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Global tissue oxygenation during normovolaemic haemodilution in young children
A Aly Hassan1, H Lochbuehler, L Frey
1Institute for Surgical Research, University of Munich, Germany.
Insights
Isovolaemic haemodilution using hydroxyethyl starch or dextran is safe and effective in young children undergoing major surgery. Both solutions maintained stable cardiovascular function and preserved tissue oxygenation, even with reduced hematocrit levels.
Area of Science:
- Anesthesiology
- Pediatric Surgery
- Critical Care Medicine
Background:
- Major general surgery in children necessitates careful hemodynamic management.
- Hemodilution is a technique used to manage blood volume during surgery.
- The safety and efficacy of different hemodilution solutions in pediatric patients require investigation.
Purpose of the Study:
- To evaluate the cardiovascular stability and tissue oxygenation during isovolaemic haemodilution in pediatric patients undergoing major general surgery.
- To compare the effects of 6% middle molecular weight hydroxyethyl starch (HES) and 6% dextran 60 (DEX) as replacement solutions for haemodilution.
Main Methods:
- Sixteen pediatric patients (1-8 years) undergoing major general surgery were divided into two groups, receiving either HES or DEX for haemodilution.
- Autologous blood was withdrawn and replaced with HES or DEX, with retransfusion at a minimum hematocrit of 17%.
- Hemodynamic parameters, oxygen content, delivery, and consumption were monitored before, during, and after haemodilution.
Main Results:
- Both HES and DEX groups maintained stable cardiovascular systems (heart rate, mean arterial pressure, cardiac index).
- Despite decreased arterial oxygen content (CaO2), oxygen delivery index (DO2I) remained within normal ranges in both groups.
- Oxygen consumption index (VO2I) showed no significant changes, indicating preserved global tissue oxygenation.
Conclusions:
- Isovolaemic haemodilution to a hematocrit of approximately 17% is well-tolerated in young children undergoing major elective surgery.
- Both HES and DEX are equally effective in preserving global tissue oxygenation during this procedure.
- No significant differences or adverse effects were observed between the two colloid solutions.
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.