Factors Associated With Chronic Respiratory Failure in Obesity

Study Overview
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Brief Summary
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Some overweight individuals develop problems with their breathing such that they gradually breathe less and less. This leads to a lack of oxygen and a buildup of carbon dioxide in the blood, called ventilatory failure. As a consequence, if such a person develops a chest infection, they are more likely to become seriously ill and need intensive care. In addition they are much more likely to develop severe complications during and following operations. This problem can be treated with a machine at home used overnight to help breathing. It is interesting that ventilatory failure only happens in some overweight individuals, and the investigators do not understand what factors make this complication develop. There are a number of theories: for example the distribution of the fat, additional lung disease (such as asthma), the addition of obstructive sleep apnoea, a condition when there are periods of cessation of breathing overnight (which is more common in obese individuals), weak muscles of breathing (perhaps due to fatty infiltration of muscles or vitamin D deficiency), and other hormonal changes. The investigators intend to measure many potential factors in a range of overweight individuals, some who have ventilatory failure, and some who do not, to try and work out which are the important factors that cause this problem. If the investigators can identify such factors, then this will help predict in advance who is at risk from chest infections and during operations; thus allowing for earlier provision of an overnight breathing machine. This should reduce complications and potentially deaths in such individuals.

Detailed Description
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To test the hypothesis that in obese patients with obesity-hypoventilation (OHS) there are specific factors related to the development of ventilatory failure, compared to obese subjects not in ventilatory failure

Official Title
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Factors Associated With Chronic Respiratory Failure in Obesity: A Cross-sectional Study

Conditions
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Obesity, Obesity Hypoventilation Syndrome

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Obese (BMI > 30) with or without obesity hypoventilation (OHS) (18 - 85yrs) Admitted for management of their OHS Attending the sleep and ventilation clinic Being assessed for bariatric surgery Willing and able to give informed consent for participation in the study Men and women aged 18 - 85 years Exclusion Criteria: Respiratory acidosis pH <7.30 Severe untreated hypothyroidism Current treatment with theophylline Current treatment with diuretics Severe restrictive or obstructive lung disease (<30% predicted) Severe comorbidities such as moderate/severe COPD, left sided heart failure, and primary CNS or neuromuscular diseases Contraindications to MRI scanning Contraindications to DXA scanning Previous participant in research in the last 12 months

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 85 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Study group<br>Obese BMI>30 18-85 years old | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| To determine the physiological between obese patients with OHS and obese patients without OHS | This will be a detailed ventilatory drive measurements and muscle strength testing. The comparison will be made within the group amongst the range of ventilatory failure | 1 year | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Obesity