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Contact Information:

Dr Christopher Turnbull
None provided
Christopher.Turnbull@ouh.nhs.uk


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Be Part of Research - Trial Details - Feasibility of providing additional oxygen in patients with resistant high blood pressure and obstructive sleep apnoea
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Feasibility of providing additional oxygen in patients with resistant high blood pressure and obstructive sleep apnoea

Not Recruiting

Open to: All Genders

Age: Adult

Oxford

Medical Conditions

Obstructive sleep apnoea in patients with difficult-to-treat hypertension

This information is provided directly by researchers, and we recognise that it isn't always easy to understand. We are working with researchers to improve the accessibility of this information. In some summaries, you may come across links to external websites. These websites will have more information to help you better understand the study.


Obstructive sleep apnoea (OSA) is common affecting 1 in 4 adults to some extent. Whilst sleeping, patients with OSA have repeated episodes of narrowing of their throat leading to loud snoring, pauses in breathing, and disturbed sleep. Patients with OSA often feel sleepy in the daytime and often have high blood pressure. OSA is particularly common in patients who have persistently high blood pressure despite the use of medications, termed difficult-to-treat hypertension. Resistant hypertension affects up to 1 in 20 adults and increases the risk of heart attack and stroke.

The standard treatment for OSA is a tight-fitting face mask, called CPAP. Whilst CPAP is very effective, patients often struggle to use CPAP, especially those with few symptoms, such as many of those with difficult-to-treat hypertension and OSA. New treatments to reduce blood pressure are needed for patients with difficult-to-treat hypertension and OSA to reduce the risk of heart attacks and stroke. Overnight oxygen is easier to deliver than CPAP, not requiring a tight-fitting face mask and we recently showed that overnight oxygen can improve morning blood pressure in patients with OSA. However, it is not known whether oxygen can be used as a treatment for resistant hypertension in OSA. We aim to see if overnight oxygen is acceptable and suitable for use in patients with OSA and resistant hypertension. It is important to know this to help design larger studies to test if it is an effective treatment.

Start dates may differ between countries and research sites. The research team are responsible for keeping the information up-to-date.  

The recruitment start and end dates are as follows:

30 Apr 2021 31 Dec 2023

To reduce the number of hospital visits, the study will be explained to a potential participant in a virtual appointment by telephone or video-call. They will have been sent the Informed Consent form along with this Patient Information Leaflet by email so they will have copies of these for their reference during that call. If they agree to participate in this virtual appointment, the researcher will document this in the consent form and provide them with a copy for their records. With their permission, the team will review their medical notes to check that they are suitable for this study. Following this, there are two stages to this study, an initial stage looking at whether the participant has OSA, and then a stage when the team will ask the participant to use supplemental oxygen for two weeks. This study will involve extra appointments outside of normal clinic appointments.

Stage 1 involves two virtual appointments lasting approximately 20 minutes. Following stage 1, if the participant is suitable for Stage 2, they will have two face-to-face appointments lasting 1-2 hours. In the event face-to-face visits are not permitted, these will instead be virtual. The study will involve sleeping two nights wearing a sleep study kit in Stage 1 and using extra oxygen for two weeks in Stage 2.

Stage 1 of the study will involve virtual appointments. One of the researchers will arrange a telephone call or video call. The participant will have the opportunity to ask any questions that they may have about the study. The team will ask them some questions about any medical problems and write down details of their current medications. The team will then arrange for them to collect, or post-out a home sleep study kit, home blood pressure monitor and a participant to them. Once they have received these, the team will arrange a second telephone call or videocall to run through how to use these. They will then be asked to use the overnight sleep kit for two nights whilst they sleep.
This is a small device worn on your chest which connects to an oxygen probe which is worn on a finger and nasal prongs which sit in the nose. Once they have finished using your sleep kit for two nights, the participant will be asked to return the equipment to the team in a stamped addressed envelope.
Once we have received your sleep kit, the study team will explain the results to the participant. If this does not show OSA, they will not be suitable to go onto Stage 2 of the study and their participation in the study will end. If the study does show that the participant has OSA, they will be able to continue on to Stage 2 of the study.
Occasionally, the sleep studies do not provide suitable recordings to make a diagnosis. In which case there will be the opportunity to repeat the sleep studies up to twice. In this case, the team will again either arrange collection or postage of the sleep kit with the participant.

