Effect of epidural and intravenous clonidine on the neuro-endocrine and immune stress response in patients undergoing lung surgery

The effects of intravenous and epidural clonidine, 4 mu g kg(-1), combined with epidural morphine, 40 mu g kg(-1), on the neuro-endocrine and immune s tress responses to thoracic surgery are reported. A control group received only epidural morphine. Anaesthesia was induced and maintained with propofo l. Catecholamines, vasopressin, cortisol, beta-endorphin concentrations and leucocyte counts were measured before drug administration, immediately aft er intubation of the trachea, after thoracotomy and at the end of surgery. Catecholamines did not change in any of the groups. The other stress hormon es increased during surgery, the pattern being similar in the three groups. Total leucocyte and neutrophil counts were increased in all groups at the end of surgery, but the increase was least in the epidural clonidine group. The number of lymphocytes was reduced at the end of surgery in the epidura l and intravenous group, compared with the control group in which the numbe r of lymphocytes did not change. The effects are more pronounced with epidu ral than with intravenous administration. We conclude that clonidine can mo dulate the immune stress response to thoracic surgery.