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NIV in Acute Respiratory Failure

　　The use of BIPAP in acute exacerbations of chronic obstructive pulmonary disease (COPD) has the most compelling clinical evidence, according to Gregory Schmidt, MD,[2] of the University of Chicago, Chicago, Illinois. In this setting, the inspiratory pressure can assist overloaded ventilatory muscles, while the expiratory pressure can reduce the breath triggering load imposed by intrinsic positive end-expiratory pressure. The ideal patient is one in whom impending respiratory failure is present but in whom cooperation with a mask system is still possible (ie, not in extremis). Multiple controlled trials have shown that in this scenario, BIPAP reduces the need for endotracheal intubation and may impact subsequent mortality.[1,3] More recent studies have also suggested that similar benefits may be obtained when using BIPAP in COPD patients with delayed deterioration while hospitalized.
　　There are fewer data supporting the use of NIV in other forms of acute respiratory failure. In status asthmaticus, observational data suggest benefit, but randomized trials are lacking. In acute hypoxemic respiratory failure, trials suggest a reduction in the need for endotracheal intubation and better outcomes (although this is not a universal finding).[4] The strongest of these data come from the immunocompromised (especially transplant) patient population, perhaps because they are at particular risk for VAP.
　　Two other applications of BIPAP in acute respiratory failure deserve comment. First, in the end-of-life patient not wishing to be endotracheally intubated, BIPAP has been shown to reduce dyspnea and, thus, potentially reduce the need for sedation. Second, in the patient with compromised lung function requiring conscious sedation for procedures (eg, bronchoscopy), BIPAP has been shown to be a useful modality to avoid endotracheal intubation periprocedure.[5]