Tracheal motion during eupnea

¹ Department of Pediatrics, Albert Einstein College of Medicine, New York City

A method is described for the direct measurement of upper airway circumference and length with mercury strain gauges fixed to the trachea and main bronchus. The gauges were permanently placed in dogs and were used in serial studies in the intact animal, anesthetized and unanesthetized. The method proved to be reliable and relatively unaffected by extraneous factors. Three types of tracheal motion were observed during eupnea: 1) Primarily passive changes in tracheal length and circumference during each respiratory cycle; the circumference changes could be related to changes in transmural pressure and the length changes related to the over-all downward movement of the lungs during inhalation. 2) The breath-by-breath tracheal motion was superimposed on rhythmic alterations of length and circumference mediated through the vagus nerves. 3) There was a tonic tracheoconstriction which was also dependent on vagal innervation. All changes in airway dimensions involved the entire trachea as a unit, with no evidence for tracheal peristalsis. Changes in airway volume were calculated from the length-circumference data.

Note:
(With the Technical Assistance of Bernard Minter)

Submitted on July 13, 1964