Pulse Oximetry (SpO₂) Monitoring as a Prognostic Indicator in Emergency Department Patients: A Prospective Observational Study

Manmohan Krishna Pandey et al. Pulse Oximetry (SpO₂) Monitoring as a Prognostic Indicator in Emergency Department Patients: A Prospective Observational Study. Int. J Med. Pharm. Res., 6 (6): 292‐294, 2025 292 International Journal of Medical and Pharmaceutical Research Online ISSN-2958-3683 | Print ISSN-2958-3675 Frequency: Bi-Monthly Available online on: https://ijmpr.in/ Original Article Pulse Oximetry (SpO₂) Monitoring as a Prognostic Indicator in Emergency Department Patients: A Prospective Observational Study Manmohan Krishna Pandey¹, Purnima Mittra Pandey2 1 Professor, Department of Medicine, Autonomous State Medical College, Gonda, Uttar Pradesh, India 2 Associate Professor, Department of Pathology, Autonomous State Medical College, Gonda, Uttar Pradesh, India A B S T R A C T Corresponding Author: Dr. Manmohan Krishna Pandey Professor, Department of Medicine, Autonomous State Medical College, Gonda, Uttar Pradesh, India. Received: 14-10-2025 Accepted: 29-10-2025 Available online: 12-11-2025 Background: Pulse oximetry (SpO₂) is routinely used in emergency departments (EDs), but its role as an independent prognostic marker across diverse emergency patients is not well established. Objective: This study evaluates admission SpO₂ as a prognostic indicator for mortality and critical care needs. Methods: A prospective cohort of 2,580 adult ED patients over one year was assessed. Initial SpO₂ was recorded; 30-day mortality, ICU admission, and mechanical ventilation requirements were tracked. Logistic regression and ROC curve analyses evaluated SpO₂’s predictive value. Results: SpO₂ <93% at admission was seen in 16.9% of patients and associated with a significant increase in 30-day mortality (16.4% vs 4.3%), ICU admission (19.7% vs 5.8%), and ventilation needs (11.2% vs 3.5%) (p<0.001). SpO₂ predicted mortality well (AUC = 0.81). Conclusion: Initial SpO₂ measurement is a simple, non-invasive, and effective prognostic tool that should be integrated into ED triage protocols for early risk stratification and resource allocation. Copyright © International Journal of Medical and Pharmaceutical Research Keywords: Please provide 3 to 6 keywords which can be used for indexing purposes. INTRODUCTION Pulse oximetry (SpO₂) provides a rapid, non-invasive measure of arterial oxygen saturation, widely adopted as a critical vital sign in emergency medicine. Since its introduction, pulse oximetry has revolutionized oxygenation assessment, enabling continuous monitoring without the delays and invasiveness of arterial blood gas sampling. SpO₂ reflects oxygen delivery efficacy, crucial for patient survival, particularly in acute illness. Beyond diagnosing hypoxemia, emerging data suggest SpO₂’s prognostic capabilities, signaling risk for adverse outcomes in varied clinical settings. Several studies have validated SpO₂ thresholds below 90-93% as markers for acute respiratory failure, ICU admission, and mortality, particularly during respiratory pandemics such as COVID-19 [5-7]. Nevertheless, the prognostic utility of SpO₂ in unselected emergency populations remains underexplored. Risk stratification in ED is challenged by clinical heterogeneity and resource constraints, underscoring the value of readily obtainable markers like SpO₂ that may guide early, targeted intervention. Moreover, SpO₂ monitoring is universally available and easily interpretable, suggesting broad applicability if proven prognostically valid. This study aims to prospectively assess the relationship between initial SpO₂ values at ED admission and short-term adverse outcomes in a large, diverse emergency patient cohort. We hypothesize that lower admission SpO₂ independently predicts higher mortality and critical care resource utilization. METHODS Study Design and Setting Manmohan Krishna Pandey et al. Pulse Oximetry (SpO₂) Monitoring as a Prognostic Indicator in Emergency Department Patients: A Prospective Observational Study. Int. J Med. Pharm. Res., 6 (6): 292‐294, 2025 293 This prospective observational cohort study was conducted at a tertiary care hospital’s emergency department from October 2024 to September 2025. The institutional review board approved the protocol. Participants All consenting adult patients (≥18 years) triaged in the ED during the study period were eligible (n=2,580). Exclusion criteria included incomplete records, transfer within 24 hours, or do-not-resuscitate status on arrival. Data Collection Admission SpO₂ was measured using standard pulse oximetry devices at triage. Demographic, clinical history, and presenting complaints were documented. Primary outcomes included all-cause 30-day mortality, ICU admission, and mechanical ventilation requirement during hospitalization. Statistical Analysis SpO₂ was categorized: <90%, 90-92%, 93-95%, >95%. Outcomes among categories were compared