Does acute normovolemic hemodilution affect intraoperative value of serum-creatinine concentration in patients undergoing cardiac surgery

Background: The possible impact of hemodilution during acute normovolemic hemodilution (ANH) using hydroxyethyl starch (HES) on intraoperative serum concentration of creatinine (s-Cr) has not been well investigated. Methods: Patients undergoing cardiac surgery were randomly allocated into Group-ANH (n = 15) or Group-C (control; n = 17). In Group-ANH, 5 ml/kg whole blood was collected, and they were administered 5 ml/kg of HES 130/0.4 after anesthesia induction and before initiating cardiopulmonary bypass (CPB). In both groups, moderate hypothermic CPB was initiated using 1,600-1,800 ml of bloodless priming solution. The changes of s-Cr, blood urea nitrogen, hematocrit (Hct), electrolytes, and osmolality were determined before ANH administration (T1), after administering ANH 5 ml/kg (T2), 30 and 60 s after the initiation of CPB (T3, T4), and at the end of surgery (T5). Results: In Group-ANH, the s-Cr values at T2 (median [IQR25-75%], 0.83 [0.71-1.00] mg/dl) were not significantly different compared to those at T1 (0.84 [0.64-1.00] mg/dl), while those at T3 and T4 (0.68 [0.61-0.80] and 0.76 [0.59-0.92] mg/dl, respectively) were significantly lower than those at T2 (0.83 [0.71-1.00] mg/dl, P < 0.001). Hct at T3, T4 and T5 were significantly lower than those of T1 in both groups, and those at T2 and T4 of Group-ANH were significantly lower than those of Group-C (P < 0.001). There was no significant inter-group difference in all other parameters. Conclusions: Intraoperative s-Cr was not affected by the administration of ANH 5 ml/kg, although it reduced transiently at the beginning of CPB. Further study is needed to determine the clinical relevancy of our results.