Stroke volume optimization after anaesthetic induction: An open randomized controlled trial comparing 0.9% NaCl...

Postinduction hypotension during general anaesthesia could be corrected by a rapid cardiac preload optimization by fluid infusion. The type of fluid to be used in this context remains debated. The aim of our study was to compare the amount of fluid challenges required to optimize stroke volume after induction of anaesthesia with colloid (HES) or crystalloid (0.9% NaCl).

Open randomized prospective parallel-group study.

Fifty-six adult patients scheduled to undergo orthopaedic surgery under general anaesthesia were randomly assigned to receive, either 0.9% NaCl (n=28), or HES (n=28). Cardiac preload optimization directed by oesophageal Doppler was performed after induction with fluid challenges of 250ml of solution until stroke volume (SV) no longer increased by 10%. Primary endpoint was: number of fluid challenges required to achieve SV optimization. Secondary endpoints were: number of patients responding to the first fluid challenge, proportion of patients requiring ephedrine and the ephedrine dose required to restore arterial pressure.

Percentages of responders were 61% and 63% in the 0.9% NaCl and HES groups, respectively. Number of fluid challenges necessary for SV optimization was not significantly different between 0.9% NaCl group and HES group (2 [1-2] versus 2 [1-2], P=0.33). Number of patients needing ephedrine, and well as the associated ephedrine dose, did not differ significantly.

Our study suggests that after induction, crystalloid and colloid expand the intravascular volume with equivalent efficacy immediately after administration and correct in a similar way the postinduction hypotension.