Nasal continuous positive airway pressure and non-invasive ventilation in preterm infants

Continuous positive airway pressure (CPAP) in newborn infants was first described in 1971. In the meantime the guidelines recommend the use of nasal CPAP (NCPAP) for the resuscitation of even the smallest preterm infants instead of immediate mechanical ventilation. Numerous NCPAP systems have appeared on the market in recent years which can be divided into two groups according to their operating mode. The first group includes jet CPAP systems which are also called variable flow NCPAP systems which create the pressure by one or two jets which blow gas with high velocity into the airways of the patients. Thus the required pressure is built up in the airways of the infants or directly in front of them. These machines generate only a low expiratory resistance; however, they produce a lot of noise which can reach noise levels of up to 100 dB(A). In the second group the pressure is created by means of an expiratory valve which works in a similar way to invasive ventilation systems. These systems generate more expiratory resistance but run much more quietly and even allow non-invasive ventilation. With jet systems non-invasive ventilation is very difficult. In small infants high flow nasal cannulas have become much more popular than conventional NCPAP systems. These systems are in between the above mentioned groups. They work by means of jets but the pressure achieved depends on the size relationship of the nostrils to the outer diameter of the nosepieces. High flow nasal cannulas are very convenient for the infants but the pressure applied by these systems cannot be controlled.