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Noninvasive ventilation has been demonstrated to benefit people who have moderate to severe chronic obstructive pulmonary disease during acute exacerbations. Studies have begun to investigate the effectiveness of noninvasive ventilation during pulmonary rehabilitation to improve outcomes for people with chronic obstructive pulmonary disease; however, the lack of portability and humidification of these devices means their use is limited, especially when performing activities of daily living. A new prototype device, RACer-PAP (rest-activity cycler-positive airways pressure), delivers battery-operated positive airway pressure via a nasal interface while regulating nasal airway apportionment bias, removing the need for supplementary humidification. This device may offer people with chronic obstructive pulmonary disease an improved ability to participate in pulmonary rehabilitation and activities of daily living.
To assess the feasibility of exercising with the RACer-PAP in situ and the acceptability of the device during exercise in normal, healthy individuals.
A total of 15 healthy adults were invited to attend 2 exercise sessions, each 1 week apart. Sessions lasted approximately 1 hour and included 2 baseline 6-minute walk distance assessments, once with and once without the RACer-PAP in situ. Vital signs and spirometry results were monitored throughout, and spirometry was performed pre- and posttesting with RACer-PAP. Subjective questionnaires ascertained participant feedback on exercising with the device in situ.
Of the 15 initial participants, 14 (93%) completed both sessions. There were no adverse events associated with exercising with the device in situ. There were no differences in vital signs or 6-minute walk distance whether exercising with or without the device in situ. There were small increases in maximum dyspnea score (on the Borg scale) when exercising with the device in situ (median score 2.0, IQR 0.5-3.0, vs 3.0, IQR 2.0-3.25). There were small increases in forced vital capacity following exercise with the RACer-PAP. None of the participants reported symptoms associated with airway drying. Participant feedback provided recommendations for modifications for the next iteration of the device prior to piloting the device with people with chronic obstructive pulmonary disease.
This study has shown RACer-PAP to be safe and feasible to use during exercise and has provided feedback for modifications to the device to improve its use during exercise. We now propose to consider the application of the device in a small pilot feasibility study to assess the safety, feasibility, and utility of the device in a population of people with moderate to severe chronic obstructive pulmonary disease.
Australian New Zealand Clinical Trials Registry ACTRN12619000478112; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=375477
Chronic obstructive pulmonary disease (COPD) is a term for progressive chronic lung diseases that cause airflow limitation, including emphysema, chronic bronchitis, and chronic asthma [
Noninvasive ventilation (NIV) has been demonstrated to benefit people who have moderate to severe COPD during acute exacerbations and can help to reduce respiratory rate, mortality and intubation rates, and improve arterial oxygenation [
Most NIV devices are impractical for undertaking everyday activities and exercise because they are large, heavy, expensive, and rely on an AC power source. A further problem with many devices is the lack of humidification of inspired gases, which can dry the airways and airway secretions and cause problems for people with COPD. Additionally, most devices use a face mask interface, which is often unacceptably claustrophobic during exercise for people with COPD [
The RACer-PAP (rest activity cycler-positive airway pressure) is an NIV device designed by author DW and his design team at the BioDesign Laboratory of the Auckland University of Technology, which specializes in biomedical engineering. The prototype device was originally designed to increase comfort for patients with sleep apnea. It has been safely tested in a small sample of this population and has been found to reduce drying of the airways and nasal congestion [
The prototype RACer-PAP uses nasal pillows (
RACer-PAP prototype in situ.
The aims of this study were to (1) assess the feasibility of exercising with the RACer-PAP prototype in situ; (2) investigate the utility and acceptability of the RACer-PAP prototype during rest and exercise; and (3) identify potential safety issues while utilizing the RACer-PAP prototype during exercise.
Ethical permission for the study was granted by the Health and Disability Ethics Committee of New Zealand on December 5, 2018 (study number 18/NTB/191). Institutional ethics approval was granted by the Auckland University of Technology Ethics Committee on April 15, 2019 (study number 19/129). The study was prospectively registered and approved on ANZCTR (ACTRN12619000478112) on March 22, 2019.
This was a feasibility study to establish the utility and acceptability of the prototype RACer-PAP device during exercise in normal, healthy individuals. Participants individually attended 2 sessions at the Auckland University of Technology (Auckland, NZ) that were held a maximum of 1 week apart. At session 1, participants completed baseline screening and became familiar with the prototype RACer-PAP device and the 6-minute walk test (6MWT). At session 2, participants completed exercise testing with and without the prototype RACer-PAP in situ in randomized order and provided feedback on exercise with the RACer-PAP. Both sessions were at a similar time of day (to negate circadian variability) and lasted a maximum of 1.5 hours.
