is a fatal lung condition that limits the oxygen levels in the blood. It is a
sudden failure of the breathing system and is a common complication of critical
illness. ARDS is associated with high mortality; long term complications are
common in survivors. Mechanical ventilation which is life saving for patients
with ARDS may however cause lung injury. The repetitive overstretching or
collapse of lung units with each respiratory cycle during mechanical
ventilation is feared to cause changes contributing to multi-organ failure and
oscillatory ventilation (HFOV) is an approach which delivers very small tidal
volumes at very high rates (tidal volume refers to the volume of air that is
inhaled or exhaled during quiet breathing). Previous trials of the use of HFOV
in adults with ARDS had shown that the strategy delivers better oxygenation and
improves survival. These trials were however limited by small sample sizes and
outdated ventilation strategies. HFOV remains an unproven therapy for adults
with ARDS despite the more common use in recent years.
carried out studies in multiple countries to evaluate the role HFOV in ARDS
patients. They randomized patients with new-onset,
moderate-to-severe ARDS to receive HFOV or to a control ventilation strategy
with the use of low tidal volumes and high positive end-expiratory
In this study, the risk of death was found to be higher in
patients on HFOV. The results therefore do not encourage the early use of HFOV
in ARDS and the study had to be terminated early due to the high in-hospital
mortality caused by HFOV.
The study also found that patients who received HFOV required
longer-duration neuromuscular blockade and sedation. More supportive care was
also required to this group of patients. In the light of this study, it is hard
to justify the use of HFOV as a 'rescue therapy' for new-onset,
moderate-to-severe ARDS patients.
Oscillation in Early Acute Respiratory Distress Syndrome; Niall Ferguson et al;
N Engl J Med 2013; 368:795-805.