The aim of the study is to investigate the additional effects of the use of NIV during exercise within a 3-week PR program on exercise capacity in COPD patients with chronic hypercapnic respiratory failure.

Scientific Background/ Rationale:

Quality of life and exercise tolerance are commonly reduced in people with chronic obstructive pulmonary disease (COPD), especially in people with chronic hypercapnic respiratory failure (CHRF). Endurance exercise training as part of a pulmonary rehabilitation (PR) programme is an important treatment for people with COPD and has been shown to improve quality of life, exercise tolerance and physical activity. However, individuals with CHRF may have difficulties performing endurance exercise at an adequate training intensity to achieve the desired physiological changes.

Non-invasive ventilation (NIV) is a method of providing breathing support using a ventilator and is usually delivered via a full face mask. A recent study showed that during a single exercise session in people with CHRF, NIV dramatically improves exercise tolerance and reduces breathlessness. Consequently, NIV used over a complete exercise training program may allow people with COPD and CHRF to exercise at a higher intensity to achieve greater improvement in exercise tolerance, quality of life and physical activity. So far this has only been tested in a small number of studies with small numbers of participants, and none with CHRF. It is currently not known from literature whether the demonstrated benefits of NIV during exercise training are clinically worthwhile or cost-effective.

Aims The aim of the study is to investigate the additional effects of the use of NIV during exercise within a 3-week PR program on exercise capacity in COPD patients with chronic hypercapnic respiratory failure.

Hypothesis It is assumed that a 3-week exercise training program with additional NIV, using titrated pressures, reduces the work of breathing. With this, it is theorized, COPD patients with CHRF are able to train for a longer duration and/ or with higher training intensities over the course of the training program and may achieve better PR outcomes.

Primary Hypothesis:

H.0: COPD-Patients with CHRF have the same increase in exercise capacity (endurance cycle time) when training with additional NIV as without NIV, during a 3-week PR program.

H.1: COPD-Patients with CHRF have a superior increase in exercise capacity (endurance cycle time) when training with additional NIV as without NIV, during a 3-week PR program.

Main Objective To determine if NIV during exercise is a useful tool for increasing exercise tolerance in hypercapnic patients, exercise tolerance (cycle endurance time) will be measured without NIV at PR admission/ discharge

Materials and Method A total of 26 COPD patient (age: 40-80 years) in GOLD Stages IV diagnosed with CHRF, already treated with nocturnal NIV and referred for a comprehensive PR program will be recruited and randomized into two groups: 1) exercise with NIV during exercise (nocturnal NIV will continue) and 2) control group - exercise without NIV during exercise (nocturnal NIV will continue).

Initially, patients will perform a maximum cardiopulmonary test to determine the Peak Work Rate (WRpeak). On a separate day, patients will perform a cycle endurance test (CET) at 75%WRpeak without NIV using oxygen as prescribed, if needed. TcPCO2, heart rate and SpO2 via SenTec will be measured continuously during CET. In addition to the continuously recorded data, dyspnoea/ respiratory effort/ leg-fatigue (10-point Borg scale), capillary blood gases and the arterial blood pressure will be taken at the beginning/ end/ recovery/ isotime of the CET.

Inclusion Criteria:

• Diagnosis of very severe COPD Gold Stage IV
• Age: 40-80 years
• PaCO2 >50mmHg (at rest, during sleep or exercise)
• Implemented nocturnal non-invasive ventilation therapy

Exclusion Criteria:

• Concomitant cardiovascular, orthopaedic or neurological conditions that are likely to be the primary impairment to exercise performance
• Other significant pulmonary disease which could affect exercise or NIV (e.g. asthma)
• BMI > 35 kg/m2
• Inability to give informed consent