Although there is relative consensus as to when mechanical ventilation should be initiated in the presence of respiratory insufficiency,1-3 the management of infants during recovery from respiratory failure remains largely subjective and is predominantly determined by institutional or individual practices or preferences. This might stem from a lack of understanding of the relative merits of the different techniques of discontinuing mechanical ventilation, given the availability of a variety of primary ventilatory modes, and limited research into the pathophysiological mechanisms responsible for an unsuccessful extubation. Moreover, weaning from mechanical ventilation is a dynamic process and is influenced, particularly in newborns, by many factors such as differing stages of lung development, changing status of the underlying lung disease, secondary complications, unique interaction of the neonatal heart and lungs, and the relation between central control of respiratory drive and respiratory muscles.4 ,5 It is not surprising that the current scientific literature fails to provide a uniform view of the most appropriate way to wean babies from mechanical ventilation.

The purpose of our paper is to review the physiological, mechanical, and clinical principles of weaning, and to highlight areas still in need of investigation. This has become even more important since the advent of high frequency and patient triggered ventilation. The older practice of decreasing ventilator rate and peak pressure has limited application to newer forms of neonatal mechanical ventilation.