Predictors of early nasal CPAP failure and effects of intubation criteria on the rate of mechanical ventilation in preterm infants

Mechanical ventilation or early nasal continuous positive airway pressure (nCPAP) may be used for early respiratory support in preterm infants. Although nCPAP may help to avoid mechanical ventilation, some infants receiving this intervention will need subsequent intubation and surfactant therapy. Therefore, identification of infants at risk of early nCPAP failure might be crucial to avoid negative effects from delayed surfactant application. No markers correctly predicting subsequent nCPAP failure have yet been identified. In addition, little information is available regarding the effects of using different criteria for intubation on the rate of infants needing mechanical ventilation.
On these bases, a German group has conducted a retrospective study to review the first 48 hours of life of all inborn infants of <29 weeks gestational age (GA), in order to identify early predictors of nCPAP failure and to calculate the potential effects of various intubation criteria on the rate and age at intubation.
Of 225 infants (GA 26.2±1.6 weeks), 140 (62%) could be stabilised with nCPAP in the delivery room, of whom 68 (49%; GA 26.9±1.5 weeks) succeeded on nCPAP with favourable outcome and 72 infants (51%; GA 26.3±1.4 weeks) failed nCPAP within 48 hours at a median age of 5.6 (interquantile range 3.3–19.3) hours. Statistical analysis showed that rate of maternal risk factors for severe respiratory distress syndrome was similar in the responder and failure group. In addition, parameters of gas exchange calculated from the first blood gas at admission were poor predictors of subsequent nCPAP failure. Possible effects of lower intubation thresholds were calculated showing that intubation at FiO2=0.35-0.45 rather than FiO2=0.6 results in a marginal increase of intubation rate and a decrease in the age at intubation (from 5.6 h to 3.1 h).
In conclusion, the results of this retrospective analysis show that, at present, there are no clinically adequate predictors of early nasal CPAP failure at time of admission to the neonatal intensive care unit. A threshold FiO2 of =0.35–0.45 as compared to =0.6 for selective intubation would shorten the time until surfactant delivery in infants with nCPAP failure without a relevant increase in the intubation rate. Therefore, an individualised approach with initial early nCPAP but with prompt intubation and surfactant treatment at a low FiO2 threshold may be, according to these results, the best approach in very low birth weight infants. It must be pointed out, however, that only a prospective randomised trial can clarify if such an approach actually results in clinically better outcomes.

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