Comparison of 6% HES 130/0.4 in a balanced electrolyte solution versus 6% HES 130/0.4 in saline solution in cardiac surgery

Background

HES containing infusion solutions are used to effectively maintain circulating blood volume (normovolaemia) or to treat hypovolaemia in various medical fields. The exclusive use of normal saline-based fluids may be associated with the development of a hyperchloraemic metabolic acidosis. The goal of this study was to prove equivalence of 6% HES 130/0.4 in a balanced electrolyte solution (HES balanced) with 6% HES 130/0.4 in saline solution (HES saline) regarding colloid volume requirements in cardiac surgery. Effects on serum chloride, arterial pH, base excess (BE) and haemodynamic effects of HES balanced were investigated in comparison with HES saline. Superiority of HES balance regarding acid-base status parameters was to be proven.

Patients and methods

A prospective, randomised, double-blind, parallel-group, multicentre, clinical phase III study. Up to 50 ml/kg study drug could be infused until 24 hours after cardiac surgery. Forty-three patients were treated with HES balanced, 38 patients were treated with HES saline. The volume of study drug needed for adequate volume therapy until 6 hours after the end of surgery, the chloride level and the arterial pH at the end of surgery were recorded. ANOVA/ANCOVA was performed as appropriate.

Results

In the IIT analysis of the primary efficacy parameter, mean volumes of HES were 2391 ml in HES balanced or 2241 ml in HES saline, and equivalence (-500 ml; 500 ml) was proven (95% CI: -77 ml; 377 ml). Serum chloride levels were significantly lower after infusion of HES balanced. There were no differences in haemodynamic parameters between groups. The mean BE was at all times less negative in patients treated with HES balanced compared with HES saline. At the end of surgery the group difference of BE was 1.17 ± 0.42 mmol/l (P = 0.0032).

Table 1

Conclusion

The volume of HES needed was equivalent between treatment groups. Serum chloride levels were significantly lower after infusion of HES balanced, which reflects the lower chloride load of similar infusion volumes. Regarding the acid–base physiology, the HES balanced solution showed clear advantages. The significant lower serum chloride values were accompanied by less acidosis, as indicated by less negative BE values at all time points after baseline, and a trend towards a higher arterial pH.