M. Shinozaki et al., EFFECT OF CONVENTIONAL MECHANICAL VENTILATION AND JET VENTILATION ON AIRWAY PRESSURE IN DOGS AND PLASTIC MODELS WITH TRACHEAL STENOSIS, Critical care medicine, 24(4), 1996, pp. 658-662
Objective: To evaluate the effect of jet ventilation on tracheal steno
sis in dogs and plastic models. Design: Prospective, randomized trial
in dogs, and multitrial tests in tracheal stenosis models. Setting: An
imal laboratory in a university setting. Interventions: Tracheal steno
sis was surgically created around the middle of the trachea, Conventio
nal mechanical ventilation and jet ventilation were compared at the sa
me value of Pace, in dogs and at the same tidal volume in tracheal ste
nosis models, Subjects: Twelve mongrel dogs and four types of plastic
models with combinations of short or long stenosis and fluid or nonflu
id stenosis. Measurements and Main Results: Canine Studies. Mean peak
airway pressure values at the distal and proximal portion of the steno
sis, and the end-expiratory pressure at the distal portion of the sten
osis, were significantly higher during conventional mechanical ventila
tion than during jet ventilation. The mean values of arterial pressure
, pulmonary arterial pressure, central venous pressure, and cardiac ou
tput did not change significantly between conventional mechanical vent
ilation and jet ventilation, except for the pulmonary artery occlusion
pressure value. Plastic Mold Studies. Peak airway pressure and end-ex
piratory airway pressure at the poststenotic trachea during jet ventil
ation with the model lung were significantly lower than during convent
ional mechanical ventilation. The difference in peak airway pressure a
nd end-expiratory airway pressure values between jet ventilation and c
onventional mechanical ventilation increased more in short stenosis an
d nonfluid stenosis, Conclusions: The jet flow that struck the portion
of the stenosed wall reversed direction, even during early expiration
, Therefore, the expiration during jet ventilation was facilitated mor
e by the reversed flow than by the expiration during conventional mech
anical ventilation. This reversed flow may provide lower end expirator
y airway pressure at the poststenotic portion with jet ventilation tha
n with conventional mechanical ventilation. We conclude that jet venti
lation was a useful method of ventilation in cases with tracheal steno
sis, especially nonfluid and short stenosis.