Oral clonidine reduces the requirement of prostaglandin E1 for induced hypotensionPurpose: 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/.tg or 150/./g donidine were administered 60 min prior to induction of anesthesia. Anesthesia was maintained with O~ : N20 (30:70) and isoflurane 1.0 %. After hemodynamic stabilization, an infusion of prostaglandin E I was started (0.05 ~g'kg -t 'min -I) 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/.tg and 150/.tg preanesthetic oral clonidine treated groups were 132 _+ 46, 117 • 37 and 129 _ 56 min, respectively. The PGE I requirement in each group were 1563 _ 180 (28.6 _ 3.2), 594 _+ 197 (I 0.8 _+ 3.6) and 283 +_ 30 (5.5 _ 3.6) pg ~g-kg-I), 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.Objectif: D6terminer les effets de I'administration pr&nesth6sique de clonidine orale sur la dose de prostaglandine E I (PGE I) n6cessaire ~ la production d'hypotension pendant I'anesth6sie. M&hode : Un placebo oral, 75/.tg ou 150 ~g de clonidine ont 6t6 administr6s 60 min avant I'induction de I'anesth&ie. I'anesth&ie a 6t6 maintenue avec un m61ange 02 : N20 (30:70) et de I'isoflurane ~ 1,0 %. Apr& la stabilisation des param~tres h6modynamiques, on a commenc6 la perfusion de prostaglandine EI (0,05 /.tg'kg -~ -min -j) et le d6bit de la perfusion a 6t6 ajust6 pour conserver la tension art6rielle moyenne (TAM) entre 60-70 mmHg pendant I'intervention. RK~ultats : La dur6e de I'hypotension avec le placebo ou 75/Jg ou 150/.tg de clonidine pr~anesth&ique orale a &6 de 132 __+ 46, I 17 _+ 37 et de 129 _+ 56 min, respectivement. Les besoins de PGE I dans chaque groupe ont 6t~ de 1563 _ 180(28,6 _ 3,2), 594 _ 197(10,8 _ 3,6) et de 283 _ 30(5,5 ___ 3,6)~g (flg.kg-I), respectivement. De plus, la perte sanguine dans chaque groupe a 6t6 de 1461 _ 389, 805 __-240 et de 931 +_ 40 ml, respectivement. Conclusion : Ladministration pr6anesth&ique de clonidine diminue la dose de PGEI n6cessaire ~ la production d'hypotension et r6duit la perte sanguine pendant I'op6ration.