Non-contact sensing of neonatal pulse rate using camera-based imaging: a clinical feasibility study

Physiological Measurement, vol. 41, pp. 024001

Abstract

OBJECTIVE: Neonates and infants are patients who would benefit from less invasive vital sign sensing, especially from fewer cables and the avoidance of adhesive electrodes. Photoplethysmography imaging (PPGI) has been studied for medical applications in recent years: it is possible to assess various vital signs remotely, non-invasively, and without contact by using video cameras and light. However, studies on infants and especially on neonates in clinical settings are still rare. Hence, we conducted a single-center study to assess heart activity by estimating the pulse rate (PR) of 19 neonates. APPROACH: Time series were generated from tracked regions of interest (ROIs) and PR was estimated via a joint time-frequency analysis using a short-time Fourier transform. Artifacts, for example, induced by movement, were detected and flagged by applying a signal quality index in the frequency domain. MAIN RESULTS: The feasibility of PR estimation was demonstrated using visible light and near-infrared light at 850 nm and 940 nm, respectively: the estimated PR was as close as 3 heartbeats per minute in artifact-free time segments. Furthermore, an improvement could be shown when selecting the best performing ROI compared to the ROI containing the whole body. The main challenges are artifacts from motion, light sources, medical devices, and the detection and tracking of suitable regions for signal retrieval. Nonetheless, the PR extracted was found to be comparable to the contact-based photoplethysmography reference and is, therefore, a viable replacement if robust signal retrieval is ensured. SIGNIFICANCE: Neonates are seldom measured by PPGI and studies reporting measurements on darker skin tones are rare. In this work, not only a single camera was used, but a synchronized camera setup using multiple wavelengths. Various ROIs were used for signal extraction to examine the capabilities of PPGI. In addition, qualitative observations regarding camera parameters and noise sources were reported and discussed.

Authors 6

1. Michael Paul corresponding Aachen Medical Information Technology (MedIT)

   RWTH Aachen University

   Affiliation as printed

   Medical Information Technology (MedIT), Helmholtz-Institute for Biomedical Engineering, RWTH Aachen University, Pauwelsstr. 20, Aachen, 52074, Germany

2. Jayaraj Joseph

   Indian Institute of Technology Madras · Healthcare Technology Innovation Centre

   Affiliation as printed

   Healthcare Technology Innovation Centre (HTIC), IIT Madras Research Park, Taramani, Chennai, 600 113, India

3. Mohanasankar Sivaprakasam

   Indian Institute of Technology Madras · Healthcare Technology Innovation Centre

   Affiliation as printed

   Healthcare Technology Innovation Centre (HTIC), IIT Madras Research Park, Taramani, Chennai, 600 113, India

4. J Kumutha corresponding

   Saveetha University

   Affiliation as printed

   Saveetha Medical College, Kanchipuram, Saveetha Nagar, Chennai, 602 105, India

5. Steffen K. Leonhardt corresponding Aachen Medical Information Technology (MedIT)

   RWTH Aachen University

   Affiliation as printed

   Medical Information Technology (MedIT), Helmholtz-Institute for Biomedical Engineering, RWTH Aachen University, Pauwelsstr. 20, Aachen, 52074, Germany

6. Christoph Hoog Antink corresponding Aachen Medical Information Technology (MedIT)

   RWTH Aachen University

   Affiliation as printed

   Medical Information Technology (MedIT), Helmholtz-Institute for Biomedical Engineering, RWTH Aachen University, Pauwelsstr. 20, Aachen, 52074, Germany