Measurement of Vital Signs Using Lifelight Remote Photoplethysmography: Results of the VISION-D and VISION-V Observational Studies

Heiden, Emily; Jones, Tom; Maczka, Annika Brogaard; Kapoor, Melissa; Chauhan, Milan; Wiffen, Laura; Barham, Helen; Holland, Jeremy; Saxena, Manish; Wegerif, Simon; Brown, Thomas; Lomax, Mitch; Massey, Heather; Rostami, Shahin; Pearce, Laurence; Chauhan, Anoop

doi:10.2196/36340

Cited by 5 publications

(3 citation statements)

References 34 publications

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“…With mean error of 6.48 ± 12.88 mmHg for measuring systolic BP and 0.43 ± 10.64 mmHg for measuring diastolic BP among patients with normotensive or Stage 1 hypertensive BP, Lifelight appears to perform in line with the state of the art; a meta-analysis of regulated state-of-the-art BP monitors (devices that measure BP using contactbased PPG e.g. bracelets, or the volume-clamp method or tonometry at the finger) reported the mean error of these devices for measuring systolic BP (across the full range) to be 6.7 ± 15.3 mmHg and 5.5 ± 8.9 mmHg for measuring diastolic BP [24].…”

Section: Discussionmentioning

confidence: 99%

Validation of the Lifelight Contactless Blood Pressure and Pulse Rate Monitor (Preprint)

Kapoor,

Holman,

Cohen

2024

Preprint

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BACKGROUND Key to reducing the immense morbidity and mortality burdens of cardiovascular diseases is helping people keep their blood pressure at safe levels. This requires that more people with hypertension be identified, diagnosed and given the tools to lower their blood pressure. Blood pressure monitors are critical to hypertension diagnosis and management. However, there are characteristics of conventional blood pressure monitors (oscillometric cuff sphygmanometers) that hinder their ability to facilitate rapid and effective hypertension diagnosis and management. Lifelight is a novel, calibration-free, software-only medical device that contactlessly measures pulse rate and blood pressure by measuring remote photoplethysmography (rPPG) signals of a patient’s face using a standard smartphone or tablet camera. OBJECTIVE Demonstrate the accuracy of Lifelight for classifying the full range of clinically relevant blood pressures as hypertensive or non-hypertensive. Demonstrate its accuracy for measuring pulse rate and the blood pressure of people with blood pressures relevant to Stage 1 hypertension. METHODS Lifelight was investigated in a study that followed the data collection and data analysis methodology outlined in ISO 81060-2:2018/AMD 1:2020 “Non-invasive Sphygmomanometers – Part 2: Clinical investigation of automated measurement type”. This validation study was conducted by independent laboratory Element Materials Technology Boulder (formerly Clinimark), a global leader for clinical testing of vital sign data for medical devices and consumer wearable products. The study generated data from 85 people aged 18-85 with the wide-ranging distribution of blood pressures specified in ISO 81060-2:2018/AMD 1:2020. At least 20% were required to have Fitzpatrick scale skin tones of 5 or 6, i.e., dark skin tones. The accuracy of Lifelight’s blood pressure measurements was assessed by comparing Lifelight’s measurements with measurements made by dual-observer manual auscultation using the same-arm sequential method specified in ISO 81060-2:2018/AMD 1:2020. The accuracy of Lifelight’s pulse rate measurements was assessed by comparing Lifelight’s measurements with concurrent ECG-derived heart rate values. RESULTS Lifelight measured pulse rate with Accuracy root-mean-square of 1.34 beats per minute. The sensitivity and specificity with which Lifelight determined that blood pressures exceeded the in-clinic systolic threshold for diagnosis of hypertension was 70.1% and 71.7%, respectively. These rates are consistent with those reported for conventional blood pressure monitors in a literature review by The National Institute for Health and Care Excellence (NICE). The mean error of Lifelight for measuring blood pressure in the range of normotension and Stage 1 hypertension (i.e., in 65 of the 85 study participants) was 6.48 ± 12.88 mmHg for systolic blood pressure, and 0.43 ± 10.64 mmHg for diastolic blood pressure. No device-related adverse events occurred. CONCLUSIONS Lifelight has been independently tested against ISO 81060-2:2018/AMD 1:2020. Its safety and performance demonstrated in this study suggests that it is a promising solution for rapid, scalable and effective screening and management of hypertension.

