[Haemodynamic effects following preoperative hypervolemic haemodilution with hypertonic hyperoncotic colloid solutions in coronary artery bypass graft surgery].

OBJECTIVE: Using hyperoncotic colloids as volume replacement to provide haemodynamic stability appears to be a suitable approach to diminish fluid overload and subsequent interstitial edema during cardiac surgery. The aim of the present study was to investigate for the first time the haemodynamic effects following preoperative haemodilution with different hypertonic hyperoncotic colloid solutions in patients undergoing coronary artery bypass grafting.

METHODS: A total of 43 patients with normal left ventricular ejection fraction, undergoing elective coronary artery bypass grafting received preoperatively after induction of anaesthesia according to randomisation the following solutions: 1: 750 ml/m(2) (body surface area) NaCl 0.9% ( n=10, control group, NACL), 2: 250 ml/m(2) 10% HES 200/0.5 plus 400 ml/m(2) NaCl 0.9% ( n=9, HES), 3: 250 ml/m(2) 10% dextran 40 plus 300 ml/m(2) NaCl 0.9% ( n=8, DEX), 4: 150 ml/m(2) hypertonic NaCl (7.2%) 10% HES 200/0.5 (n=8, HYPER-HES), 5: 150 ml/m(2) hypertonic NaCl (7.2%) 10% dextran 60 ( n=8, HYPER-DEX). Haemodynamic measurements were performed immediately before and 15 min after haemodilution and up to 60 min after termination of extracorporeal circulation in 10 min intervals. Fluid balances were calculated separately, during the time period of surgery, postoperatively up to 24 h after termination of surgery, and during the course of extracorporeal circulation.

RESULTS: After haemodilution with colloid solutions, a marked increase was observed in all patients and with HYPER-HES and HYPER-DEX a statistically significant increase in cardiac index (CI: +38%, +54%), stroke volume index (SVI: +42%, +40%), and oxygen availability (DO2: +34%; +41%), respectively, was observed during the pre-bypass period. At the same time right and left ventricular filling pressures increased slightly in all patients but these changes did not differ among the treatment groups. Heart rate and mean arterial pressure remained almost unchanged in all groups. The amount of crystalloid solutions required by the patients during surgery was markedly decreased with HES and DEX and significantly decreased with HYPER-HES and HYPER-DEX (1,013+/-341 ml/m(2), 1,096+/-234 ml/m(2)) compared to the control group NACL (1629+/-426 ml/m(2)). Serum sodium concentrations increased with HYPER-HES and HYPER-DEX to maximal values of 150+/-3 mmol/l and 149+/-4 mmol/l, respectively (baseline 141+/-3 mmol/l, 141+/-1 mmol/l)

CONCLUSIONS: Compared to isotonic saline solution, preoperative volume replacement with hyperoncotic colloids improves haemodynamic conditions during the pre-bypass period in patients with normal left ventricular function undergoing coronary artery bypass grafting. Additionally intraoperative crystalloid solution requirements are reduced. The volume saving effects are increased with administration of hyperoncotic colloids in a preparation with hypertonic saline solution, whereas the choice of the colloid, either hydroxyethyl starch or dextran seems to be of minor importance.