Difference between spo2 and sao2 levels in patients NH phuc

Difference between SpO2 and SaO2 levels in patients with acute respiratory failure and development of a SaO2 predictive model Nguyen Hoang Phuc, MD Dec 24, 2022 Nguyen Hoang Phuc1*, Huynh Ha Xuyen2, Vo Minh Son2, Tran Nguyen Trong Phu2,3 1College of Health Sciences, VinUniversity, Ha Noi, Vietnam Tho University of Medicine and Pharmacy, Can Tho city 90000, Vietnam 3Faculty of Medicine, Chulalongkorn University, Thailand 2Can OUTLINE Acute respiratory failure (ARF): the inability of the respiratory system to meet the oxygenation, ventilation, or metabolic requirements Two major types  Hypoxemic  Hypercapnic The overall mortality rate of major ARF is 27-32%, severe ARF is 53-69% In Vietnam, mortality rate of severe ARF is approximately 57.1%1 Most patients with severe ARF has an etiology of pneumonia1, non-survivor made up 94.4% During COVID-19 pandemic, up to 79% of hospitalized patients developed respiratory failure requiring invasive mechanical ventilation.2 1Chinh LQ, Manabe T, Son DN, Chi NV, Fujikura Y, Binh NG, Co DX, Tuan DQ, Ton MD, Dai KQ, Thach PT, Nagase H, Kudo K, Nguyen DA Clinical epidemiology and mortality on patients with acute respiratory distress syndrome (ARDS) in Vietnam PLoS One 2019 Aug 15;14(8):e0221114 s 2Cummings MJ, Baldwin MR, Abrams D, Jacobson SD, Meyer BJ, Balough EM, Aaron JG, Claassen J, Rabbani LE, Hastie J, Hochman BR, Salazar-Schicchi J, Yip NH, Brodie D, O'Donnell MR Epidemiology, clinical course, and outcomes of critically ill adults with COVID-19 in New York City: a prospective cohort study Lancet 2020 Jun 06;395(10239):1763-1770 ARF is diagnosed and further classified with Arterial Blood Gas (gold standard) PaO2 is shown to strictly correlate with arterial oxygen saturation => using oxygen saturation to monitor patients who are at risk or having ARF Monitoring patients’ oxygen saturation with pulse oximeter (SpO2) is considered a standard of care (5th vital sign) Correct oxygen saturation measured with pulse oximeter can reduce ABG It’s more viable, non-invasive, noncomplicated, and costs lower compared to ABG Objectives Studying the correlation between SpO2 and SaO2 in ARF patients Studying factors that affect this correlation coefficient Developing a SaO2 predictive model Demographic characteristics (Age, Sex), Hemoglobin Correlation between SpO2 and SaO2 Patients with acute respiratory hypoxemic failure Vital signs (Systolic/Diastolic Blood Pressure, Pulse, Temperature) SpO2, ABG (SaO2, PaO2, pH) Correlation between SpO2 and SaO2 among subgroups SaO2 predictive linear regression model Study design Single-centered, descriptive study Patient recruitment 125 patients above 16 years of age Having ARHF Can Tho Central General Hospital Time of study May 2019 – October 2020 Data analysis Stata 15.1 PARTICIPANTS’ CHARACTERISTIC Sex Male Female 67 (53.6%) 58 (46.4%) Age Acidosis/Alkalosis status Acidosis (pH < 7.35) Alkalosis (pH > 7.45) 41 (32.8%) 35 (28%) Anemia status 16-64 > 64 50 (40%) 75 (60%) Body temperature Hb ≥ 11 g/L Hb < 11 g/L 54 (43.2%) 71 (56.8%) ≥ 90 mmHg < 90 mmHg 103 (82.4%) 22 (17.6%) Systolic blood pressure 37.7oC < ≥ 37.7oC 93 (74.4%) 32 (25.6%) Pulse rate SaO2 60-100 bpm > 100 pbm 51 (40.8%) 73 (58.4%) FiO2 Mean SD 93.406% 9.63% Mean SD 88,224% 12,68% SpO2 21%-40% 40%-60% 60%-80% 80%-100% 93 (74.4%) 16 (12.8%) (5.6%) (7.2%) SpO2 and SaO2 had a moderate degree Pearson's correlation coefficient (r = 0.391, p < 0,0001) Not correlated in subgroup analysis (67 patients with SpO2 below 95% (r = 0.18, p = 0.15)) Pearson’s correlation coefficient High-degree Moderate-degree Low-degree - r = 0,395 - - Body temperature < 37.7oC ≥ 37.7oC Pulse rate 60-100 bpm > 100 pbm r = 0,473 r = 0,356 ≥ 90 mmHg < 90 mmHg - r = 0.434 - - Hb ≥ 11 g/L Hb < 11 g/L r = 0,795 - - - - r = 0.425 - - Systolic blood pressure Anemia status Acidosis/Alkalosis status Acidosis (pH < 7.35) Alkalosis (pH > 7.45) FiO2 21%-40% 40%-60% 60%-80% 80%-100% r = 0.355 r = 0.451 r = 914 - - - Bayesian Information Criterion algorithm was employed to select the best models => Model was the best fit for predicting SaO2 Comparing models with and without interaction analysis => Model a had lower BIC CONCLUSION SpO2 and FiO2 were the major predictors of SaO2 in patients with ARHF ABG should be indicated to monitor SaO2 closely in patients with low SpO2 THANK YOU FOR YOUR ATTENTION