Alternative modalities of ventilation in acute respiratory failure.

Acute respiratory failure continues to complicate the management of critically ill trauma and surgical patients. Despite an increased understanding of the pathophysiology of this process, there is no golden bullet with which to stop or reverse it. Management remains directed toward maintenance of gas exchange and minimizing complications until such time as the process that initiated the respiratory failure has resolved and the lungs have an opportunity to recover. Continuous positive pressure ventilation with PEEP and oxygen is the conventional modality for achieving this goal. It is apparent that some patients are refractory to this therapy. In addition, there is evidence that alveolar injury may occur as a result of increasing airway pressures and shear forces. These authors have reviewed a number of modalities that seek to address these issues. IRV, whether pressure or volume controlled, appears at least able to provide adequate gas exchange in some patients who are refractory to conventional therapies. The same appears to be true for pressure control ventilation, airway pressure release ventilation, and volume control ventilation with a modified decelerating flow waveform. Whether any of these modalities will prove to alter outcome with respect to mortality remains to be seen. Work continues in the arena of extrapulmonary oxygenation. Results of recent studies are improved compared to the results of the NIH trial reflecting advances in technology, technique, and experience. The IVOX is a fascinating device that has been shown to effectively transfer respiratory gases, as has perfluorocarbon associated gas exchange. Whether these technologies will find a role in the treatment of adult respiratory failure awaits further study.