The hemodynamic effects of cocaine during acute controlled hemorrhage in conscious rats

Background: Cocaine is often associated with trauma; however, little is known about how its use alters the response to blood loss. The effect of cocaine on hemodynamics following acute hemorrhage was studied in a rat model. Methods: Following baseline measurements, rats were administered either intravenous cocaine, or saline as a control. Both groups then underwent arterial catheter hemorrhage of 30% of total blood volume. Outcome variables include blood pressure, heart rate, hematocrit, pH, Pco₂, Po₂, and serum bicarbonate. Results: Following hemorrhage, blood pressure decreased in both groups but the hypotension was significantly greater in the saline group than the intravenous cocaine group at 0 and 5 minutes posthemorrhage. Heart rate was increased significantly for the intravenous cocaine group compared to the saline group starting at 15 minutes postcocaine and lasting for the next 25 minutes. No difference was noted for hematocrit, pH, Po₂, or serum bicarbonate. Conclusion: Although transient, cocaine blunted the hypotensive response to acute controlled hemorrhage and resulted in tachycardia.