2023, Number 8
Standardization of PaO2 to PaCO2 in PaO2/FiO2 ratio as a predictor of mortality in patients with prone position and severe COVID-19
Márquez TCB, Gómez GN, Guerrero THE, Jiménez CC, Rodríguez CCE, Moreno RG
Full text
10.35366/115224
Language: Spanish
References: 19
Page: 666-671
PDF size: 220.60 Kb.
ABSTRACT
Introduction: in 2019, severe acute respiratory syndrome (SARS-CoV-2) became universally known, caused by the coronavirus (COVID-19), which can manifest from asymptomatic forms or to clinical stages characterized by acute respiratory failure. pneumonia, septic shock and multiple organ failure, which require mechanical ventilation requirements. Mortality prediction markers are useful to prioritize patients at higher risk, improving the care of these patients. Objective: to evaluate the standardization of PaO2 to PaCO2 in the PaO2/FiO2 ratio as a predictor of hospital mortality in patients with prone position and invasive mechanical ventilation with acute respiratory failure by COVID-19. Material and methods: observational, retrospective, analytical cohort of patients admitted to the Intensive Care Unit service in the period from April to September 2020. Those with laboratory-confirmed SARS-CoV-2 infection; presence of consolidation and/or ground-glass opacities on chest X-ray and/or pulmonary computed tomography and presence of acute respiratory failure, requiring invasive mechanical ventilation, were included. Acute respiratory failure was considered to be present when PaO2 was < 60 mmHg with FiO2 0.21, excluding those in whom arterial blood gas records were not available before and after prone positioning. Demographic, clinical and blood gas data were recorded to obtain the PaO2 value standardized for PaCO2 (STPaO2), as well as mortality and days of mechanical ventilation in the unit. Results: a total of 74 patients were analyzed, with a mean age of 53.50 ± 12.77 years, with a predominance of men 63%, most patients were located in the groups of mild and moderate obesity according to their BMI 31 ± 4.71 kg/m2. Gasometric parameters before prone position were PaO2 of 81.94 ± 29.11 and PaCO2 of 44.62 ± 10.51 vs 97.37 ± 44.50 mmHg and 40.45 ± 8.51 mmHg respectively after being placed in the position. Reported STPaO2 pre-prone was 89.62 ± 39.77 vs 98.11 ± 45.02 post-prone. Mortality in this cohort was 44.6%. The population was then divided into two groups (survivors vs non-survivors), where no significant differences were found between the two groups for any of the blood gas parameters. After the patients were placed in prone position and arterial blood gas monitoring was performed, only for FiO2 and SpO2/FiO2 ratio a significant difference was found between survivors and non-survivors (p = 0.03 for both variables). In the ROC analysis FiO2 obtained an AUC 0.644 (95% CI 0.517-772) p = 0.034 to predict mortality and SpO2/FiO2 AUC 0.647 (95% CI 0.520-0.775) with a value of p = 0.03 to predict survival, in the postpronation period; STPaO2 did not obtain AUC with values of p < 0.05 neither before nor after the change of position to discriminate mortality. Conclusion: although the results in this study do not favor the standardization of PaO2 to PaCO2 in the PaO2/FiO2 ratio, it does suggest the use of FiO2 and SpO2/FiO2 ratio as predictors of mortality, specifically in those patients who developed respiratory failure under invasive mechanical ventilation by COVID-19.REFERENCES
Accini Mendoza JL, Nieto Estrada VH, Beltrán López N, Ramos Bolaños E, Molano Franco D, Dueñas Castell C, et al. Actualización de la declaración de consenso en medicina crítica para la atención multidisciplinaria del paciente con sospecha o confirmación diagnóstica de COVID-19. Acta Colomb Cuid Intensivo. 2020;20(S1):1-112.