Photoplethysmography behind the Ear Outperforms Electrocardiogram for Cardiovascular Monitoring in Dynamic Environments.

Brian S Bradke,Bradford Everman,Tiffany A Miller

doi:10.3390/s21134543

Abstract

An increasing proportion of occupational mishaps in dynamic, high-risk operational environments have been attributed to human error, yet there are currently no devices to routinely provide accurate physiological data for insights into underlying contributing factors. This is most commonly due to limitations of commercial and clinical devices for collecting physiological data in environments of high motion. Herein, a novel Photoplethysmography (PPG) sensor device was tested, called SPYDR (Standalone Performance Yielding Deliberate Risk), reading from a behind-the-ear location, specifically designed for high-fidelity data collection in highly dynamic high-motion, high-pressure, low-oxygen, and high-G-force environments. For this study, SPYDR was installed as a functional ear-cup replacement in flight helmets worn by rated US Navy aircrew. Subjects were exposed to reduced atmospheric pressure using a hypobaric chamber to simulated altitudes of 25,000 feet and high G-forces in a human-rated centrifuge up to 9 G acceleration. Data were compared to control devices, finger and forehead PPG sensors, and a chest-mounted 12-lead ECG. SPYDR produced high-fidelity data compared to controls with little motion-artifact controls in the no-motion environment of the hypobaric chamber. However, in the high-motion, high-force environment of the centrifuge, SPYDR recorded consistent, accurate data, whereas PPG controls and ECG data were unusable due to a high-degree-motion artifacts. The data demonstrate that SPYDR provides an accurate and reliable system for continuous physiological monitoring in high-motion, high-risk environments, yielding a novel method for collecting low-artifact cardiovascular assessment data important for investigating currently inaccessible parameters of human physiology.

Highlights

Safe conduct during high-risk activities in extreme environments, such as those within tactical military flight, are highly dependent on the mental, physical, and emotional wellness of the personnel involved, yet there are currently no devices capable of routinely and reliably quantifying physiological and cognitive performance, nor warning the user of potential decremental dangers [1,2,3]
In tactical flight, reduced atmospheric pressure in high altitudes, high and varied G-forces, and high motion are all extreme environmental conditions known to exert a large toll on normal operations of many physiological systems [11,12,13]
Hypobaric chamber tests were run to determine that SPYDR can provide accurate and reliable data for blood oxygen saturation (SpO2) and Pulse Rate (PR) in reduced atmospheric pressure

Summary

Introduction

Safe conduct during high-risk activities in extreme environments, such as those within tactical military flight, are highly dependent on the mental, physical, and emotional wellness of the personnel involved, yet there are currently no devices capable of routinely and reliably quantifying physiological and cognitive performance, nor warning the user of potential decremental dangers [1,2,3]. Mandatory training, personal protective equipment, and “how do I feel” questionnaires are becoming commonplace, these methods fail to capture the individual nature of human factor risks involving the relationship between physiology and environment in hazardous environments [4,5,6]. As a result, they are not reducing the incidence or severity of human error-related accidents in high-risk professions [3,7,8]. Increasing our currently limited understanding of human physiology in highly dynamic environments with novel technologies capable of overcoming the challenges is a logical and important first step

Methods

Results

Conclusion