Blood rheology and haemodynamic alterations during cardiopulmonary bypass under fentanyl anaesthesia

ABSTRACT

Changes in blood viscosity, systemic vascular resistance [SVR], and cardiac output [CO], were studied on twenty patients, undergoing mitral valve replacement during cardiopulmonary bypass [CPB]; under Fentanyl-Oxygen-Pancuronium anaesthesia. The haemodynamic measurements were calculated by utilizing a Swanz-Ganz catheter, while viscosity was measured by means of Ostwald viscometer. Although Fentanyl does not affect the haemodynamic parameters, during the induction of anaesthesia; yet the already decreased CO is much reduced following sternotomy, and improvement occurred at the end of bypass and continued in the postoperative period. With the beginning of bypass, due to haemodilution, blood viscosity decreased and subsequently the SVR; this leads to a decrease in after load and an increase in preload, the venous return is enhanced with improvement on cardiac output and cardiac performance. A positive correlation existed between blood viscosity and SVR at beginning of CPB, following CPB and immediately postoperatively. Negative correlation was found between SVR and CO post-sternotomy, following CPB and early postoperatively