POSTOPERATIVE HEMODYNAMICS DEPEND ON CARDIOPULMONARY BYPASS TEMPERATURE - THE POTENTIAL ROLE OF ENDOTHELIN-1

Objective: There is a growing body of evidence that perfusion temperat ure during cardiopulmonary bypass (CPB) in influences postoperative sy stemic vascular resistance (SVR). The reason for this is not clear. Ex tracorporeal circulation can provoke raised plasma levels of endotheli n-1 (ET-1), a very potent vasoconstrictor peptide produced by endothel ial cells. We therefore analysed the effect of CPB temperature on post operative vascular resistance and plasma concentrations of ET-1. Metho ds: Thirty four patients undergoing elective coronary artery bypass gr afting procedures were randomly assigned for either normothermic (37 d egrees C, n = 17) or hypothermic CPB (28 degrees C, n = 17). Serial me asurements of SVR and plasma ET-1 concentrations were performed before , during, and until 9 h after CPB measured. Results: As a consequence of CPB, plasma ET-1 levels increased slightly in both groups. In normo thermic patients, ET-1 reached maximal levels at the end of CPB wherea s ET-1 levels in patients after hypothermic CPB had a tendency to furt her increase during the stay in the intensive care unit. Plasma ET-1 l evels were significantly higher in patients 9 h postoperatively after hypothermic CPB (1.94 +/- 0.28 vs. 1.30 +/- 0.12 pg/ml, P = 0.033), wh ich was associated with significantly higher systemic vascular resista nce index (SVRI) in these patients (area under the curve; 1978 +/- 76 vs. 1626 +/- 69 dyne s/cm(5) per m(2), P = 0.003). Plasma ET-1 levels showed a positive correlation with postoperative SVRI (P = 0.008, r = 0.51) and a negative correlation with minimal rectal temperature durin g CPB (P = 0.006, r = 0.55). Conclusions: These results suggests that the hemodynamic differences after normothermic and hypothermic CPB mig ht be mediated, at least in part, by temperature dependent changes in ET-1 plasma levels. Copyright (C) 1997 Elsevier Science B.V.