Comparative Analysis of Oxygen Saturation by Pulse Oximetry and Arterial Blood Gas in Hypoxemic Patients in a Tertiary Care Hospital

Introduction: Oxygen saturation is essential for medical care and is closely regulated within the body. Arterial blood gas (ABG) analysis is used to evaluate critically ill individuals' ventilation, oxygenation, acid-base status, and metabolic condition. Pulse oximetry is an easy and non-invasive way to measure the status of oxygen saturation non-invasively in clinical settings and provides a quick and precise assessment of oxygenation and reduces medical errors. SpO(2) may not always be a reliable predictor of arterial oxygen saturation (SaO(2)), and hypoxemic, hemodynamically compromised, and critically ill patients may have lower SpO(2) accuracy. A study is needed to assess and compare various oxygen saturation methods. Aims and objectives: The study aimed to compare the oxygen saturation levels measured by pulse oximetry and ABG analysis in hypoxemic patients. The objectives were to compare the values between SaO(2), PaO(2), and SpO(2) values obtained from the patients, and correlate the study parameters among both techniques. Materials and methods: The study was conducted from February 2021 to June 2022 among the 102 hypoxemic patients who were admitted to the emergency and surgical intensive care unit (ICU) of Sree Balaji Medical College and Hospital in Chennai. Primary data on ABG analysis and pulse oximetry readings were collected from the study subjects. The patient and their past medical records, physical exam, chest x-ray findings, pulse oximetry, and ABG results were all reviewed. Each patient had their ABG, and pulse oximetry measured simultaneously. A comparison was made between SpO(2) and partial pressure of oxygen (PaO(2)) and arterial oxygen saturation (SaO(2)) parameters using a paired t-test. The correlation was done against the SpO(2) and ABG parameters and assessed for association using the correlation coefficient value; gender was also considered while correlating. Results and discussion: An observational study was done among 102 study samples to comparatively analyze the oxygen saturation by two methods, namely pulse oximetry and ABG, in hypoxemic patients. While comparing the mean values of SaO(2) and SpO(2), they were 84.41 ± 4.24 and 80.58 ± 5.77, respectively, and this difference was statistically very significant (p < 0.001). While comparing the mean values of PaO(2) and SaO(2), they were 61.02 ± 5.01 and 84.41 ± 4.24, respectively, and this difference was statistically significant (p = 0.043). While comparing the mean values of PaO(2) and SpO(2), they were 61.02 ± 5.01 and 80.58 ± 5.77, respectively, and this difference was statistically significant (p = 0.054). Among the study population, with regard to the correlation factor, there is notably a very high and strong positive correlation between SaO(2) and SpO(2) and between SpO(2) and PaO(2). There was a negative correlation between SpO(2) and finger abnormalities and between SpO(2) and blood pressure. Conclusion: The ABG method is considered the gold standard. When SpO(2) levels fall below 90%, pulse oximetry may not be accurate enough to reliably assess oxygenation. In such cases, where alveolar hypoventilation is suspected, it is recommended to complement pulse oximetry with ABG studies. This is because ABG analysis provides a more comprehensive assessment of oxygenation and acid-base status, which can aid in the diagnosis and management of respiratory conditions.