PREMEDICATION WITH CLONIDINE DOES NOT ATTENUATE SUPPRESSION OF CERTAIN LYMPHOCYTE SUBSETS AFTER SURGERY

Sixty-four patients undergoing elective major surgery were randomly as signed into a double-blinded, placebo-controlled, clinical trial to te st the hypothesis that premedication with clonidine would attenuate po stoperative reductions in circulating lymphocytes. The treatment group (n = 28) received a clonidine skin patch (0.3 mg/d) and a 0.6-mg oral loading dose 60-90 min before surgery. The control group (n = 36) rec eived placebo patches and pills. Absolute blood levels of the followin g lymphocyte subsets were measured before induction of a standardized general anesthetic (baseline) and the morning after surgery: CD2, CD3, CD4, CD8, CD20, CD56, and the CD4:CD8 ratio. Significant decreases in lymphocyte subsets CD2, CD3, and CD4 were found in both groups; CD56 was significantly decreased only in the placebo group. However, the ex tent of lymphocyte depletion from baseline to Postoperative Day 1 betw een the clonidine and placebo groups was not different. Plasma concent rations of epinephrine, norepinephrine, and cortisol were measured fro m blood samples drawn at 8:00 AM On Postoperative Day 1. Plasma norepi nephrine levels were significantly lower among patients who received c lonidine. However, no significant differences were found in plasma epi nephrine or cortisol levels between the clonidine and placebo groups. With a clinical dose, clonidine did not prevent postoperative lymphocy te depletion. alpha(2)-Agonists may not suppress adrenocortical stress responses sufficiently to prevent postoperative immune suppression Im plications: Lymphocyte (white blood cell) counts often decrease after major surgery. We hypothesized that clonidine would reduce hormonal st ress and blunt reductions in lymphocytes after major surgery. In a ran domized trial, we found no differences from placebo in cortisol levels or lymphocyte changes. Lymphocyte levels did not predict infectious c omplications.