Study Overview
| Authors | Philippus A., Nupp J., MacIntyre B., Welch A., Ali A., vanderValk J., Monden K.R. |
| Institution | Craig Hospital, Englewood, Colorado, USA |
| Journal | Topics in Spinal Cord Injury Rehabilitation |
| Year | 2022 |
| DOI | 10.46292/sci22-00012 |
| PubMed | PMC9678216 |
| Product | eSense Pulse |
| Participants | 30 adults with spinal cord injury or disease |
| Design | Pilot RCT (study protocol publication) |
What was investigated?
Researchers at Craig Hospital in Englewood, Colorado — a facility specializing in neurorehabilitation — investigated whether HRV biofeedback training can reduce anxiety symptoms in adults with spinal cord injuries or diseases (SCI/D). The starting point was the known elevated prevalence of anxiety disorders in people with spinal cord injury. Additionally, the study documented how the originally clinic-based protocol was successfully transitioned to a fully home-based treatment format due to the COVID-19 pandemic — with the eSense Pulse as the central home device.
Methods
30 adults with spinal cord injury or disease were assigned to two groups in a randomized, controlled pilot study design. After a single initial assessment on-site, participants completed eight treatment sessions over four weeks in their home environment. The individual resonance frequency for breathing exercises was initially determined clinically. Randomization was performed using a minimization method with adjustment for baseline anxiety levels. Primary outcome measures were the proportion of time in the low-frequency HRV band and anxiety scores on the DASS-21 scale (Depression Anxiety Stress Scale).
Mindfield Product in this Study
The eSense Pulse (Mindfield Biosystems) was the central measurement instrument for all home-based HRV biofeedback sessions. After the initial clinical determination of the individual resonance frequency, participants in the intervention group completed their eight home sessions independently with the eSense Pulse and the associated smartphone application. The sensor captured heart rate variability via photoplethysmography; the app guided participants through individually calibrated resonance frequency breathing exercises. HRV data were exported directly from the app and transferred to the study data system (REDCap). The eSense Pulse thus proved to be a suitable instrument for unsupervised home use — including by individuals with physical limitations due to spinal cord injury.
Results
The study published the revised study protocol; final efficacy results were not yet available at the time of publication. However, the researchers documented the following feasibility findings:
- The complete transition from clinic-based to home-based implementation was technically feasible and accepted by participants
- The eSense Pulse was suitable for unsupervised home use by individuals with spinal cord injury
- HIPAA-compliant technologies (Zoom, DocuSign, REDCap) enabled privacy-compliant operation of remote treatment
- All protocol-related adaptations were systematically documented according to the FRAME framework, which is considered the methodological standard for adaptive clinical trial management
Significance
This study demonstrates that HRV biofeedback with the eSense Pulse is feasible in the home environment — without clinical supervision at every session. This substantially increases practical transferability: People with spinal cord injury frequently have limited access to psychological care facilities; a home-based protocol significantly lowers this barrier.
The use of a consumer sensor (eSense Pulse) under real-world conditions — rather than clinical laboratory equipment — strengthens the external validity of the study. The protocol paper also exemplifies how clinical research protocols can adaptively respond to changing conditions without compromising scientific integrity. It should be noted that this is a protocol publication; efficacy data will be reported in a subsequent results publication.
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