Four nasal respiratory support systems on apnoea of prematurity: a randomized crossover trial

Nasal continuous positive airway pressure (NCPAP) is often used as respiratory support in infants with apnoea of prematurity (AOP), since it improves oxygenation and lung function, reduces upper airway resistance, preserves lung volume and reduces work of breathing. Following publication of a meta-analysis in 2002, nasal intermittent positive pressure ventilation (NIPPV), in addition to caffeine, is increasingly used instead of NCPAP to treat AOP. Furthermore, clinical experience suggests that other devices delivering NCPAP or NIPPV, such as bubble NCPAP or variable flow devices may be equally effective.
A German group conducted a randomized controlled trial with a cross-over design to compare three NCPAP/NIPPV devices and a conventional ventilator in NIPPV mode, for their effect on bradycardia and desaturation events, which are the most important symptoms of AOP.
In total, 16 infants (mean gestational age: 31 weeks) with AOP were allocated to receive nasal pressure support for 6 hours each, using four different modes: NIPPV via a conventional ventilator, NIPPV and NCPAP via a variable flow device (both non-synchronized), and NCPAP delivered via a constant flow Underwater Bubble System. The primary outcome was the cumulative event rate of bradycardias (= 80 beats per minute) and desaturation events (= 80% arterial oxygen saturation).
The median event rate was 6.7 per hour with the conventional ventilator in NIPPV mode, and 2.8 and 4.4 per hour with the variable flow device in NCPAP and NIPPV mode, respectively (p<0.03 for both compared to NIPPV/conventional ventilator). There was no significant difference between the NIPPV/conventional ventilator and the Underwater Bubble System.
Overall, these findings suggest that symptoms related to AOP could most effectively treated with a variable flow NCPAP device, and that non-synchronized NIPPV offered no advantage over NCPAP. These results are in contrast to a recent meta-analysis, which concluded that NIPPV reduces the frequency of AOP more effectively than NCPAP. However, this meta-analysis included only two studies, for a total of 54 infants, and one reported no significant difference in apnoea rate. No study focused on bradycardia or desaturation events or compared NIPPV against NCPAP delivered via a variable flow device. Moreover, NIPPV in both studies was delivered in synchronized mode: this may preclude the comparison with the German trial. In fact, the finding that non-synchronized NIPPV offered no further advantage over NCPAP can suggest that synchronizing the infant's own respiratory efforts during NIPPV is important to ensure the persistent opening of the lungs when applying nasal positive airway pressure support.
In conclusion, this study has shown marked differences in the effect of four nasal respiratory support systems on symptoms of AOP. In particular, a variable flow device in NCPAP and NIPPV mode may be more effective in the treatment of AOP than a conventional ventilator in NIPPV mode, since it could markedly reduce the work of breathing.

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