OBJECTIVETo compare the characteristics of normal nasal airflow during periodic breathing and steady-state breathing.

METHODSFluent software was used to simulate the nasal cavity and paranasal sinus structures following CT scanning of a normal adult subject. Air flow velocity, pressure, distribution and streamlines were calculated and compared during periodic breathing and steady-state breathing.

RESULTSThe same flux, the performance of nasal airflow on 15.600 s of periodic breathing and steady-state expiratory (entrance flow was 697.25 ml/s) were as follows: air flow in the common and middle meatus accounted for more than 50% and 30% of total nasal cavity flow during two respiratory status. Flow velocity and pressure of nasal cavity and each paranasal sinus were extremely similar. The flow trace during two respiratory status in the inferior and lower part of the common meatus were predominately straight in form.Flow were parabolic in the middle and superior meatus and the middle and upper parts of the common meatus. The flow trace of nasal airflow on 16.495 s of periodic breathing had wide areas vortex in nasopharynx and limen nasi, the average speed was 0.0706 m/s, while the entrance flow 7.62 ml/s stable state of the left nasal expiratory, the average speed was 0.0415 m/s, the flow trace was similar to 697.25 ml/s.

CONCLUSIONThe same flow, except in the junction of the respiratory cycle, the performance of normal nasal airflow during periodic breathing and steady-state breathing were similar.