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 (CPA P) on the dimensions of the laryngeal opening. Methods-Nine preterm infants who had previously received ventilatory suppor t 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 sel ective beneficial effects of CPAP on mixed and obstructive apnoea.