A model for the central control of airflow patterns within the human nasal cycle.

BACKGROUND: The nasal cycle exhibits mainly reciprocal changes in nasal airflow that may be controlled from centres in the hypothalamus and brainstem. This study aims to gather new knowledge about the nasal cycle to help develop a control model.

METHOD: Right and left nasal airflow was measured in healthy human subjects by rhinomanometry. This was performed over 7-hour periods on 2 study days separated by approximately 1 week. The correlation coefficient for nasal airflow was calculated for day 1 and day 2.

RESULTS: Thirty subjects (mean age, 22.7 years) completed the study. The correlation coefficient for nasal airflow varied between r = 0.97 with in-phase changes in airflow and r = -0.89 with reciprocal changes in airflow. The majority of r values were negative, indicating reciprocal changes in airflow (50 out of 60). There was a tendency for r values to become more negative between day 1 and day 2 (p < 0.001).

CONCLUSION: A control model involving a hypothalamic centre and two brainstem half centres is proposed to explain both the in-phase and reciprocal changes in airflow associated with the nasal cycle.