ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

The variation of flow rate with time in sinus I during nasal blow was very different from
the same sinus at 15 L/min. The flow rate through NO rapidly increased to nearly the
maximum at the very beginning, while the flow in both AOs each showed a short period
of low magnitude flow reversal, similar that seen in sinus II. Flow in AO1 initially held
steady, then increased until the midpoint of the blow, and finally declined, while flow in
AO2 increased at the very beginning, and decreased thereafter. Combined flows through
AO1 and AO2 equaled the flow through NO. Most of the time, the flow rate through
AO1 was proportional to the gross flow rate through the nasal cavity. Unlike sinus I
during nasal blow, both the variation of flow rate with time, and the magnitude of the
flow rate, for both the AO and the NO in sinus II were comparable to the responses of
the same sinuses during expiration at 15 L/min. At peak load during nasal blow, the
maximum flow rate through sinus I was 0.43 L/min compared to 0.46 L/min at 15
L/min, while the maximum flow rates through sinuses II during nasal blow were 0.74,
L/min, compared with 0.54 L/min at 15 L/min.
Fig. 3 Flow rate through the ostia during respiration.
Fig. 4 shows airflow streamlines passing through the ostia of maxillary sinuses at 15
L/min during peak inspiration and peak expiration. In sinus I, air entered NO and exited
AO2 during inspiration. No streamline was found passing through AO1 due to the low
flow through AO1. During expiration, sinus airflow reversed, by entering both AO1 and
AO2, and exiting NO. In sinus II, air entered AO and exited NO during both inspiration
and expiration. In addition, in both sinuses I and II, the streamlines through AOs were
relatively parallel to the cross-sections of AOs at both peak inspiration and peak
expiration. The streamlines through NOs, however, were almost perpendicular to the
cross-sections of NOs. In sinus III, the airflow entered and exited NO during respiration.
In addition, airflow circulated within all the three sinuses during both inspiration and
expiration.