David N Hager1. 1. Johns Hopkins University, Baltimore, Maryland 21205, USA. dhager1@jhmi.edu
Abstract
PURPOSE OF REVIEW: High-frequency oscillatory ventilation (HFOV) is an attractive alternative to conventional lung protective ventilation. Adequate gas exchange is achieved with very small tidal volumes cycling at a high mean airway pressure. This may prevent injury from inspiratory overdistention and expiratory alveolar collapse. Most patients demonstrate improvements in oxygenation on HFOV though reductions in mortality are lacking. This may be explained by suboptimal technique. In this Opinion, the clinical experience using HFOV in adults in acute respiratory distress syndrome and the evolution of this ventilator technique are reviewed. RECENT FINDINGS: At some settings, currently available high-frequency ventilators may deliver tidal volumes that approach the magnitude of those delivered during conventional ventilation. Significantly smaller tidal volumes are achieved at higher frequencies (>6 Hz) and are tolerated in most patients. The aggressive use of recruitment maneuvers can significantly improve oxygenation during HFOV. Two large randomized controlled trials are underway that incorporate these findings into their protocols. However, not all patients tolerate HFOV and increased rates of barotrauma have been reported in some studies. SUMMARY: Although HFOV is theoretically appealing and may improve outcomes in adults with acute respiratory distress syndrome, it should be reserved for patients failing conventional ventilation until definitive trials are completed.
PURPOSE OF REVIEW: High-frequency oscillatory ventilation (HFOV) is an attractive alternative to conventional lung protective ventilation. Adequate gas exchange is achieved with very small tidal volumes cycling at a high mean airway pressure. This may prevent injury from inspiratory overdistention and expiratory alveolar collapse. Most patients demonstrate improvements in oxygenation on HFOV though reductions in mortality are lacking. This may be explained by suboptimal technique. In this Opinion, the clinical experience using HFOV in adults in acute respiratory distress syndrome and the evolution of this ventilator technique are reviewed. RECENT FINDINGS: At some settings, currently available high-frequency ventilators may deliver tidal volumes that approach the magnitude of those delivered during conventional ventilation. Significantly smaller tidal volumes are achieved at higher frequencies (>6 Hz) and are tolerated in most patients. The aggressive use of recruitment maneuvers can significantly improve oxygenation during HFOV. Two large randomized controlled trials are underway that incorporate these findings into their protocols. However, not all patients tolerate HFOV and increased rates of barotrauma have been reported in some studies. SUMMARY: Although HFOV is theoretically appealing and may improve outcomes in adults with acute respiratory distress syndrome, it should be reserved for patients failing conventional ventilation until definitive trials are completed.