Effects of cardiopulmonary bypass on systemic vascular resistance.

During cardiopulmonary bypass (CPB), complex neuroendocrine responses occur and result in haemodynamic changes. Systemic vascular resistance (SVR) before, during, and after CPB was documented in patients undergoing coronary artery bypass surgery. Whilst the overall effect was an increased SVR, transient profound decreases in SVR at the commencement of CPB, during the rewarming phase, and immediately on weaning off CPB were demonstrated.