Humans breathe through only one nostril at a time due to the nasal cycle
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Peer-reviewed literature demonstrates that human nasal airflow alternates predominantly through one nostril at a time due to a cyclical congestion and decongestion of the nasal passages known as the nasal cycle.
BACKGROUND
Human unilateral nasal airflow shows spontaneous changes over a period of hours due to the alternating congestion and decongestion of the venous sinuses within the nasal turbinates and nasal septum. The aim of the present study was to compare PNIF and unilateral PNIF with nasal resistances measured by means of AAR in the evaluation of the nasal cycle.
METHODS
PNIF, unilateral PNIF and AAR measurements were randomly performed in 20 non-smokers, non-asthmatic volunteers, with a SNOT 22 score lower than 1. Nasal measurements were done four times in a single day at 08.30, 11.00, 13.30 and 16.00. The correlation between PNIF, unilateral PNIF and nasal resistances was studied. The pattern of nasal airflow for each subject was also analyzed.
RESULTS
A significant negative correlation between PNIF-lPNIF-rPNIF and respectively AAR-lAAR-rAAR was found. Only 1 subject did not show nasal cycle, while all the rest were equally distributed between a reciprocal pattern of the nasal cycle, or an in-phase changes of the nasal cycle, both at PNIF and AAR.
CONCLUSIONS
Nasal cycle can be easily assessed by means of PNIF. In fact, AAR and PNIF showed a reasonable correlation in the measurement of nasal cycle, although PNIF offered a lower variability. Reciprocal and in-phase patterns of the nasal cycle were equally distributed in our population.
To study the characteristics of nasal airflow in the presence of nasal cycle by computational fluid dynamics. CT scan data of a healthy Chinese individual was used to construct a three-dimensional model of the nasal cavity to be used as simulation domain. A sinusoidal airflow velocity is set at the nasal cavity entrance to reproduce the breathing pattern of a healthy human. There was a significant difference in the cross-sectional area between the two sides of the nasal cavity. Particularly, the decongested side is characterized by a larger cross-section area, and consequently, by a larger volume with respect to the congested side. The airflow velocity, pressure, and nasal resistance were higher on the congested narrow side. The temperature regulation ability on the congested narrow side was stronger than that on the decongested wider side. During the nasal cycle, there are differences in the nasal cavity function between the congested and decongested sides. Therefore, when evaluating the impact of various factors on nasal cavity function, the nasal cycle should be considered.
Work of nasal breathing: measurement of each nostril independently using a split mask.
The work of nasal breathing was determined in human subjects as a measure of impedance to respiratory airflow. The nasal cavities were examined separately and simultaneously with a split mask; flow and pressure signals were fed to a microprocessor for on-line computation and printout of respired volumes and work of nasal breathing. An alternating resistive nasal cycle of 3--4 hours' duration was demonstrated in the majority of normal, resting subjects. Reciprocity of the resistive changes in each nasal cavity maintained a constant total nasal respiratory work load of about 0.2 Joules/litre. Moderate changes in breathing rate and tidal volume had little influence on work. Inspiratory work was 1.6 times that of expiration. Increases in resistance of the dependent nostril were seen when the lateral decubitus position was adopted. Increase in cephalic venous pressure and pathological nasal obstruction increased the work of nasal breathing.
Published in Acta oto-laryngologica (1979)
Alternating cerebral hemispheric activity and the lateralization of autonomic nervous function.
Alternating dominance of cerebral hemispheric activity was demonstrated in humans by use of the electroencephalogram (EEG). Relative changes of electrocortical activity have a direct correlation with changes in the relative nostril dominance, the so-called nasal cycle. The nasal cycle is a phenomenon where efficiency of breathing alternates predominantly through right or left nostril with a periodicity ranging from 25 to greater than 200 minutes. Relatively greater integrated EEG value in one hemisphere correlates with predominant airflow in the contralateral nostril, defining a new interrelationship between cerebral dominance and peripheral autonomic nervous function.
Published in Human neurobiology (1983)
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