NIV in the acute setting: technical aspects, initiation, monitoring, and choice of interface

Noninvasive ventilation (NIV) reduces the work of breathing, improves gas exchange and may improve clinical outcome in patients with acute respiratory failure (ARF) of various origin. Failure of NIV occurs, however, in y20 30% of patients with hypercapnic ARF and in an even higher percentage of patients with hypoxaemic ARF. NIV failure may be due to clinical or technical factors such as the ventilatory mode and settings. Poor adaptation to the interface may also be responsible for some cases of NIV failure. It is therefore important to take into account these technical aspects in order to increase the efficacy of NIV. Both home and intensive care unit ventilators have been used to delivered NIV but the latter are preferred in the most severe critically ill patients. Three main types of interfaces are currently available in acute situation: facial, nasal and the helmet. The facial mask is generally considered the first choice in terms of efficacy. The helmet is an acceptable alternative to deliver continuous positive airway pressure in selected patients with hypoxaemic ARF. The most rational approach is, however, to adapt the type and the size of the interface on an individual basis. Humidification of inspired gas, often considered of minor relevance, is important to improve patient s comfort. In spite of a theoretical superiority of heated humidifiers over heat and moisture exchangers, particularly in patients with hypercapnic ARF, no study has yet confirmed it to date. Finally, adequate patient selection, preparation and monitoring are crucial in making NIV successful.