Original Investigation| Volume 30, ISSUE 5, P893-899, May 2023

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Use of the PaO2/FiO2 Ratio in Pulmonary Embolism: Evaluation of its Correlation with Pulmonary Arterial Computed Tomography Obstruction Index

      Rationale and Objectives

      The pulmonary arterial computed tomography obstruction index ratio (PACTOIR) is a parameter that provides an idea of the clinical severity of acute pulmonary embolism (APE). This study aimed to examine the correlation between the PaO₂ /FiO₂ ratio and PACTOIR in patients who presented to the emergency department and received a preliminary diagnosis of APE.

      Materials and Methods

      This study was conducted prospectively in the emergency department. The patients’ sociodemographic characteristics, vital signs, PACTOIR, and PaO₂ /FiO₂ ratio were obtained. The correlation between PACTOIR and PaO₂ /FiO₂ ratio was then statistically evaluated.


      The study included 50 patients, of whom 31 (62%) were women, and 19(38%) were men. The female patients had a PaO₂ /FiO₂ ratio of 209 ± 67 and PACTOIR of 36.3 ± 15.5. The male patients had a PaO₂ /FiO₂ ratio of 169 ± 43 and PACTOIR of 39.7 ± 19. The PaO₂ /FiO₂ ratio of the patients with APE was negatively correlated with the PACTOIR value at a statistically significant level (r = -0.308, p = 0.031). The regression equation was as follows: PACTOIR = (-0.0869) x (PaO₂ / FiO₂) + (54.489).


      By calculating the PaO₂ /FiO₂ ratio in patients with APE, the degree of pulmonary artery obstruction and clinical severity can be predicted. Therefore, the ratio PaO₂ /FiO₂ can be used instead of PACTOIR.

      Key Words

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