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Respir Res ; 23(1): 33, 2022 Feb 17.
Article in English | MEDLINE | ID: covidwho-2196283


BACKGROUND: High flow nasal cannula (HFNC) therapy is widely employed in acute hypoxemic respiratory failure (AHRF) patients. However, the techniques for predicting HFNC outcome remain scarce. METHODS: PubMed, EMBASE, and Cochrane Library were searched until April 20, 2021. We included the studies that evaluated the potential predictive value of ROX (respiratory rate-oxygenation) index for HFNC outcome. This meta-analysis determined sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic score, diagnostic odds ratio (DOR), and pooled area under the summary receiver operating characteristic (SROC) curve. RESULTS: We assessed nine studies with 1933 patients, of which 745 patients experienced HFNC failure. This meta-analysis found that sensitivity, specificity, PLR, NLR, diagnostic score, and DOR of ROX index in predicting HFNC failure were 0.67 (95% CI 0.57-0.76), 0.72 (95% CI 0.65-0.78), 2.4 (95% CI 2.0-2.8), 0.46 (95% CI 0.37-0.58), 1.65(95% CI 1.37-1.93), and 5.0 (95% CI 4.0-7.0), respectively. In addition, SROC was 0.75 (95% CI 0.71-0.79). Besides, our subgroup analyses revealed that ROX index had higher sensitivity and specificity for predicting HFNC failure in COVID-19 patients, use the cut-off value > 5, and the acquisition time of other times after receiving HFNC had a greater sensitivity and specificity when compared to 6 h. CONCLUSIONS: This study demonstrated that ROX index could function as a novel potential marker to identify patients with a higher risk of HFNC failure. However, the prediction efficiency was moderate, and additional research is required to determine the optimal cut-off value and propel acquisition time of ROX index in the future. PROSPERO registration number: CRD42021240607.

Catheterization , Nasal Cavity , Oximetry , Respiratory Rate , Animals , Catheterization/adverse effects , Humans , Noninvasive Ventilation , Predictive Value of Tests , ROC Curve , Sensitivity and Specificity
Medicine (Baltimore) ; 100(40): e27422, 2021 Oct 08.
Article in English | MEDLINE | ID: covidwho-2191077


ABSTRACT: As severe acute respiratory syndrome coronavirus 2 continues to spread, easy-to-use risk models that predict hospital mortality can assist in clinical decision making and triage. We aimed to develop a risk score model for in-hospital mortality in patients hospitalized with 2019 novel coronavirus (COVID-19) that was robust across hospitals and used clinical factors that are readily available and measured standardly across hospitals.In this retrospective observational study, we developed a risk score model using data collected by trained abstractors for patients in 20 diverse hospitals across the state of Michigan (Mi-COVID19) who were discharged between March 5, 2020 and August 14, 2020. Patients who tested positive for severe acute respiratory syndrome coronavirus 2 during hospitalization or were discharged with an ICD-10 code for COVID-19 (U07.1) were included. We employed an iterative forward selection approach to consider the inclusion of 145 potential risk factors available at hospital presentation. Model performance was externally validated with patients from 19 hospitals in the Mi-COVID19 registry not used in model development. We shared the model in an easy-to-use online application that allows the user to predict in-hospital mortality risk for a patient if they have any subset of the variables in the final model.Two thousand one hundred and ninety-three patients in the Mi-COVID19 registry met our inclusion criteria. The derivation and validation sets ultimately included 1690 and 398 patients, respectively, with mortality rates of 19.6% and 18.6%, respectively. The average age of participants in the study after exclusions was 64 years old, and the participants were 48% female, 49% Black, and 87% non-Hispanic. Our final model includes the patient's age, first recorded respiratory rate, first recorded pulse oximetry, highest creatinine level on day of presentation, and hospital's COVID-19 mortality rate. No other factors showed sufficient incremental model improvement to warrant inclusion. The area under the receiver operating characteristics curve for the derivation and validation sets were .796 (95% confidence interval, .767-.826) and .829 (95% confidence interval, .782-.876) respectively.We conclude that the risk of in-hospital mortality in COVID-19 patients can be reliably estimated using a few factors, which are standardly measured and available to physicians very early in a hospital encounter.

