Oral clonidine reduces the requirement of prostaglandin E1 for induced hypotension

Purpose: To determine the effects of preanesthetic oral clonidine on the dose of prostaglandin E1 (PGE1) required to produce hypotension during anesthesia. Method: Oral placebo, 75 mu g or 150 mu g clonidine were administered 60 min prior to induction of anesthesia. Anesthesia was maintained with O-2: N2O (30:70) and isoflurane 1.0%. After hemodynamic stabilization, an infusion of prostaglandin E1 was started (0.05 mu g.kg(-1).min(-1)) and the rate of infusion was adjusted to maintain mean arterial pressure (MAP) between 60-70 mmHg during operation. Results: Duration of hypotension in placebo, 75 mu g and 150 mu g preanesthetic oral clonidine treated groups were 132 +/- 46, 117 +/- 37 and 129 +/- 56 min, respectively. The PGE1 requirement in each group were 1563 +/- 180 (28.6 +/- 3.2), 594 +/- 197 (10.8 +/- 3.6) and 283 +/- 30 (5.5 +/- 3.6;) mu g (ug.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 PGE1 required to produce hypotension, and decreased the blood loss during operation.