Effects of deliberate hypotension combined with acute isovolemic hemodilution on glomerular filtration rate in rabbits / 中华麻醉学杂志

ABSTRACT

Objective To determine the effects of acute normovolemic hemodilution combined with deliberate hypotension induced by sodium nitroprusside on glomerular filtration rate. Methods Forty rabbits weighing 2.6-4.0kg were anesthetized with intramuscular ketamine(1mg?kg-1). The animals were tracheotomized and intubated.Anesthesia was maintained with 0.5% halothane inhalation and fentanyl infusion (2?g?kg-1?min-1 ) . Carotid artery was cannulated for blood pressure monitoring and blood gas analysis and external jugular vein was cannulated for CVP monitoring and blood sampling. The animals were randomly allocated to one of four groups of ten animals in each group: control group; deliberate hypotension group;hemodilution group and combined hemodilution-deliberate hypotension group. Deliberate hypotension was induced with 0.02% sodium nitroprusside and MAP was reduced to 35-40mm Hg. In hemodilution group and combined group blood was removed from artery until Hct was reduced to 20 % -25 % and normovolemia was maintained by simultaneous infusion of Ringer's lactate solution, 3 times the volume of blood removed. Glomerular filtration rate was assessed by inulin clearance rate. 1% inulin 3 ml was injected I. V. over 30 s and blood samples were taken from CVP line for determination of blood inulin concentration at 1,3,5, 10, 30, 60, and 100 min after injection of inulin. Results Urine output decreased significantly in hypotension group and increased in hemodilution group. There was no significantly difference in urine output between control and combined groups. Inulin clearance decreased significantly in hypotension group as compared with that in control group, but there was no significantly difference in inulin clearance between control and combined groups. Conclusions Deliberate hypotension can decrease renal blood flow and deliberate hypotension combined with hemodilution can maintain kidney microcirculation.