Participants were purposefully selected to include a diversity of ages, sexes, and ethnicities. Subjects were included if they were healthy adults aged >25 years and were able to attend both scheduled sessions. Subjects were excluded if they had facial deformities, nasal polyps, or turbinate abnormalities, such as a sinus infection or other conditions, that might have influenced nasal airflow regulation; were unwilling to wear the device or unable to tolerate the nasal pillow interface; had a diagnosis of heart disease, high blood pressure, respiratory disease, or any illness or injury that impaired physical performance; had an active infection; had positive findings from the Physical Activity Readiness Questionnaire (PAR-Q) and Electronic Physical Activity Readiness Medical Examination (ePARmed-X+) risk assessment tools; were under advice from a medical practitioner to avoid exercise; had spirometry results indicating airflow obstruction, with a forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC) ratio of less than 70% [
Two health care professionals were present at each session. The participants were screened for their suitability to participate using the PAR-Q risk assessment tool. If the PAR-Q result was positive, the participant completed an ePARmed-X+ [
Following baseline testing, the participant was shown the RACer-PAP, the device was explained, and the participant was fitted with the device at rest and during exercise (see
RACer-PAP at rest (side view).
RACer-PAP at rest (posterior view).
Immediately following removal of the RACer-PAP, spirometry testing and vital sign measurement were undertaken and the “RACer-PAP at rest” questionnaire was completed. Participants were allocated their own RACer-PAP nasal interface and tubing, which were sterilized and used for both assessments. After 1 week, the participants underwent baseline testing of vital signs and spirometry (as per session 1) and then completed two 6MWT assessments, one with the PACer-PAP in situ, and one without. The order in which these assessments were undertaken was randomized using computer-generated numbers to wash out any order effect. The allocation of the first assessment was stored in a sealed envelope and was either 6MWT with RACer-PAP in situ at the participant-determined comfortable PEEP level or 6MWT without RACer-PAP in situ. Immediately following the 6MWT, vital signs and spirometry were assessed. Participants then had a 30-minute rest, completed the second 6MWT, and underwent spirometry and vital sign measurements. The second RACer-PAP questionnaire (on exercise) was completed prior to the end of the session, when participants were encouraged to provide feedback through a Likert scale and an open-ended question requesting “any other comments.”
RACer-PAP during exercise.
As this was a small feasibility study (N=15), the only reason to conduct statistical testing was to ascertain a measure of variance and within-subject differences. Demographic data were analyzed using descriptive statistics. Normally distributed data were described using the mean (SD) and nonnormally distributed data using the median (IQR). Data were analyzed for within-subject differences using paired-sample 2-tailed
Fifteen participants were recruited via display posters at the Auckland University of Technology between December 2019 and December 2020. Fifteen participants attended session 1. One participant dropped out following session 1 (no reason for the dropout was given); thus, session 2 was attended by 14 participants. Although there was an 18-week study shutdown period in the middle of data collection due to COVID-19 lockdowns, the target sample size was achieved. The authors consider that the data from the sample of 15 participants is adequate to provide useful information about the feasibility, usability, and acceptability of this device [
Baseline characteristics of all participants (N=15).
Characteristics | Values | |
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Female | 6 (40) |
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Male | 9 (60) |
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New Zealander European | 8 (54) |
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Māori | 2 (13) |
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Asian | 2 (13) |
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Pacific Peoples | 1 (7) |
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European | 1 (7) |
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Other | 1 (7) |
Age (years), mean (SD, range) | 50.6 (12.6, 26-68) | |
Height (cm), mean (SD, range) | 171.4 (9.2, 154-184) | |
Weight (kg), mean (SD, range) | 79.7 (15.7, 51.9-105.8) | |
Resting heart rate (bpm), mean (SD, range) | 74.2 (12.9, 55-100) | |
Systolic blood pressure (mm Hg), mean (SD, range) | 127.9 (14.9, 105-152) | |
Diastolic blood pressure (mm Hg), mean (SD, range) | 79.1 (8.4, 66-99) | |
Resting SpO2 (%), mean (SD, range) | 97.4 (1.5, 95-100) | |
Forced expiratory volume in 1 second (L/min), mean (SD, range) | 3.14 (0.77, 1.57-4.76) | |
Forced vital capacity (L/min), mean (SD, range) | 3.95 (0.98, 2.28-5.87) | |
Forced expiratory volume in 1 second/forced vital capacity ratio, mean (SD, range) | 0.79 (0.06, 0.69-0.92) | |
6-minute walk distance (meters), mean (SD, range) | 651.3 (86.6, 490-751) |
Outcomes following 6-minute walk test with and without the device (rest-activity cycler-positive airways pressure) in situ.
