Imputation of arterial oxygen partial pressures using pulse oximetry in surgical patients under general anaesthesia: A prospective cohort study

Mohamad F. El-Khatib; Marwan Rizk; Amro Khalili; Thuraya HajAli; Ibrahim El Mallah; Rasha Shreim; Carine Zeeni

doi:10.4103/ija.ija_153_25

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Imputation of arterial oxygen partial pressures using pulse oximetry in surgical patients under general anaesthesia: A prospective cohort study

Journal article

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Imputation of arterial oxygen partial pressures using pulse oximetry in surgical patients under general anaesthesia: A prospective cohort study

Mohamad F. El-Khatib, Marwan Rizk, Amro Khalili, Thuraya HajAli, Ibrahim El Mallah, Rasha Shreim and Carine Zeeni

Indian journal of anaesthesia, Vol.69(10), pp.1047-1054

10/2025

DOI: 10.4103/ija.ija_153_25

PMCID: PMC12445760

PMID: 40979776

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Abstract

Background and Aims: Monitoring oxygen saturation (SpO2) during general anaesthesia using pulse oximetry is mandatory, though it may not always reflect the actual oxygenation status. Arterial blood gas (ABG) analysis remains the gold standard for measuring the partial pressure of oxygen (PaO2), but it is invasive and limited by complications. This study aims to validate five existing equations for predicting PaO2 from SpO2 and, if applicable, to derive and validate a new equation in adult patients undergoing surgeries under general anaesthesia. Methods: A prospective cohort study was conducted on adult patients undergoing general anaesthesia and requiring ABG measurements at several time points intraoperatively. Using SPSS software, a Bland-Altman analysis was performed to assess the agreement between derived and measured PaO2 values using five existing equations. Regression analysis was then performed to develop a new equation for predicting PaO2, which was validated in a second cohort. Results: During the initial phase, 150 ABG samples were collected from 83 patients. Bland-Altman analysis revealed weak agreements with all existing equations. A new logarithmic equation, El-Khatib’s equation (PaO2 = 10−25.6 × SpO213.9), was derived. The validation phase involved 150 ABG samples from 65 patients, demonstrating strong agreement with El-Khatib’s equation (systematic bias of 13 mmHg, limits of agreement: −189 to 214 mmHg). Conclusion: Five existing equations for predicting PaO2 from SpO2 revealed weak agreement in adult patients under general anaesthesia. El-Khatib’s equation demonstrated strong potential for predicting PaO2, providing a reliable non-invasive alternative for determining PaO2 in clinical practice.

Anaesthesia

blood gas analysis

oxygen

oxygen saturation

PaO2

partial pressure

pulse oximetry

SpO2

ventilation

Details

Title: Subtitle: Imputation of arterial oxygen partial pressures using pulse oximetry in surgical patients under general anaesthesia: A prospective cohort study
Creators: Mohamad F. El-Khatib - American University of Beirut Medical Center
Marwan Rizk - American University of Beirut Medical Center
Amro Khalili - American University of Beirut Medical Center
Thuraya HajAli - American University of Beirut Medical Center
Ibrahim El Mallah - American University of Beirut Medical Center
Rasha Shreim - American University of Beirut Medical Center
Carine Zeeni - American University of Beirut Medical Center
Resource Type: Journal article
Publication Details: Indian journal of anaesthesia, Vol.69(10), pp.1047-1054
DOI: 10.4103/ija.ija_153_25
PMID: 40979776
PMCID: PMC12445760
NLM abbreviation: Indian J Anaesth
ISSN: 0019-5049
eISSN: 0976-2817
Publisher: WOLTERS KLUWER MEDKNOW PUBLICATIONS
Number of pages: 8
Language: English
Date published: 10/2025
Academic Unit: Anesthesia
Record Identifier: 9984962643002771

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