Experimental And Clinical Studies Of Combined Hemodilution And Controlled Hypotension Technique

Background and Objective:The cost and hazards involved with homologous transfusions have promoted the development of methods to minimize blood loss during surgery. Such techniques have included hemodilution and production of controlled hypotension using drugs such as nitroprusside or adenosine. Recently, anesthesiologists have used a combination of these two techniques to produce a hemodiluted , hypotensive state. But the safety of this new technique is still not clear. The aim of this study is to evaluate the safety of the new technique.Animal Experiment:Methods:18 healthy mongrel dogs, were anesthetized with isoflurane-N₂O-O₂ inhalation and intravenous fentanyl supplementation. Vecuronium infusion was used to facillitate controlled ventilation. Animals were randomly allocated to one hypotension group(n=5), one hemodilution group(n=6) or one combine group(n=7). Hypotension was induced with isoflurane-nitroprusside-esmolol. In hemodiluted group, different levels of hemodilution were achieved by exchanging whole blood with Gelofusine. The combine group used the two techniques simultaneously. Blood gases, plasma lactate and hemodynamic variables were measured at different hemodiluted and/or different hypotensive state. After experiment end point arrived, ATP and AMP of myocardial and cerebral sample were measured by HPLC.Results:During experiment, esophagus temperature maintained at normal range. In hemodiluted group, the reduction in Hct was associated with a significant decrease in CaO₂ and SVR. SI and CI increased significantly. DO₂ were maintained due to the increase in CI till Hct was lowered to 20%.. HR and MAP remained unchanged. When Hct<20%, DO₂...