Pulse Oximeters and Violation of Federal Antidiscrimination Law.

This Viewpoint discusses how some pulse oximeters can provide incorrect oxygen saturation data for dark-skinned patients compared with light-skinned patients, describes the reasons that biased oximeters remained in use, and highlights why a rule recently proposed by the US Department of Health and Human Services may bring about needed change in the use of pulse oximetry for patients with dark skin.

Disparities in Hypoxemia Detection by Pulse Oximetry Across Self-Identified Racial Groups and Associations With Clinical Outcomes.

OBJECTIVES: To assess disparities in hypoxemia detection by pulse oximetry across self-identified racial groups and associations with clinical outcomes. DESIGN: Observational cohort study from May 5, 2018, to December 31, 2020. SETTING: Three academic medical centers in the United States. PATIENTS: Adults greater than or equal to 18 years who self-identified as White, Black, Asian, or American Indian admitted to the ICU or undergoing surgery during inpatient hospitalization with simultaneous measurements of pulse oximetry-estimated oxygen saturation and arterial blood gas-derived oxygen saturation. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Multivariable models were employed to assess the relationships between race, occult hypoxemia (i.e., arterial blood gas-derived oxygen saturation < 88% despite pulse oximetry-estimated oxygen saturation ≥ 92%), and clinical outcomes of hospital mortality and hospital-free days. One-hundred twenty-eight-thousand two-hundred eighty-five paired pulse oximetry-estimated oxygen saturation-arterial blood gas-derived oxygen saturation measurements were included from 26,603 patients. Pulse oximetry-estimated oxygen saturation on average overestimated arterial blood gas-derived oxygen saturation by 1.57% (1.54-1.61%). Black, Asian, and American Indian patients were more likely to experience occult hypoxemia during hospitalization (estimated probability 6.2% [5.1-7.6%], 6.6% [4.9-8.8%], and 6.6% [4.4-10.0%], respectively) compared with White patients (3.6% [3.4-3.8%]). Black patients had increased odds of occult hypoxemia compared with White patients after adjustment (odds ratio, 1.65; 1.28-2.14; p < 0.001). Differences in occult hypoxemia between Asian and American Indian patients compared with White patients were not significant after adjustment (odds ratio, 1.53; 0.95-2.47; p = 0.077 and odds ratio, 1.31; 0.80-2.16; p = 0.288, respectively). Occult hypoxemia was associated with increased odds of mortality in surgical (odds ratio, 2.96; 1.20-7.28; p = 0.019) and ICU patients (1.36; 1.03-1.80; p = 0.033). Occult hypoxemia was associated with fewer hospital-free days in surgical (-2.5 d [-3.9 to -1.2 d]; p < 0.001) but not ICU patients (0.4 d [-0.7 to 1.4 d]; p = 0.500). CONCLUSIONS: Occult hypoxemia is more common in Black patients compared with White patients and is associated with increased mortality, suggesting potentially important outcome implications for undetected hypoxemia. It is imperative to validate pulse oximetry with expanded racial inclusion.

Peri-operative neurological monitoring with electroencephalography and cerebral oximetry: a narrative review.

Surgery and anaesthesia subject the brain to considerable stress in the peri-operative period. This may be caused by potentially neurotoxic anaesthetic drugs, impaired cerebral perfusion and reperfusion injury related to surgery or thromboembolic events. Patient monitoring using electroencephalogram and cerebral oximetry can assist in optimising depth of anaesthesia and assessment of cerebral metabolic activity. However, research findings have been contradictory as to whether these monitors can help ameliorate peri-operative neurocognitive complications. In this narrative review, we will discuss recent evidence in the use of electroencephalography and cerebral oximetry and the underlying scientific principles. It is important to appreciate the raw electroencephalographic changes under anaesthesia and those associated with ageing, in order to interpret depth of anaesthesia indices correctly. Cerebral oximetry is useful not only for the detection of cerebral desaturation but also to identify those patients who are particularly vulnerable to injury, for better risk stratification. An algorithm-based approach may be most effective in managing the episodes of cerebral desaturation.

The effect of patient ethnicity on the accuracy of peripheral pulse oximetry in patients with COVID-19 pneumonitis: a single-centre, retrospective analysis.

