Global tissue oxygenation during normovolaemic haemodilution in young children.

Abstract

Sixteen patients (1-8 years) scheduled for major general surgery were chosen for the study. They were divided into two groups according to the replacement solution used for haemodilution (HD); whether 6% middle molecular weight hydroxyethyl starch (HES) or 6% dextran 60 (DEX). After induction of general anaesthesia and pulmonary artery catheterization, a precalculated amount of autologous blood was withdrawn while the patient's autologous blood was simultaneously replaced by either HES or DEX. Autologous blood was retransfused at a minimum haematocrit (Hct.) of 17% or at the end of surgery. The following parameters were measured and/or calculated before and after HD, every 20 min intraoperatively and hourly for 6 h postoperatively: heart rate (HR), mean arterial pressure (MAP), Cardiac index (CI), Hct., arterial and mixed venous oxygen content (CaO2, CvO2) and arterio-venous difference of oxygen content (avDO2), oxygen delivery index (DO2I), oxygen consumption index (VO2I). The cardiovascular system remained stable. There was no significant difference as regards SvO2, despite a significant decrease in CaO2 to 10.8 and 10.0 ml.dl-1 (median values) due to reduction of haemoglobin concentration in the HES and DEX groups respectively. In spite of the low hct. values during surgery DO2I remained in normal range (median value 602 and 710 ml.min-1.m-2) in HEX and DEX group respectively. There was no significant change in VO2I after haemodilution (median value 212 and 243 ml.min-1.m-2) in either group. No statistically significant difference was noticed between either groups regarding: CaO2, CvO2, DO2I, VO2I, and no side effects of the colloids were observed. Isovolaemic haemodilution (Hct. approximately 17%) is well tolerated by young children undergoing major elective surgery; global tissue oxygenation was preserved throughout the procedure and both solutions used for haemodilution were equally effective.