Effects Of Acute Normovolemic Hemodilution With Crystalloid And/or Colloid On Extravascular Lung Water And Oxygenation

Objectives To investigate the effects of acute normovolemic hemodilution(ANH) with crystalloid and/or colloid on the extravascular lung water(EVLW) and oxygenation in patients undergoing orthopedic surgery.Methods Forty - eight ASAâ… orâ…¡patients of either sex aged 18 - 70 yrs weighing 55 - 79 kg undergoing extensive orthopedic surgery were included in the study.The preoperative hematocrit(Hct) of the patients was 35%and Hb＞120 g·L^-1.The estimated intraoperative blood loss was 1 000-1 500 mL.The patients were randomly divided into 3 groups(n = 16 each):groupâ… lactated Ringer' s solution(LR);groupâ…¡LR-6%HES and groupâ…¢colloid(6%HES ).Blood was removed from radial artery after induction of anesthesia.The target Hct was 28%.The volume of blood removed = body weight(kg)×70×(preop Hct- target Hct )/ 0.5×(preop Hct + target Hct ).The removed whole blood was replaced with lactated Ringer' s solution in a three to one ratio in groupâ… or with 6%HES in a one to one ratio in groupâ…¢.In groupâ…¡half of the removed whole blood was replaced with LR(3:1) and the other half with 6%HES(1:1). The EVLW,HR,BP,Cardiac Output(CO),Cardiac index(CI) and dp/dt_max were monitored by PiCCO and recorded before induction of anesthesia(T₀), immediately after induction of anesthesia(T₁),immediately after and 15 min after ANH(T_2,3),immediately before and after reinfusion(T_4,5). Hct,colloid osmotic pressure and blood gases were also measured and recorded.Results The 3 groups were comparable with respect to M/F ratio,age, body weight and the volume of whole blood removed.MAP,HR,SpO₂ and CVP were stable during operation in all 3 groups.Hct was significantly decreased after AMH as compared with the baseline at T₀ in all 3 groups. The osmotic pressure was significantly decreased after ANH in groupâ… andâ…¡and was significantly higher in groupâ…¡andâ…¢than in groupâ… after ANH.CO(except at T₅),CI and dp/dt_max were significantly decreased after ANH as compared to the baseline at T₀ in all 3 groups.There was no significant difference in EVLW,PaO₂ and[HCO₃^-]among the 3 groups.Conclusion Moderate ANH with crystalloid or colloid has little effect on EVLW and oxygenation in patients with normal cardio - pulmonary function.