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Trial registered on ANZCTR

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

Titles & IDs
Public title
A Study to Investigate the Effects of Oxygen in Obesity Hypoventilation Syndrome
Scientific title
A Randomised, Double-Blind, Cross-Over Study to Investigate the Effects of Hyperoxia on Carbon Dioxide Levels and Ventilation In Patients with Obesity Hypoventilation Syndrome
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Obesity Hypoventialtion Syndrome 3225 0
Condition category
Condition code
Respiratory 3390 3390 0 0
Other respiratory disorders / diseases

Study type
Description of intervention(s) / exposure
Subjects will be exposed to 2 interventions:
1. Inhaled 100% oxygen via a face mask for 20 minutes
2. Inhaled 21% oxygen via an identical facemask for 20 minutes.
3. There will be a wash out phase of at least 24 hours between the 2 interventions.
4. The two gases will be administered via douglas bags filled by 21% and 100% oxygen cylinders by a third party
Intervention code [1] 2966 0
Treatment: Other
Comparator / control treatment
21% oxygen inhaled via a face mask for 20 minutes
Control group

Primary outcome [1] 4286 0
Change in PaCO2 from baseline measured by a transcutaneous carbon dioxide device attached to the earlobe.
Timepoint [1] 4286 0
20 minutes
Secondary outcome [1] 7223 0
Change in minute ventilation measured by gas flow through an electronic pneumotachygraph attached to the mouthpiece of the facemask
Timepoint [1] 7223 0
20 minutes
Secondary outcome [2] 7224 0
Change in dead space to tidal volume ratio. Measured by calculation: a combination of PaCO2 from the transcutaneous carbon dioxide device and mixed expired carbon dioxide measured by an electronic sensor on the mouthpiece of the face mask
Timepoint [2] 7224 0
20 minutes
Secondary outcome [3] 7225 0
A change in PaCO2 from baseline of greater then 4mmHg measured by transcutaneous carbon dioxide device
Timepoint [3] 7225 0
20 minutes

Key inclusion criteria
Patients with a new diagnosis of Obesity Hypoventilation Syndrome:
1. Body mass index (BMI) >30kg/m2,
2. Daytime hypercapnia (pCO2 >45mmHg)
Minimum age
No limit
Maximum age
No limit
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
1. Diagnosis of chronic airflow obstruction: post-bronchodilator Forced Expiratory Volume in 1 second (FEV1) to Forced Vital Capacity (FVC) ratio <0.7 and Forced Expiratory Volume in 1 second (FEV1) <80% predicted and > 10 pack year smoking history

2. Patients already receiving treatment with Continuous Positive Airway Pressure (CPAP) or non-invasive positive pressure ventilation

Study design
Purpose of the study
Educational / counselling / training
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Allocation involved contacting the holder of the allocation schedule who was based at a central administration site.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Computer generated randomisation block
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
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment outside Australia
Country [1] 997 0
New Zealand
State/province [1] 997 0

Funding & Sponsors
Funding source category [1] 3449 0
Self funded/Unfunded
Name [1] 3449 0
Address [1] 3449 0
Country [1] 3449 0
Primary sponsor type
Medical Research Institute of New Zealand
Medical Research Institute of New Zealand
99 The Terrace
Wellington 6143
New Zealand
Secondary sponsor category [1] 3091 0
Name [1] 3091 0
Address [1] 3091 0
Country [1] 3091 0

Ethics approval
Ethics application status
Ethics committee name [1] 5477 0
Central Regional Ethics Committee
Ethics committee address [1] 5477 0
Level 2
1 - 3 The Terrace
PO Box 5013
Wellington 6011
Ethics committee country [1] 5477 0
New Zealand
Date submitted for ethics approval [1] 5477 0
Approval date [1] 5477 0
Ethics approval number [1] 5477 0

Brief summary
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 28642 0
Address 28642 0
Country 28642 0
Phone 28642 0
Fax 28642 0
Email 28642 0
Contact person for public queries
Name 11799 0
Meme Wijesinghe
Address 11799 0
Medical Research Institute of New Zealand
99 The Terrace
Wellington 6143
Country 11799 0
New Zealand
Phone 11799 0
+64 21 024 777 30
Fax 11799 0
Email 11799 0
Contact person for scientific queries
Name 2727 0
Meme Wijesinghe
Address 2727 0
Medical Research Institute of New Zealand
99 The Terrace
Wellington 6143
Country 2727 0
New Zealand
Phone 2727 0
+64 21 024 777 30
Fax 2727 0
Email 2727 0

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