No longer recruiting: participants are no longer being recruited or enrolled

Measurement of Work of breathing (WOB), as well as pressure time product (PTP) of transdiaphragmatic pressures to evaluate the degree of muscle activity and muscle unloading during non-invasive ventilation.

The study makes comparison of a new developed auto adjusting controlled mode and a regular spontaneous mode.

Non-invasive ventilation (NIV) reduces carbon dioxide in hypercapnic respiratory failure by unloading the respiratory muscles. Spontaneous modes of NIV are usually being used in these situations. Spontaneous modes have the disadvantage, that the patient has to trigger the ventilator. The work to activate the trigger (WT) is estimated to be as high as up to 50% of the total work of breathing dependent on the underlying disease. Elimination of WT would increase the degree of respiratory muscle unloading.

A new pressure controlled mode incorporated into the ventilogic mechanical ventilator (Weinmann, Germany) is capable of self adjusting respiratory parameters in a preset range according to the patient requirements.

After a short period where the patients spontaneous respiratory parameters are being analyzed, the ventilator slowly implements a pressure controlled mode that matches the patients requirements.

This study intends to investigate if this new mode achieves a higher degree of respiratory muscle unloading compared to a spontaneous mode.

Inclusion Criteria:

• Healthy voluntary individuals
• PFT within normal limits

Exclusion Criteria:

• Disease of the upper GI-tract
• Any form of lung disease or disease of the upper airways
• Any form of muscular disease, especially neuromuscular disease pregnancy