Insufficient evidence exists to support the use of high frequency oscillatory ventilation instead of conventional ventilation for preterm infants with severe lung disease who are given positive pressure ventilation. High frequency oscillatory ventilation (HFOV) is a newer way of providing artificial ventilation of the lungs. Theoretically, HFOV may produce less injury to the lungs, particularly when high pressures are used on conventional positive pressure ventilation. This review of the evidence from one randomised controlled trial suggests there might be less short-term lung injury from high frequency oscillatory ventilation. However, more babies in this group developed haemorrhage in and around the fluid spaces in the brain (cerebral ventricles) and this harm might outweigh any benefit. More information is needed to clarify the balance between benefits and harms of high frequency oscillatory ventilation instead of conventional positive pressure ventilation for preterm infants with severe lung disease.
There is insufficient information on the use of rescue HFOV to make recommendations for practice. The small amount of data that exists suggest that harm might outweigh any benefit. Any future use of HFOV as rescue therapy for preterm infants with severe RDS should be within randomised controlled trials and address important outcomes such as longer term pulmonary and neurological function.
Despite the increased use of antenatal steroids and surfactant replacement therapy, pulmonary disease, principally due to the respiratory distress syndrome (RDS), continues to be a major cause of mortality and morbidity in neonates. In addition to immaturity, lung distension during conventional ventilation (CV) is thought to be responsible for pulmonary air leak (PAL) and, together with oxygen toxicity, may be important in the cause of chronic lung disease (CLD). Studies of animals have suggested that high frequency oscillatory ventilation (HFOV) is an effective method of providing ventilation and oxygenation in severe experimental pulmonary disease and may result in less lung injury.
To determine the effects of HFOV compared to conventional ventilation (CV) on pulmonary air leak and CLD in preterm infants with very severe lung disease requiring ventilation.
A search was carried out for all randomised controlled trials from MEDLINE (1980 - April 2007) and EMBASE (1982 - April 2007) using the MeSH and text terms, "high frequency ventilation", "high frequency oscillatory ventilation", "oscillatory ventilation". The Oxford Database of Perinatal Trials and trials identified by the Neonatal Review Group of the Cochrane Collaboration (CENTRAL, The Cochrane Library, Issue 2 2007) were also reviewed. Information was also sought from experts in the field, cross references from studies and proceedings of meetings of the American Society for Pediatric Research (1991 - 2006).
Randomised controlled trials of HFOV vs. CV as rescue therapy in preterm infants with severe pulmonary dysfunction.
The standard review method of the Neonatal Review Group was used. This includes independent quality assessment and data extraction by the second author. Relative risk (RR), risk difference (RD) and number needed to treat (NNT) were used to express treatment effects.
Only one trial was found and this showed that rescue HFOV caused a reduction in any new pulmonary air leak (PAL) [RR 0.73 (95% CI 0.55,0.96), RD -0.17 (95% CI -0.32, -0.03)]. The number of infants that needed to be treated (NNT) to prevent one infant having any PAL was six (95% CI 3, 37). There was no significant difference in the rate of PIE or of gross pulmonary air leak, such as pneumomediastinum or pneumothorax. There was no significant effect on mortality or the use of IPPV at 30 days.
The rate of intraventricular haemorrhage (IVH) of any grade was increased in infants treated with HFOV, [RR 1.77 (95% CI 1.06, 2.96), RD 0.16 (95% CI 0.02, 0.29)]. Thus, for every six infants (95% CI 3, 50) given rescue HFOV, one infant developed IVH of any grade. There was a stronger, but non-significant trend towards an increase in severe IVH (grades 3 or 4 IVH).