Cardiopulmonary effects of an intravenous infusion of guaifenesin, ketamine, and xylazine in dogs.

A 5% solution of dextrose in water containing 50 mg of guaifenesin, 0.25 mg of xylazine, and 1 mg of ketamine/ml was infused IV at the rate of 2.2 ml X kg-1 X hour-1 in dogs. Heart rate, systemic vascular resistance, mean arterial blood pressure, rate-pressure product, and arterial oxygen tension were not altered significantly from baseline values during 2 hours of anesthesia. Cardiac index was significantly (P less than 0.05) decreased from base-line values. Hypoventilation resulted in increased arterial carbon dioxide tension and decreased arterial pH. After the dogs were given glycopyrrolate, cardiac index returned to base line, and heart rate, mean arterial pressure, and rate-pressure product were significantly greater (P less than 0.05) than base-line values.