LAUSR

OBJECTIVE To determine the cardiovascular and acid-base effects of 6% hydroxyethyl starch (HES) 130/0.4 and 0.9% sodium chloride (NaCl) administered to anaesthetized greyhounds with haemorrhagic shock. 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.