Clinical use of high-frequency oscillatory ventilation in adult patients with acute respiratory distress syndrome.
OBJECTIVE
High-frequency oscillatory ventilation (HFOV) is an emerging ventilatory strategy for adults that has been used successfully in the neonatal and pediatric population. This modality utilizes high mean airway pressures to maintain an open lung and low tidal volumes at a high frequency that allow for adequate ventilation while at the same time preventing alveolar overdistension. With the current understanding that excessive lung stretch and inadequate end-expiratory ventilatory volume may be injurious to the lungs, HFOV seems to be the ideal lung-protective ventilatory mode. During the past 8 yrs, there have been increasing numbers of studies describing its use in adult patients with acute respiratory distress syndrome. This article aims to review the published studies of HFOV in adults with acute respiratory distress syndrome with regard to its safety and efficacy.


METHODS
To assist us with our review, we did a search of MEDLINE (from 1966 to present) and EMBASE (1980 to present) databases to identify adult, clinical, English-language, research articles related to HFOV use. In addition, we reviewed relevant animal and mechanical ventilation studies. We did not perform a formal systematic review.


RESULTS
The application of HFOV was mainly reported as a rescue ventilatory mode in adult patients with acute respiratory distress syndrome who were thought to have failed conventional ventilation. In these patients, HFOV has consistently been shown to improve oxygenation without obvious increases in complications measured. There was only one randomized, controlled trial comparing HFOV with conventional ventilation. This study showed that there was a nonsignificant trend toward a lower mortality rate in the HFOV group. In addition, HFOV was as effective and safe as conventional ventilation. Although there are limitations, multiple studies have shown that earlier initiation of HFOV in patients with severe acute respiratory distress syndrome may also be associated with a lower mortality.


CONCLUSIONS
HFOV seems to be safe and effective for adults with severe acute respiratory distress syndrome who have failed conventional ventilation. Further research is needed to determine the ideal patients, timing, and optimal technique with which to provide HFOV. When considering HFOV as an early, lung-protective mode of ventilation, there is still a need to perform an adequately powered, randomized, controlled trial comparing it with the best available form of conventional ventilation. However, we believe that such a trial should wait until we have a better understanding of HFOV in adults.
Chan
Kenneth P W
KP
Inter-Departmental Division of Critical Care, Department of Medicine and Anaesthesiology, University of Toronto, Mount Sinai Hospital and University Health Network, Toronto, Ontario, Canada.
Stewart
Thomas E
TE
D000328:Adult; D006612:High-Frequency Ventilation; D006801:Humans; D012128:Respiratory Distress Syndrome / Q000628:therapy*