Page 41 - Physiological based CPAP for preterm infants at birth Tessa Martherus

CPAP and is feasible to use in the delivery room. The CPAP levels generated by nasal high flow are, however, dependent on fluctuating factors, for example, mouth opening and cannula size in relation to the infants’ anatomy, therefore it is hard to predict and measure the generated CPAP level.
Currently, there are several CPAP devices used in the delivery room. Bench test implicate that
the WOB that they produce can significantly differ and novel devices are designed to reduce
WOB. The bench test setting is not completely comparable to clinical practice, but the new
device is now tested in the delivery room for safety and efficiency. 1
Interfaces for non-invasive respiratory support
The facemask is currently the most commonly used interface for delivering CPAP in the delivery room (13-16), but sometimes we observe a change in breathing pattern when applying too much pressure on the facemask. As the facemask is placed on the nasotrigeminal area, it could influence the breathing pattern via the trigeminal nerve. Stimulation of this area is well known to cause a cessation of breathing pattern bradycardia, peripheral vasoconstriction and closure of the larynx (48-51). This may provide explanation for failure of CPAP in a number of infants. Observational studies in human adults (52, 53) and infants (54, 55), however, described an initial increase in tidal volume after positioning a facemask. The increase could have been due to an increase in dead space volume as tidal volume and respiratory rate were restored after removal of mask (51, 55). Although healthcare providers should be aware of the possibility of mask leak, it seems prudent to place the mask as gently as possible to prevent any inhibition of breathing.
To avoid mask leak and/or potential reflexes of the facial nerves inhibiting breathing, alternative interfaces for delivering CPAP could be used. Kamlin et al. (56) reported no difference in intubation rate or any other outcome when the nasal tube was compared with the facemask for providing PPV to preterm infants at birth and concluded that the nasal tube would be a good alternative to the facemask. Hereafter, van Vonderen et al. (57) performed a subgroup analysis on the physiological parameters. Forty-three of 363 infants, whose resuscitation was recorded by a respiratory function monitor, were included in the analysis. This analysis showed more leak and obstruction when using the nasal tube, leading to lower tidal volumes and oxygen saturations and higher requirement for supplemental oxygen.
McCarthy et al. (58) compared single nasal prongs with facemasks in preterm infants requiring CPAP in the delivery room. No difference in intubation rate was observed between groups, but higher oxygen saturations and lower supplemental oxygen levels were reported when using prongs. The clinical relevance of this primary outcome was questioned by the authors, as all other clinical outcomes, in both the delivery room and at the ward, were similar between groups. The authors suggested binasal prongs as these are superior to single nasal prongs after extubation at the clinical unit (59).
Supporting breathing of preterm infants at birth
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