Plain English Summary
Background and study aims
Obstructive sleep apnoea syndrome (OSAS) is a sleep-related breathing problem. In OSAS the back of the throat collapses during sleep, causing pauses in breathing (an apnoea), falls in oxygen levels and waking the patient from sleep many times an hour (an arousal). Because of this patients are not only sleepy during the daytime but also have higher daytime blood pressures. This puts them at risk of heart attacks and strokes. Currently the best treatment for OSAS is continuous positive airways pressure (CPAP). This is a breathing mask worn at night, blowing air onto the back of the throat at night and holding it open. This stops the throat from collapsing, stops falls in oxygen levels and stops large changes in pressure swings in the chest seen with an apnoea. CPAP treatment is effective in making patients less sleepy during the daytime and in improves daytime blood pressure. It is not known whether it is the falls in oxygen levels, the arousal or the pressure changes that cause the rise in daytime blood pressure. Oxygen treatment is given long term to patients with other chronic lung diseases safely like chronic obstructive pulmonary disease (COPD). By giving patients oxygen overnight instead of CPAP we aim to study the effect of stopping oxygen levels falling (intermittent hypoxia) on blood pressure, without affecting apnoeas or arousals. In this study we will look at the effect of giving oxygen overnight to OSAS patients previously treated with CPAP.
Who can participate?
Adults aged between 20-75 with obstructive sleep apnoea treated with CPAP for at least a year.
What does the study involve?
Patients are randomly allocated into one of two groups. Those in group 1 are given the treatment (oxygen) overnight instead of their normal CPAP for 14 days. Those in group 2 are given a placebo (air) overnight instead of their usual CPAP for 14 days. The patients are then crossed-over so that those receiving oxygen are now given the placebo treatment and vice versa.
What are the possible benefits and risks of participating?
Not provided at time of registration
Where is the study run from?
Churchill Hospital, UKCRC Oxford Respiratory Trials Unit (UK)
When is the study starting and how long is it expected to run for?
February 2015 to June 2017
Who is funding the study?
1. Oxford Radcliffe Hospitals Charitable Fund (UK)
2. ResMed (UK)
Who is the main contact?
Miss Magda Laskawiec-Szkonter
Trial website
Contact information
Type
Public
Primary contact
Miss Magda Laskawiec-Szkonter
ORCID ID
Contact details
Churchill Hospital
UKCRC Oxford Respiratory Trials Unit
Oxford Centre for Respiratory Medicine
Churchill Hospital
Old Road
Oxford
OX3 7LE
United Kingdom
Type
Scientific
Additional contact
Prof John Stradling
ORCID ID
http://orcid.org/0000-0003-4971-5018
Contact details
Churchill Hospital
UKCRC Oxford Respiratory Trials Unit
Oxford Centre for Respiratory Medicine
Churchill Hospital
Old Road
Oxford
OX3 7LE
United Kingdom
Type
Scientific
Additional contact
Dr Christopher Turnbull
ORCID ID
http://orcid.org/0000-0001-8942-5424
Contact details
Churchill Hospital
UKCRC Oxford Respiratory Trials Unit
Oxford Centre for Respiratory Medicine
Churchill Hospital
Old Road
Oxford
OX3 7LE
United Kingdom
Additional identifiers
EudraCT number
ClinicalTrials.gov number
Protocol/serial number
18299
Study information
Scientific title
The effects of supplemental oxygen on obstructive sleep apnoea (OSA) and its vascular consequences during continuous positive airway pressure therapy withdrawal
Acronym
Study hypothesis
In this study we will look at the effect of giving oxygen overnight to patients suffering from obstructive sleep apnoea syndrome (OSAS) that have previously been treated with continuous positive airways pressure (CPAP). We hypothesize that treatment of OSA patients with oxygen alone has a beneficial effect on the surrogate markers of cardiovascular risk, predominately arterial blood pressure.
Ethics approval
NRES Committee South Central - Oxford B, 04/02/2015, ref: 15/SC/0007
Study design
Randomised; Interventional; Design type: Not specified
Primary study design
Interventional
Secondary study design
Randomised controlled trial
Trial setting
Hospitals
Trial type
Treatment
Patient information sheet
Not available in web format, please use contact details to request a patient information sheet
Condition
Topic: Respiratory disorders; Subtopic: Respiratory (all Subtopics); Disease: Respiratory
Intervention
Participants will be treated with oxygen or sham (air) whilst off CPAP for 14 days.
