Nasal flow limitation in children

Nasal congestion due to the common cold may be exacerbated in small childre n because of their small nasal passages. Our aims were 1) to test the hypot hesis that smaller children have relatively larger nasal airways compared t o the intrathoracic airways, and 2) to examine the effect of stenting and a decongestant on nasal patency and nasal flow. During oral forced vital cap acity (FVC) maneuvers, expiratory flow is limited by intrathoracic airways. During nasal FVC, flow at high volumes is limited by the nose. The point w here the nasal flow-volume curve becomes superimposable on the oral curve ( %Sup) depends on the relative resistance of nasal and intrathoracic airways . Fifty-four healthy children (28 male), median age 9.5 years (range 5.9-16 .0), performed full forced respiratory maneuvers through. I)the mouth, 2) t he nose, 3) the nose after application of an external stent (Breathe Right( R) (BR) strip), and 4) the nose following instillation of xylometazoline. P eak inspiratory and expiratory flow (PIF and PEF), and mid-inspiratory and expiratory flow (MIF50 and MEF50) all showed a significant decrease from th e oral to the nasal baseline maneuver. Mean (SD) %Sup of the nasal baseline was 35.6 (13.7)% and was unrelated to height. PIF and MIF50 increased with the BR strip (P < 0.05). Xylometazoline also caused a significant increase in all measured flows (P < 0.05), Mean (SD) %Sup of the nasal maneuver aft er application of xylometazoline increased to 53.3 (14.0)%. We conclude tha t there is no evidence that relative resistance of nasal and intrathoracic airways change with height. The %Sup is easy to obtain and may prove a usef ul index of nasal patency. Pediatr Pulmonol, 1999; 27:32-36, (C) 1999 Wiley -Liss, Inc.