Noninvasive Ventilation: Challenges and Pitfalls

Abstract

Noninvasive ventilation (NIV) is frequently used in patients with acute respiratory failure and its success is dependent on the underlying cause of the condition. When used for cases with a more rapid, reversible nature, like cardiogenic pulmonary oedema or acute exacerbations of chronic obstructive pulmonary disease, early intervention before patient deterioration is a key factor in success. Gastric distention-associated anastomose leakage after bariatric surgery is overestimated and the success of NIV trials in patients with encephalopathy has a strong association with the triggering cause rather than the severity of a coma. Immunocompromised patients mostly benefit from a short period of ventilation and more invasive ventilation is associated with excessively high mortality independent of the cause. In other diseases with parenchyma inflammation or infection, little success with NIV has been shown. Limiting ventilator-induced lung injury in these patients is another issue and is mostly achieved with heavy sedation or paralysis. Since NIV failure increases the risk of mortality, determination of a failing patient is of paramount importance. Clinical and laboratory surrogates of muscle fatigue can also be assessed. Adequate pressure support and positive end-expiratory pressure levels vary and the haemodynamic status of the patients must be considered. Ventilator–patient asynchrony increases NIV failure. Unfit interfaces also result in asynchrony, which will inevitably lead to failure, and observing waveforms can address this issue. The aims of this review were to understand the mechanism of NIV that leads to its failure or success, to become aware that delaying the appropriate therapy increases mortality, and to elucidate that spontaneous breathing can be a double-edged sword in some circumstances.