Effects Of Acute Hypervolemic Hemodilution On Hemodynamics, Electrolytes And Arteryial Blood Gas Analysis In Patients Undergoing Scheduled Gastrointestinal Surgery

Objects To study the effects of acute hypervolemic hemodilution (AHHD) on hemodynamics, electrolytes and arterial blood gas analysis in patients undergoing scheduled gastrointestinal surgery.Methods Patients undergoing scheduled gastrointestinal surgery with ASA status I/II, age below 65, hemoglobin (Hb) above 110g/L, hematocrit (HCT) above 35% and serum potassium([K+]) above 3.5mmol/L are selected. No hypertension, heart diseases and other systemic disorders could be detected when admitting. Patients are sent to the operating room after routine preparations such as clysters, and induced with general anesthetics. Central venous passage is established to infuse Gelofusine 20ml/kg with a rate of 30ml/kgh for AHHD. Analysis of arterial blood gas, electrolytes and Hb, HCT are recorded before and after AHHD, and non-invasive blood pressure (NIBP), electrocardiogram (ECG), heart rate (HR) are monitored during AHHD. Lactated Ringer's solution is infused for the physiological fluid lost such as urine and evaporation. Calculate the expansion factor of Gelofusine and analyze the changes of NIBP, HR, Hb, HCT, and items of blood gas and electrolytes.Results Fifteen patients, 8 male and 7 female, were selected for the study.The average age is 56.6±6.6 years and the average body weight is 62.1±12.9kg. Six patients received simple clysters for gastric operations and 7 patients received thorough clysters for intestinal operations. No other special preparations were administered.There were no differences for NIBP and HR (P>0.05) between admitting and before AHHD. Serum natrium ([Na~+]), [K~+], and calcium([Ca~2+]) decreased markedly before AHHD (p<0.05), and hypokalemia and hypocalcemia were common (P<0.05) before AHHD. No marked changes for Hb and HCT (P>0.05).For a more detailed contrast, the patients were divided into two groups according to the preoperative clysters. [K~+] decreased more markedly (P<0.05) in the thorough clysters group than in the simple clysters group, and incidence of hypokalemia is higher (P<0.05) in the thorough clysters group.The average volume of Gelofusine for AHHD was llll±220ml, and the average volume of lactated Ringer's solution for physiological lost is 456±88ml. HCT decreased to 36.0%±4.0% from 40.6%±4.3% and got a slight AHHD. The calculated expansion factor of Gelofusine is 0.73±0.18. Ventricular premature beat was detected in one case through constant ECG monitoring. There was no significant changes (P>0.05) of NIBP and HR during AHHD, but CVP increased markedly (P<0.05)., There was more decrease in [K~+](P<0.05) than that in [Na~+] and [Ca~2+] (p>0.05). Blood gas analysis showed a little respiratory alkalosis before AHHD, and nearly compensated through AHHD.Conclusion Disorders of electrolytes is likely to arise in patients undergoing scheduled gastrointestinal surgery whose laboratory tests are within normal before preoperative preparations such as clysters.The expansion factor of Gelofusine is 0.73±0.18. CVP increasedsignificantly but not NIBP with 20ml/kg gelofusin during AHHD, and there may be more disorders of electrolytes if without management. There are no marked changes of blood gas during AHHD with Gelofusine.