Peri-operative changes of haemodynamics and oxygen transport in patients undergoing haemodilution with bovine haemoglobin
© BioMed Central Ltd 2001
Published: 1 March 1997
Haemodynamic reactions following infusions of haemoglobin solutions have been shown in several animal experiments and may be of clinical concern. There is some evidence that vasoconstriction is a function of impurities of haemoglobin solutions. As a consequence, purification and chemical modification of haemoglobin should reduce adverse circulatory reactions. In animal models, ultrapurified polymerized bovine haemoglobin (HBOC-201) appears to be free of severe side effects. The present prospective study investigates haemodynamic changes and oxygen transport parameters in patients undergoing pre-operative haemodilution with HBOC-201 in comparison to hetastarch.
After institutional approval and written informed consent, 12 patients (6 m and 6 f, mean age 59 ± 10 years) underwent pre-operative haemodilution prior to elective liver resection. After induction of general anaesthesia, patients received an arterial line, a central venous and pulmonary catheter. Haemodynamic parameters and blood gases were measured before and after patients donated 1 l of their own blood and received 1 1 of Ringer's lactate (RL). Following haemodilution, patients were randomly allocated to receive either 0.4 g/kg HBOC-201 (Biopure, MA, group 1), or an equal volume of 6% hetastarch 70,000/0.5 (B Braun, FRG, group 2) plus 1 l of RL within 30 min. Haemodynamic and blood gas measurements were performed every 10 min during infusion of HBOC-201 or hetastarch, at the beginning of surgery and 4 h after arriving at the ICU. Values were tested using ANOVA and Mann-Whitney U-test with P < 0.05 considered as significant.
Demographic characteristics did not differ between groups. In contrast to group 2, the mean arterial blood pressure increased by 18% over baseline in group 1. While the pulmonary vascular resistance did not change in both groups, the systemic vascular resistance (SVR) increased to a maximum of 42% over baseline in group 1. Cardiac output (CO), mixed-venous oxygen content and oxygen delivery were lower in the HBOC-201 group. In contrast, arteriovenous oxygen difference and oxygen extraction ratio were higher in group 1 than in group 2, even on the ICU. Free haemoglobin reached a maximal concentration of 1.0 ± 0.2 g/dl 30 min after the HBOC-201 infusion was started.
In spite of ultrapurification of HBOC-201, the present haemodynamic data are consistent with different studies which show increased SVR and decreased CO following application of haemoglobin solutions. However, the long-lasting increase of oxygen extraction after HBOC-201 infusion which is provided by the low oxygen affinity of this compound may overcome potential adverse haemodynamic side effects.