High frequency oscillatory ventilation in adult patients with acute respiratory distress syndrome

Clinical trials on the use of mechanical ventilation in Acute Respiratory Distress Syndrome (ARDS) showed that use of low tidal volumes reduces the mortality significantly. Another approach that proved beneficial was to open the lung and keep it open. Theoretically, this can be best achieved with High Frequency Oscillatory Ventilation (HFOV). HFOV provides oscillations at three to ten Hertz in adults. Both inspiration and expiration are active. Gas exchange occurs even though the tidal volume delivered during each oscillation is less than the anatomical dead space. Furthermore, the potential adverse effects of the conventional ventilation such as alveolar overdistension, and repeated opening and collapse of alveoli are reduced. Many investigators have studied the potential benefit of HFOV in neonatal and paediatric population but the evidence for its use in adult population is limited. A lot of work is being done and two large ongoing trials OSCAR and OSCILLATE should give better idea regarding its use in adults. This review article mainly focuses on the principles and practices of HFOV in adults and current evidence regarding its use in adults.