Premedication with clonidine does not attenuate suppression of certain lymphocyte subsets after surgery.

UNLABELLED

Sixty-four patients undergoing elective major surgery were randomly assigned into a double-blinded, placebo-controlled, clinical trial to test the hypothesis that premedication with clonidine would attenuate postoperative 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) received placebo patches and pills. Absolute blood levels of the following 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 extent of lymphocyte depletion from baseline to Postoperative Day 1 between the clonidine and placebo groups was not different. Plasma concentrations of epinephrine, norepinephrine, and cortisol were measured from blood samples drawn at 8:00 AM on Postoperative Day 1. Plasma norepinephrine levels were significantly lower among patients who received clonidine. However, no significant differences were found in plasma epinephrine or cortisol levels between the clonidine and placebo groups. With a clinical dose, clonidine did not prevent postoperative lymphocyte depletion. alpha2-Agonists may not suppress adrenocortical stress responses sufficiently to prevent postoperative immune suppression.

IMPLICATIONS

Lymphocyte (white blood cell) counts often decrease after major surgery. We hypothesized that clonidine would reduce hormonal stress and blunt reductions in lymphocytes after major surgery. In a randomized trial, we found no differences from placebo in cortisol levels or lymphocyte changes. Lymphocyte levels did not predict infectious complications.