Development of a severity scoring system for acute haemorrhage in anaesthetized domestic cats: The CABSS score

Abstract Objective To determine if there are physiological, haematological, biochemical or electrolyte variables that can predict severe haemorrhage in cats. Study design Randomized crossover study whereby each cat underwent mild and severe haemorrhage, with a 2-month period between events. Animals A group of six domestic cats (mean ± standard deviation; 21 ± 1 months old; 4.9 ± 1.2 kg). Methods The cats were anaesthetized (buprenorphine, alfaxalone, isoflurane in oxygen at a fixed end-tidal concentration of 1.7%) before the haemorrhage event. A total of 34 variables were measured twice (prehaemorrhage and posthaemorrhage). The difference and percent change for each variable were compared between haemorrhage events (paired t-test). Significant variables were placed into 13 different ratios (post-haemorrhage value of one variable divided by a post-haemorrhage value of a second variable) and compared (paired t-test) and Cohen’s d (d) was calculated. Receiver operating characteristic curves were plotted and cut-off values for weak, moderate and strong indicators of severe haemorrhage were obtained. Results The blood loss was 4.5 ± 1.1 mL kg-1 and 26.8 ± 5.5 mL kg-1 for the mild and severe haemorrhage events, respectively. The most significant variables with large effect-sizes were heart rate (HR), systolic arterial blood pressure (SAP), end-tidal carbon dioxide (PE´CO2), serum albumin, haematocrit and actual bicarbonate ion concentration [HCO3(act)]. The most robust ratios were the 1) shock index (d = -2.8; HR:SAP), 2) HR:PE´CO2 (d = -2.9), 3) serum albumin: haematocrit (d = 1.5), and 4) HR:HCO3(act) (d = -1.6). These ratios were included in the final proposed Cat Acute Bleeding Scoring System (CABSS). Conclusion and clinical relevance Cats subjected to mild and severe haemorrhage demonstrated statistically and clinically relevant changes whereby four ratios could be created to make up the CABSS. The ratios detected and quantified the presence of severe haemorrhage in anaesthetized cats.