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Section: Discussionmentioning

confidence: 99%

Validation of the Lifelight Contactless Blood Pressure and Pulse Rate Monitor (Preprint)

Kapoor,

Holman,

Cohen

2024

Preprint

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“…The data were used for machine learning to improve the accuracy of the Lifelight algorithms used to calculate VS. The smaller VISION-V (Measurement of Vital Signs by Lifelight Software in Comparison to the Standard of Care–Validation) study demonstrated the accuracy of the Lifelight app compared with standard-of-care methods for measuring pulse rate, respiratory rate, and diastolic BP [ 14 ], providing the basis for the current class I Conformité Européenne (CE) registration [ 15 ]. However, some of the methods used in the VISION-V study differed from the procedures described in the standard for BP measurement (ISO81060-2) because of the novel nature of the Lifelight technology.…”

Section: Introductionmentioning

confidence: 99%

Measurement of Vital Signs by Lifelight Software in Comparison to Standard of Care Multisite Development (VISION-MD): Protocol for an Observational Study

Wiffen¹,

Brown²,

Maczka³

et al. 2023

JMIR Res Protoc

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Background Measuring vital signs (VS) is an important aspect of clinical care but is time-consuming and requires multiple pieces of equipment and trained staff. Interest in the contactless measurement of VS has grown since the COVID-19 pandemic, including in nonclinical situations. Lifelight is an app being developed as a medical device for the contactless measurement of VS using remote photoplethysmography (rPPG) via the camera on smart devices. The VISION-D (Measurement of Vital Signs by Lifelight Software in Comparison to the Standard of Care—Development) and VISION-V (Validation) studies demonstrated the accuracy of Lifelight compared with standard-of-care measurement of blood pressure, pulse rate, and respiratory rate, supporting the certification of Lifelight as a class I Conformité Européenne (CE) medical device. Objective To support further development of the Lifelight app, the observational VISION Multisite Development (VISION-MD) study is collecting high-quality data from a broad range of patients, including those with VS measurements outside the normal healthy range and patients who are critically ill. Methods The study is recruiting adults (aged ≥16 years) who are inpatients (some critically ill), outpatients, and healthy volunteers, aiming to cover a broad range of normal and clinically relevant VS values; there are no exclusion criteria. High-resolution 60-second videos of the face are recorded by the Lifelight app while simultaneously measuring VS using standard-of-care methods (automated sphygmomanometer for blood pressure; finger clip sensor for pulse rate and oxygen saturation; manual counting of respiratory rate). Feedback from patients and nurses who use Lifelight is collected via a questionnaire. Data to estimate the cost-effectiveness of Lifelight compared with standard-of-care VS measurement are also being collected. A new method for rPPG signal processing is currently being developed, based on the identification of small areas of high-quality signals in each individual. Anticipated recruitment is 1950 participants, with the expectation that data from approximately 1700 will be used for software development. Data from 250 participants will be retained to test the performance of Lifelight against predefined performance targets. Results Recruitment began in May 2021 but was hindered by the restrictions instigated during the COVID-19 pandemic. The development of data processing methodology is in progress. The data for analysis will become available from September 2022, and the algorithms will be refined continuously to improve clinical accuracy. The performance of Lifelight compared with that of the standard-of-care measurement of VS will then be tested. Recruitment will resume if further data are required. The analyses are expected to be completed in early 2023. Conclusions This study will support the refinement of data collection and processing toward the development of a robust app that is suitable for routine clinical use. Trial Registration ClinicalTrials.gov NCT04763746; https://clinicaltrials.gov/ct2/show/NCT04763746 International Registered Report Identifier (IRRID) DERR1-10.2196/41533

