Feasibility Study of Pulse Width at Half Amplitude of Camera PPG for Contactless Blood Pressure Estimation

Ding, Xiaorong; Wang, Wenjin; Chen, Yifan; Yang, Yumin; Zhao, Yan; Kong, Deyuan

doi:10.1109/embc46164.2021.9630964

Cited by 11 publications

(5 citation statements)

References 20 publications

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“…Table 5 overviews previous works that invoked PWHA. Our results regarding face and earlobe PPG are in line with Ding et al., who recently reported a negative correlation of PWHA from facial iPPG and blood pressure Ding et al. (2021) .…”

Section: Discussionsupporting

confidence: 93%

“…Table 5 overviews previous works that invoked PWHA. Our results regarding face and earlobe PPG are in line with Ding et al, who recently reported a negative correlation of PWHA from facial iPPG and blood pressure Ding et al (2021). Awad et al report differences in PWHA from finger and earlobe in patients undergoing coronary artery bypass grafting Awad et al (2001a).…”

Section: Figuresupporting

confidence: 91%

“…Other related works do not compare iPPG directly to contact PPG but investigate the suitability of morphological features with respect to blood pressure estimation. E.g., Ding et al showed PWHA to decay with blood pressure Ding et al (2021). Rong and Li (2021) and Jain et al (2016) used multiple morphological features to estimate blood pressure.…”

Section: Figurementioning

confidence: 99%

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Photoplethysmography upon cold stress—impact of measurement site and acquisition mode

Fleischhauer¹,

Bruhn²,

Rasche

et al. 2023

Front. Physiol.

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Photoplethysmography (PPG) allows various statements about the physiological state. It supports multiple recording setups, i.e., application to various body sites and different acquisition modes, rendering the technique a versatile tool for various situations. Owing to anatomical, physiological and metrological factors, PPG signals differ with the actual setup. Research on such differences can deepen the understanding of prevailing physiological mechanisms and path the way towards improved or novel methods for PPG analysis. The presented work systematically investigates the impact of the cold pressor test (CPT), i.e., a painful stimulus, on the morphology of PPG signals considering different recording setups. Our investigation compares contact PPG recorded at the finger, contact PPG recorded at the earlobe and imaging PPG (iPPG), i.e., non-contact PPG, recorded at the face. The study bases on own experimental data from 39 healthy volunteers. We derived for each recording setup four common morphological PPG features from three intervals around CPT. For the same intervals, we derived blood pressure and heart rate as reference. To assess differences between the intervals, we used repeated measures ANOVA together with paired t-tests for each feature and we calculated Hedges’ g to quantify effect sizes. Our analyses show a distinct impact of CPT. As expected, blood pressure shows a highly significant and persistent increase. Independently of the recording setup, all PPG features show significant changes upon CPT as well. However, there are marked differences between recording setups. Effect sizes generally differ with the finger PPG showing the strongest response. Moreover, one feature (pulse width at half amplitude) shows an inverse behavior in finger PPG and head PPG (earlobe PPG and iPPG). In addition, iPPG features behave partially different from contact PPG features as they tend to return to baseline values while contact PPG features remain altered. Our findings underline the importance of recording setup and physiological as well as metrological differences that relate to the setups. The actual setup must be considered in order to properly interpret features and use PPG. The existence of differences between recording setups and a deepened knowledge on such differences might open up novel diagnostic methods in the future.

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Section: Discussionsupporting

confidence: 93%

Section: Figuresupporting

confidence: 91%

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Photoplethysmography upon cold stress—impact of measurement site and acquisition mode

Fleischhauer¹,

Bruhn²,

Rasche

et al. 2023

Front. Physiol.

