Project description:The reliability of pulse oximetry is crucial, especially in cases of rapid changes in body oxygenation. In order to evaluate the performance of pulse oximeters during rapidly developing short periods of concurrent hypoxemia and hypercapnia, 13 healthy volunteers underwent 3 breathing phases during outdoor experiments (39 phases in total), monitored simultaneously by five different pulse oximeters. A significant incongruity in values displayed by the tested pulse oximeters was observed, even when the accuracy declared by the manufacturers were considered. In 28.2% of breathing phases, the five used devices did not show any congruent values. The longest uninterrupted congruent period formed 74.4% of total recorded time. Moreover, the congruent periods were rarely observed during the critical desaturation phase of the experiment. The time difference between the moments when the first and the last pulse oximeter showed the typical study endpoint values of SpO2 85% and 75% was 32.1 ± 23.6 s and 24.7 ± 19.3 s, respectively. These results suggest that SpO2 might not be a reliable parameter as a study endpoint, or more importantly as a safety limit in outdoor experiments. In the design of future studies, more parameters and continuous clinical assessment should be included.
Project description:ObjectiveTo assess the performance of reusable pulse oximeter probe and microprocessor box combinations, of varying price-points, in the context of a low-income pediatric setting.MethodsA prospective, randomized cross-over study comparing time to biologically plausible oxygen saturation (SpO2 ) between: (1) Lifebox LB-01 probe with Masimo Rad-87 box (L + M) and (2) a weight-appropriate reusable Masimo probe with Masimo Rad-87 box (M + M). A post hoc secondary analysis comparison with historical usability testing data with the Lifebox LB-01 probe and Lifebox V1.5 box (L + L) was also conducted. Participants, children aged 0 to 35 months, were recruited from pediatric wards and outpatient clinics in the central region of Malawi. The primary outcome was time taken to achieve a biologically plausible SpO 2 measurement, compared using t tests for equivalence.ResultsWe recruited 572 children. Plausible SpO2 measurements were obtained in less than 1 minute, 71%, 70%, and 63% for the M + M, L + M, and L + L combinations, respectively. A similar pattern was seen for less than 2 minutes, however, this effect disappeared at less than 5 minutes with 96%, 96%, and 95% plausible measurements. Using a ±10 second threshold for equivalence, we found L + M and M + M to be equivalent, but were under-powered to assess equivalence for L + L.ConclusionsThe novel reusable pediatric Lifebox probe can achieve a quality SpO2 measurement within a pragmatic time range of weight-appropriate Masimo equivalent probes. Further research, which considers the cost of the devices, is needed to assess the added value of sophisticated motion tolerance software.
Project description:ObjectivePulse oximetry is commonly used in Neonatology, however recent adult data suggest racial disparity in accuracy, with overestimation of oxygen saturation for Black patients.Study designBlack and White infants <32 weeks gestation underwent simultaneous arterial blood gas and pulse oximetry measurement. Error by race was examined using mean bias, Arms, Bland-Altman, and linear/non-linear analysis.ResultsA total of 294 infants (124 Black, 170 White) were identified with mean GA of 25.8 ± 2.1 weeks and mean BW of 845 ± 265 grams, yielding 4387 SaO2-SpO2 datapoints. SpO2 overestimation, measured by mean bias, was 2.4-fold greater for Black infants and resulted in greater occult hypoxemia (SpO2 > 90% when SaO2 < 85%; 9.2% vs. 7.7% of samples). Sensitivity and specificity for detection of true hypoxemia were similar between groups (39 vs. 38%; 81 vs. 78%).ConclusionThere is a modest but consistent difference in SpO2 error between Black and White infants, with increased incidence of occult hypoxemia in Black infants.
Project description:ObjectiveDo newborns, children and adolescents up to 19 years have lower mortality rates, lower morbidity and shorter length of stay in health facilities where pulse oximeters are used to inform diagnosis and treatment (excluding surgical care) compared with health facilities where pulse oximeters are not used?DesignStudies were obtained for this systematic literature review by systematically searching the Database of Abstracts of Reviews of Effects, Cochrane, Medion, PubMed, Web of Science, Embase, Global Health, CINAHL, WHO Global Health Library, international health organisation and NGO websites, and study references.PatientsChildren 0-19 years presenting for the first time to hospitals, emergency departments or primary care facilities.InterventionsIncluded studies compared outcomes where pulse oximeters were used for diagnosis and/or management, with outcomes where pulse oximeters were not used.Main outcome measuresmortality, morbidity, length of stay, and treatment and management changes.ResultsThe evidence is low quality and hypoxaemia definitions varied across studies, but the evidence suggests pulse oximeter use with children can reduce mortality rates (when combined with improved oxygen administration) and length of emergency department stay, increase admission of children with previously unrecognised hypoxaemia, and change physicians' decisions on illness severity, diagnosis and treatment. Pulse oximeter use generally increased resource utilisation.ConclusionsAs international organisations are investing in programmes to increase pulse oximeter use in low-income settings, more research is needed on the optimal use of pulse oximeters (eg, appropriate oxygen saturation thresholds), and how pulse oximeter use affects referral and admission rates, length of stay, resource utilisation and health outcomes.