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“…The accuracy of Lifelight in estimating PR, RR, and BP has been demonstrated in the VISION-D and VISION-V studies, the former based on 17,233 measurements from 8585 participants [ 13 ]. Data from these studies supported the certification of Lifelight as a Class 1 Conformité Européenne medical device [ 14 ].…”

Section: Introductionmentioning

confidence: 99%

Dynamic Region of Interest Selection in Remote Photoplethysmography: Proof-of-Concept Study

Barham¹,

Wegerif²,

Petronzio³

2023

JMIR Form Res

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Background Remote photoplethysmography (rPPG) can record vital signs (VSs) by detecting subtle changes in the light reflected from the skin. Lifelight (Xim Ltd) is a novel software being developed as a medical device for the contactless measurement of VSs using rPPG via integral cameras on smart devices. Research to date has focused on extracting the pulsatile VS from the raw signal, which can be influenced by factors such as ambient light, skin thickness, facial movements, and skin tone. Objective This preliminary proof-of-concept study outlines a dynamic approach to rPPG signal processing wherein green channel signals from the most relevant areas of the face (the midface, comprising the cheeks, nose, and top of the lip) are optimized for each subject using tiling and aggregation (T&A) algorithms. Methods High-resolution 60-second videos were recorded during the VISION-MD study. The midface was divided into 62 tiles of 20×20 pixels, and the signals from multiple tiles were evaluated using bespoke algorithms through weighting according to signal-to-noise ratio in the frequency domain (SNR-F) score or segmentation. Midface signals before and after T&A were categorized by a trained observer blinded to the data processing as 0 (high quality, suitable for algorithm training), 1 (suitable for algorithm testing), or 2 (inadequate quality). On secondary analysis, observer categories were compared for signals predicted to improve categories following T&A based on the SNR-F score. Observer ratings and SNR-F scores were also compared before and after T&A for Fitzpatrick skin tones 5 and 6, wherein rPPG is hampered by light absorption by melanin. Results The analysis used 4310 videos recorded from 1315 participants. Category 2 and 1 signals had lower mean SNR-F scores than category 0 signals. T&A improved the mean SNR-F score using all algorithms. Depending on the algorithm, 18% (763/4212) to 31% (1306/4212) of signals improved by at least one category, with up to 10% (438/4212) improving into category 0, and 67% (2834/4212) to 79% (3337/4212) remaining in the same category. Importantly, 9% (396/4212) to 21% (875/4212) improved from category 2 (not usable) into category 1. All algorithms showed improvements. No more than 3% (137/4212) of signals were assigned to a lower-quality category following T&A. On secondary analysis, 62% of signals (32/52) were recategorized, as predicted from the SNR-F score. T&A improved SNR-F scores in darker skin tones; 41% of signals (151/369) improved from category 2 to 1 and 12% (44/369) from category 1 to 0. Conclusions The T&A approach to dynamic region of interest selection improved signal quality, including in dark skin tones. The method was verified by comparison with a trained observer’s rating. T&A could overcome factors that compromise whole-face rPPG. This method’s performance in estimating VS is currently being assessed. Trial Registration ClinicalTrials.gov NCT04763746; https://clinicaltrials.gov/ct2/show/NCT04763746

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Measurement of Vital Signs Using Lifelight Remote Photoplethysmography: Results of the VISION-D and VISION-V Observational Studies

Cited by 5 publications

References 34 publications

Validation of the Lifelight Contactless Blood Pressure and Pulse Rate Monitor (Preprint)

Validation of the Lifelight Contactless Blood Pressure and Pulse Rate Monitor (Preprint)

Measurement of Vital Signs by Lifelight Software in Comparison to Standard of Care Multisite Development (VISION-MD): Protocol for an Observational Study

Dynamic Region of Interest Selection in Remote Photoplethysmography: Proof-of-Concept Study

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