Breathing is impacted by obesity. Early changes are characterised by significant breathing abnormalities during sleep (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. This study aims to understand breathing changes that occurs due to obesity and their resolution after weight loss surgery. The investigators are aiming to recruit participants with sleep disordered breathing who are currently awaiting bariatric surgery. In particular, the investigators are interested in comparing breathing changes in participants with OHS, who have abnormal regulation of their carbon dioxide levels, and participants with sleep disordered breathing with normal CO2 regulation. Participants will be recruited through outpatient clinics for sleep disordered breathing. The participants will undergo comprehensive breathing assessments on enrolment including an overnight sleep study. Participants will undergo further daytime breathing assessments before and after their bariatric surgery. End of study will be 6 months after surgery - participants 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 participants will be enrolled in the study for 2 years.
Study Type
OBSERVATIONAL
Enrollment
30
Weight loss surgery with either gastric sleeve or gastric bypass surgery
Guy's and St Thomas' NHS Trust
London, United Kingdom
RECRUITINGExpiratory flow limitation as measured by forced oscillation testing
Measurement of expiratory flow limitation at different position including upright, 45 degrees and supine. We will explore whether expiratory flow limitation can differentiate hypercapnic and eucapnic patients
Time frame: Measurements on enrolment into study; measurements prior to bariatric surgery (once patients has a surgery date); measurements 2-4 weeks after bariatric surgery; and end of study measurements 6 months after bariatric surgery
Degree of change in expiratory flow limitation
Explore whether the degree of positional change in expiratory flow limitation can differentiate between eucapnic and hypercapnic patients
Time frame: Measurements on enrolment into study; measurements prior to bariatric surgery (once patient has a surgery date); measurements 2-4 weeks after bariatric surgery; and end of study measurements 6 months after bariatric surgery
Closing capacity
Measurement of closing capacity at different position including upright, 45 degrees and supine. We will explore whether expiratory flow limitation can differentiate hypercapnic and eucapnic patients
Time frame: Measurements on enrolment into study; measurements prior to bariatric surgery (once patient has a surgery date); measurements 2-4 weeks after bariatric surgery; and end of study measurements 6 months after bariatric surgery
Degree of change in closing capacity
Explore whether the degree of positional change in closing capacity can differentiate between eucapnic and hypercapnic patients
Time frame: Measurements on enrolment into study; measurements prior to bariatric surgery (once patient has a surgery date); measurements 2-4 weeks after bariatric surgery; and end of study measurements 6 months after bariatric surgery
Correlation between closing capacity and expiratory flow limitation
Compare outcome 1 and 3 to explore whether there is a relationship between expiratory flow limitation and closing capacity
Time frame: Measurements on enrolment into study; measurements prior to bariatric surgery (once patient has a surgery date); measurements 2-4 weeks after bariatric surgery; and end of study measurements 6 months after bariatric surgery
Intra-abdominal pressure
We will measure intra-abdominal pressure and explore whether hypercapnic patients have increased intra-abdominal pressure. Positional changes will be measured
Time frame: Measurements on enrolment into study; measurements prior to bariatric surgery (once patient has a surgery date); measurements 2-4 weeks after bariatric surgery; and end of study measurements 6 months after bariatric surgery
Correlation between intra-abdominal pressure, closing capacity and expriatory flow limitation
Compare outcome 1,3 and 6. This is a complex multi-compartment model that can differentiate hypercapnia and eucapnic patients
Time frame: Measurements on enrolment into study; measurements prior to bariatric surgery (once patient has a surgery date); measurements 2-4 weeks after bariatric surgery; and end of study measurements 6 months after bariatric surgery
Upper airway collapsibility
Measurement of upper airway collapsibility as measure by negative expiratory pressure. Explore whether there is a relationship between hypercapnic and eucapnic patients depending on degree of upper airway collapsibility
Time frame: Measurements on enrolment into study; measurements prior to bariatric surgery (once patient has a surgery date); measurements 2-4 weeks after bariatric surgery; and end of study measurements 6 months after bariatric surgery
Lung compliance
Measurement of lung compliance with pressure volume curve including measurements in different positions (upright, 45 degrees and supine)
Time frame: Measurements on enrolment into study; measurements prior to bariatric surgery (once patient has a surgery date); measurements 2-4 weeks after bariatric surgery; and end of study measurements 6 months after bariatric surgery
Respiratory muscle strength (maximal inspiratory pressure/maximal expiratory)
Measurement of inspiratory and expiratory muscle strength
Time frame: Measurements on enrolment into study; measurements prior to bariatric surgery (once patient has a surgery date); measurements 2-4 weeks after bariatric surgery; and end of study measurements 6 months after bariatric surgery
Respiratory muscle strength (SNIP test)
Measurement of sniff nasal inspiratory pressure
Time frame: Measurements on enrolment into study; measurements prior to bariatric surgery (once patient has a surgery date); measurements 2-4 weeks after bariatric surgery; and end of study measurements 6 months after bariatric surgery
Daytime neural respiratory drive (para-sternal electromyography measurements)
Daytime neural respiratory drive as measured by parasternal electromyography (EMG) measurements can differentiate between hypercapnic and eucapnic patients
Time frame: Measurements on enrolment into study; measurements prior to bariatric surgery (once patient has a surgery date); measurements 2-4 weeks after bariatric surgery; and end of study measurements 6 months after bariatric surgery
