Can PCO2 be a mortality predictor in COVID-19 patients?

Abstract

Aim: The clinical course of Corona Virus Disease 2019 (COVID-19) infection is ranging from asymptomatic to moderate and severe disease with low survival rates. Therefore, reliable prediction of COVID-19 mortality and identification of contributing factors would allow targeted therapies for high-risk individuals. We aimed to determine whether partial carbon dioxide (PCO2) concentrations could predict mortality in patients treated in the intensive care unit (ICU).
 Material and Method: Acute Physiology and Chronic Health Evaluation (APACHE -2) scores, ferritin, lymphocyte count, neutrophil lymphocyte ratio (NLR), PCO2, partial oxygen concentration to inspired oxygen fraction (P/F) ratio were retrospectively determined and were compared between survivors and non-survivors. 
 Results: The mean APACHE-2 value was higher in Group Non-survivors than in Group Survivors. Patients in Group Non-survivors were significantly older than those in Group Survivors (p=0,012). From day 7, low baseline lymphocyte counts were significant for mortality (p=0,046). NLR was also high at ICU admission, and it was significant for mortality from the 7th day (p=0.022). From day 10, PCO2 and ferritin levels increased in Group Non-survivors. The P/F ratio increased with treatment in both groups during the first 10 days, and after day 13, the increase continued in Group Survivors, whereas the values decreased in Group Non-survivors. We found that PCO2 concentrations in patients at ICU admission were as expected and that the increase in PCO2 could predict mortality along with increased ferritin levels, older age, high APACHE scores, low lymphocyte count, elevated NLR and high P/F ratio. 
 Conclusion: This study showed that in patients with COVID -19, an increase in PCO2 concentration can predict mortality along with increased ferritin levels, older age, high APACHE scores, low lymphocyte count, elevated NLR and high P/F ratio.