Effects Of Pre-operative Acute Hypervolemic Hemodilution On The Blood Volume

Objective:This investigation was designed using hydroxythy starch as a dilution marker to measure blood volume, observing the effect of acute pre-operative acute hypervolemic hemodilution with Gelofusine on blood volume during perioperative period.Methods:In this study, forty ASA grade Ⅰ-Ⅱ patients, scheduled for elective resection esophagus carcinoma under general anesthesia were randomly allocated to two groups. Patients were excluded if they had cardiac, pulmonary, renal, hepatic disease or blood sugar was abmormal. Twenty patients recieved acute hypervolemic hemodilution(group AHH,n=20), and the others did not as controll( group C, n=20). All patients were premedicated with diazepam 0.2mg/kg, atropine 0.01mg/kg intramuscularly 0.5h before anesthesia and lactated Ringer's solution was infused to compensate for preoperation fluid restriction after midnight. Anesthesia was induced with fentanyl 2-4ug/kg, midazolam 0.2-0.25mg/kg and vecuronium 0.1mg/kg and maintained with inhalation of 1.3MAC isoflurane after tracheal intubation. Arterial blood pressure (SP,DP,MAP), ECG, HR, SpO2, PetCO2 and inhalation concentration of isoflurane werecontinuously monitored through operation. Right internal jugular vein was cannulated for CVP monitoring and injecting fluid. Left radial artery was cannulated for taking blood sample. After 10 min of rest in the supine position, blood volume was measured with hydroxyethyl starch method : through the radial artery catheter, EDTA-blood samples(5ml) were taken immediately before, and 5 min after hydroxyethyl starch injecting through a central venous catheter. Hemoglobin concentration and hematocrit were measured before and after hydroxyethyl starch injected, and plasma was separated for further analysis. After the background blood volume was measured, Gelofusine fluid 15ml/kg was intravenously infused at a rate of 50 ml/min in AHH group. After hemodilution 15 min, the blood volume was measured again. Monitered the change of SP,DP,MAP,SPO2,ECG,CVP during the whole procedure. During the operation, blood loss was replaced by an equal volume of Gelofusine solution, Ringer's solution was infused in a volume equal to the fluids loss; the patints in group C were infused as usual. The blood volume were measured 2h after the operation initiation. The arterial blood sample were taken for measure Hb,Hct,blood gas,plasma electrolure and plasma colloid osmotic pressure. Blood volume was determined by hydroxyethyle starch method: Plasma was separated by centrifugation (5min, 2000r/min). For all measurement we used HAES-steril, a 6% solution of hydroxyethyl starch( molecular weight 200000, degree of substitution 0.40-0.55 ) in isotonic saline. hydroxyethyl starch consist of glucose and hydroxyethyl glucose that are interconnected by α-glycosidic bonding. Plasma (0.6ml) was transferred into a steamtight screw cup containing concentrated hydrochloric acid ( 0.15ml ) and then placed into a boiling water bath. After 45 min of incubation, the acid was neutralized by adding 3.33M of Tris buffer (0.6ml). With no acid lost during the boiling procedure, the resulting pH was 7.0±0.5 using indicator paper, complete hydrolysis of hydroxyethyl starch into glucose and hydroxyethyl glucose was achieved after 45 min of incubation, as indicated by no further increase in glucose concentration when extending the boiling time up to 1.5 hr. To obtain a clear supernatant, precipitate protein and debris were separated by centrifugation( 5min, 8000r/min ). Glucose in the supernatant was measured using COBASMIRA automatic biochemistry analyzer in the laboratory. Hydroxyethyl starch concentration in the plasma is proportional to the difference of glucose concentration obtained by hydrolysis of the plasma before and after injection of hydroxyethyl starch. Under the conditions chosen, hydroxyethl starch in the plasma is completed hydrolyzed, or at least hydrolyzed to a constant percentage to glucose and hydroxyethyl glucose. Therefore, the difference of glucose concentration after hydrolysi...