Project description:ObjectivesCapillary refill time is a noninvasive method to assess tissue perfusion to determine shock status. Capillary refill time is defined as the time required to regain skin color after blanching pressure is applied. Although common methods to measure capillary refill time depend on clinicians' visual assessment, a new approach using a pulse oximeter waveform analysis exists, referred to as full finger reperfusion time. We aim to evaluate reproducibility and validity of the novel full finger reperfusion time measurement using clinicians' visual capillary refill time assessment as a reference standard.DesignProspective observational study.SettingPICUs and operating suites at a large academic children's hospital.PatientsNinety-nine children 1-12 years old with various skin color tones.InterventionsEach child had 10 measurements, including five full finger reperfusion time and five clinician capillary refill time, alternating second and third digits.Measurements and main resultsEighteen children had prolonged capillary refill time (> 2 s) and four children with capillary refill time greater than 3 seconds. Four-hundred eighty-five data pairs were analyzed. Intraclass correlation coefficient of full finger reperfusion time within each patient was 0.76 (95% CI, 0.68-0.83), demonstrating good reproducibility. Correlation coefficient between full finger reperfusion time and clinician capillary refill time was moderate: r = 0.37 (p < 0.0001; 95% CI, 0.29-0.44) for the pairs and r = 0.52 (p < 0.0001; 95% CI, 0.36-0.65) for patient average. Bland-Altman plot showed a consistent difference between full finger reperfusion time and clinician capillary refill time (full finger reperfusion time 1.14 s longer). Weak association was found between force and full finger reperfusion time (β = -0.033 ± 0.016; 95% CI, -0.065 to -0.0016; p = 0.04), finger thickness (β = -0.20 ± 0.089; 95% CI, -0.37 to -0.19; p = 0.03), except for color tone (p = 0.31). Finger temperature was associated with full finger reperfusion time (β = -0.18 ± 0.041; 95% CI, -0.26 to -0.0999; p < 0.0001).ConclusionsFull finger reperfusion time demonstrated good reproducibility. Full finger reperfusion time showed moderate correlation with clinician capillary refill time. Full finger reperfusion time was 1.14 seconds longer than capillary refill time. Future studies should focus on the clinical value of full finger reperfusion time as a monitoring device for hemodynamics in critically ill children.
Project description:IntroductionRespiratory diseases such as chronic obstructive pulmonary disease, obstructive sleep apnea syndrome, and COVID-19 may cause a decrease in arterial oxygen saturation (SaO2). The continuous monitoring of oxygen levels may be beneficial for the early detection of hypoxemia and timely intervention. Wearable non-invasive pulse oximetry devices measuring peripheral oxygen saturation (SpO2) have been garnering increasing popularity. However, there is still a strong need for extended and robust clinical validation of such devices, especially to address topical concerns about disparities in performances across racial groups. This prospective clinical validation aimed to assess the accuracy of the reflective pulse oximeter function of the EmbracePlus wristband during a controlled hypoxia study in accordance with the ISO 80601-2-61:2017 standard and the Food & Drug Administration (FDA) guidance.MethodsHealthy adult participants were recruited in a controlled desaturation protocol to reproduce mild, moderate, and severe hypoxic conditions with SaO2 ranging from 100% to 70% (ClinicalTrials.gov registration #NCT04964609). The SpO2 level was estimated with an EmbracePlus device placed on the participant's wrist and the reference SaO2 was obtained from blood samples analyzed with a multiwavelength co-oximeter.ResultsThe controlled hypoxia study yielded 373 conclusive measurements on 15 subjects, including 30% of participants with dark skin pigmentation (V-VI on the Fitzpatrick scale). The accuracy root mean square (Arms) error was found to be 2.4%, within the 3.5% limit recommended by the FDA. A strong positive correlation between the wristband SpO2 and the reference SaO2 was observed (r = 0.96, P < 0.001), and a good concordance was found with Bland-Altman analysis (bias, 0.05%; standard deviation, 1.66; lower limit, -4.7%; and upper limit, 4.8%). Moreover, acceptable accuracy was observed when stratifying data points by skin pigmentation (Arms 2.2% in Fitzpatrick V-VI, 2.5% in Fitzpatrick I-IV), and sex (Arms 1.9% in females, and 2.9% in males).DiscussionThis study demonstrates that the EmbracePlus wristband could be used to assess SpO2 with clinically acceptable accuracy under no-motion and high perfusion conditions for individuals of different ethnicities across the claimed range. This study paves the way for further accuracy evaluations on unhealthy subjects and during prolonged use in ambulatory settings.
