Evaluating the Prognostic Value of Central Venous-to-Arterial PCO2 Difference in COVID-19 Patients Admitted to the Intensive Care Unit

Background: This study aimed to evaluate the relationship between the central venous-to-arterial PCO2 gap, serum lactate level, ScvO2, and prognosis of COVID-19 patients admitted to the intensive care unit. The study was performed in the intensive care unit of Imam Reza Hospital of Mashhad University of Medical Sciences. Methods: The baseline sample and ABG sample were checked in terms of the PCO2 gap for 3 consecutive days. Lactate serum was also evaluated on the second day. Vital signs, oxygenation status, need for vasopressor, type of respiratory support, and calorie intake were recorded simultaneously. The length of stay in the intensive care unit, the duration of mechanical ventilation, and the patient’s discharge or death were also recorded. Results: In this study, 147 COVID-19 patients were evaluated, of whom 115 patients died and 32 patients were discharged. The patients’ outcomes were assessed as the normal PCO2 gap (less than 6) and high gap (above 6). There were no significant differences between the high gap and mortality on the first day (p=0.833), second day (p> 0.99), and third day (p=0.82). PCo2 gap was not associated with ICU length of stay, duration of mechanical ventilation, SOFA, and APACHE score. The high gap patients had a significantly lower ScvO2 on the three days. Lactate serum was higher in the dead patients than in those discharged. The P/F ratio was significantly higher on the three days in the discharged patients than in the dead patients. Conclusion: There is no relationship between the central venous-to-arterial PCO2 gap with the 28-day mortality rate in covid-19 patients.