Cardiac and Respiratory Function With Non-invasive Ventilation

Study Overview
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Brief Summary
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To assess patients with hypercapnic respiratory failure using echocardiography,cardiac output measurements and markers of neural respiratory drive (EMGpara) prior to, during and after non-invasive ventilation (NIV) initiation, and to follow the patients for 3 months. The investigators hypothesize that the improvement in cardiac function and/or respiratory mechanics over time are associated with ongoing improvements in oxygenation, quality of life and exercise capacity.

Detailed Description
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Respiratory failure is characterized by the incapacity of the respiratory system to maintain the normal arterial blood gas homeostasis. Specifically, the overlap of hypoxaemia and hypercapnia (PaCO2 >6 kPa) is referred to as Hypercapnic Respiratory Failure (HRF). HRF is one of the most common causes for hospital admission with high re-admission rates, therefore constitute a major burden on healthcare systems. Non Invasive Ventilation (NIV) is a well established treatment in patients with hypercapnic respiratory failure who frequently suffer with associated pulmonary hypertension (PH). NIV helps to increase arterial oxygenation and reduces hypercapnia. It is used in patients with hypercapnic respiratory failure caused by Obesity Hypoventilation Syndrome (OHS). The associated degree of PH can lead to an increased afterload of the right ventricle (RV) that causes progressive remodelling of the right heart. RV dysfunction is correlated with a reduced long term prognosis in respiratory conditions. In literature NIV is shown as effective method to treat acute hypercapnic respiratory failure in OHS. It has not been described how NIV impacts on cardiac function and NRD in OHS.

Official Title
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Improvement of Cardiac Function and Neural Respiratory Drive Following Set up of Non-invasive Ventilation in Patients With Hypercapnic Respiratory Failure Caused by Obesity Hypoventilation Syndrome

Conditions
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OHS, Hypercapnic Respiratory Failure

Intervention / Treatment
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* Other: Parasternal EMG (EMGpara) and Transthoracic Echocardiography


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Confirmed diagnosis of OHS and Overlap Syndrome Hypercapnic respiratory failure with the need to commence NIV Expected to remain an inpatient for ≥ 24 hours Age ≥ 18 and <80 years BMI >30 kg/m2 Confirmed sleep-disordered breathing Able to give informed consent to participation in the evaluation study Clinically stable without exacerbations for ≥ 6 weeks Exclusion Criteria: Patients established on NIV Inability to tolerate NIV (< 4 hours usage at during hospital titration) Contraindication to NIV Requirement for immediate invasive mechanical ventilation at admission or any other acute critical illness Acute infective exacerbation Presence of other acute pathology or critical illness (such as pulmonary embolism) Presence of acute or chronic Left ventricular Cardiac Failure Significant Kidney or Liver disease Significant Anaemia History of Pulmonary Embolism in the previous 2 years Presence of cardiac congenital disease Presence of Primary Pulmonary Hypertension Presence of other severe medical problem, e.g. cancer and systemic connective tissue disease and vasculitides Pregnancy Psychological and social factors that would impair compliance with the evaluation

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 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

| Intervention/Treatment |
| --- |
|Other: Parasternal EMG (EMGpara) and Transthoracic Echocardiography|OHS patients recruited will have EMGpara and Transthoracic Echocardiography at admission and when established on NIV at 3 months.|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Patients commencing on Non Invasive Ventilation (NIV); change in Cardiac Function from baseline and at 3 months | Patients with hypercapnic respiratory failure caused by obesity hypoventilation syndrome commencing on NIV; change in cardiac function using echocardiography at baseline and 3 months. Measurements taken prior to NIV initiation, and follow up at 3 months. | 3 months | 
| Patients commencing on Non Invasive Ventilation (NIV); change on Nueral Respiratory Drive (NRD) from baseline and at 3 months | Patients with hypercapnic respiratory failure caused by obesity hypoventilation syndrome commencing on NIV; change in markers of nerual respiratory drive/EMG para. Measurements taken prior to, and after NIV initiation, and follow up at 3 months. | 3 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Patients commencing on Non Invasive Ventilation (NIV); change in Oxygenation from baseline, 6 weeks post initiation and at 3 months | To demonstrate that the improvement in cardiac function and/or respiratory mechanics over time are associated with ongoing improvements in oxygenation by taking samples of arterial blood gases. Measurements are made prior to, during and after NIV initiation, and follow up at 3 months. | 3 months | 
| Patients commencing on Non Invasive Ventilation (NIV); change in Quality of Life from baseline, 6 weeks post initiation and at 3 months | To demonstrate the hypothesis that the improvement in cardiac function and/or respiratory mechanics over time are associated with ongoing improvements in quality of life by asking participants to complete the Medical Research Council (MRC) dyspnoea scale. Measurement will be taken prior to NIV initiation, 6 weeks post initiation and at follow up at 3 months. | 3 months | 
| Patients commencing on Non Invasive Ventilation (NIV); change in Quality of Life from baseline, 6 weeks post initiation and at 3 months | To demonstrate the hypothesis that the improvement in cardiac function and/or respiratory mechanics over time are associated with ongoing improvements in quality of life by asking participants to complete the modified BORG Scale (breathlessness). Measurement will be taken prior to NIV initiation, 6 weeks post initiation and at follow up at 3 months. | 3 months | 
| Patients commencing on Non Invasive Ventilation (NIV); change in Quality of Life from baseline, 6 weeks post initiation and at 3 months | To demonstrate the hypothesis that the improvement in cardiac function and/or respiratory mechanics over time are associated with ongoing improvements in quality of life by asking participants to complete the St George's Respiratory Questionnaire (SGRQ). Measurement will be taken prior to NIV initiation, 6 weeks post initiation and at follow up at 3 months. | 3 months | 
| Patients commencing on Non Invasive Ventilation (NIV); change in Quality of Life from baseline, 6 weeks post initiation and at 3 months | To demonstrate the hypothesis that the improvement in cardiac function and/or respiratory mechanics over time are associated with ongoing improvements in quality of life by asking participants to complete the Hospital Anxiety and Depression Scale (HADS). Measurement will be taken prior to NIV initiation, 6 weeks post initiation and at follow up at 3 months. | 3 months | 
| Patients commencing on Non Invasive Ventilation (NIV); change in Quality of Life from baseline, 6 weeks post initiation and at 3 months | To demonstrate the hypothesis that the improvement in cardiac function and/or respiratory mechanics over time are associated with ongoing improvements in quality of life by asking participants to complete the Epworth Sleepiness Scale (ESS). Measurement will be taken prior to NIV initiation, 6 weeks post initiation and at follow up at 3 months. | 3 months | 
| Patients commencing on Non Invasive Ventilation (NIV); change in Exercise Capacity. | To demonstrate that the improvement in cardiac function and/or respiratory mechanics over time are associated with ongoing improvements in oxygenation by participants performing the Gate speed of 4 metres test prior to,during and after NIV initiation and at 6 weeks post initiation, and follow up at 3 months. | 3 months |