Abstract
Plasma catecholamines have been measured before, during and after operation in 40 patients undergoing elective major abdominal surgery and in 12 patients during open heart surgery. Plasma concentrations did not increase during abdominal surgery and showed only small increases during cardiopulmonary bypass. It appears that it is not possible to assess individual intra-operative sympatho-adrenal responses to surgical trauma by measurement of plasma catecholamine concentrations because of the efficiency of catecholamine uptake mechanisms.