PHOEBI
Research type
Research Study
Full title
Pathophysiology of Hypoventilation in Obesity and Effect of Bariatric Intervention (PHOEBI Study)
IRAS ID
258045
Contact name
Joerg Steier
Contact email
Sponsor organisation
Guy's and St Thomas' NHS Foundation Trust
Duration of Study in the UK
4 years, 0 months, 1 days
Research summary
The way that we breathe is impacted by obesity. Early changes are characterised by significant breathing
abnormalities when we are asleep (a condition called sleep disordered breathing, the most common of which is
obstructive sleep apnoea). As the breathing changes worsen in severity, it may result in a rise in carbon dioxide levels
during daytime causing a condition called obesity hypoventilation syndrome (OHS). The current treatment for obesity
related breathing changes include supportive breathing therapy at night, optimisation of associated medical
conditions and weight loss.
Weight management is an important part of obesity treatment. Weight loss strategies such as life-style modification
do not always work. Weight loss surgery (bariatric surgery) has been shown to be an effective weight management
intervention with long-term results. Our study aims to understand the breathing changes that occurs due to obesity
and their resolution after weight loss surgery. We are aiming to recruit patients with sleep disordered breathing who
are currently awaiting bariatric surgery. In particular, we are interested in comparing breathing changes in patients
with OHS, who have abnormal regulation of their carbon dioxide levels, and patients with sleep disordered breathing
with normal CO2 regulation.
Patients will be recruited through outpatient clinics for sleep disordered breathing. The subjects will undergo
comprehensive breathing assessments on enrolment including an overnight sleep study. Subjects will undergo
further daytime breathing assessments before and after their bariatric surgery. End of study will be 6 months after
surgery – subjects will have a final comprehensive breathing assessment including an overnight sleep study to review
resolution of their breathing changes. Depending on the wait list time for the bariatric surgery, it is anticipated that
patients will be enrolled in the study for 2 years.REC name
East Midlands - Leicester South Research Ethics Committee
REC reference
19/EM/0108
Date of REC Opinion
20 May 2019
REC opinion
Further Information Favourable Opinion