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“…We process the video to remove the frames where the hand/face is incorrectly positioned or occluded, causing a loss of hand/face tracking. Studies have demonstrated that the forehead and the cheeks contain crucial information for estimating the PPG signal from the face [61,62] and the palm contains crucial information for PPG signal extraction from the hand [63,62]. V-BPE extracts a region of interest using specific landmarks bounding the forehead and the palm to ensure the consistent detection of a suitably sized region of interest that scales according to the distance of the subject from the camera.…”

Section: Overviewmentioning

confidence: 99%

Video-based Estimation of Blood Pressure

Tucker,

Dasari,

Jeni

2023

Preprint

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In this work, we propose a non-contact video-based approach that estimates an individual’s blood pressure. The estimation of blood pressure is critical for monitoring hypertension and cardiovascular diseases such as coronary artery disease or stroke. Estimation of blood pressure is typically achieved using contact-based devices which apply pressure on the arm through a cuff. Such contact-based devices are cost-prohibitive as well as limited in their scalability due to the requirement of specialized equipment. The ubiquity of mobile phones and video-based capturing devices motivates the development of a non-contact blood pressure estimation method - Video-based Blood Pressure Estimation (V-BPE). We leverage the time difference of the blood pulse arrival at two different locations in the body (Pulse Transit Time) and the inverse relation between the blood pressure and the velocity of blood in the artery to analytically estimate the blood pressure. Through statistical hypothesis testing, we demonstrate that Pulse Transit Time-based approaches to estimate blood pressure require knowledge of subject specific blood vessel parameters, such as the length of the blood vessel. We utilize a combination of computer vision techniques and demographic information (such as the height and the weight of the subject) to capture and incorporate the aforementioned subject specific blood vessel parameters into our estimation of blood pressure. We demonstrate the robustness of V-BPEby evaluating the efficacy of blood pressure estimation in demographically diverse, outside-the-lab conditions. V-BPE is advantageous in two ways; 1) it is non-contact-based, reducing the possibility of infection due to contact and 2) it is scalable, given the ubiquity of video recording devices.

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“…BP estimation methods based on pulse features extracted from iPPG pulse signals have gained significant attention in the field of non-contact BP measurement. Ding et al [ 14 ] propose that there is a quite strong correlation between the feature of pulse width at half amplitude and BP values. Djeldjli et al [ 15 ] have validated the strong correlation between the pulse features extracted from iPPG and cPPG in an ideal acquisition environment.…”

Section: Introductionmentioning

confidence: 99%

Preserving shape details of pulse signals for video-based blood pressure estimation

Han,

Yang,

Fang

et al. 2024

Biomed. Opt. Express

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In recent years, imaging photoplethysmograph (iPPG) pulse signals have been widely used in the research of non-contact blood pressure (BP) estimation, in which BP estimation based on pulse features is the main research direction. Pulse features are directly related to the shape of pulse signals while iPPG pulse signals are easily disturbed during the extraction process. To mitigate the impact of pulse feature distortion on BP estimation, it is necessary to eliminate interference while retaining valuable shape details in the iPPG pulse signal. Contact photoplethysmograph (cPPG) pulse signals measured at rest can be considered as the undisturbed reference signal. Transforming the iPPG pulse signal to the corresponding cPPG pulse signal is a method to ensure the effectiveness of shape details. However, achieving the required shape accuracy through direct transformation from iPPG to the corresponding cPPG pulse signals is challenging. We propose a method to mitigate this challenge by replacing the reference signal with an average cardiac cycle (ACC) signal, which can approximately represent the shape information of all cardiac cycles in a short time. A neural network using multi-scale convolution and self-attention mechanisms is developed for this transformation. Our method demonstrates a significant improvement in the maximal information coefficient (MIC) between pulse features and BP values, indicating a stronger correlation. Moreover, pulse signals transformed by our method exhibit enhanced performance in BP estimation using different model types. Experiments are conducted on a real-world database with 491 subjects in the hospital, averaging 60 years of age.

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Feasibility Study of Pulse Width at Half Amplitude of Camera PPG for Contactless Blood Pressure Estimation

Cited by 11 publications

References 20 publications

Photoplethysmography upon cold stress—impact of measurement site and acquisition mode

Photoplethysmography upon cold stress—impact of measurement site and acquisition mode

Video-based Estimation of Blood Pressure

Preserving shape details of pulse signals for video-based blood pressure estimation

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