COVID-19/mortality , Hospital Mortality/trends , Age Factors , Aged , Aged, 80 and over , Body Mass Index , Comorbidity , Creatinine/blood , Female , Health Behavior , Humans , Logistic Models , Male , Michigan/epidemiology , Middle Aged , Oximetry , Prognosis , ROC Curve , Retrospective Studies , Risk Assessment , Risk Factors , SARS-CoV-2 , Severity of Illness Index , Sex Factors , Socioeconomic Factors
N Engl J Med ; 387(19): 1759-1769, 2022 11 10.
Article in English | MEDLINE | ID: covidwho-2112693


BACKGROUND: Invasive mechanical ventilation in critically ill adults involves adjusting the fraction of inspired oxygen to maintain arterial oxygen saturation. The oxygen-saturation target that will optimize clinical outcomes in this patient population remains unknown. METHODS: In a pragmatic, cluster-randomized, cluster-crossover trial conducted in the emergency department and medical intensive care unit at an academic center, we assigned adults who were receiving mechanical ventilation to a lower target for oxygen saturation as measured by pulse oximetry (Spo2) (90%; goal range, 88 to 92%), an intermediate target (94%; goal range, 92 to 96%), or a higher target (98%; goal range, 96 to 100%). The primary outcome was the number of days alive and free of mechanical ventilation (ventilator-free days) through day 28. The secondary outcome was death by day 28, with data censored at hospital discharge. RESULTS: A total of 2541 patients were included in the primary analysis. The median number of ventilator-free days was 20 (interquartile range, 0 to 25) in the lower-target group, 21 (interquartile range, 0 to 25) in the intermediate-target group, and 21 (interquartile range, 0 to 26) in the higher-target group (P = 0.81). In-hospital death by day 28 occurred in 281 of the 808 patients (34.8%) in the lower-target group, 292 of the 859 patients (34.0%) in the intermediate-target group, and 290 of the 874 patients (33.2%) in the higher-target group. The incidences of cardiac arrest, arrhythmia, myocardial infarction, stroke, and pneumothorax were similar in the three groups. CONCLUSIONS: Among critically ill adults receiving invasive mechanical ventilation, the number of ventilator-free days did not differ among groups in which a lower, intermediate, or higher Spo2 target was used. (Supported by the National Heart, Lung, and Blood Institute and others; PILOT number, NCT03537937.).

Critical Illness , Oxygen , Respiration, Artificial , Adult , Humans , Critical Illness/therapy , Hospital Mortality , Intensive Care Units , Oxygen/administration & dosage , Oxygen/blood , Oxygen/therapeutic use , Respiration, Artificial/methods , Critical Care/methods , Cross-Over Studies , Emergency Service, Hospital , Academic Medical Centers , Oximetry
PLoS One ; 17(10): e0273402, 2022.
Article in English | MEDLINE | ID: covidwho-2079731