Outcome | Subjects, n | After test 1 (without RACer-PAPa) | After test 2 (with RACer-PAP) | Test statistic | |
Six-minute walk distance (meters), mean (SD) | 14 | 657.9 (109.5) | 653.5 (103.4) | t13=0.274 | .79 |
Forced expiratory volume in 1 second (L/min), mean (SD) | 12b | 3.19 (0.68) | 3.18 (0.79) | t11=0.237 | .82 |
Forced vital capacity (L/min), mean (SD) | 12b | 3.95 (0.98) | 4.11 (1.02) | t11=–2.506 | .03 |
Forced expiratory volume in 1 second/forced vital capacity ratio, mean (SD) | 12b | 0.81 (0.11) | 0.77 (0.03) | t11=1.294 | .22 |
Resting heart rate (bpm), mean (SD) | 14 | 87.1 (18.6) | 91.3 (16.3) | t13=–1.537 | .15 |
Systolic blood pressure (mm Hg), mean (SD) | 8b | 129 (9.8) | 132 (11.1) | .26 | |
Diastolic blood pressure (mm Hg), mean (SD) | 8b | 81.9 (5.1) | 84.1 (6.3) | .38 | |
Resting SpO2 (%), mean (SD) | 14 | 97.8 (0.89) | 97.6 (1.3) | t13=0.715 | .49 |
Maximum dyspnea (Borg scale), median (IQR) | 14 | 2.0 (0.5-3.0) | 3.0 (2.0-3.25) | Z=–2.41 | .02 |
aRACer-PAP: rest-activity cycler-positive airways pressure
bThe number of participants was lower for these outcomes, as data were unavailable due to equipment error, malfunction, or poor participant technique.
There were no adverse events at any time during the testing period and no participants asked for the RACer-PAP to be removed at any point. Participants were asked to select their own breathing pressure (range 6-10 cm H2O). Six of 15 participants (40%) selected 6 cm H2O pressure, 3/15 participants (20%) selected 7 cm H2O, 4/15 participants (27%) selected 8 cm H2O, and 2/15 participants (13%) selected 10 cm H2O. The mean pressure selected was 7.3 (SD 1.4) cm H2O.
Participants were asked to rate the utility and comfort of the RACer-PAP at rest and during exercise using a Likert scale. The results are shown in
Likert scale ranking of utility and comfort of the device (rest-activity cycler-positive airways pressure) at rest (N=15).
Question | Scale | Participant ratings, n (%) | Rank mode (mean) | |||||
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1 | 2 | 3 | 4 | 5 |
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How easy was it to fit the device? | Very easy (1) to very difficult (5) | 0 | 5 (33) | 5 (33) | 5 (33) | 0 | 2 (2.93) | |
How do you find wearing the device? | Very comfortable (1) to very uncomfortable (5) | 0 | 8 (53) | 4 (27) | 2 (13) | 1 (7) | 2 (2.63) | |
How would you rate the overall comfort of wearing this device? | Very comfortable (1) to very uncomfortable (5) | 0 | 7 (47) | 5 (33) | 3 (20) | 0 | 2 (2.7) | |
How well does the device fit at rest? | Very well (1) to not well at all (5) | 1 (7) | 9 (60) | 3 (20) | 2 (13) | 0 | 2 (2.4) | |
How would you rate the comfort of the waist strap? | Very comfortable (1) to very uncomfortable (5) | 3 (20) | 7 (47) | 1 (7) | 2 (13) | 1 (7) | 2 (2.29) | |
How would you rate the overall comfort with the nasal mask whilst wearing this device? | Very comfortable (1) to very uncomfortable (5) | 0 | 6 (40) | 5 (33) | 4 (27) | 0 | 2 (2.77) | |
How do you rate the weight of the device? | Very light (1) to very heavy (5) | 2 (13) | 2 (13) | 5 (33) | 6 (40) | 0 | 3 (2.93) | |
How would you rate your overall ability to breathe whilst wearing the device at rest? | Very easy (1) to very difficult (5) | 1 (7) | 4 (27) | 5 (33) | 5 (33) | 0 | 3 (2.90) | |
How would you rate the dryness in your nose (mouth) whilst wearing the device at rest? | Very moist (1) to very dry (5) | 1 (7) | 3 (20) | 9 (60) | 1 (7) | 1 (7) | 3 (2.83) |
Likert scale ranking of utility and comfort of the device (rest-activity cycler-positive airways pressure) during exercise (N=14).
