Effect of acute hypervolemic hemodilution on cerebral O_2 supply/consumption and energy metabolism during general anesthesia combined with epidural block in adults / 中华麻醉学杂志

ABSTRACT

Objective To investigate the effects of acute hypervolemic hemodilution (AHH) on cerebral O2 supply/consumption and energy metabolism in patients undergoing elective surgery under general anesthesia combined with continuous epidural block. Methods Fourteen ASA Ⅰ or Ⅱ patients of both sexes (9 male, 5 female) aged 44-62 yrs weighing 55-70 kg undergoing elective surgery under general anesthesia combined with epidural block were enrolled in this study. Lactated Ringer's solution 6-8 ml?kg-1 was infused before anesthesia. After correct placement of epidural catheter was confirmed radial artery was cannulated for BP monitoring and blood sampling. BP, EGG, SpO2 and PET CO2 were continuously monitored during anesthesia. General anesthesia was induced with fentanyl, midazolam, propofol and rocuronium and maintained with iaoflurane and intermittent i. v. boluses of vecuronium. The patients were intubated and mechanically ventilated. PET CO2 was maintained at 30-35 mm Hg. Epidural block was produced by a mixture of 1.33 % lidocaine + 0.167 % dicaine. Right internal jugular vein was retrogradely cannulated and advanced cephalad until jugular bulb for blood sampling. AHH was conducted by infusing 6% HES 20 ml?kg-1 at 50 ml?min-1 after induction of general anesthesia. Blood samples were taken from artery (a) and jugular venous bulb (jv) simultaneously before AHH (T0) at 15 min (T1) and 120 min (T2) after AHH was accomplished for blood gas analysis and determination of Hb, glucose and lactate concentrations. Cerebral O2 extraction rate (CERO2), glucose extraction rate (CMRglu) , arterial-jugular bulb venous O2 content difference (D a-jvO2) and arterial-jugular bulb venous lactate difference (VADL) were calculated. Results At the end of AHH Hct and Hb decreased by 20% as compared to the baseline values before AHH. S jvO2 was significantly higher, D a-jvO2 smaller and CERO2 lower at T1 than at T0. There were no significant differences in BP, HR, CMRglu and VADL at all time points. Conclusion AHH can increase cerebral O2 supply and has no significant effect on cerebral glucose metabolism during operation performed under general anesthesia combined with epidural block.