Intra-airway gas transport during high-frequency chest vibration
with tracheal insufflation in dogs.
Gavriely, Noam, David M. Eckmann, and James B. Grotberg.
Department of Anesthesia, Northwestern University Medical School,
Chicago IL 60611, the Biomedical Engineering Department McCormick
School of Engineering and Applied Sciences - Northwestern University,
Evanston IL 60201; and Department of Physiology and Biophysics, Bruce
Rappaport Faculty of Medicine and the Rappaport Family Institute for
Research in the Medical Sciences, Technion - Israel Institute of
Technology, Haifa, Israel;
APStracts 2:0090A, 1995.
High frequency external chest vibration with tracheal insufflation
(High Frequency Vibration Ventilation - HFVibV) has previously been
shown to be an effective mode of artificial ventilation in
experimental animals. To investigate the intra-airway gas mixing
during HFVibV (frequency = 30 Hz, Amplitude 0.4 cm), we used an
analysis of the single breath washout curve that gives the vibration
-induced mixing coefficient distribution relative to the no-vibration
situation. Data from four anesthetized dogs were collected during
constant flow insufflation at 6 rates (0.05 - 0.4 l/min/kg), 3
insufflation durations (2s, 4s, and 7s), with the insufflation
catheter outlet at 3 positions (carina, trachea and a bronchus),
while the vibration was on and off. Vibration enhanced intra-airway
gas mixing 14.1+/-3.9 fold, with the peak of the enhancement
distribution located 125+/-29 ml from the airway opening, and with a
distribution width of 121+/-29ml. As insufflation flow increased, the
position of the peak enhancement shifted towards the alveolar zone
and diminished in peak amplitude. Changing the insufflation duration
and the catheter position did not affect the intra-airway mixing
induced by vibration. External chest vibration causes a substantial
increase of intra-airway gas mixing, bringing alveolar gas to central
airways. This leads to overall increased pulmonary gas transport when
fresh gas is insufflating the tracheal carina area.
Received 30 August 1994; accepted in final form 27 February 1995.
APS Manuscript Number A916-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 21 March 1995.