Assessment of effect of nasal continuous positive pressure on laryngeal opening using fibre optic laryngoscopy.

Aim: To assess the effect of nasal continuous positive airways pressure (CPAP) on the dimensions of the laryngeal opening.

Methods: Nine preterm infants who had previously received ventilatory support for respiratory distress syndrome (RDS) were studied. All were receiving nasal CPAP. The laryngeal opening was visualised using a fibre optic video camera system. The ratio of width to length of the opening was measured on and off CPAP.

Results: In eight of the infants the width: length ratio increased on CPAP; mean change for group +24.4% (95% CI +11.9 to +37.9).

Conclusions: Nasal CPAP seems to dilate the larynx. This may explain the selective beneficial effects of CPAP on mixed and obstructive apnoea.