Stage 2 involves two face-to-face visits, a baseline and a follow-up visit. The team will phone the participant ahead of this appointment to check that they are well and to run through a COVID-19 safety check list. At baseline visit the participant will be asked to complete a questionnaire about their sleep and how it impacts their daily life. The participant’s blood pressure, heart rate, height, weight and neck circumference will be measured. The team will also take a 1ml blood sample from the participant’s earlobe to measure the levels of carbon dioxide in their blood.
The participant will be provided with an oxygen concentrator, tubing and given a choice of a face-mask or nasal prongs and shown how to use this. They will be asked to turn the oxygen concentrator on immediately before going to sleep and to turn it off immediately when they wake up in the morning. They will be provided with a pulse oximeter, which is a small device worn like a wrist-watch, and shown how to use this. They will then be instructed to sleep using both the oxygen concentrator and pulse oximeter for the next 14 nights.
In the event face-to-face visits are not permitted, this visit will instead be virtual. In this case, the blood test will not be done and the team will supply all of the equipment the participant will need ahead of this visit. If this appointment is virtual, the team will supply the participant with a single use tape measure and ask them to record your own height, weight and neck circumference if possible. After 14-17 nights, the team will arrange for the participant to come back to have a follow-up visit. At their follow-up visit they will again be asked to complete a questionnaire about their sleep and how this impacts their daily life. The team will measure the participant’s blood pressure and heart rate and will also take a repeat blood sample from their earlobe as on the first face-to-face visit. The team will collect the oxygen concentrator, pulse oximeter, blood pressure machine will not be taken.


Adults over 18 years, from the specialist cardiology hypertension clinic who have high blood pressure which is not controlled on at least one medication. We are not looking for participants with known OSA.
The study was initially designed to recruit patients with high blood pressure despite using at least three medications for blood pressure, but recruitment of these patients was not feasible and the protocol was amended.

You can take part if:



You may not be able to take part if:


1. Significant renal or hepatic impairment2. Scheduled elective surgery or other procedures requiring general anaesthesia during the trial3. Any other significant disease or disorder which, in the opinion of the Investigator, may either put the participants at risk because of participation in the trial, or may influence the result of the trial, or the participant’s ability to participate in the trial4. Participants who have participated in another research trial involving an investigational product in the past 12 weeks5. Secondary causes of hypertension (other than OSA)6. Excessive sleepiness with an ESS >16 (as assessed clinically prior to enrolment) or a history of sleepiness-related driving related accident 7. Professional drivers or vigilance critical occupation8. Any prior use of CPAP9. Current smoker or other cause of increased fire risk with oxygen therapy (i.e. relative smoking in the participant's residence)10. An AHI of <=15 on both nights of screening polygraphy 11. Baseline capillary blood gas PCO2 > 6.5kPa, or if unavailable, awake saturations < 93% on overnight polygraphy (assessed at the face to face Baseline visit prior to proceeding with the visit)


Below are the locations for where you can take part in the trial. Please note that not all sites may be open.

  • John Radcliffe Hopsital
    Oxford University Hospitals NHS Foundation Trust Headley Way
    Oxford
    OX3 9DU

Benefits: Taking part in this study may show that the participant has undiagnosed OSA. If this identified, the team can discuss the participant’s options for treating OSA at the end of the study.
Risks: Stage 2 of this study involves the use of oxygen therapy. Oxygen is a flammable gas. When using oxygen therapy during Stage 2, it is important that no-one smokes in the house and that the oxygen or air concentrator does not come into contact with naked flames (e.g. candles) as this would pose a fire risk. Oxygen therapy can cause a dry or blocked nose. Rarely oxygen therapy can cause nose bleeds or morning headaches.
The blood tests taken as part of the study can be slightly painful but should not be any more painful than normal blood tests. There is also a very low risk of tissue damage although this is very unlikely and the test will be conducted by an experienced clinician.

Dr Christopher Turnbull
None provided
Christopher.Turnbull@ouh.nhs.uk



The study is sponsored by University of Oxford and funded by Academy of Medical Sciences; Grant Codes: SGL022\1063.



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Read full details for Trial ID: ISRCTN51046126

Or CPMS 48021

Last updated 04 April 2023

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