Patients-ventilator Interaction During Sleep: the Role of Humidification. A Pilot Short Term Study

BACKGROUND Non-invasive mechanical ventilation (NIMV), usually delivered during night time, is widely used at home in chronic hypercapnic respiratory, both in patients with COPD and restrictive thoracic diseases (RTD). The aim of chronic NIMV is to improve daytime arterial blood gases, sleep quality decreasing symptoms of hypoventilation (mainly during sleep), quality of life and mood.

Scarce data is available about the NIMV compliance at home; poor compliance may reduce the positive effects of mechanical ventilation. Previous data shows that patients enrolled to long-term home ventilation program may drop out early, mainly because of skin irritation, upper airway problems, and air leaks.

Studies performed on patients with sleep apnea, receiving CPAP therapy at home, showed that the occurrence of leaks during ventilation can cause the development of mucosal inflammation, nasal congestion and increased nasal airways resistance. On the other hand, the presence or the development of nasal obstruction makes the arise or the worsening of air leaks (the vicious cycle) more reliable.

A lack of humidification may increase nasal resistance and nasal symptoms and, therefore, contribute to reduction in compliance. Furthermore, leaks may have significant consequences on inspiratory and expiratory trigger functions, inducing poor patient-ventilator interactions. Indeed, the presence of ineffective efforts, the most common phenomenon of bad patient-ventilation interactions, is very common in patients receiving long term home ventilation and usually associated with poorer gas exchange during sleep.

At present, little data is available in the medical literature regarding the affects of humidification on NIMV efficacy, sleep quality and upper airway symptoms in patients undergoing nocturnal NIMV.