High frequency oscillatory ventilation: is equivalence with conventional mechanical ventilation enough?

Several investigators have reported short term results of trials comparing high frequency ventilation with conventional mechanical ventilation in premature infants with respiratory distress syndrome. However, very few data are available on longer term outcomes in infants randomised to these two very different modes of mechanical ventilation.^1,2 In this issue, Marlow et al for the United Kingdom Oscillation Study Group (UKOS) report 2 year respiratory and neurological outcomes for the study cohort in their randomised trial of high frequency oscillatory ventilation (HFOV) compared with conventional mechanical ventilation. Although the prevalence of disability in their study cohort was high, they found no significant differences in neurodevelopmental scores or report of respiratory symptoms at 2 years of age between infants randomised to the two modes of ventilatory support.

The original report of the short term outcomes of their trial, published in 2002, showed no difference in the primary outcome (death or chronic lung disease at 36 weeks postmenstrual age) between the two ventilatory strategies.³ In addition, they found no differences in other complications of prematurity between the two groups, including cranial ultrasound abnormalities or air leak. The strengths of their study design include the rapid assignment of mode of ventilation (within one hour), its large size (797 infants randomised), near universal use of antenatal glucocorticoids and postnatal surfactant, and enrolment of infants at 28 weeks gestation or less, who are at highest risk of developing chronic lung disease. The lack of differences in outcome at 2 years in their present study is …