Recommendations for clinical practice

The efficiency of NIV in patients with acute hypoxemic respiratory failure due to ALI, ARDS, or severe pulmonary infiltrates, and for whom endotracheal intubation is not mandatory, depends on the degree of hypoxia, the presence of comorbidities and complications, and the illness severity scores. It also probably depends on the respiratory drive of the patients. The high rate of NIV failure suggests a cautious approach with these patients, consisting of early NIV trial and no delay of needed intubation. Measurement of tidal volume under NIV may be important, and patients having tidal volume above 8 mL/kg of predicted body weight may be at higher risk of failure and of having an injurious breathing pattern. In those patients, lung- protective ventilation may be considered as a therapy. In addition, when using NIV in a patient with acute hypoxic respiratory failure, in an attempt to avoid intubation, one should always consider the risks of inappropriate intubation delay. Demoule et al. found that the effect of NIV differs between acute hypoxemic respiratory failure (including mainly in this definition, ALI and ARDS) and patients with cardiogenic pulmonary edema or acute exacerbation of COPD, because NIV failure was associated with higher mortality in patients with acute hypoxemic respiratory failure [32]. This finding should therefore raise a note of caution when applying NIV for this indication and make the clinician wonder whether a lung-protective ventilation is not more appropriate. Close monitoring is therefore crucial when using this technique as a first-line therapy in patients with ARDS. Delaying intubation may contribute to mortality [43]. NIV should not be considered primarily as an alternative to invasive ventilation.