesthesia was induced; for the Postind group, this order was reversed. This was done in a double-blind fashion. The anesthetic induction was standardized by the intravenous administration of thiopental and vecuronium and anesthetic maintenance by inhalation of nitrous oxide and enflurane. End-tidal enflurane, heart rate (HR), and blood pressure (BP) were measured every 3 min. Independent (unpaired) t-test was used in data analysis. The groups did not differ significantly. We conclude that vancomycin infusion may be given under anesthesia without significant adverse hemodynamic consequences if administered over a 30-60 min period of time.