Pulse oximetry is used widely to titrate oxygen therapy and for triage in patients who are critically ill. However, there are concerns regarding the accuracy of pulse oximetry in patients with COVID-19 pneumonitis and in patients who have a greater degree of skin pigmentation. We aimed to determine the impact of patient ethnicity on the accuracy of peripheral pulse oximetry in patients who were critically ill with COVID-19 pneumonitis by conducting a retrospective observational study comparing paired measurements of arterial oxygen saturation measured by co-oximetry on arterial blood gas analysis (SaO2 ) and the corresponding peripheral oxygenation saturation measured by pulse oximetry (Sp O2 ). Bias was calculated as the mean difference between SaO2 and Sp O2 measurements and limits of agreement were calculated as bias ±1.96 SD. Data from 194 patients (135 White ethnic origin, 34 Asian ethnic origin, 19 Black ethnic origin and 6 other ethnic origin) were analysed consisting of 6216 paired SaO2 and Sp O2 measurements. Bias (limits of agreement) between SaO2 and Sp O2 measurements was 0.05% (-2.21-2.30). Patient ethnicity did not alter this to a clinically significant degree: 0.28% (1.79-2.35), -0.33% (-2.47-2.35) and -0.75% (-3.47-1.97) for patients of White, Asian and Black ethnic origin, respectively. In patients with COVID-19 pneumonitis, Sp O2 measurements showed a level of agreement with SaO2 values that was in line with previous work, and this was not affected by patient ethnicity.

The Editor's Desk: Science and Clinical Potpourri for Your Life and Your Practice.

In a series of commentaries in recent issues of the New England Journal of Medicine, potential bias in pulse oximetry has been questioned.

Outdoor-Useable, Wireless/Battery-Free Patch-Type Tissue Oximeter with Radiative Cooling.

For wearable electronics/optoelectronics, thermal management should be provided for accurate signal acquisition as well as thermal comfort. However, outdoor solar energy gain has restricted the efficiency of some wearable devices like oximeters. Herein, wireless/battery-free and thermally regulated patch-type tissue oximeter (PTO) with radiative cooling structures are presented, which can measure tissue oxygenation under sunlight in reliable manner and will benefit athlete training. To maximize the radiative cooling performance, a nano/microvoids polymer (NMVP) is introduced by combining two perforated polymers to both reduce sunlight absorption and maximize thermal radiation. The optimized NMVP exhibits sub-ambient cooling of 6 °C in daytime under various conditions such as scattered/overcast clouds, high humidity, and clear weather. The NMVP-integrated PTO enables maintaining temperature within ≈1 °C on the skin under sunlight relative to indoor measurement, whereas the normally used, black encapsulated PTO shows over 40 °C owing to solar absorption. The heated PTO exhibits an inaccurate tissue oxygen saturation (StO2) value of ≈67% compared with StO2 in a normal state (i.e., ≈80%). However, the thermally protected PTO presents reliable StO2 of ≈80%. This successful demonstration provides a feasible strategy of thermal management in wearable devices for outdoor applications.

Accuracy of two pulse-oximetry measurements for INTELLiVENT-ASV in mechanically ventilated patients: a prospective observational study.

Recently, maintaining a certain oxygen saturation measured by pulse oximetry (SpO2) range in mechanically ventilated patients was recommended; attaching the INTELLiVENT-ASV to ventilators might be beneficial. We evaluated the SpO2 measurement accuracy of a Nihon Kohden and a Masimo monitor compared to actual arterial oxygen saturation (SaO2). SpO2 was simultaneously measured by a Nihon Kohden and Masimo monitor in patients consecutively admitted to a general intensive care unit and mechanically ventilated. Bland-Altman plots were used to compare measured SpO2 with actual SaO2. One hundred mechanically ventilated patients and 1497 arterial blood gas results were reviewed. Mean SaO2 values, Nihon Kohden SpO2 measurements, and Masimo SpO2 measurements were 95.7%, 96.4%, and 96.9%, respectively. The Nihon Kohden SpO2 measurements were less biased than Masimo measurements; their precision was not significantly different. Nihon Kohden and Masimo SpO2 measurements were not significantly different in the "SaO2 < 94%" group (P = 0.083). In the "94% ≤ SaO2 < 98%" and "SaO2 ≥ 98%" groups, there were significant differences between the Nihon Kohden and Masimo SpO2 measurements (P < 0.0001; P = 0.006; respectively). Therefore, when using automatically controlling oxygenation with INTELLiVENT-ASV in mechanically ventilated patients, the Nihon Kohden SpO2 sensor is preferable.Trial registration UMIN000027671. Registered 7 June 2017.