Question | Scale | Participant ratings, n (%) | Rank mode (mean) | ||||
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1 | 2 | 3 | 4 | 5 |
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How did you find the weight of the device during exercise? | Very light (1) to very heavy (5) | 0 | 4 (29) | 5 (36) | 4 (29) | 1 (7) | 3 (3.10) |
How did you rate the overall portability of the device during exercise? | Very portable (1) to not portable (5) | 4 (29) | 3 (22) | 1 (7) | 5 (36) | 1 (7) | 4 (2.71) |
How did you rate the overall comfort of the nasal mask during exercise? | Very comfortable (1) to very uncomfortable (5) | 1 (7) | 5 (36) | 3 (22) | 5 (36) | 0 | 2 and 4 (2.82) |
How did you rate the overall comfort of the waist strap during exercise? | Very comfortable (1) to very uncomfortable (5) | 1 (7) | 4 (29) | 7 (50) | 1 (7) | 1 (7) | 3 (2.75) |
How do you rate your overall ability to move whilst exercising with the device compared to exercising without the device? | Much easier (1) to much harder (5) | 0 | 0 | 3 (21) | 11 (79) | 0 | 4 (3.71) |
How stable did the device feel during exercise? | Very stable (1) to very unstable (5) | 0 | 7 (50) | 5 (36) | 1 (7) | 1 (7) | 2 (2.64) |
How do you rate your overall ability to breathe while exercising with the device, compared to exercising without the device? | Much easier (1) to much harder (5) | 0 | 0 | 0 | 11 (79) | 3 (21) | 4 (4.14) |
How do you rate your overall ability to exercise with the device, compared to exercising without the device? | Much easier (1) to much harder (5) | 0 | 2 (14) | 2 (14) | 8 (57) | 2 (14) | 4 (3.68) |
How would you rate the dryness in your nose (mouth whilst wearing the device during exercise? | Very moist (1) to very dry (5) | 0 | 7 (50) | 3 (21) | 2 (14) | 2 (14) | 2 (2.93) |
Participant feedback was obtained both at rest (during session 1) and following exercise (during session 2). At both time points, comments centered around 3 emergent themes: the device and related interfaces, the effect of the device on breathing, and recommendations for future use.
The weight of the device was a dominant theme, with several participants describing the weight of the device as unfavorable. A smaller device was recommended to enhance the clinical utility of the device and allow future users to use the device more discreetly. Participants also suggested that shorter, less bulky tubing would be desirable. The nasal interface was described by a small number of participants as uncomfortable, causing their noses to become wet.
Several participants commented on the effect of the device on their breathing. One participant reported that their breathing was easier, one reported that their breathing felt “strange,” resulting in increased awareness, one reported difficulty synchronizing their breathing at rest, and one person described the removal of the device as resulting in “...a wave of relaxed sensation lasting 5 seconds.”
The weight of the device was again considered too heavy and potentially cumbersome, with some participants recommending a smaller device. Participants found that the device bounced against the lower back, noting that improved stabilization of the device was necessary. Some participants felt that the belt with the device in situ felt “unbalanced,” requiring frequent adjustment. Some suggested that this might impact breathing or cause discomfort during exercise. Some comments noted that the tubing was too long and that the nasal interface was uncomfortable. A softer, smaller, more discreet interface was suggested for use during activities of daily living. Some participants also noted mild discomfort during exercise in relation to the air temperature: they experienced nostril dampness and their spectacles steamed up.
Several participants commented on the effect of the device on their breathing during exercise. For some, breathing required increased awareness and effort, especially during the expiratory phase. One participant described difficulty with nose breathing during exercise.
Suggestions from participants included reduced device operating noise and a smaller, lighter device, which would be more discreet and aesthetically pleasing when undertaking activities. They also suggested that improved portability and flexibility of the interfaces (tubing, head strap, and nasal interface) would improve the usability of the device. It was also recommended that the device be simple and compact, to ensure that individuals can assemble and put on the device independently.
This small study found that in healthy individuals, exercising with the RACer-PAP in situ was safe, feasible, and acceptable to participants. Suggestions to increase comfort and utility of the device for exercise rehabilitation purposes and everyday activity were provided and will enable the development team to make ongoing modifications to the device.
