Abstract
A death during sodium ethyl 1-methyl-butyl thiobarbituric acid (pentothal) intravenous anesthesia, given shortly after acute, inadequately treated hemorrhage prompted a study of its effects on circulation when given to animals during similar circumstances.
Method. Nineteen experiments were performed on 7 cats and 10 dogs. Arterial blood pressure determinations were recorded by can-nulating a carotid or femoral artery during infiltration anesthesia. Control mean blood pressure readings averaged 127 mm Hg in both species. Hemorrhage was produced by direct arterial bleeding (averaging 6-8 minutes) until the mean arterial blood pressure level was reduced to an average of 70 mm Hg. Twenty-five to 30% of the estimated blood volume was withdrawn.
Freshly prepared 2 % solutions of pentothal given intravenously at an average rate of 3.4 cc per minute were administered at a time averaging 24 minutes following bleeding. Sub-anesthetic amounts were used because in earlier experiments, not included in this study, the recommended anesthetic dose for normal dogs and cats when administered following hemorrhage caused prompt circulatory failure and death. All animals used had responded normally to the full anesthetic dose several days before being subjected to experiment. The usual dose of 25 mg/kg for dogs was reduced to an average of 11 mg/kg and cats were given 12 instead of the recommended 40 to 50 mg/kg. No preanesthetic medication was given.
An additional cat and 2 dogs were similarly prepared but received no pentothal. They were observed for 4 hours. After the initial fall following hemorrhage, no rapid fluctuations in blood pressure were observed for the control period.
Oxygen was administered by tracheotomy or endotracheal airway to 3 cats and 4 dogs preceding and during pentothal injection. Its use had no effect upon the results obtained.
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