Validation of the Withings ScanWatch as a Wrist-Worn Reflective Pulse Oximeter: Prospective Interventional Clinical Study.

BACKGROUND: A decrease in the level of pulse oxygen saturation as measured by pulse oximetry (SpO2) is an indicator of hypoxemia that may occur in various respiratory diseases, such as chronic obstructive pulmonary disease (COPD), sleep apnea syndrome, and COVID-19. Currently, no mass-market wrist-worn SpO2 monitor meets the medical standards for pulse oximeters. OBJECTIVE: The main objective of this monocentric and prospective clinical study with single-blind analysis was to test and validate the accuracy of the reflective pulse oximeter function of the Withings ScanWatch to measure SpO2 levels at different stages of hypoxia. The secondary objective was to confirm the safety of this device when used as intended. METHODS: To achieve these objectives, we included 14 healthy participants aged 23-39 years in the study, and we induced several stable plateaus of arterial oxygen saturation (SaO2) ranging from 100%-70% to mimic nonhypoxic conditions and then mild, moderate, and severe hypoxic conditions. We measured the SpO2 level with a Withings ScanWatch on each participant's wrist and the SaO2 from blood samples with a co-oximeter, the ABL90 hemoximeter (Radiometer Medical ApS). RESULTS: After removal of the inconclusive measurements, we obtained 275 and 244 conclusive measurements with the two ScanWatches on the participants' right and left wrists, respectively, evenly distributed among the 3 predetermined SpO2 groups: SpO2≤80%, 80%

Pulse Oximetry May Be Inaccurate in Patients with Darker Skin.

Study highlights the need for symptom assessment in addition to oximetry measurement.

Smartphone Biosensor With App Meets FDA/ISO Standards for Clinical Pulse Oximetry and Can Be Reliably Used by a Wide Range of Patients.

BACKGROUND: Millions of smartphones contain a photoplethysmography (PPG) biosensor (Maxim Integrated) that accurately measures pulse oximetry. No clinical use of these embedded sensors is currently being made, despite the relevance of remote clinical pulse oximetry to the management of chronic cardiopulmonary disease, and the triage, initial management, and remote monitoring of people affected by respiratory viral pandemics, such as severe acute respiratory syndrome coronavirus 2 or influenza. To be used for clinical pulse oximetry the embedded PPG system must be paired with an application (app) and meet US Food and Drug Administration (FDA) and International Organization for Standardization (ISO) requirements. RESEARCH QUESTION: Does this smartphone sensor with app meet FDA/ISO requirements? Are measurements obtained using this system comparable to those of hospital reference devices, across a wide range of people? STUDY DESIGN AND METHODS: We performed laboratory testing addressing ISO and FDA requirements in 10 participants using the smartphone sensor with app. Subsequently, we performed an open-label clinical study on 320 participants with widely varying characteristics, to compare the accuracy and precision of readings obtained by patients with those of hospital reference devices, using rigorous statistical methodology. RESULTS: "Breathe down" testing in the laboratory showed that the total root-mean-square deviation of oxygen saturation (Spo2) measurement was 2.2%, meeting FDA/ISO standards. Clinical comparison of the smartphone sensor with app vs hospital reference devices determined that Spo2 and heart rate accuracy were 0.48% points (95% CI, 0.38-0.58; P < .001) and 0.73 bpm (95% CI, 0.33-1.14; P < .001), respectively; Spo2 and heart rate precision were 1.25 vs reference 0.95% points (P < .001) and 5.99 vs reference 3.80 bpm (P < .001), respectively. These small differences were similar to the variation found between two FDA-approved reference instruments for Spo2: accuracy, 0.52% points (95% CI, 0.41-0.64; P < .001) and precision, 1.01 vs 0.86% points (P < .001). INTERPRETATION: Our findings support the application for full FDA/ISO approval of the smartphone sensor with app tested for use in clinical pulse oximetry. Given the immense and immediate practical medical importance of remote intermittent clinical pulse oximetry to both chronic disease management and the global ability to respond to respiratory viral pandemics, the smartphone sensor with app should be prioritized and fast-tracked for FDA/ISO approval to allow clinical use. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT04233827; URL: www.clinicaltrials.gov.

Accuracy and Reliability of Commercial Wrist-Worn Pulse Oximeter During Normobaric Hypoxia Exposure Under Resting Conditions.

