BACKGROUND: Gas trapping in
emphysema
results in resting and dynamic hyperinflation.
We tested the hypothesis that a direct connection between the lung
parenchyma and the atmosphere could increase expiratory flow and thereby
potentially improve dyspnea through the relief of gas trapping.
METHODS: Ex vivo we studied 7 emphysematous lungs and 3 fibrotic
lungs (as controls) and measured expiratory flow before and after airway
bypass insertion during a forced maneuver in an artificial thorax.
Pilot studies were conducted in vivo in 6 patients with advanced
emphysema using a size 9 endotracheal tube as a bypass surgically placed through the chest wall into the upper lobe.
RESULTS: In the ex vivo emphysematous lungs the volume expelled
during a forced expiratory maneuver increased from 169 to 235 mL (p <
0.05).
In the in vivo group 4 patients retained the bypass tube for 3 months or
more; total lung capacity was reduced, and the forced expiratory volume
in 1 second increased by 23% (mean percent predicted at baseline versus
3 months, 24.4% versus 29.5%).
CONCLUSIONS: An extrapulmonary airway bypass increases expiratory flow in
emphysema.
This may be a useful approach in hyperinflated patients with homogeneous
emphysema.