Effects Of Different Colloids On Volume And Their Elimination During Early Period Of Anesthesia Induction In Cardiac Surgery

Objective:During the early period of general anesthesia induction for Coronary Artery Bypass Graft(CABG) surgery,either hydroxythyl starch 130/0.4(HES 130/0.4) or modified fluid gelatin(MFG, Gelofusion,GEL) were infused to record and analyse dynamic changes of plasma colloid osmotic pressure, hemoglobin concentration as well as hemodynamic changes.Based on the mass conservation law of hemoglobin and the quantity conservation law of colloid molecules along with the measured data of the above parameters, equations could be set up, in order to assess volume status changes after using different kinds of volume substitutes at different time points. Moreover, colloid molecule quantity elimination within the circulation an hour after infusion can be figured out with the second equation group. The last parameter (elimination rate) will further confirm the basis for volume and hemodynamic changes induced by different kind of colloid solution infusion.Method:32 patients undergoing CABG, ASAⅢ, were randomized into 2 groups, HES group and GEL group,16 each. Every patient experienced 8 hours fasting, and colloid fluid infusion was forbidden before anesthesia induction. Patients received either HES 130/0.4 or GEL within 10 minutes after induction. In the following observing hour, no extra colloid infusion was performed.3.5ml blood sample was taken at each different time point before infusion, immediate after infusion and an hour after infusion. From which,2.5ml is for Hemoglobin concentration(Hb0, Hb1,Hb2)and Hematocrit(HCT0, HCT1, HCT2)measurement, the rest 1ml is for plasma colloid osmotic pressure (COP0, COP1, COP2)measurement. Then solve the equation groups (1) and (2)with the measured data.(1)V0×Hb0=(V0+VA1)×Hb1(1)V0×(1-HCT0)×COP0+Vinfusion×COPinfusion=(V0+V△41)×(1-HCT1)×COP(2)V0×Hb0=(V0+V△2)×Hb2(2)V0×(1-HCT0)×COP0+Vinfusion×COPinfusion×(1-x%)=(V0+V△2)×(1-HCT2)×COP2Calculated data includes intravascular volume at 3 different time points(V0, V1, V2),immediate volume expansion ratio at 2 different time points and elimination rate of HES and GEL an hour after infusion. Meanwhile, mean arterial pressure at different time points (MAP0, MAP1, MAP2)and urine output an hour after infusion were noted.Results:Demographic data were comparable between groups (P>0.05).COP were comparable between groups(P>0.05). COP1 is significantly higher than COP0 and COP2 within groups (P<0.05).Hb decreased significantly immediate after infusion(P<0.05). In HES group Hb2 is lower than Hb1(P<0.05), however in GEL group Hb2 and Hb1 have no statistical differences (P>0.05). MAP0 and MAP1 were comparable within both groups (P>0.05), however MAP2 decreased significantly an hour after infusion(P<0.05). MAP were comparable between groups at 3 time points(P>0.05).Urine outputs were comparable between groups(P>0.05), and larger than 40ml(P<0.05). V1 is larger than V0 in both groups(P<0.05),V2 is larger than V1 in HES group (P＜0.05), however comparable to V1 in GEL group (P>0.05). V△1 /Vinfusion and V△2/Vinfusion are higher than 100%in both groups (P<0.05). V△2 is higher than V△1 and V△2/Vinfusion is higher than V△1/Vinfusion in HES group (P<0.05). Hower GEL group showed no differences (P>0.05). Elimination rate is lower in HES group than in GEL group (P<0.05).Conclusions:(1) Both HES130/0.4 and GEL could significantly increase plasma COP after infusion during early period of anesthesia induction in cardiovascular surgery.(2) During the process of clinical anesthesia induction,equations out of Hb concentration law and colloid quantity concentration law help demonstrate that both HES130/0.4 and GEL have strong volume expansion and maintenance ability.However HES130/0.4 has a stronger maintaining effect than GEL an hour after infusion. Hemodynamic parameters and urine output showed no differences between groups.(3) Final results of the molecule quantity elimination rate from the equation groups reconfirmed a stronger volume maintenance effect of HES130/0.4 than that of GEL in a more direct way.(4) With the use of a clinical-facilitating hemoglobin and colloid oncotic pressure conservation method, the results of volume evaluation suggest that HES130/0.4 and GEL can both be used as effective and safe volume substitutes during early period of anesthesia induction in CABG.