Daytime neural respiratory drive (diaphragm electromyography measurements)
Daytime neural respiratory drive as measured by diaphragm electromyography (EMG) measurements can differentiate between hypercapnic and eucapnic patients
Time frame: Measurements on enrolment into study; measurements prior to bariatric surgery (once patient has a surgery date); measurements 2-4 weeks after bariatric surgery; and end of study measurements 6 months after bariatric surgery
Nocturnal neural respiratory drive (para-sternal electromyography measurements)
Nocturnal neural respiratory drive as measured by parasternal electromyography (EMG) measurements can differentiate between hypercapnic and eucapnic patients
Time frame: Measurements on enrolment into study; measurements prior to bariatric surgery (once patient has a surgery date); measurements 2-4 weeks after bariatric surgery; and end of study measurements 6 months after bariatric surgery
Nocturnal neural respiratory drive (diaphragm electromyography measurements)
Nocturnal neural respiratory drive as measured by diaphragm electromyography (EMG) measurements can differentiate between hypercapnic and eucapnic patients
Time frame: Measurements on enrolment into study; measurements prior to bariatric surgery (once patient has a surgery date); measurements 2-4 weeks after bariatric surgery; and end of study measurements 6 months after bariatric surgery
Quality of life post bariatric surgery with SF-36
Quality of life changes after bariatric surgery more than with standard medical therapy
Time frame: Measurements on enrolment into study; measurements prior to bariatric surgery (once patient has a surgery date); measurements 2-4 weeks after bariatric surgery; and end of study measurements 6 months after bariatric surgery
Quality of life post bariatric surgery with EQ-5D
Quality of life changes after bariatric surgery more than with standard medical therapy
Time frame: Measurements on enrolment into study; measurements prior to bariatric surgery (once patient has a surgery date); measurements 2-4 weeks after bariatric surgery; and end of study measurements 6 months after bariatric surgery
Symptom change after commencement of medical therapy compared to bariatric surgery measured with Epworth Sleepiness Scale
Symptom change after bariatric surgery is more than with standard medical therapy
Time frame: Measurements on enrolment into study; measurements prior to bariatric surgery (once patient has a surgery date); measurements 2-4 weeks after bariatric surgery; and end of study measurements 6 months after bariatric surgery
Symptom change after commencement of medical therapy compared to bariatric surgery measured with mMRC (modified medical research council) dypnoea score
Symptom change after bariatric surgery is more than with standard medical therapy
Time frame: Measurements on enrolment into study; measurements prior to bariatric surgery (once patient has a surgery date); measurements 2-4 weeks after bariatric surgery; and end of study measurements 6 months after bariatric surgery
Symptom change after commencement of medical therapy compared to bariatric surgery measured with Multi-dimensional dyspnoea profile
Symptom change after bariatric surgery is more than with standard medical therapy
Time frame: Measurements on enrolment into study; measurements prior to bariatric surgery (once patient has a surgery date); measurements 2-4 weeks after bariatric surgery; and end of study measurements 6 months after bariatric surgery
Symptom change after commencement of medical therapy compared to bariatric surgery measured with Severe Respiratory Insufficiency Questionnaire
Symptom change after bariatric surgery is more than with standard medical therapy
Time frame: Measurements on enrolment into study; measurements prior to bariatric surgery (once patient has a surgery date); measurements 2-4 weeks after bariatric surgery; and end of study measurements 6 months after bariatric surgery
Changes in healthcare resource usage in OHS patients post bariatric surgery
Estimation of healthcare usage cost in the 6 months prior to surgery and 6 months post surgery including medication costs and re-admissions to hospital
Time frame: 6 months pre bariatric surgery and 6 months post bariatric surgery
Improvement in daytime CO2 levels
Arterial blood gas performed before and after bariatric surgery with improvement in CO2 levels
Time frame: Measurements on enrolment into study; measurements prior to bariatric surgery (once patient has a surgery date); measurements 2-4 weeks after bariatric surgery; and end of study measurements 6 months after bariatric surgery
Improvement in apnoea-hyponoea index
Patients will have diagnostic sleep study before and after bariatric surgery
Time frame: Before bariatric surgery on enrolment and 6 months after bariatric surgery
Improvement in mean nocturnal oxygen saturation during sleep
Patients will have diagnostic sleep study before and after bariatric surgery
Time frame: Before bariatric surgery on enrolment and 6 months after bariatric surgery
Improvement in mean time spent below 90% oxygen saturation during sleep
Patients will have diagnostic sleep study before and after bariatric surgery
Time frame: Before bariatric surgery on enrolment and 6 months after bariatric surgery
Changes in sleep architecture measured by %slow wave sleep and %REM sleep
Patients will have diagnostic sleep study before and after bariatric surgery
Time frame: Before bariatric surgery on enrolment and 6 months after bariatric surgery
Improvement in diaphragm function
Diaphragm thickening will be measured by ultrasound assessment
Time frame: Measurements on enrolment into study; measurements prior to bariatric surgery (once patient has a surgery date); measurements 2-4 weeks after bariatric surgery; and end of study measurements 6 months after bariatric surgery
Improvement in glycaemic control
HbA1C will be measured before and after bariatric surgery
Time frame: Measurements on enrolment into study; measurements prior to bariatric surgery (once patient has a surgery date); measurements 2-4 weeks after bariatric surgery; and end of study measurements 6 months after bariatric surgery
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