key: cord-0857311-63vo8f2s authors: Núñez, Isaac; Soto-Mota, Adrian title: Heterogeneidad de la severidad de hipoxemia de acuerdo a oximetría de pulso y gases arteriales en neumonía COVID-19 date: 2021-10-27 journal: Med Intensiva DOI: 10.1016/j.medin.2021.10.004 sha: ecca229c5dc048317a5d9df2b5115f34825c6cc5 doc_id: 857311 cord_uid: 63vo8f2s nan Title: Heterogeneity of hypoxemia severity according to pulse oximetry and blood gas analysis in COVID-19 pneumonia Heterogeneidad de la severidad de hipoxemia de acuerdo a oximetría de pulso y gases arteriales en neumonía COVID-19 Authors: Pneumonia is the hallmark of severe COVID-19 [1] . Strain in healthcare systems across the world has forced countless hospitals to conduct grueling triages to decide who gets to be admitted when healthcare saturation was rampant [2] . As these decisions are inherently complex, numerous risk scores and predictor factors have been described to aid the attending medical team [3] [4] [5] . These often include clinical and laboratory values. One commonly utilized criteria to determine patient severity is the severity of hypoxemia [6] . This can be assessed with arterial oxygen pressure (PaO2), PaO2 to inspired fraction of oxygen (FiO2) ratio, arterial oxygen saturation (SatO2), pulse oximeter oxygen saturation (SpO2), SatO2 to FiO2 ratio, SpO2 to FiO2 ratio, and the prescribed oxygen device [7] . The use of these criteria for hypoxemia severity in non-intubated patients has been criticized given the expected high inter-patient variability in FiO2, shunt fraction, and physician's choice of oxygenation device and oxygen flow [7] . Therefore, relying on these criteria is suboptimal given the low comparability between different patients. In this study, we aimed to compare the severity of hypoxemia in patients with severe COVID-19 according to oxygenation index arriving at an emergency department. arrived at the emergency department (ED) of a reference COVID-19 tertiary center between Our study shows there is considerable heterogeneity when classifying hypoxemia severity with different oxygenation indexes. While good correlation was observed among the three evaluated pairs, the lower correlation between SpO2/FiO2 and the others could be due to inaccuracy of pulse oximeters when used in patients with low oxygen saturation, physician imprecision when estimating FiO2, and/or mixed blood in the gas analysis [9] . It is likely multiple factors are involved in most cases, which is consistent with the previously mentioned concerns [7] . For example, if solely based on SpO2 at triage, a patient could be wrongly classified as having a more severe disease, giving preference to a patient in better condition. Also, follow up could be hard if it is done only with oxygenation parameters. The morning medical team could classify the patient with a given severity with blood gas analysis, while the evening group could use a pulse oximeter and determine intubation is indicated. Degree of hypoxemia is not a good measure when considered by itself in non-intubated patients with COVID-19 pneumonia, as considerable variation occurs depending on whether pulse oximetry or blood gas analysis is utilized. Code used for the analysis will be freely available in the un-blinded version. Data will be made available upon reasonable request to the corresponding author. Severe Covid-19 Humanitarian crises in a global pandemic The low-harm score for predicting mortality in patients diagnosed with COVID-19: A multicentric validation study Common hematological values predict unfavorable outcomes in hospitalized COVID-19 patients Prediction models for diagnosis and prognosis of covid-19: systematic review and critical appraisal Why COVID-19 Silent Hypoxemia Is Baffling to Physicians P aO 2 / F IO 2 ratio: the mismeasure of oxygenation in COVID-19 Volume-Targeted Versus Pressure-Limited Noninvasive Ventilation in Subjects With Acute Hypercapnic Respiratory Failure: A Multicenter Randomized Controlled Trial Pulse oximetry: Understanding its basic principles facilitates appreciation of its limitations The authors would like to thank the triage personnel of their institution for their invaluable work during the pandemic, as well as an anonymous reviewer for helpful comments to improve the manuscript. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. The authors have no conflicts of interest.