Continuous positive airway pressure (CPAP) is widely used in neonatal units both 
as a primary mode of respiratory support and following extubation from 
mechanical ventilation. In this review, the evidence for CPAP use particularly 
in prematurely born infants is considered. Studies comparing methods of CPAP 
generation have yielded conflicting results, but meta-analysis of randomised 
trials has demonstrated that delivering CPAP via short nasal prongs is most 
effective in preventing re-intubation. At present, there is insufficient 
evidence to establish the safety or efficacy of high flow nasal cannulae for 
prematurely born infants. Observational studies highlighted that early CPAP use 
rather than intubation and ventilation was associated with a lower incidence of 
bronchopulmonary dysplasia (BPD), but this has not been confirmed in three large 
randomised trials. Meta-analysis of the results of randomised trials has 
demonstrated that use of CPAP reduces extubation failure, particularly if a CPAP 
level of 5 cm H2O or more is used. Nasal injury can occur and is related to the 
length of time CPAP is used; weaning CPAP by pressure rather than by 
"time-cycling" reduces the weaning time and may reduce BPD. In conclusion, 
further studies are required to identify the optimum mode of CPAP generation and 
it is important that prematurely born infants are weaned from CPAP as soon as 
possible.