BACKGROUND: The pathophysiology of COVID-19 remains poorly understood. We aimed to estimate the contribution of intrapulmonary shunting and ventilation-to-perfusion (VA/Q) mismatch using a mathematical model to construct oxygen-haemoglobin dissociation curves (ODCs). METHODS: ODCs were constructed using transcutaneous pulse oximetry at two different fractions of inspired oxygen (FiO2). 199 patients were included from two large district general hospitals in the South East of England from 1st to 14th January 2021. The study was supported by the National Institute of Health Research (NIHR) Clinical Research Network. RESULTS: Overall mortality was 29%. Mean age was 68.2 years (SEM 1·2) with 46% female. Median shunt on admission was 17% (IQR 8-24.5); VA/Q was 0.61 (IQR 0.52-0.73). Shunt was 37.5% higher in deaths (median 22%, IQR 9-29) compared to survivors (16%, 8-21; p = 0.0088) and was a predictor of mortality (OR 1.04; 95% CI 1.01-1.07). Admission oxygen saturations were more strongly predictive of mortality (OR 0.91, 95% CI 0.87-0.96). There was no difference in VA/Q mismatch between deaths (0.60; IQR 0.50-0.73) and survivors (0.61; IQR 0.52-0.73; p = 0.63) and it was not predictive of mortality (OR 0.68; 95% CI 0.18-2.52; p = 0.55). Shunt negatively correlated with admission oxygen saturation (R -0.533; p<0.0001) whereas VA/Q was not (R 0.1137; p = 0.12). INTERPRETATION: Shunt, not VA/Q mismatch, was associated with worsening hypoxia, though calculating shunt was not of prognostic value. This study adds to our understanding of the pathophysiology of hypoxaemia in COVID-19. Our inexpensive and reliable technique may provide further insights into the pathophysiology of hypoxia in other respiratory diseases.

COVID-19 , Lung Diseases , Humans , Female , Aged , Male , Ventilation-Perfusion Ratio/physiology , Hypoxia , Oximetry/methods , Oxygen/physiology
Annu Int Conf IEEE Eng Med Biol Soc ; 2022: 4303-4307, 2022 07.
Article in English | MEDLINE | ID: covidwho-2018749


Continuous clinical grade measurement of SpO2 in out-of-hospital settings remains a challenge despite the widespread use of photoplethysmography (PPG) based wearable devices for health and wellness applications. This article presents two SpO2 algorithms: PRR (pulse rate derived ratio-of-ratios) and GPDR (green-assisted peak detection ratio-of-ratios), that utilize unique pulse rate frequency estimations to isolate the pulsatile (AC) component of red and infrared PPG signals and derive SpO2 measurements. The performance of the proposed SpO2 algorithms are evaluated using an upper-arm wearable device derived green, red, and infrared PPG signals, recorded in both controlled laboratory settings involving healthy subjects (n=36) and an uncontrolled clinic application involving COVID-19 patients (n=52). GPDR exhibits the lowest root mean square error (RMSE) of 1.6±0.6% for a respiratory exercise test, 3.6 ±1.0% for a standard hypoxia test, and 2.2±1.3% for an uncontrolled clinic use-case. In contrast, PRR provides relatively higher error but with greater coverage overall. Mean error across all combined datasets were 0.2±2.8% and 0.3±2.4% for PRR and GPDR respectively. Both SpO2 algorithms achieve great performance of low error with high coverage on both uncontrolled clinic and controlled laboratory conditions.

COVID-19 , Wearable Electronic Devices , COVID-19/diagnosis , Heart Rate , Humans , Oximetry , Oxygen Saturation
PLoS One ; 17(9): e0273744, 2022.
Article in English | MEDLINE | ID: covidwho-2009707


INTRODUCTION: Peer workers (those with lived/living experience of substance use) are at the forefront of overdose response initiatives in British Columbia, Canada. The onset of the coronavirus disease pandemic has significantly compounded the impact of the overdose crisis. Peer workers are integral in supporting people who use substances. However, despite the important work they do, peer workers often lack formalized credibility and do not have the same resources available to them as service providers without lived experience. The peer-led project titled the Peer2Peer Project implemented several support programs for peer workers, including providing pulse oximeters to peer workers to supplement their overdose response procedures. MATERIALS AND METHODS: This study was a component of a larger evaluation of the pulse oximeter program at two organizations in BC. The study aims to highlight the competencies of peer workers who use pulse oximeters. Telephone interviews were conducted with seven peer workers who were given pulse oximeters. The transcripts were thematically coded using Covert et al.'s framework of core competencies of community health workers to compare our sample with other widely recognized professions. FINDINGS: We found that peer workers who used pulse oximeters described several core competencies in their work and these were aligned with Covert et al.'s core competencies for community health workers, including assessment, community health practice, communication, diversity and inclusion, professional practice, and disease prevention and management. CONCLUSION: By aligning peer workers' skills to those of community health workers, we create awareness on the competencies of peer workers in using oximeters to supplement overdose response and advocate for them to receive more recognition and respect within the workplace. Further, our findings act as groundwork for future research in identifying the professional proficiencies of peer workers.

