Advancing PPG Signal Quality and Know-How Through Knowledge Translation—From Experts to Student and Researcher

Abstract

Objective: Despite the vast number of photoplethysmography (PPG) research publications and growing demands for such sensing in Digital and Wearable Health platforms, there appears little published on signal quality expectations for morphological pulse analysis. Aim: to determine a consensus regarding the minimum number of undistorted i.e., diagnostic quality pulses required, as well as a threshold proportion of noisy beats for recording rejection.Approach: Questionnaire distributed to international fellow researchers in skin contact PPG measurements on signal quality expectations and associated factors concerning recording length, expected artifact-free pulses (“diagnostic quality”) in a trace, proportion of trace having artifact to justify excluding/repeating measurements, minimum beats required, and number of respiratory cycles.Main Results: 18 (of 26) PPG researchers responded. Modal range estimates considered a 2-min recording time as target for morphological analysis. Respondents expected a recording to have 86–95% of diagnostic quality pulses, at least 11–20 sequential pulses of diagnostic quality and advocated a 26–50% noise threshold for recording rejection. There were broader responses found for the required number of undistorted beats (although a modal range of 51–60 beats for both finger and toe sites was indicated).Significance: For morphological PPG pulse wave analysis recording acceptability was indicated if <50% of beats have artifact and preferably that a minimum of 50 non-distorted PPG pulses are present (with at least 11–20 sequential) to be of diagnostic quality. Estimates from this knowledge transfer exercise should help inform students and researchers as a guide in standards development for PPG study design.

Assessing hemodynamics from the photoplethysmogram to gain insights into vascular age: a review from VascAgeNet

“…This should consider also the attachment of sensor to tissue for repeatable measurements, for example to stabilize the contact by applying an external pressure ( 76 , 78 ). PPG sensors should be designed to mitigate against probe-tissue signal artifacts and to help obtain high-quality signals ( 241 ). Ideally, PPG sensors should be standardized to ensure measurements are replicable.…”

Filtering-induced time shifts in photoplethysmography pulse features measured at different body sites: the importance of filter definition and standardization

“…Therefore, in this preliminary study we focused on the IIR filters as it has been used in earlier research studies (Waugh et al, 2018;Chatterjee and Roy, 2018). In the majority of PPG studies, there is a lack of consistency in filtering where the settings/parameters of the filters are often not quoted (Huthart et al, 2020). Besides the difference in cut-off frequency and type (IIR and FIR) as aforementioned, filters with different responses such as Elliptic (Liang et al, 2018), Chebyshev (Tang et al, 2020 and Butterworth (Allen and Murray, 2000;Peng et al, 2015;Karimian et al, 2017) have been widely applied in PPG signal processing.…”

Beat-Based PPG-ABP Cleaning Technique for Blood Pressure Estimation

“…It is collected and archived without paying attention to its quality. Hence, many techniques were introduced for data cleaning and abnormality/artifact detection [17][18][19][20][21][22][23].…”