Purpose: The present study analyzed peripheral blood oxygen saturation (SpO2) and heart rate (HR) measurements taken on the Garmin fenix® 5X Plus watch, comparing them to measurements taken on a standard medical-grade pulse oximeter during normobaric hypoxia exposure under resting conditions. Methods: Thirteen women (mean ± SD: Age 20 ± 1 years, height 165 ± 5 cm, mass, 67 ± 9 kg) and ten men (mean ± SD: Age 21 ± 3 years, height 177 ± 6 cm, mass 78 ± 11 kg) sat inside a customized environmental chamber while the fraction of inspired oxygen (FIO2) was adjusted to simulate altitudes of 12,000; 10,000; 8,000; 6,000; and 900 ft. The novel commercial device (Garmin fenix®) and a medical-grade pulse oximeter (Nonin® 7500) were used to measure SpO2 and HR in triplicate at each simulated altitude. Bland-Altman analyses were used to assess differences between methods. Results: Bland-Altman analysis indicated 3.3% bias for SpO2 measurements taken on the Garmin fenix® at 12,000 ft of simulated altitude (limits of agreement: -1.9-8.6%). Mean differences in SpO2 measurements were smaller at the remaining simulated altitudes, where bias measurements ranged from 0.7% to 0.8%. The Garmin fenix® also underestimated heart rate, but those discrepancies were minimal (bias measurements at all simulated altitude exposures were < 1.0 bpm). Conclusions: With the exception of readings taken at 12,000 ft of simulated altitude, the Garmin fenix® exhibits minimal overestimation of SpO2 and minimal underestimation of HR during simulated altitude exposure. These data suggest the Garmin fenix® watch may be a viable method to monitor SpO2 and HR under most ambient environmental conditions.

Working accuracy of pulse oximetry in COVID-19 patients stepping down from intensive care: a clinical evaluation.

INTRODUCTION: UK guidelines suggest that pulse oximetry, rather than blood gas sampling, is adequate for monitoring of patients with COVID-19 if CO2 retention is not suspected. However, pulse oximetry has impaired accuracy in certain patient groups, and data are lacking on its accuracy in patients with COVID-19 stepping down from intensive care unit (ICU) to non-ICU settings or being transferred to another ICU. METHODS: We assessed the bias, precision and limits of agreement using 90 paired SpO2 and SaO2 from 30 patients (3 paired samples per patient). To assess the agreement between pulse oximetry (SpO2) and arterial blood gas analysis (SaO2) in patients with COVID-19, deemed clinically stable to step down from an ICU to a non-ICU ward, or be transferred to another ICU. This was done to evaluate whether the guidelines were appropriate for our setting. RESULTS: Mean difference between SaO2 and SpO2 (bias) was 0.4%, with an SD of 2.4 (precision). The limits of agreement between SpO2 and SaO2 were as follows: upper limit of 5.2% (95% CI 6.5% to 4.2%) and lower limit of -4.3% (95% CI -3.4% to -5.7%). CONCLUSIONS: In our setting, pulse oximetry showed a level of agreement with SaO2 measurement that was slightly suboptimal, although within acceptable levels for Food and Drug Authority approval, in people with COVID-19 judged clinically ready to step down from ICU to a non-ICU ward, or who were being transferred to another hospital's ICU. In such patients, SpO2 should be interpreted with caution. Arterial blood gas assessment of SaO2 may still be clinically indicated.

Sensibilidad de un modelo secuencial basado en cuestionario (STOP-Bang vs. Dixon) y pulsioximetría nocturna para el screening de apnea obstructiva del sueño en pacientes obesos mórbidos candidatos a cirugía bariátrica / Sensitivity of a sequential model based on a questionnaire (STOP-Bang vs Dixon) and nocturnal pulse oximetry for screening obstructive sleep apnea in patients with morbid obesity candidates for bariatric surgery

