Non-invasive ventilation in acute respiratory distress syndrome: helmet use saves lives?

Acute respiratory distress syndrome (ARDS) is a syndrome characterized by acute hypoxemic respiratory failure resulting from myriad of causes that injure the alveolar epithelium or the capillary endothelium or both (1,2). ARDS was first described by Ashbaugh et al. in 1967 (3). Over the years, there have been several changes in the definition of ARDS. The initial definition relied on the measurement of pulmonary capillary wedge pressure and did not include the application of positive end expiratory pressure (PEEP) as a criterion (4). The current widely accepted definition not only specifies the duration of the acuteness of presentation but also quantifies the severity of ARDS based on the degree of hypoxemia and includes PEEP in the definition (5). The management of ARDS is primarily based on a combination of supportive care and invasive mechanical ventilation. Apart from low tidal volume strategy and prone position ventilation, none of the other approaches have been shown to reduce mortality (6,7). The application of invasive mechanical ventilation is associated with several complications related to endotracheal intubation including ventilator-associated pneumonia (8). The current mortality rates across various centers varies between 30% and 40% (5,9). One strategy to avoid invasive mechanical ventilation is the use of non-invasive ventilation (NIV). NIV is the provision of positive airway pressure for mechanical ventilation without the need of an endotracheal airway (10,11). Positive airway pressure can be delivered either as continuous positive airway pressure (CPAP) or as bilevel positive airway pressure wherein the positive pressure is either same or different during inspiration and expiration, respectively (10,11). NIV can be administered either with the dedicated portable NIV ventilators or the intensive care unit (ICU) ventilators (12).