Humidification therapy; long-term effects in COPD and OSAS patients.

Humidification therapy is widely used in patients during invasive ventilation and the importance of heating and humidifying the inhaled air is well defined in both the acute and long term setting. On the other hand the continuous usage of humidification in noninvasive ventilation is controversial and the long term effects are still not well defined. The usage of noninvasive ventilation is especially important in hypercapnic Chronic obstructive pulmonary disease (COPD) and also the obstructive sleep apnea syndrome (OSAS) patients and compliance to this treatment is essential in long term. Limited number of studies have shown that heated humidification is preferred by COPD patients and might help in mucus clearance, reduce mucus viscosity and help in expectoration, but there was shown no priority as far as concerns the lung function or blood gas parameters. Humidification might also be important in long term oxygen treatment since the inhalation of dry air can lead to ciliary dysfunction, alterations in mucus properties and mucociliary clearance impairment. Studies concerning OSAS patients showed that humidification helps to reduce the nasal symptoms but plays no role in increasing the compliance of patients in long term. Multi-center studies with large number of patients are needed to identify patients' groups who are likely to benefit from the addition of humidification to noninvasive therapy.