Endothelin plasma levels in old and young patients during open heart surgery: correlations to cardiopulmonary and endocrinology parameters.

We compared endothelin (ET) plasma levels during and after aortocoronary bypass (CPB) grafting in old and young patients. Correlations to cardiopulmonary parameters and catecholamines were tested. The study included 22 patients (11 aged greater than 70 years and 11 aged less than 55 years). Measurements were performed after induction of anesthesia (baseline), before bypass, during bypass, after patients were weaned off bypass, at the end of operation, and after 4-h intensive care (IC) treatment. ET [radioimmunoassay (RIA) technique] and catecholamines [high pressure liquid chromatography (HPLC) technique] plasma levels were determined from arterial blood samples; hemodynamics (pulmonary artery catheter), oxygen data, and laser Doppler flow were also monitored. Baseline ET plasma levels were within normal range (young, 3.1 +/- 0.9 pg/ml, old, 4.5 +/- 1.4 pg/ml). Old patients had higher values during the entire investigation period. During CPB ET plasma levels increased to a maximum immediately after patients were weaned off bypass. A significant increase (twofold to baseline) was noted during IC therapy. ET plasma levels did not correlate to catecholamine plasma levels or to hemodynamic or laser Doppler flow parameters. A significant correlation existed between ET plasma levels and oxygen consumption. Monitoring ET plasma levels appears to be of minor value in predicting circulatory changes and assessing surgical stress. Further investigations must elucidate the increase in oxygen consumption and its correlation to ET plasma level.