A comparison of traditional and quantitative analysis of acid-base and electrolyte imbalance in 87 cats

Acid–base and electrolyte disorders are commonly found in critically ill patients in human and veterinary medicine [1-4]. In particular, metabolic acid–base disorders have been reported in various critical diseases, such as diabetic ketoacidosis, hepatitis, and kidney disease [1,2,5]. In cats, acid–base disorders have prognostic relevance, and the bicarbonate concentration in feline patients is inversely proportional to mortality [6,7]. Therefore, accurate diagnosis and proper treatment of acid–base disorders in critically ill patients are essential. Various acid–base analysis methods, such as traditional and physicochemical approaches, have been developed to manage acid–base disorders successfully. The traditional approach called the physiologic approach is based on the Henderson– Hasselbalch equation to evaluate the acid–base status using the pH, partial pressure of carbon dioxide (pCO2), bicarbonate (HCO3 ), anion gap (AG), and base excess (BE) [8]. This method can describe the compensations [9], but it has the disadvantage of being incompetent in detecting complex metabolic acid–base disorders, which are often found in severely ill patients [10,11]. Physicochemical approaches include the Stewart method (strong ion model, quantitative approach) [12-14] and the Fencl–Stewart method (semiquantitative approach) [15] and are more useful for analyzing the underlying cause than the traditional method. The Acid–base disorder is a common problem in veterinary emergency and critical care. Traditional methods, as well as the Stewart method based on strong ion difference concepts and the Fencl–Stewart method, can be used to analyze the underlying causes. On the other hand, there are insufficient comparative study data on these methods in cats. From 2018 to 2020, 327 acid–base analysis data were collected from 69 sick and 18 healthy cats. The three most well-known methods (traditional method, Stewart method, and Fencl–Stewart method) were used to analyze the acid–base status. The frequency of acid–base imbalances and the degree of variation according to the disease were also evaluated. In the traditional acid-base analysis, 5/69 (7.2%) cats showed a normal acid-base status, and 23.2% and 40.6% of the simple and mixed disorders, respectively. The Fencl–Stewart method showed changes in both the acidotic and alkalotic processes in 64/69 (92.8%), whereas all cats showed an abnormal status in the Fencl–Stewart method (semiquantitative approach). The frequencies of the different acid-base imbalances were identified according to the analysis method. These findings can assist in analyzing the underlying causes of acid–base imbalance and developing the appropriate treatment.