INTRODUCCIÓN: La apnea obstructiva del sueño (AOS) tiene una elevada incidencia en obesos mórbidos candidatos a cirugía bariátrica (CB). Un screening adecuado reduciría el número de poligrafías (PR). OBJETIVO: Analizar la utilidad de un modelo secuencial con un cuestionario (Dixon modificado [DXM] vs. STOP-Bang) y pulsioximetría nocturna en pacientes candidatos a CB. MÉTODOS: Estudio prospectivo, desde el 1 de julio de 2014 hasta el 1 de julio de 2015. Se incluyeron candidatos a CB, excluyéndose aquellos que ya se habían sometido a una PR. VARIABLES: cuestionarios (Epworth, STOP-Bang y DXM), medidas antropométricas, PR y analítica de sangre y gases. Se dividió la muestra entre los que no tenían AOS o era leve (No AOS) y los que tuvieron una AOS moderada-grave (IAH>15). RESULTADOS: Se analizaron 70 pacientes, de los cuales 46 (65,7%) eran mujeres. Se diagnosticaron 26 (37,1%) de AOS moderada-grave. Comparamos STOP-Bang y DXM mediante curvas ROC con una mayor área bajo la curva (AUC) para este último (0,873 [0,74-0,930] vs. 0,781 [0,673-0,888]). La sensibilidad fue superior para el STOP-Bang con un 100% vs. 73,1% de DXM. El IDO3% presentó mayor rentabilidad diagnóstica AUC=0,982 (0,970-1). La aplicación del modelo secuencial con STOP-Bang>3, DXM>5 y DXM>3 hubiese evitado 41 (58,5%), 50 (71,4%) y 41 (58,5%) PR y 0, 7 (10%) y 0 falsos negativos, respectivamente. CONCLUSIÓN: La aplicación de un modelo secuencial basado en el STOP-Bang y pulsioximetría nocturna es una herramienta útil para el screening de AOS en obesos mórbidos candidatos a CB, reduciendo el número de PR

INTRODUCTION: Obstructive sleep apnea (OSA) has a high incidence in patients with morbid obesity who are candidates for bariatric surgery (BS). Adequate screening would decrease the number of respiratory polygraphies (RPs). OBJECTIVE: To analyze the value of a sequential model consisting of a questionnaire (modified Dixon [DXM] vs STOP-Bang) and nocturnal pulse oximetry in patients who were candidates for BS. METHODS: A prospective study was conducted from July 1, 2014 to July 1, 2015 on candidates for BS, excluding those who have already undergone RP. VARIABLES: questionnaires (Epworth, STOP-Bang, and DXM), anthropometric measurements, RP, and blood and gas tests. The sample was divided into patients with no or mild OSA (no OSA) and those with moderate to severe OSA (AHI>15). RESULTS: A total of 70 patients were analyzed, 46 (65.7%) of them females. Moderate to severe OSA was diagnosed in 26 (37.1%) patients. STOP-Bang and DXM were compared using ROC curves, and greater area under the curve (AUC) was found for the latter (0.873 [0.74 -0.930] vs 0.781 [0.673-0.888]). STOP-Bang had greater sensitivity, 100%, as compared to 73.1% for DXM. ODI3% showed greater diagnostic yield (AUC=0.982 [0.970-1]). Use of the sequential model with STOP-Bang>3, DXM>5, and DXM>3 would have avoided 41 (58.5%), 50 (71.4%), and 41 (58.5%) RPs and 0, 7 (10%), and 0 false negatives, respectively. CONCLUSION: Use of a sequential model based on the STOP-Bang and nocturnal pulse oximetry is a useful tool for screening OSA in patients with morbid obesity candidates for BS, decreasing the number of RPs

Aspectos técnicos y regulatorios sobre el uso de oxímetros de pulso en el monitoreo de pacientes con COVID-19, 7 de agosto del 2020 / Technical and Regulatory Aspects of the Use of Pulse Oximeters in Monitoring COVID-19 Patients, 7 August 2020

En este documento se presentan consideraciones técnicas y regulatorias para el uso de oxímetros de pulso como herramienta en el monitoreo clínico de pacientes con COVID-19. Asimismo, se resume la evidencia disponible sobre la eficacia, efectividad y seguridad de los diferentes tipos de oxímetros de pulso, sus limitaciones y recomendaciones de utilización. Está destinado a profesionales de la salud, así como a autoridades sanitarias y demás tomadores de decisiones sobre el uso de tecnologías sanitarias para la atención y cuidado de pacientes con COVID-19.

This document presents technical and regulatory considerations for the use of pulse oximeters as a tool in clinical monitoring of COVID-19 patients. It also summarizes available evidence on the efficacy, effectiveness, and safety of different types of pulse oximeters, their limitations, and recommendations for use. It is intended for health professionals, as well as health authorities and other decision makers responsible for health technologies for the care of COVID-19 patients.