Patients are crossed-over, so that they are allocated to either CPAP withdrawal with supplemental oxygen, if they had previously received sham (air) and CPAP withdrawal with sham (air), if they had previously received supplemental oxygen after Visit 3
Intervention type
Device
Phase
Drug names
Primary outcome measure
Home blood pressure change over 14 days; Timepoint: Home blood pressure measured every morning by the patient
Secondary outcome measures
1. Home heart rate change over 14 days; Timepoint; home heart rate measured every morning by the patient
2. Change in OSA severity: Timepoint: home sleep study measured before study visits 1, 2, 3, and 4
3. Change in subjective (questionnaire ESS) and objective sleepiness (OSLER test); Timepoint: ESS and OSLER measured at study visits 1,2 3, and 4
4. Change in overnight urinary catecholamine secretion; Timepoint: Overnight urine collection for catecholamines prior to visits 1, 2, 3, and 4
5. Change in gene expression (mRNA and microRNA); Timepoint; Bloods samples at visits 1, 2, 3, and 4
Overall trial start date
01/02/2015
Overall trial end date
31/12/2016
Reason abandoned (if study stopped)
Eligibility
Participant inclusion criteria
1. Objectively confirmed obstructive sleep apnoea (at the time of original diagnosis) with an oxygen desaturation index (ODI, =4% dips) of >20/h or/and an apnoea/ hypopnoea index of >20/h (this threshold will exclude subjects with borderline OSA, in whom there may be little treatment effect).
2. Currently >20/h oxygen desaturations (=4% dips) returning on any night during an ambulatory nocturnal pulse oximetry performed during a 4-night period without CPAP.
3. Treated with CPAP for more than 12 months, minimum compliance 4h per night, AHI <10 with treatment (according to machine download data) and ODI<10 confirmed on CPAP during screening oximetry.
4. Written informed consent
5. Upper Age Limit 75 years, lower Age Limit 20 years
Participant type
Patient
Age group
Adult
Gender
Both
Target number of participants
Planned Sample Size: 30; UK Sample Size: 30; Description: Min. SS required 24 patients. 30 incorporates anticipated drop out rate.
Participant exclusion criteria
1. Previous ventilatory failure (awake resting arterial oxygen saturation <93% or arterial PCO2 > 6kPa) or severe respiratory disorders other than OSA
2. Unstable, untreated coronary or peripheral artery disease, severe arterial hypertension (>180/110mmHg), severe arterial hypotension (<90/60mmHg).
3. Previously diagnosed with CheyneStokes breathing.
4. Current professional driver.
5. Any sleep related accident.
6. Age <20 or >75 years at trial entry.
7. Severe nasal congestion.
8. Mental or physical disability precluding informed consent or compliance with the protocol
9. Nonfeasible trial followup (for example, distance from follow-up centre, physical inability).
10. Current smoker
Recruitment start date
02/03/2015
Recruitment end date
31/12/2016
Locations
Countries of recruitment
United Kingdom
Trial participating centre
Churchill Hospital
UKCRC Oxford Respiratory Trials Unit
Oxford Centre for Respiratory Medicine
Churchill Hospital Old Road
Oxford
OX3 7LE
United Kingdom
Funders
Funder type
Government
Funder name
Oxford Radcliffe Hospitals Charitable Fund (UK)
Alternative name(s)
Funding Body Type
Funding Body Subtype
Location
Funder name
ResMed (UK)
Alternative name(s)
Funding Body Type
Funding Body Subtype
Location
Results and Publications
Publication and dissemination plan
Data and findings from this trial will be disseminated as widely as possible at the end of the trial. There are no plans for an interim analysis in this trial due to there being only 30 patients in total.
Results will be presented in abstract form at national and international conferences to a respiratory audience at the British Thoracic Society Conferences, European Respiratory Society Congress, and American Thoracic Society Conference. Following on from this the research will be published in high-impact peer review medical journals, where possible utilising Open Access publication policies, to ensure a wide clinical and academic audience is reached to inform clinicians of the results and to inform future research.
In addition we plan to disseminate results to patients via collaboration with the charitable organization SATA (Sleep Apnoea Trust). Important research results are summarised in their regular newsletter, Sleep Matters and presented at their annual meeting, SATAday. Patients and public will also be kept informed of the progress and results of the study from local public patient involvement events organised by the Oxford BRC and Thames Valley CRN where appropriate.
Intention to publish date
Participant level data
Not provided at time of registration
Basic results (scientific)
Publication list
2018 results in: https://www.ncbi.nlm.nih.gov/pubmed/30025470