Hemodynamic and hemorheological effects of hypovolemic hemodilution with hydroxyethyl starch / 中华麻醉学杂志

ABSTRACT

Objective To investigate the hemodynamic and rheological effects of acute hypovolemic hemodilution with 6% hydroxyethyl starch (HES) at different infusion rates. Methods 20 ASA Ⅰ adult patients undergoing elective surgery were randomized to one of two groups with 10 patients each. The patients were premedicated with intramuscular midazolam 0.06 mg/kg and atropine 0.01 mg/kg 30 min before anesthesia. Before anesthesia an intravenous line was established and lacted ringer solution was infused at a rate of 5 ml. kg-1. h-1 . Anesthesia was induced with midazolam 0.2mg/kg , fentanyl 5μg/kg and vecuronium 0. lmg/kg and maintained with inhalation of 50 % N2O and 1% isoflurane. After tracheal intubation the patients were mechanically ventilated and PET CO2 was maintainted between 4.6-6.0 kPa.Swan-Ganz catheter was inserted via right internal jugular vein. The dorsalis pedis artery was cannulated for direct measurement of arterial pressure. 6% HES infusion rates were 10 ml.kg-1.h-1 in group Ⅰ and 20ml.kg-1 .h-1 in group Ⅱ respectively. ECG, heart rate (HR), arterial blood pressure (SBP, DBP and MAP), CO, CL, CVP, PAP, PCWP, SpO2, PET CO2 and inhalation concentrations of N2O and isoflurane were monitored before and 30, and 60 min after infusion was started. Arterial and venous blood samples were taken for blood gas analysis and rheological studies. Results The two groups were comparable with respect to demographic data. During HES infusion HR decreased and CL increased in both groups and there was no significant difference between the two groups. BP increased slightly at 60 min in group Ⅰ , whereas in group Ⅱ it tended to decrease. CVP, PAP and PCWP increased significantly in both groups especially at 60 min. Hct decreased from 36.2% ±4.5% to 30.4% ±4.1% in group Ⅰ and from 39.6%±8.0 % to 30.8% ± 5.9 % in group Ⅱ at 60 min. Hb and K value of erythrocyte sedimentation rate (ESR) equation decreased significantly in both groups especially at 60 min. Conclusions Intravascular volume expansion ismore efficient with increased infusion rate of HES but the influences on hemodynamics would be more significant. HES infused at 20 ml. kg-1 . h -1 is safe in healthy patient during operation with blood loss.[Key Words] Hemodilution; Hydroxyethyl starch; Hemodynamics; Hemorheology