Insights into the baseline blood pH homeostasis at admission and the risk of in-hospital mortality in COVID-19 patients

<b>Aim:</b> A laboratory finding in critically ill COVID-19 patients is blood academia (pH <7.35). We investigated its cause in connection with the admission baseline blood pH homeostasis.<b>Patients & methods:</b> We retrospectively monitored the baseline blood pH homeostasis of 1215 COVID-19 patients who were admitted with pneumonia using data-driven knowledge. Two categories of patients were identified: non-survivors (107) and survivors (1108).<b>Results:</b> Non-survivors showed greater levels of lactate and lower blood pH, saturation, and partial pressure of oxygen than survivors. A bivariate Spearman's correlation matrix showed that the [HCO₃^-]/pCO₂ and pCO₂ of non-survivors exhibited an unmatched connection, but not in the survivor group. When comparing non-survivors to survivors, the dendrograms derived from the bivariate comparison matrix showed differences in gasometry parameters like blood pH, [HCO₃^-]/pCO₂ ratio, anion gap and pO₂.<b>Conclusion:</b> The little variations in the gasometry readings between survivors and non-survivors upon admission suggested abnormal changes in the complementary renal and respiratory systems that bring blood pH back to normal. In advanced COVID-19, modest blood acid-base imbalances could become blood acidemia if these compensatory strategies were overused. Data-driven monitoring of acid-base parameters may help predict abnormal blood pH and the advancement of metabolic acidemia before it is too late.