Patient ventilator interfaces: practical aspects in the chronic situation.

In the ventilator-dependent patient, the nonpsychological problems of the chronic phase relate mainly to aspects of the patient ventilator interface. Humidification, suctioning of secretions, and ventilatory circuit and monitoring are the three most important aspects to which careful attention is needed. Good humidification can be obtained by means of various devices, which can provide humidity directly or indirectly: in the tracheostomized patient, the heat and moisture exchanger appears to be a good method because of its antibacterial properties. Airway suctioning is frequently needed in patients receiving ventilation invasively. Suctioning of secretions might possibly be associated with the risk of major cardiorespiratory complications: bacterial colonization of the airways and the subsequent increased risk of infection should be carefully considered. Problems concerning the ventilatory circuit and monitoring can be specific in patients with a tracheal cannula and those with a nasal/facial interface. Long-term tracheostomy in itself represents a real risk for bacterial colonization, damage to the tracheal mucosa, and to functioning of the vocal cords (both for speech and swallowing): therefore, a switch from invasive to noninvasive ventilatory interface may be proposed. Most problems with the nasal mask interface concern air leakage and the skin mucosal lesions. Two major aspects must be taken into account when considering the long-term effects of noninvasive ventilatory support monitoring: the possible effect of CO2 rebreathing, and the inadequate volume/pressure delivery, so that proper ventilation cannot be achieved. Use of an oral/mouth interface is of limited interest in subjects with restrictive disorders: air gastric distension and orthodontic problems are the most common side-effects in chronic use.