Abstracts of Posters Presented at the International Anesthesia Research Society; 72nd Clinical and Scientific Congress; Orlando, FL; March 7-11, 1998: Cardiovascular Anesthesia
Introduction: In order to elucidate the mechanisms of arterial hypotension, we compared mean arterial blood pressure (MAP), heart rate (HR), and renal sympathetic nerve activity (RSNA) after bolus injections of propofol (P), etomidate (E) and thiopental (T) in totally baroreceptor-denervated rabbits.
Methods: New Zealand white rabbits were anesthetized with i.v. urethane and received a combined denervation of carotid sinus, aortic and vagal nerves to eliminate both arterial and cardiopulmonary baroreflexes. The left kidney was exposed, and RSNA along with MAP and HR were recorded. After a steady state was established, P (2 or 4mg/kg), E (0.3 or 0.6 mg/kg) or T (4mg/kg) was injected (n=6 each group). ANOVA and Fisher's LSD were used for statistical analysis.
Results: Time course changes of variables are shown below (error bars are omitted).
Discussion: Since the animals were totally barodenervated, reductions of RSNA were due to depressant effects of agents on the central nervous system and possibly on the sympathetic ganglions. Significant and compatible reductions of RSNA after P (4mg/kg) and T (4mg/kg) correspond to significant decreases in MAP and HR. Twice as much induction dose of E (0.6mg/kg) and the induction dose of P(2mg/kg) appeared equipotent and caused only a transient reduction of RSNA and MAP. Data indicate that stable MAP and HR after E(0.3mg/kg) are due to its inability to depress sympathetic outflow. (Figure 1)
1. Anesth Analg 1992; 74:547-58