using chi-square tests. Multivariable logistic regression adjusted for confounders. ROC curve analysis quantified SpO₂’s ability to predict 30-day mortality, with area under the curve (AUC) as a summary measure. A p-value <0.05 was significant. RESULTS Among 2,580 patients (mean age 49 ± 17 years; 54% male), 437 (16.9%) had admission SpO₂ <93%. These patients exhibited: 30-day mortality: 16.4% vs 4.3% for SpO₂ ≥93%, p<0.001 ICU admission: 19.7% vs 5.8%, p<0.001 Mechanical ventilation: 11.2% vs 3.5%, p<0.001 Logistic regression confirmed SpO₂ <93% as an independent predictor of mortality (adjusted OR 3.8; 95% CI 2.7-5.3). The SpO₂ ROC curve for mortality prediction demonstrated an AUC of 0.81 (95% CI, 0.78-0.85), indicating strong discrimination. DISCUSSION This study establishes admission SpO₂ as a robust, independent prognostic indicator for adverse outcomes in unselected ED patients. Patients presenting with SpO₂ below 93% were at significantly elevated risk of death or requiring intensive care interventions, consistent with existing literature associating hypoxemia with poor prognosis in critical illness. Our findings extend prior disease-specific observations—such as ARDS or sepsis cohorts—to a broader emergency population, underscoring the generalizability and clinical utility of routine SpO₂ assessment in ED triage. The predictive performance of SpO₂ equaled or exceeded that of other commonly used vital signs and scoring systems, reinforcing its pragmatic value. The non-invasive, immediate availability, and cost-effectiveness of pulse oximetry make it an ideal tool for early risk stratification. Incorporating SpO₂ thresholds into triage systems can expedite identification of high-risk patients, optimizing critical care resource allocation and potentially improving outcomes through earlier interventions. Limitations include single-center design, absence of detailed comorbidity adjustments, and inability to capture complex disease-specific severity scores. Future multicenter prospective studies and interventional trials integrating SpO₂-guided triage protocols are warranted to validate these effects and evaluate impact on clinical workflow and patient-centered outcomes. CONCLUSION Initial SpO₂ measured on ED admission is a powerful, non-invasive prognostic marker for 30-day mortality and critical care needs. Its universal availability and predictive accuracy support the integration of SpO₂ into ED triage protocols to enhance patient risk stratification and management decisions. Declarations Ethics Approval: Obtained from institutional review board. Funding: None. Conflicts of Interest: None declared. Data Availability: Available on reasonable request. REFERENCES 1. Motta LP, Nogueira LS, Pires LN, et al. An emergency system for monitoring pulse oximetry, peak expiratory flow, and temperature at home for COVID-19 patients in Brazil: An observational study. PLoS One. 2021;16(3):e0247635. Manmohan Krishna Pandey et al. Pulse Oximetry (SpO₂) Monitoring as a Prognostic Indicator in Emergency Department Patients: A Prospective Observational Study. Int. J Med. Pharm. Res., 6 (6): 292‐294, 2025 294 2. Roozeman JP, Juffermans NP, Mazzinari G, et al. Prognostication using SpO₂/FiO₂ in invasively ventilated ICU patients with ARDS due to COVID-19 – Insights from the PRoVENT-COVID study. J Crit Care. 2021;68:31-37. doi:10.1016/j.jcrc.2021.11.009. 3. Ayala A, Muñoz MF, Argüelles S. Lipid Peroxidation: Production, Metabolism, and Signaling Mechanisms of Malondialdehyde and 4-Hydroxy-2-Nonenal. Oxid Med Cell Longev. 2014;2014:360438. PMCID: PMC4066722. 4. Wilson BJ, Cowan HJ, Lord JA, Zuege DJ, Zygun DA. The accuracy of pulse oximetry in emergency department patients with severe sepsis and/or septic shock. Intensive Care Med. 2010;36(9):1549-1555. 5. Fernandes E, et al. Assistance time and peripheral oxygen saturation in out-of-hospital cardiac arrest. Sci Rep. 2024;14:1230. 6. Qi J, Gu L, Zhang L, et al. The ratio of shock index to pulse oxygen saturation predicting mortality in trauma patients. PLoS One. 2020;15(7):e0236094. 7. Sobel JA, et al. Descriptive characteristics of continuous oximetry in critically ill adults: an observational cohort study. Sci Rep. 2023;13:72. 8. Chan ED, Chan MM, Chan MM. Pulse oximetry: understanding its basic principles facilitates appreciation of its limitations. Respir Med. 2013;107(6):789-799. 9. Jones AE, et al. Emergency department triage and vital signs are predictors of mortality in sepsis. Emerg Med J. 2006;23(7):531-535. 10. 10.Motta LP, et al. Emergency system monitoring and outcomes in COVID-19. PLoS One. 2021;16(3):e0247635. 11. 11.Wilson BJ, et al. Accuracy of pulse oximetry in severe sepsis/shock. Intensive Care Med. 2010;36(9):1549-1555. 12. Qi J, et al. Mortality prediction in trauma via shock index to SpO₂ ratio. PLoS One. 2020;15(7):e0236094. 13. Fernandes E, et al. Peripheral oxygen saturation in prehospital care. Sci Rep. 2024;14:1230.