Dynamics of vascular volume and hemodilution of lactated Ringer's solution in patients during induction of general and epidural anesthesia.
OBJECTIVE
To investigate the dynamics of vascular volume and the plasma dilution of lactated Ringer's solution in patients during the induction of general and epidural anesthesia.


METHODS
The hemodilution of i.v. infusion of 1000 ml of lactated Ringer's solution over 60 min was studied in patients undergoing general (n=31) and epidural (n=22) anesthesia. Heart rate, arterial blood pressure and hemoglobin (Hb) concentration were measured every 5 min during the study. Surgery was not started until the study period had been completed.


RESULTS
General anesthesia caused the greater decrease of mean arterial blood pressure (MAP) (mean 15% versus 9%; P<0.01) and thereby followed by a more pronounced plasma dilution, blood volume expansion (VE) and blood volume expansion efficiency (VEE). A strong linear correlation between hemodilution and the reduction in MAP (r=-0.50; P<0.01) was found. At the end of infusion, patients undergoing general anesthesia retained 47% (SD 19%) of the infused fluid in the circulation, while epidural anesthesia retained 29% (SD 13%) (P<0.001). Correspondingly, a fewer urine output (mean 89 ml versus 156 ml; P<0.05) and extravascular expansion (454 ml versus 551 ml; P<0.05) were found during general anesthesia.


CONCLUSIONS
We concluded that the induction of general anesthesia caused more hemodilution, volume expansion and volume expansion efficiency than epidural anesthesia, which was triggered only by the lower MAP.
Li
Yu-hong
YH
Department of Anesthesiology, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, China. yuh_li2002@hotmail.com
Lou
Xian-feng
XF
Bao
Fang-ping
FP
D000328:Adult; D000368:Aged; D000767:Anesthesia, Epidural; D000768:Anesthesia, General; D001794:Blood Pressure; D001810:Blood Volume; D005260:Female; D006438:Hemodilution; D006801:Humans; D007552:Isotonic Solutions / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D000077325:Ringer's Lactate
D007552:Isotonic Solutions; D000077325:Ringer's Lactate