Oscillation of the lung by chest-wall vibration

Vibration of the thoracic surface has been shown to modify the drive to breathe and the sensation of dyspnea. It has been suggested that respiratory muscle afferents generate these effects. The possibility that the consequences of chest-wall vibration also involve intra-pulmonary afferents led us to investigate whether such vibration reaches the airways. Two vibratory stimuli were independently applied to four chest-wall sites and two control sites on eight healthy subjects. During separate breath holds, the vibrator was held on each site while subjects periodically opened and closed the pharynx. Airway pressure (P(AW)) was measured at the mouth. Spectral analysis of P(AW) showed pressure oscillations occurred at the same frequency as that of the vibrators when the pharynx was open; oscillation amplitude was vastly reduced when the pharynx was closed. Oscillation amplitude was also significantly larger during vibration at greater amplitude. These data demonstrate that vibration over the chest-wall vibrates the lung and could potentially excite intrapulmonary receptors.