Journal of Research in Medical Sciences

ORIGINAL ARTICLE
Year
: 2022  |  Volume : 27  |  Issue : 1  |  Page : 38-

Estimating the best fraction of inspired oxygen for calculation of PaO2/FiO2 ratio in acute respiratory distress syndrome due to COVID-19 pneumonia


Leila Kadkhodai, Mahmoud Saghaei, Mohammadreza Habibzadeh, Babak Alikiaii, Seyed Jalal Hashemi 
 Department of Anesthesia, Isfahan University of Medical Sciences; Anesthesiology and Critical Care Research Center, Isfahan University of Medical Sciences, Isfahan, Iran

Correspondence Address:
Dr. Mahmoud Saghaei
Al-Zahra Medical Center, Isfahan
Iran

Background: The ratio of partial pressure of oxygen in arterial blood (PaO2) to the fraction of inspiratory oxygen concentration (FiO2) is an indicator of pulmonary shunt fraction. PaO2/FiO2 (P/F) ratio is used to classify severity of acute respiratory distress syndrome (ARDS). With the same shunt fraction, P/F ratio decreases with increases in FiO2 which may lead to errors in classifying severity of ARDS. The effect of FiO2 on P/F ratio has not been investigated in COVID-19 pneumonia. In this study, we estimated the best FiO2 for the calculation of P/F ratio in a sample of patients with ARDS due to COVID-19 pneumonia. Materials and Methods: Blood gas and ventilatory data of 108 COVID-19 ARDS patients were analyzed in a cross-sectional observational study. Using Oxygen Status Algorithm the calculated shunt fraction served a basis for calculating P/F ratio for different FiO2. The severity of ARDS determined by P/F ratios at each FiO2s was compared with the shunt-based severity to find the optimum FiO2 for calculation of P/F ratio so the resulting classification has the best match with the reference classification. Results: A FiO2 of 1.0 for calculation of P/F ratio and ARDS classification showed the best match with shunt-based ARDS classification. A regression model was obtained with the PaO2, patient's original FiO2, Hemoglobin concentration, and SaO2 as the independent predictors of the P/F ratio for the FiO2 of 1.0. Conclusion: This study shows a FiO2 of 1.0 as the best value for correct calculation of P/F ratio and proper classification of ARDS.


How to cite this article:
Kadkhodai L, Saghaei M, Habibzadeh M, Alikiaii B, Hashemi SJ. Estimating the best fraction of inspired oxygen for calculation of PaO2/FiO2 ratio in acute respiratory distress syndrome due to COVID-19 pneumonia.J Res Med Sci 2022;27:38-38


How to cite this URL:
Kadkhodai L, Saghaei M, Habibzadeh M, Alikiaii B, Hashemi SJ. Estimating the best fraction of inspired oxygen for calculation of PaO2/FiO2 ratio in acute respiratory distress syndrome due to COVID-19 pneumonia. J Res Med Sci [serial online] 2022 [cited 2022 Aug 20 ];27:38-38
Available from: https://www.jmsjournal.net/article.asp?issn=1735-1995;year=2022;volume=27;issue=1;spage=38;epage=38;aulast=Kadkhodai;type=0