Background: The aim of this study was to evaluate the effects of low molecular weight hydroxyethyl starch (HES) and other colloids on hemodynamic parameters, coagulation factors, liver and renal function tests and colloid oncotic pressure (COP) values and also to compare these parameters to each other.

Methods: We randomized 60 patients who would have coronary bypass or valve replacement operation as group Gelofusine (Gelatine infusion), group Isohes (Medium size molecular HES infusion), and group Voluven (low molecular weight HES infusion). The same type of colloid was used as open heart machine priming solution, during anesthesia maintenance as well as intensive care period. The highest infusion rates were 30 ml/kg/24 hour in Isohes and Gelofusion, and 50 ml/kg/24 hour in Voluven group if needed. Blood samples were taken to evaluate ABG, Hb, Htc, Plt, fibrinogen and COP levels during the 1st period (preoperative), 2nd period (going on pump) 3^rd period (coming off pump), 4^th period (early postoperative) and 5^th period (postoperative first 24 hours). Hemodynamic parameters were recorded at the same time intervals. PT, aPTT, INR, BUN, creatinine, SGOT, and SGPT were measured preoperatively and the first 24 hours post-operatively.

Results: No statistical significance was detected between three groups regarding demographic characteristics, hemodynamic parameters, the length of pump and aorta clamping period, blood loss, Hb, Htc, Cretinine, BUN, SGOT, and SGPT values. PT, aPTT and INR values were similar in all groups, but fibrinogen values during the pump exiting was significantly higher in the Gelofucin and the Isohes groups than the Voluven group. In addition, COP values were significantly higher in the Gelofucine and Isohes groups than the Voluven group during coming off pump period and it was significantly higher in the Isohes group than the other two groups both during the pump exiting period and at the postoperative 24^th hour. The within-group comparison with respect to COP in the Gelofucine and the Isohes groups in the periods 2, 3, 4 were found to be significantly low. But values were similar in the 5^th period. In the Voluven group all values were found to be low compared to the beginning period.

Conclusion: Low molecular weight HES can be infused safely during cardiac surgery for hemodynamic stabilization like medium size molecular HES and Gelatines. The 50 ml/kg/24 hour dose might be preferred especially for patients who need large infusion doses. Medium size HES is more effective for oncotic pressure maintenance.

Keywords : Colloid oncotic pressure; colloid solution; priming solution