Enabling people with respiratory disease to improve exercise capabilities, reduce dyspnea, and improve QOL has been the focus of PR for several decades. High quality evidence has shown PR to be a cornerstone intervention in achieving such outcomes [
Our study has focused on assessing the feasibility and utility of this new novel assistive ventilatory device in healthy individuals during exercise, with a view to extending this to a population of people with COPD. The prototype device has previously been investigated and found to be safe in several populations (including in healthy people at rest and in those with sleep apnea) [
In people with COPD, it is possible that dyspnea and the perceived work of breathing may improve with the use of the RACer-PAP. One study of people with oxygen-dependent COPD found that using nasal high flow oxygen therapy (HFOT) increased tidal volume and end-expiratory lung volume and reduced respiratory rate at rest [
Interestingly, in this study, there was a significant increase in FVC following exercise with the RACer-PAP in situ. This was not accompanied by an increase in FEV1 or FEV1/FVC ratio. Nonetheless, the actual mean difference in FVC with and without RACer-PAP in situ was only 160 ml (95% CI 19 ml-295 ml), which is unlikely to be clinically significant in healthy adults. It is possible that this data is either spurious or dependent on improvement in participant technique; it requires ongoing evaluation.
The use of other types of NIV during exercise in people with COPD has shown an unloading of both the inspiratory and expiratory respiratory muscle pumps [
Dynamic hyperinflation (DH) of the lungs occurs in people with COPD during exercise when inspiration is initiated prior to complete exhalation of the previous breath, resulting in an increase in end-expiratory lung volume and subsequent restrictions on inspiratory capacity. Patients with airflow obstruction and subsequent gas trapping breathe at higher lung volumes, which requires a greater inspiratory effort to overcome elastic load. During exercise, an increase in respiratory rate, air trapping, expiratory flow limitation, and reduced expiratory time occurs. These changes can become significantly disabling and lead to exertional dyspnea. The use of strategies to reduce DH during exercise has been investigated, including pursed lip breathing, expiratory positive airway pressure devices, and NIV. A recent systematic review and meta-analysis [
No limitations of the study design were identified by the research team. Several limitations related to the device were identified—participants’ comments about the prototype RACer-PAP highlight feasibility and utility issues. Prior to recruitment, participants were informed that the purpose of this initial study was to test the RACer-PAP during exercise in healthy individuals, with a view to determining the comfort and ease of use of the device prior to assessing the device in those with lung disease. Many participants commented on the device with this future objective in mind. It should be noted that none of the participants had previously used any form of positive pressure device and that their study experiences were not compared to any other NIV or positive pressure technologies. The participants made the following suggestions for future prototypes: reduce device weight and bulk, reduce length and size of tubing, improve device appearance (including the interfaces) to increase aesthetic discreetness when patients exercise or perform activities of daily living away from home, develop an alternative to the waist straps, increase the ease of self-administration of the RACer-PAP device, and develop an alternative to the current nasal interface.
Given the findings of this study, the research team hypothesizes that in those with COPD, the physiological effect of exercising with RACer-PAP in situ may reduce exercise-induced dyspnea, potentially leading to improvements in exercise and health-related QOL outcomes. We now propose to consider the application of the device in a small pilot feasibility study to assess the safety, feasibility, and utility of the device in a population of patients with moderate to severe COPD.
The current study has shown the prototype RACer-PAP to be safe and feasible to use during exercise in healthy participants. Further modifications to the device, as highlighted by the participants, are underway, and studies to assess the feasibility of use of the RACer-PAP with people with COPD have been proposed.
6-minute walk test
blood pressure
chronic obstructive pulmonary disease
continuous positive airways pressure
dynamic hyperinflation
expiratory positive airways pressure
Electronic Physical Activity Readiness Medical Examination
forced expiratory volume in 1 second
forced vital capacity
high flow oxygen therapy
heart rate
noninvasive ventilation
Physical Activity Readiness Questionnaire
positive end-expiratory pressure
pulmonary rehabilitation
quality of life
rest-activity cycler-positive airways pressure
peripheral oxygen saturation
We would like to thank the following Auckland University of Technology physiotherapy students who acted as research assistants during this project’s planning and data collection: Matthew Joubert, Oceane Maihi, Sam Kingi, and Cheri Koh.
The data sets generated and analyzed during the current study are available from the corresponding author on reasonable request.
DW is listed as co-inventor in the RACer-PAP patent.