Study design

Prospective, experimental, complete randomized block design.

Animals

Twelve healthy adult greyhounds.

Methods

After 60 minutes of isoflurane anaesthesia, 48 mL kg^?1 of blood was removed to induce hypotension. Dogs were randomized to receive either 20 mL kg^?1 of HES 130/0.4 or 80 mL kg^?1 of 0.9% NaCl over 20 minutes. Haemoglobin, arterial and central venous blood gas and electrolytes, lactate, mean arterial pressure (MAP) and cardiac index were measured at: T0, 60 minutes after induction of anaesthesia, immediately prior to blood removal; T1, immediately after blood removal; T2, immediately after fluid administration; and T3, 40 minutes after fluid administration. Oxygen extraction ratio (O₂ER) was calculated at each sample time.

Results

O₂ER increased at T1 and decreased at T2 and T3, with no difference between the two groups. Dogs administered HES 130/0.4 had higher lactate at T2 mean (95% confidence interval) 1.3 (0.8–1.9) mmol L^?1] than dogs administered 0.9% NaCl 0.8 (0.5–1.1) mmol L^?1]; p = 0.045. Dogs administered HES 130/0.4 had a higher MAP at T3 88 (74–102) mmHg] than dogs administered 0.9% NaCl 69 (60–79) mmHg]; p = 0.019. Dogs administered 0.9% NaCl were more acidaemic at T2 and T3, including higher hydrogen ion, lower bicarbonate, lower base excess and higher chloride concentrations.

Conclusion

and clinical relevance The effect of 20 mL kg^?1 of HES 130/0.4 on shock, as measured by O₂ER, was no different than that of 80 mL kg^?1 of 0.9% NaCl in dogs under general anaesthesia. Acidaemia in the NaCl group is likely attributable to hyperchloraemic metabolic acidosis from the larger volume administered.