[The influence of infusion volume on hemodynamics during experimental laparotomy]

The influence of infusion volume on hemodynamics was studied in adult mongrel dogs undergoing laparotomy. Study 1: Total blood volume (TBV) was measured in 5 dogs undergoing laparotomy without fluid administration for 180 min. TBV before surgery was 71.2 +/- 10.7 ml.kg-1 and remarkably decreased to 59.9 +/- 11.5 ml.kg-1, at a rate of 3.8 ml.kg-1.h-1. Study 2: 21 dogs were divided into 3 groups. Group C had restricted fluids during the study. Group I had infusion of lactated Ringer's solution (LR) at a rate of 10 ml.kg-1.min-1 and Group II at a rate of 20 ml.kg-1.min-1 for 180 min. In group C, mAP and HR were unchanged but CVP, cardiac output, renal blood flow (RBF) and skin blood flow decreased after laparotomy. On the other hand, CVP and RBF were maintained until 180 min in Group I. In Group II, though the hemodynamic parameters were well maintained and urine output was maximal, Ht, Na, concentration and especially plasma colloid osmotic pressure (Pcop) decreased. These results suggest that administration of LR at a rate of 20 ml.kg-1.min-1 is rational to prevent the decrease of TBV and to maintain the peripheral circulation during the surgical procedure, but it may decrease Pcop.