Neonatal nasal intermittent positive pressure ventilation: current knowledge

Neonatal nasal intermittent positive pressure ventilation (NIPPV) provides non-invasive respiratory support to premature infants who may otherwise require endotracheal intubation and ventilation. These techniques are potentially life saving, but they are associated with increased pulmonary morbidity. NIPPV is the augmentation of continuous positive airway pressure (CPAP) with superimposed inflations, to a set peak pressure. Neonatal CPAP was shown to significantly improve pulmonary outcomes.

However, CPAP may be associated with important adverse effects and in 25-40% of low birthweight infants there is failure to extubate to CPAP. Efforts to reduce these failure rates prompted the use of NIPPV, as it may provide sufficient support to avoid endotracheal intubation in some infants. Current evidence indicates that NIPPV after extubation of very premature infants reduces the rate of reintubation. However, much is still not known about NIPPV including its mechanism of action.

It has been suggested that NIPPV may increase pharyngeal dilation, improve the respiratory drive, induce Head's paradoxical reflex and increase mean airway pressure (allowing recruitment of aveoli) and functional residual capacity. Moreover, some clinical results indicate that NIPPV may improve pulmonary mechanisms, tidal volume and minute ventilation but more studies are required to confirm these findings. There is some evidence that NIPPV marginally improves gas exchange. NIPPV is given through a tight-fitting mask covering the mouth and nose, or the nose alone, with minimal leak and an in-circuit flow trigger allows synchronisation.

For neonatal NIPPV, nasal prongs are used with variable leak via the mouth and nose, and no flow trigger. However, several different nasal and nasopharyngeal prongs have been used to deliver NIPPV. At present, more research is needed to establish which device is the best and which is the optimal setting. Moreover, there is still no definitive data regarding the use of synchronised rather than non-synchronised NIPPV. Synchronisation, defined as mechanical inflation commencing within 100 ms of the onset of inspiration, uses a capsule to detect abdominal movement at the start of inspiration.

No studies have compared strategies for weaning from NIPPV. Early in the history of NIPPV concerns were raised about excessive gastrointestinal perforations and cerebellar haemorrhage with face masks. These have not been reported in recent studies. Complications of nCPAP are well established and include gastric distension, nasal trauma and pneumothorax. These effects could reasonably be expected with NIPPV, although none have been formally reported.

Other possible complications may include middle ear infection, hearing impairment and chronic mucosal inflammation, although none have been reported. NIPPV is widely used. In fact, a recent survey of 91 neonatal units in England showed that 48% of nurseries are currently using NIPPV. However, more research is needed to define its role among techniques of neonatal respiratory support and exactly delineate in what conditions, and by what methods, it provides the most benefit with the least harm.

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