Project description:Current oxygen delivery modes lack monitoring and can be cumbersome for patients with chronic respiratory diseases. Integrating a pulse oximeter and nasal oxygen cannulas into eyeglasses would reduce the burden of current solutions. An ear pulse oximeter (OxyFrame) was evaluated on 16 healthy volunteers and 20 hypoxemic patients with chronic respiratory diseases undergoing a prespecified protocol simulating daily activities. Correlation, error, and accuracy root mean square error (ARMS) were calculated to compare SpO2 measured by OxyFrame, a standard pulse oximeter (MASIMO), and arterial blood gas analysis (aBGA). SpO2 measured by OxyFrame and MASIMO correlated strongly in volunteers, with low error and high accuracy (r = 0.85, error = 0.2 ± 2.9%, ARMS = 2.88%). Performances were similar in patients (r = 0.87, error 0 ± 2.5%, ARMS = 2.49% compared with MASIMO; and r = 0.93, error = 0.4 ± 1.9%, ARMS = 1.94% compared with aBGA). However, the percentage of rejected measurements was high (volunteers 77.2%, patients 46.9%). The OxyFrame cavum conchae pulse oximeter was successfully evaluated, and demonstrated accurate SpO2 measurements, compliant with ISO 80601-2-61:2017. Several reasons for the high rejection rate were identified, and potential solutions were proposed, which might be valuable for optimization of the sensor hardware.
Project description:BackgroundA 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.ObjectiveThe 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.MethodsTo 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).ResultsAfter 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%<SpO2≤90%, and 90%<SpO2. We found a strong association and a high level of agreement between the measurements collected from the devices, with high Pearson correlation coefficients of r=0.944 and r=0.954 on the correlation plots, low Pearson correlation coefficients of r=0.083 (P=.17) and r=0.23 (P=.001) on Bland-Altman plots, biases of 0.98% (95% CI 0.65-1.32) and 1.56% (95% CI 1.24-1.87), and root mean square errors of 2.97% and 3.00% from the participants' right and left hands, respectively.ConclusionsIn conclusion, the Withings ScanWatch is able to measure SpO2 levels with adequate accuracy at a clinical grade. No undesirable effects or adverse events were reported during the study.Trial registrationClinicalTrials.gov NCT04380389; http://clinicaltrials.gov/ct2/show/NCT04380389.
Project description:Background: The success of many machine learning applications depends on knowledge about the relationship between the input data and the task of interest (output), hindering the application of machine learning to novel tasks. End-to-end deep learning, which does not require intermediate feature engineering, has been recommended to overcome this challenge but end-to-end deep learning models require large labelled training data sets often unavailable in many medical applications. In this study, we trained self-supervised learning (SSL) models for automatic feature extraction from raw photoplethysmography (PPG) obtained using a pulse oximeter, with the aim of predicting paediatric hospitalization. Methods: We compared logistic regression models fitted using features extracted using SSL with models trained using both clinical and SSL features. In addition, we compared end-to-end deep learning models initialized randomly or using weights from the SSL models. We also compared the performance of SSL models trained on labelled data alone (n=1,031) with SSL trained using both labelled and unlabelled signals (n=7,578). Results: Logistic regression models were more predictive of hospitalization when trained on features extracted using labelled PPG signals only compared to SSL models trained on both labelled and unlabelled signals (AUC 0.83 vs 0.80). However, features extracted using SSL model trained on both labelled and unlabelled PPG signals were more predictive of hospitalization when concatenated with clinical features (AUC 0.89 vs 0.87). The end-to-end deep learning model had an AUC of 0.80 when initialized using the SSL model trained on all PPG signals, 0.77 when initialized using SSL trained on labelled data only, and 0.73 when initialized randomly. Conclusions: This study shows that SSL can extract features from PPG signals that are predictive of hospitalization or initialize end-to-end deep learning models. Furthermore, SSL can leverage larger unlabelled data sets to improve performance of models fitted using small labelled data sets.