Drug Overdose , Oximetry , British Columbia , Humans , Oxygen , Peer Group
JAMA Intern Med ; 182(8): 858, 2022 08 01.
Article in English | MEDLINE | ID: covidwho-2003580
Medicina (Kaunas) ; 58(8)2022 Aug 21.
Article in English | MEDLINE | ID: covidwho-1997706


Background and objectives: Acute respiratory distress syndrome (ARDS) is the most common complication occurring in COVID-19 patients admitted to the ICU. Given the increased respiratory work of these patients, it is necessary to evaluate their actual breathing efforts. The aim of this study is to report the incidence and determinants of increased effort of breathing (EOB) in critical COVID-19 patients. Materials and Methods: This was a retrospective study of COVID-19 patients admitted to the ICU during the year of 2020. Respiratory rate (RR) was chosen as an indicator of EOB. The cut-off value was set at more than 20 breaths per minute. ROC-AUC analysis was performed to identify the accuracy of the PaO2 and PaCO2 to determine increased EOB. Furthermore, multivariate regression analysis was performed to reveal the determinants of increased EOB. Results: 213 patients were included in the study. Mean RR in the population was 24.20 ± 6.28. 138 (64.8%) of the patients had increased EOB. The ROC-AUC analysis revealed the PaO2 (0.656 (CI 95%: 0.579-0.734, p < 0.001) as more accurate predictor of EOB than PaCO2 (0.584 (CI 95%: 0.505-0.662, p = 0.043). In the final multivariate model, the SpO2 (exp(B) = 0.922, CI 95%: 0.874-0.97 p = 0.033), PaO2/FiO2 ratio (exp(B) = 0.996, CI 95%: 0.922-1.000, p = 0.003) and PaO2 (exp(B) = 0.989 CI 95%: 0.982-0.996 p = 0.003) prevailed as independent predictors of increased EOB. Conclusions: To conclude, PaO2 was revealed as a more accurate predictor of increased EOB than PaCO2. Further investigation revealed the independent determinants of EOB: blood oxygen saturation, PaO2 and PaO2/FiO2 ratio.

COVID-19 , Respiratory Distress Syndrome , Humans , Oximetry , Oxygen , Retrospective Studies
BMC Med ; 20(1): 267, 2022 08 16.
Article in English | MEDLINE | ID: covidwho-1993362


BACKGROUND: During the COVID-19 pandemic, there have been concerns regarding potential bias in pulse oximetry measurements for people with high levels of skin pigmentation. We systematically reviewed the effects of skin pigmentation on the accuracy of oxygen saturation measurement by pulse oximetry (SpO2) compared with the gold standard SaO2 measured by CO-oximetry. METHODS: We searched Ovid MEDLINE, Ovid Embase, EBSCO CINAHL,, and WHO International Clinical Trials Registry Platform (up to December 2021) for studies with SpO2-SaO2 comparisons and measuring the impact of skin pigmentation or ethnicity on pulse oximetry accuracy. We performed meta-analyses for mean bias (the primary outcome in this review) and its standard deviations (SDs) across studies included for each subgroup of skin pigmentation and ethnicity and used these pooled mean biases and SDs to calculate accuracy root-mean-square (Arms) and 95% limits of agreement. The review was registered with the Open Science Framework ( ). RESULTS: We included 32 studies (6505 participants): 15 measured skin pigmentation and 22 referred to ethnicity. Compared with standard SaO2 measurement, pulse oximetry probably overestimates oxygen saturation in people with the high level of skin pigmentation (pooled mean bias 1.11%; 95% confidence interval 0.29 to 1.93%) and people described as Black/African American (1.52%; 0.95 to 2.09%) (moderate- and low-certainty evidence). The bias of pulse oximetry measurements for people with other levels of skin pigmentation or those from other ethnic groups is either more uncertain or suggests no overestimation. Whilst the extent of mean bias is small or negligible for all subgroups evaluated, the associated imprecision is unacceptably large (pooled SDs > 1%). When the extent of measurement bias and precision is considered jointly, pulse oximetry measurements for all the subgroups appear acceptably accurate (with Arms < 4%). CONCLUSIONS: Pulse oximetry may overestimate oxygen saturation in people with high levels of skin pigmentation and people whose ethnicity is reported as Black/African American, compared with SaO2. The extent of overestimation may be small in hospital settings but unknown in community settings. REVIEW PROTOCOL REGISTRATION:

COVID-19 , Skin Pigmentation , Humans , Oximetry/methods , Oxygen , Oxygen Saturation , Pandemics
Ethiop J Health Sci ; 32(4): 841-848, 2022 Jul.
Article in English | MEDLINE | ID: covidwho-1988251


Background: Measurement of blood oxygen saturation is a vital part of monitoring coronavirus 2019 (COVID-19) patients. Pulse oximetry is commonly used to measure blood oxygen saturation and pulse rate for appropriate clinical intervention. But the majority of direct-to-consumer grade pulse oximeters did not pass through in-vivo testing, which results in their accuracy being questionable. Besides this, the ongoing COVID-19 pandemic exposed the limitations of the device in resource limited areas since independent monitoring is needed for COVID-19 patients. The purpose of this study was to perform an in-vivo evaluation of a newly developed smartphone powered low-cost pulse oximeter. Methods: The new prototype of a smartphone powered pulse oximeter was evaluated against the standard pulse oximeter by taking measurements from fifteen healthy volunteers. The accuracy of measurement was evaluated by calculating the percentage error and standard deviation. A repeatability and reproducibility test were carried out using the ANOVA method. Results: The average accuracy for measuring spot oxygen saturation (SPO2) and pulse rate (PR) was 99.18% with a standard deviation of 0.57 and 98.78% with a standard deviation of 0.61, respectively, when compared with the standard pulse oximeter device. The repeatability and reproducibility of SPO2 measurements were 0.28 and 0.86, respectively, which is in the acceptable range. Conclusion: The new prototype of smartphone powered pulse oximeter demonstrated better performance compared to the existing low-cost fingertip pulse oximeters. The device could be used for independent monitoring of COVID-19 patients at health institutions and also for home care.

COVID-19 , Smartphone , COVID-19/diagnosis , Humans , Oximetry , Oxygen , Pandemics , Reproducibility of Results
BMJ ; 378: e071474, 2022 07 07.
Article in English | MEDLINE | ID: covidwho-1932665

Oximetry , Pandemics , Humans , Oxygen
JAMA Intern Med ; 182(7): 699-700, 2022 07 01.
Article in English | MEDLINE | ID: covidwho-1929700

Oximetry , Oxygen , Bias , Humans , Racial Groups
Trop Doct ; 52(4): 593-595, 2022 Oct.
Article in English | MEDLINE | ID: covidwho-1916713


Hypoxaemia in COVID-19 does not necessarily imply COVID pneumonia or post-COVID lung fibrosis, and the caveats of finger pulse oximetry should be remembered. Drug-induced methaemoglobinemia should be considered in individuals with unexplained cyanosis, refractory hypoxaemia, or the presence of a saturation gap. Here, we share our recent encounter of 'spurious hypoxia' in a patient with COVID-19 and methaemoglobinemia.

COVID-19 , Pneumonia , COVID-19/complications , Humans , Hypoxia/diagnosis , Hypoxia/etiology , Oximetry , SARS-CoV-2
Eur Respir J ; 59(6)2022 06.
Article in English | MEDLINE | ID: covidwho-1910259

COVID-19 , Ethnicity , Humans , Oximetry , Oxygen
Med Intensiva (Engl Ed) ; 46(7): 410-412, 2022 07.
Article in English | MEDLINE | ID: covidwho-1907580