Reflex reversal of nostril dominance by application of pressure to the axilla by a crutch.

Effect of pressure application by a crutch to the axilla of the side of the dominant right nostril on the pattern of nostril dominance with emphasis on the time sequence of changes and recovery was studied in the young male Nigerians. The nostril dominance was assessed from the percentage of tidal volume flowing through the right and left nostril passages during expiratory phase (7). Application of pressure to right axilla for 20 min caused tidal volume flowing through left nostril to change from the control value of 20.3 +/- 15.8% (SD) to 74.1 +/- 10.4% while the rest of the tidal volume passed through the right nostril. The effect started in the first minute; air flow through both nostrils was equalized by 4 min; reversal of nostril dominance occurred thenceforth; and peak change was obtained by 17 min after application of pressure to the axilla. Removal of crutch could not lead to recovery.