Blood Gas Analysis among COVID-19 Patients: A Single Centre Retrospective Observational Study

Abstract

Introduction: The dominant respiratory feature of Coronavirus Disease 2019 (COVID-19) is arterial hypoxaemia, greatly exceeding abnormalities in pulmonary mechanics. Arterial Blood Gas (ABG) analysis helps to find out respiratory, metabolic acidosis and alkalosis. Aim: To evaluate the blood gas levels among critically ill COVID- 19 positive patients admitted in Intensive Care Unit (ICU). Materials and Methods: A retrospective, observational study was conducted in East Midnapore district of West Bengal, India from July 2020 to February 2021. Data of ABG analysis {pH, PaO2 (partial pressure of oxygen in arterial blood), PaCO2 (partial pressure of carbon dioxide in arterial blood) and bicarbonate (HCO3)} in 314 adult COVID-19 positive cases, were obtained from ICU records. All critically ill COVID-19 patients those who were admitted in ICU with more than 15 years of age were included in this study. Data were analysed and Pearson correlation test was applied for statistical significance. Results: Among the study subjects, 234 (74.5%) were males. Most affected age group was 51-60 years among males and above 60 years among females. Most common ABG finding was high pH indicating alkalosis, found among 183 (58.3%) patients. Acidosis was rare and seen in only 19 (6.0%) patients. A total of 174 (55.4%) patients developed respiratory alkalosis with low PaCO2. Hypoxaemia was found in 144 (45.9%) patients. High HCO3, indicating metabolic alkalosis, was seen in 144 (45.9%) patients. Statistically significant correlation was found between PaCO2 and pH (pearson correlation coefficient (r)=-0.153, p=0.007) and PaCO2 and HCO3 standard (r=0.185, p=0.001). Conclusion: ABG should be done in all COVID-19 patients during admission. A regular interval monitoring of ABG can help in early identification of respiratory damage, silent hypoxia and cytokine storm and with early detection many lives can be saved with early initiation of management.