| ObjectiveTo evaluate the feasibility and the particularity of acute hypervolemic hemodilution to the canines with one-lung ventilation by monitoring hemodynamics, lung water , oxygenation and cruor function. To seek physiological limit and critical point of acute hypervolemic hemodilution during one-lung ventilation in canines.MethodsThirty-two healthy grown mongrel canines weighting 12 to 21kg were divided into four groups at random(H0,H1,H2,H3) , every group had eight canines. Group Ho was anesthetized with ketamine(8mg kg-1), thiopentone(15mg kg-1), vecuronium(0.12mg kg-1) and a cuffed endobronchial tube was inserted and artificial respiration with 100% oxygen was provide by a respiratory pump, respiratory rate was 6-10bpm and tide volume was 12-15 ml kg-1, so that the arterial PCO2 was kept in a range of 30 to 40 mm Hg.Ten minutes later, hemachrome and Hct were measured, then analysised lung water in terms of postmortem methods.Group H1,H2,H3 were anesthetized in the same way and acute hypervolemic hemodilution was carried out by 6% HES at a rate of 80ml kg-1 h-1, Hct was reduced to 25%,20%,15% respectively. And then analysised lung water by means of postmortem methods(A central venous catheter was placed via the right jugular vein for monitoring central venous pressure and collecting venous sample, another thermal hemodilution catheter was inserted femoral artery in group H3, then connected with PICCO and multifunction monitor, hemodynamics parameters were recorded , arterial blood gas and venous blood gas were analysised, and cruor function were tested).ResultsGroup H1,H2,H3 reached the target Hct respectively and the volume of HES was 53.88±21.76ml kg-1, 76.83±20.39ml kg-1, 97.91±30.47 ml kg-1. CO, SV, HR, SVR, SBP, MAP, DBP and GEDV didn't change significantly when one lung was ventilated(P>0.05), HR SBP MAP DBP also didn't vary after carring out acutehypervolemic hemodilution (P>0.05). With the growth of hemodilution, there was the remarkable increse in CO SV EF CVP GEDI(P<0.05), meanwhile, SVR decreased gradually(P<0.05). PH and PaO2 failed after one-lung ventilation(P<0.05), SaO2 maintained stable, PaCO2 tend to increase(P<0.05). PH, PaO2and SaO2 didn't change after carring out acute hypervolemic hemodilution, PaCO2 increased constantly(P<0.05). DO2 begin to decrease with one-lung ventilation, however, DO2 rised to the maximum dramatically at H1, VO2 increased at the same time, H2 was similar with H1, on the country, DO2 and VO2 were on the decline in the group H3, namely, VO2 pathologically relied on DO2. The baseline of extravascular lung water of non-dependent lung was higher than dependent lung, there was no significant diffence yet(p>0.05). With the growth of the extent of AHHD, there was a little increase in extravascular lung water, nevertheless, the growth of extravascular lung water was remarkble when Hct reached 15%(P<0.05),the increase in extravascular lung water of non-dependent lung was more significant than dependent lung, there was distinctive diffience(P<0.05). The baseline of intravascular lung water of non-dependent lung was lower than dependent lung, there was no significant diffence(P>0.05). There was a dramatic increase in intravascular lung water after blood was diluted. However, the extent of the increase was similar(P>0.05). Although HES had the effect on cruor function after AHHD, there was no significant effect on cruor function in group H2.ConclusionsOne-lung ventilation has a little effect on hemodynamics of the body circulation, with AHHD, SVR is on the decline, hemodynamics become excessiveness. With the growth of the extent of AHHD, The possibility of pulmonary edema to nonventilated lung is greater than to ventilated lung, however, with the great ability of lung water regulation, clinical pulmonary edema hardly occurs when Hct reach 15%.VO2 began to rest on the vary of DO2. Therefore , AHHD can be applied to one-lung ventilation, physiological limit shoud be limited to Hct 20%.
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