[Fitness training during nasal ventilation in diseases limited by dyspnea]

Five patients with chronic ventilatory failure demonstrated by arterial hyperkapnia and overloaded respiratory muscles under spontaneous ventilation (P01/P01 max) were adapted to passive noninvasive ventilation (ISB). Three of them suffered from severe COPD (FEV1 < 50%), two patients from severe restriction (VC < 30%). These patients had to undergo a bicycle ergometer exercise with and without nasal ventilation until they reached physical exhaustion with standardised incremental increase in external workload.

In both settings all patients were able to manage exercise up to their physical exhaustion. The anaerobic limit was exceeded each time. The total ventilation volume had to be increased two- to threefold during exercise with nasal ventilation to maintain the passive ventilation. The reduced load on the respiratory muscles was generally proven by lower pCO2 and higher pH levels. Without ventilation discontinuation of the exercise was caused by dyspnoea, whereas this was due to weakness in the legs under ventilation. In all five cases the achieved level of external workload was higher when supporting the respiratory muscles (43 watts vs. 36 watts) at lower lactate levels.

On a bicycle ergometer the respiratory muscles can be sufficiently relieved using noninvasive nasal ventilation. A higher level of workload, longer duration and a higher quality of exercise can be achieved thereby. The fact that patients without relief of load of the respiratory muscles complained of dyspnoea, whereas the fact that patients with ventilation complained of weakness in their legs indicates the high efficiency of this method, although the tested patients are severely handicapped individuals who usually do not undergo comparable physical exercise in their daily activities.