To Guide Transfusion During Operation By Determining Hematocrit With The Modified Microhematocrit Method

Object To guide transfusion during operation by determining hematocrit (Hct). To set up the linear equation of Hct among blood samples drawn from different locations. To explore the correlation and agreement of Hct under different relative centrifugal force (RCF), to provide experiment data for the modified microhematocrit method to determine Hct, and to invent a new type hematocritometer that can be widely used, to promote blood conservation. To compare the reliability of Hct measured by the new centrifuge with other devices. Methods Experiment one: To draw blood samples from the following locations : (l)Direct venous blood sample(Blood drawn from the vein directly which is untransfused ; (2)Transfusional line blood sample(Blood drawn from the transfusional line); (3)Earlobe blood sample(Blood directly drawn from the earlobe by puncturing ); (4) Fingertipblood sample (Blood drawn directly from either long fingertip by puncturing). The analysis of correlation among these Hct results would be done, and the corresponding linear equation would be gotten. The agreement analysis also would be done which can provide experiment data for alternative blood sample when it is difficult to draw blood from vein directly. The alternative blood sample would be from fingertip or transfusional line. After statistic analysis and clinic validation, blood sample can be drawn from the locations that had been set up linear equation with venous blood sample. Experiment Two: 326 ASAI-II physical status limited time operation patients had been chosen from 5 hospitals whose operations are over 200 a month. These subjects randomly entered into the experiment group or the control group. In the experiment group, the blood transfusion is guided by Hct below 24%, and the transfusion would be stop if the Hct was higher than 24%. In the control group, the transfusion based on traditional way and the anesthetist was unknown to the measurement results of the Hct, he decided whether to transfusion depend on his own clinic experience and the transfusion guideline which promulgated in 2000. To compare the fluid (including crystalloid, colloid, and blood) administered intraoperation (especially the volume of blood transfusion) and postoperation between groups, and to compare thevolume of blood loss and the urine, and to compare the transfusion relatedcosts, the clinical outcome between groups. Experiment There: The bankedblood was centrifuged for 5 min at about 10 000 G The plasma and red cellswere partly separated and the plasma was extracted. The Hct of the remainingred cells was determined (12 000 rpm for 5 min) (generally, 60%-70%). Aseries of Hct blood specimens were made by adding the extracted plasma tothe red cells in different proportion, whose Hct standards were 15%,16%—40%, 45%, 50% and 70%, respectively. Each Hct blood specimen wasdetermined by the same centrifuge at about 93 G (1000 rpm for 5 min), 375G (2000 rpm for 5 min), 845 G (3000 rpm for 5 min), 1502 G (4000 rpmfor 5 min), 13 600 G (12 000 rpm for 5 min), respectively with the parallelmethod. The results should be very close, and the differences of the samespecimens between the parallel tubes should be no more than 0.1%, otherwisethe measurement should be made again. Experiment Four: A new type ofhematocritometer would be invented. Experiment Five: To compare the Hctresults among STS-6100, TGL-12B, B-Hemaglobin Photometer, SYSMEXXE2100, i-STAT PORTABLE CLINICAL ANAYLYZER. Results (l)TheHct results among venous, transfusional line, earlobe and fingertip bloodsamples have good correlation, and the correlation coefficient for them is0.9779 , 0.9397,0.9816 respectively. The Hct results among venous, transfusional line and fingertip blood samples have good agreement, but between venous and earlobe blood samples the Hct results have poor agreement. (2) The transfusion volume can be decreased significantly by determining Hct to guide transfusion intraoperation (P<0.05), and transfusion-related expense also can be decreased significantly (PO.05). The prognosis of the wounds between groups shows no significantly difference, and neither does the in-hospital days. (3) The RCF of 93 G (1000 rpm for 5 min) and 375 G (2000 rpm for 5 min) could not separate the plasma and the red cells effectively; but the RCF of 845 G (3000 rpm for 5 min) and 1502 G (4000 rpm for 5 min) could divide them obviously. The determination results had a satisfactory correlation with RCF of 13 600 G (12 000 rpm for 5 min). The correlation between RCF of 13 600 G and 845 G was Y = 0.7141 X + 0.4733 (Y meaning RCF = 13600G, X meaning RCF = 845 G, R2 = 0.95, P < 0.001); the correlation between RCF of 13 600 G and 1502 G was Y = 0.9074 X +1.2113 (Y meaning RCF =13 600 G, X meaning RCF = 1502 G, R2= 0.99, P < 0.001) (0 < X < 100). The Altman-Bland analysis indicated the Hct results showed a good agreement between RCF (1502 G) and RCF (13 600 G). The mean difference of Hct was 0.1802% (95% CI, 1.4007%-2.2403%),the upper limit was 4.41% (95% CI, 3.6838%-5.1378%), and the lower limit was -0.7698% (95% CI, -1.4969% -0.0428%). (4)STS-6100 has been invented successfully which will be used specially for determining Hct intraoperation with the modified microhematocrit method. The correlation of Hct between STS-6100 and TGL-12B was Y = 1.0079 X - 0.0479 (Y meaning Hct measured by TGL-12B, X meaning Hct measured by STS-6100, R2 = 0.9977, P<0.05).The mean difference of Hct between TGL-12B and STS-6100 was 0.1905% (95% CI, 0.0569%- 0.3240%). (5) The Hct measured by STS-6100 had the most satisfactory correlation with SYSMEX XE 2100, and the Hct measured by blood-gas analyzer had the more satisfactory correlation, and the Hct estimated by the surgeons or the anesthesiologists had the worst correlation. Conclusions (1) The Hct results have good correlation and agreement among transfusional line, fingertip and venous blood samples; they can be replaced for each other. But for earlobe blood sample, the Hct results only have good correlation with venous blood sample, and have poor agreement with venous blood sample. Therefore, the Hct results from earlobe blood sample can not replace venous blood sample's results directly. After converting by the linear equation, the Hct results can be alternative. (2) To guide blood transfusion by determining Hct duringoperation can avoid transfusion blindly. (3) The results indicate that the modified microhematocrit method (RCF=1502 G) can be used as an alternative way to measure Hct. A new type centrifuge, which is specially used for measuring Hct with the modified microhematocrit method, has been invented. This new machine can obtain Hct results automatically, so it can avoid errors from the eyes. (4) The correlation and agreement of Hct results compared with the traditional centrifuge are satisfactory. The determining result by STS -6100 is reliable. (5) STS-6100, the new type of hematocritometer, is the best choice to measure Hct during operation for many kinds of hospitals.