The use of the Rest Activity Cycler-Positive Airway Pressure (RACER-PAP) during exercise in normal healthy adults

This research will investigate a new non-invasive portable assisted ventilatory device called the RACer-PAP. The RACer-PAP (Rest Activity Cycler-positive airway pressure) works similarly to a Continuous Positive Airways Pressure (CPAP) device (a device which is readily available for the treatment of people with breathing disorders) by assisting respiration and reducing the work of breathing. CPAP is a widely utilised form of NIV and has been shown to splint open the airways at end expiration, counter intrinsic positive end expiratory pressure (PEEPi - the inspiratory load threshold) and thus reduce the work of breathing (Ambosino & Xie, 2017, Kallet & Diaz, 2009). Use of CPAP during exercise has also demonstrated reduced breathlessness and improved exercise tolerance in patients with COPD (Ambrosino & Xie 2017, O’Donnell, Sanii & Younes, 1988, Petrof, Calderini & Gottfried, 1990). RACer-PAP has previously been safely used and investigated in a number of populations (including in healthy people and in those with sleep apnoea) but has not yet been tested during exercise. The RACer-PAP uses nasal pillows to deliver CPAP through the nostrils and accommodates to the individuals nasal breathing cycle, regulating the amount of air that passes through each nostril. The nasal breathing cycle is not fully understood; however, it is thought that, under usual circumstances, one nostril allows more airflow to pass through than the other, the flow alternating between nostrils approximately every three hours (White, Bartley & Nates, 2015). This is caused by periodic unilateral obstruction by turbinate hypertrophy and is believed to aid in the removal of contaminants (White, Bartley & Nates, 2015). The RACer–PAP determines the dominant nostril for each individual within its first few assisted breaths, and after this the device ramps up to an operator determined pressure to ensure that the dominant nostril receives a higher pressure than the non-dominant nostril. A positive end expiratory pressure is adjusted to each patient’s comfort level (6-20 cm H2O). This continues for a pre-set time, then switches so the other nostril receives the higher pressure. This cycle continues for the time determined by the therapist to assist the patient with breathing. It is important that the pressure is adjustable to accommodate each patient's PEEPi which is influenced by the compliance of the individual’s lungs (Kallet & Diaz, 2009). RACer-PAP has been shown to reduce dryness in nose, mouth and throat compared to CPAP with supplementary humidification which is non-portable (Neill & Campbell, 2017). Thus RACer-PAP eliminates the need for supplementary humidification and offers the convenience of treatment portability. Additionally, the device can deliver up to 73 liters a minute of room air through each of the hoses (per nostril) ensuring that the device is able to meet the air flow demands of participants even during exercise. Fifteen healthy volunteers will individually attend two sessions at AUT university a maximum of one week apart. Both sessions will be at the same time of day (or within an hour). Sessions will last up to 1.5 hours each. Two healthcare professionals (one of whom is from the research team and a qualified physiotherapist with a minimum of 10 years experience in chronic lung disease management) will be present at each session. Session 1. Informed consent will be ascertained and a widely used exercise risk assessment tool (PAR-Q) will be completed by the participant. If this is positive, an extended exercise risk assessment tool (ePARmed-X+) will be used to determine if the participant requires referral to a medical professional for exercise clearance. If ePARmed-X+ is positive, participants will be excluded. Baseline screening of vital signs (heart rate, blood pressure, oxygen saturation). Baseline breathing testing (spirometry) will be undertaken. A test six minute walk test (6MWT) will be undertaken.This is followed by 30 minutes rest then a test 6MWT will be undertaken (see protocol in Step 11). Following return to baseline status after the test 6MWT, the RACer-PAP will be applied to the participant to be worn at rest for 10 minutes at a participant determined ventilatory comfortable level. Spirometry and vital signs will be undertaken immediately following RACer-PAP removal.A RACer-PAP questionnaire will be undertaken following removal. End of session 1. Session 2 Baseline testing of vital signs and spirometry (as session 1 above). Randomisation of order of RACer-PAP testing as below via via computer generated numbers stored in sealed envelopes: 1. 6MWT with RACer-PAP in situ during exercise 2. RACer-PAP worn at rest for 10 minutes, removed and, immediately following removal the participant undertakes a 6MWT Procedure at session 2. 6MWT 1 or 2 (followed immediately by spirometry and vital sign measures) 30 minutes rest 6MWT 1 or 2 (followed immediately by spirometry and vital sign measures) RACer-PAP questionnaire 2 undertaken. End of session. No risks to participation are anticipated. 6MWTs are self administered sub maximal walking tests where participants can stop and start activity as they determine necessary. Such walking tests are safely and widely used in both healthy populations and in populations with health and disability problems. The RACER-PAP has been shown to be safe in healthy populations and in those with sleep apnoea. Testing will take part in a clinical environment with standard emergency equipment available.