Editor—Cools and Offringa’s recent meta-analysis of elective high frequency ventilation (HFV) in preterm infants with respiratory distress syndrome1 concludes that HFV reduces the risk of chronic lung disease (CLD) at 36 weeks of postconceptional age, but may be associated with an increased risk of severe intraventricular bleeding. Several areas of uncertainty remain, however, and they suggest that new clinical trials should be done in very preterm infants to evaluate the usefulness of elective HFV, using a high lung volume strategy, started as soon as possible after birth. We are currently running exactly such a trial in the UK—the United Kingdom Oscillation Study (UKOS).

This is a multicentre trial comparing high frequency oscillatory ventilation (HFOV) with conventional ventilation in preterm infants < 29 weeks of gestation. Previous trials have included more mature babies, but we have restricted recruitment to those babies with the highest incidence of chronic lung disease and of neurological complications. We expect to recruit 1200 babies over two years, making this the largest study of its kind so far, with the greatest statistical power. To avoid selection bias, treatment allocation is by a central telephone randomisation service. Infants are given their allocated mode of ventilation within one hour of birth (up to 15 hours in previous studies) to assess the effect of early intervention with HFOV, which has been shown to be most beneficial in animal studies.2 Long term neurodevelopmental and pulmonary outcome will be evaluated up to 2 years of corrected gestational age; only two previously published studies3 4 have done this.

Keszler and Dunn in North America (personal communication) also have an ongoing study of a similar nature, and we hope that the results of these trials will provide the evidence for future ventilation policy for very preterm infants.