The effect of 7.2% hypertonic saline solution on echocardiographic parameters of healthy horses.

REASONS FOR PERFORMING STUDY: The cardiovascular effects and duration of action of hypertonic saline are not yet fully understood in the horse. OBJECTIVE: To determine the effects of hypertonic saline on cardiac measurements derived from echocardiography over a period of 90 min after infusion in euvolaemic and healthy horses. STUDY DESIGN: Experimental study. METHODS: Five healthy conscious euvolaemic horses were infused with 5 ml/kg bwt hypertonic saline via a jugular catheter over 1 h. Immediately prior to infusion and at 0, 20, 40, 60 and 90 min after the completion of the infusion, echocardiographic images were obtained from the right parasternal window. The left ventricular internal diameter at end diastole and left ventricular internal diameter in peak systole were measured and ventricular volume measurements were calculated by the Teicholz method. Data were analysed using a mixed effects model, which included horse as a random effect. The effect of observation time was assessed accounting for correlation between observations. RESULTS: Fractional shortening and ejection fraction increased significantly 40 min after completion of infusion. Left ventricular internal diameter at end diastole, end diastolic volume and stroke volume all followed the same pattern and were increased at 20, 40 and 60 min compared to preinfusion values. There were also significant differences between the 0 and 40, 40 and 90, 60 and 90 time points. Other parameters did not differ significantly between time points. CONCLUSIONS: Hypertonic saline increases end-diastolic and stroke volume for approximately 1 h after completion of a 60 min infusion in euvolaemic horses. This adds to the evidence available to clinicians regarding the duration of action of hypertonic saline.