Purpose: To determine the effects of preanesthetic oral clonidine on the dose of prostaglandin EI (PGEI) required to produce hypotension during anesthesia.
Method: Oral placebo, 75 microg or 150 microg clonidine were administered 60 min prior to induction of anesthesia. Anesthesia was maintained with O2:N2O (30:70) and isoflurane 1.0%. After hemodynamic stabilization, an infusion of prostaglandin EI was started (0.05 microg x kg(-1) x min(-1)) and the rate of infusion was adjusted to maintain mean arterial pressure (MAP) between 60-70 mm Hg during operation.
Results: Duration of hypotension in placebo, 75 microg and 150 microg preanesthetic oral clonidine treated groups were 132+/-46, 117+/-37 and 129+/-56 min, respectively. The PGEI requirement in each group were 1563+/-180 (28.6+/-3.2), 594+/-197 (10.8+/-3.6) and 283+/-30 (5.5+/-3.6) microg (microg x kg(-1)), respectively. In addition, blood loss in each group were 1461+/-389, 805+/-240 and 931+/-40 ml, respectively.
Conclusion: Preanesthetic oral clonidine decreased the dose of PGEI required to produce hypotension, and decreased the blood loss during operation.