Aortic surgery: effect of clonidine on intraoperative catecholaminergic and circulatory stability

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Abstract
Twenty‐eight patients presenting for aortic surgery were randomly assigned in a double‐blind, placebo‐controlled protocol to receive placebo (n=14) or clonidine (4.7 ± 1.2 μg · kg‐1po; n=14), in addition to flunitrazepam 120 min before induction of anesthesia. Plasma catecholamines (CA) and hemodynamic variables were determined at 7 stages during surgery. In the placebo group, plasma epinephrine (E) and norepinephrine (NE) had risen twofold at skin closure compared to baseline (E: from 109 ± 51 pg p ml‐1to 294 ± 161 pg · ml‐1; NE: from 658 ± 226 to 1150 ± 494 pg · ml‐1). Plasma CA were significantly lower in the clonidine group (PP0.05) upon declamping. This improved stability in the clonidine group was achieved with a halving in the number of anesthetic/circulatory interventions (P>0.05 vs placebo). Provided intravascular volume is adequate, clonidine suppresses the increase in plasma catecholamines induced by aortic surgery and improves circulatory stability, with a reduced number of anesthetic/ circulatory adjustments.