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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Prospectively registered

Titles & IDs
Public title
Oxygen as Second-Line Therapy for Obstructive Sleep Apnoea.
Scientific title
A parallel group, placebo controlled, randomised trial of oxygen supplementation for obstructive sleep apnea in those that have refused or failed continuous positive airway pressure treatment.
Secondary ID [1] 273514 0
Royal Prince Alfred Hospital, NSW
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Obstructive Sleep Apnoea 279313 0
Condition category
Condition code
Respiratory 279505 279505 0 0
Sleep apnoea

Study type
Description of intervention(s) / exposure
Oxygen. To be administered every night during sleep at a flow rate of 3L/min via nasal cannulae for 2 months.
Intervention code [1] 283829 0
Treatment: Other
Comparator / control treatment
Air. To be administered nocturnally every night during sleep at a flow rate of 3L/min via nasal cannulae for 2 months.

This arm will act as the sham comparator and will not affect physiological function, as does not contain an 'active' agent beyond what the subject would normally breathe during sleep.
Control group

Primary outcome [1] 286122 0
Polysomnographic apnea-hypopnoea index (AHI). The total number of apnoeas and hypopnoeas divided by the total sleep duration.
Timepoint [1] 286122 0
2 months
Secondary outcome [1] 295187 0
Modfied AHI - including Respiratory Effort Related Arousals (RERA's) according to AASM 2007 scoring criteria VII.5.A
Timepoint [1] 295187 0
2 months
Secondary outcome [2] 295188 0
Nocturnal Oxygenation, measured by overnight in-lab polysomnography, with variables of interest being the average oxygen saturation during sleep, oxygen desaturation index, percent of total sleep time spent at saturation <90%, arousal index.
Timepoint [2] 295188 0
2 months
Secondary outcome [3] 295189 0
Sleep quality, measured by overnight in-lab polysomnography - total sleep time, arousal index. Sleep quality will also be assessed by automated techniques of power spectral analysis.
Timepoint [3] 295189 0
2 months
Secondary outcome [4] 295190 0
24 hour urinary catecholamine assay
Timepoint [4] 295190 0
2 months
Secondary outcome [5] 295191 0
Blood pressure. Automated blood pressure cuff at clinical visits.
Timepoint [5] 295191 0
2 months
Secondary outcome [6] 295192 0
Epworth Sleepiness Scale - a widely used, validated self-report measure of daytime sleepiness. Reference: Sleep 14 (6): 540-5.
Timepoint [6] 295192 0
2 months
Secondary outcome [7] 295193 0
Device adherence/compliance - measured by an internal counter recording device run-time in hours, divided by the number of days of the intervention period.
Timepoint [7] 295193 0
2 months
Secondary outcome [8] 295194 0
Ventilatory loop gain will be measured by ventilatory response testing, using the pseudorandom binary stimulation (PRBS) method, an engineering technique that uses inhalation of CO2 enriched gas (4% CO2) and room air in a pseudorandom sequence of breaths to probe the response of the respiratory system to carefully controlled CO2 disturbances.
Timepoint [8] 295194 0
2 months

Key inclusion criteria
Obstructive sleep apnoea (AHI greater than 15 events per hour)
Refused, or unable to tolerate continuous positive airway pressure treatment
Minimum age
18 Years
Maximum age
70 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
Using other therapy for obstructive sleep apnoea - i.e. mandibular advancement splint
Waking hypoxaemia (SaO2 less than 95%)
BMI greater than 38
Severe COPD or other lung disease
Uncontrolled cardiac disease
Participant or household member currently smoking
Severe nasal occlusion

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Participants will be recruited from outpatient clinics and sleep laboratories at Royal Prince Alfred Hospital and The Woolcock Institute. Allocation will be performed with a computerised random allocation generator program.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Randomisation will be stratified by centre and performed by a central party independent of investigators and research staff having direct contact with study participants. Participants meeting eligibility criteria will be randomly assigned in a 1:1 ratio to oxygen or room air, delivered by nasal cannula from oxygen concentrators modified specifically for the research study.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?

Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis

Recruitment status
Not yet recruiting
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)
Recruitment postcode(s) [1] 4778 0

Funding & Sponsors
Funding source category [1] 284360 0
Self funded/Unfunded
Name [1] 284360 0
Address [1] 284360 0
Country [1] 284360 0
Primary sponsor type
Department of Respiratory and Sleep Medicine
Royal Prince Alfred Hospital
Missenden Road
Camperdown NSW 2050
Secondary sponsor category [1] 283300 0
Commercial sector/Industry
Name [1] 283300 0
Air Liquide Health Care
Address [1] 283300 0
43-47 Pine Road, Fairfield NSW 2165
Country [1] 283300 0

Ethics approval
Ethics application status
Ethics committee name [1] 286320 0
Ethics Review Committe, RPAH Zone, Sydney Local Health District
Ethics committee address [1] 286320 0
Research Development Office, Royal Prince Alfred Hospital, CAMPERDOWN NSW 2050
Ethics committee country [1] 286320 0
Date submitted for ethics approval [1] 286320 0
Approval date [1] 286320 0
Ethics approval number [1] 286320 0

Brief summary
We aim to develop alternative treatments in patients refusing CPAP therapy. We hypothesize that 2 months of low-flow oxygen compared with room air, each delivered via nasal cannulae will improve sleep-disordered breathing, hypoxia during sleep, symptoms and maladaptive cardiovascular response in patients with OSA refusing CPAP treatment. Secondly, we hypothesize that patients with higher loop gain will derive a greater benefit (reduction in apnoea-hypopnoea index) from oxygen therapy.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 33475 0
Address 33475 0
Country 33475 0
Phone 33475 0
Fax 33475 0
Email 33475 0
Contact person for public queries
Name 16722 0
Dr Keith Wong
Address 16722 0
Department of Respiratory Medicine
Royal Prince Alfred Hospital
Missenden Road
NSW 2050
Country 16722 0
Phone 16722 0
+61 2 9515 8195
Fax 16722 0
+61 2 9515 8196
Email 16722 0
Contact person for scientific queries
Name 7650 0
Dr Keith Wong
Address 7650 0
Department of Respiratory Medicine
Royal Prince Alfred Hospital
Missenden Road
NSW 2050
Country 7650 0
Phone 7650 0
+61 2 9515 8195
Fax 7650 0
+61 2 9515 8196
Email 7650 0

No information has been provided regarding IPD availability
Summary results
No Results