Reciprocating nasal airflow resistances.

Reciprocal changes in airflow resistance between nasal cavities are induced by lateral recumbency, and also by unilateral pressures to body surfaces in postures which avoid hydrostatic differences between sides. The reciprocating spontaneous nasal cycle in erect subjects and these nasal responses to lateral posture and pressure maintain total nasal resistance in the range of 2-3 cmH2O (0.2-0.3 KPa)/l/sec. In the resting subject, erect or recumbent, the centrally mediated autonomic tone of capacitance vessels of nasal erectile mucosa maintains an adequately patent nasal airway despite marked differences in airflow resistance between the nasal cavities which accompany lateral recumbency, asymmetrical body surface pressures or the spontaneous nasal cycle. In addition to passive hydrostatic influences on nasal mucosal blood content, activity of the vasomotor centre modified by impulses from pressure sensors of the body surfaces reciprocally alters the tone of the nasal capacitance vessels. Nasal disorders hamper these stabilizing reciprocal adjustments in airflow resistance and adversely affect breathing mechanics in recumbent subjects.