Clinicopathological factors associated with the presence of hypercapnia at admission in hospitalised cats with decompensated chronic kidney disease.

AIMS: To evaluate associations between clinicopathological variables and hypercapnia measured in cats with decompensated chronic kidney disease (CKD) on admission to a veterinary hospital. METHODS: This is a retrospective, cross-sectional study of cats (n = 39) that presented to a tertiary veterinary hospital in Argentina between June 2015 and December 2017 with blood creatinine concentrations >140 µmol/L, and abdominal ultrasound results consistent with CKD. Data recorded included venous partial pressure of CO2 (PvCO2), blood pH, haematocrit and concentrations of glucose, potassium, sodium, corrected sodium (Na+c), and ionised calcium in blood. A logistic regression model was used to assess associations between the presence of hypercapnia (PvCO2 ≥ 44.7 mmHg) and the other clinicopathologic variables. The duration of hospitalisation was compared in cats with and without hypercapnia using the Wilcoxon Rank Sum test. RESULTS: The final study population comprised 39 cats. Eleven cats (28.2%) had hypercapnia. In the logistic regression model, two independent variables were associated with the presence of hypercapnia at admission in cats with CKD: the concentration of creatinine in blood (OR = 1.06 (95% CI = 1.016-1.108); p = 0.007) and Na+c (OR = 1.33 (95% CI = 1.08-1.63); p = 0.005). There were no statistically significant differences in the length of hospital stay between the two groups. CONCLUSIONS AND CLINICAL RELEVANCE: There appears to be an association between elevated concentrations of creatinine and Na+c in blood, and hypercapnia in cats with CKD, suggesting careful assessment of blood gas and electrolyte parameters during hospitalisation is required. Further prospective studies are needed to evaluate the mechanisms behind this association and the association of hypercapnia with disease outcome including mortality.