IDENTIFICATION OF PULSE OXIMETRY CUT-OFF POINT WITH HIGHER SPECIFICITY FOR SEVERE HYPOXEMIA IDENTIFICATION IN PATIENTS WITH CHRONIC OBSTRUCTIVE PULMONARY DISEASE: A RETROSPECTIVE STUDY.

• Grant number: 24/07508-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2024
• End date: January 31, 2025
• Field of knowledge: Health Sciences - Physiotherapy and Occupational Therapy
• Principal Investigator: Robson Aparecido Prudente
• Grantee: Jonathas William de Morais
• Host Institution: Hospital das Clínicas da Faculdade de Medicina de Botucatu. Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil

Abstract

Introduction: Patients with chronic obstructive pulmonary disease (COPD) exhibit varying degrees of hypoxemia depending on the stage of the disease, with pulse oximetry (SpO2) being a practical and non-invasive method to assess blood oxygen saturation. In clinical situations where patients may have moderate hypoxemia [partial pressure of arterial oxygen (PaO2) > 55 to < 60 mmHg], the device may record values within the normal range (SpO2 > 90%), resulting in a false negative (FN). This situation can compromise the diagnosis of COPD severity and consequently the oxygen supplementation treatment, directly impacting the mortality of these patients. This becomes more evident when there is variation in PaO2 during physical exercise and arterial oxygen saturation (SaO2) drops below 90%, further amplifying the inaccuracy of SpO2 readings. Objective: To identify a more sensitive SpO2 cut-off point for the determination of severe hypoxemia (PaO2 d 55 mmHg) in patients with severe COPD. Additionally, to analyze the degree of correlation, sensitivity, specificity, and false positives and negatives between SpO2 cut-off values (<90% or 88%) and PaO2 (d60 mmHg and d55 mmHg) in patients with COPD undergoing long-term home oxygen therapy (LTOT). Methods: A retrospective study, with data reviewed from medical records of patients seen at the oxygen therapy outpatient clinic of the Hospital das Clínicas da Faculdade de Medicina de Botucatu (HCFMB), from January 2022 to December 2023. Information retrieval will be restricted to relevant data available in the hospital system, ensuring confidentiality as stipulated by Brazilian legislation. This facility has a structured procedures manual for accurate and consistent data collection, minimizing the risk of missing information and procedural variations. Demographic, clinical, and functional data of patients, arterial blood gas values: SaO2, SpO2, PaO2, and PaCO2 will be collected. COPD diagnosis will be confirmed by post-bronchodilator spirometry with forced expiratory volume in one second (FEV1) / forced vital capacity (FVC) < 0.7. COPD severity will be classified according to GOLD recommendations. Arterial blood gas is collected in ambient air after 20 minutes without oxygen supplementation by radial artery puncture. Expected outcomes: We expect to identify the correlation, positive and negative predictive values, sensitivity, and specificity between SpO2 cut-off points < 90% and < 88% and PaO2 <60 mmHg and <55 mmHg. Determine severity groups of patients where SpO2 has lower sensitivity to identify hypoxemia.