Bronchoscopic measurement of collateral ventilation in a sheep model of emphysema.
BACKGROUND
The development of bronchoscopic therapies for emphysema has renewed interest in collateral ventilation. The success or failure of bronchoscopically placed valves or biologic glues may be determined by collateral ventilation, which is exaggerated in emphysema. Furthermore, the validity of various animal models of emphysema for testing such techniques must be understood in the context of their species-specific collateral ventilation.


OBJECTIVE
To quantify collateral ventilation in a sheep model of emphysema using a simple in vivo bronchoscopic method.


METHODS
Collateral ventilation was measured in 8 anesthetized sheep using a simple method which measured pressure and flow through the working channel of a bronchoscope wedged in a segmental lung orifice. Animals then underwent nebulized papain treatments to generate emphysema, followed by repeat bronchoscopic measurements.


RESULTS
There was a 33% decrease in resistance to collateral ventilation following papain treatment. Changes in collateral resistance were closely correlated with disease severity as measured by changes in segmental compliance, which increased 267%.


CONCLUSIONS
Collateral ventilation is significantly increased in sheep following nebulized papain. Bronchoscopic measurement of collateral ventilation may be useful for evaluating other animal models of emphysema and for predicting the response to bronchoscopic therapies in human emphysema patients.
Tsai
Larry W
LW
Brigham and Women's Hospital, Boston, MA 02115, USA. ltsai@partners.org
Hoffman
Andrew M
AM
Mazan
Melissa R
MR
Ingenito
Edward P
EP
D000818:Animals; D001999:Bronchoscopy; D004195:Disease Models, Animal; D010206:Papain / Q000494:pharmacology; D011650:Pulmonary Alveoli / Q000502:physiology*; D011656:Pulmonary Emphysema / Q000503:physiopathology*; D011659:Pulmonary Gas Exchange / Q000502:physiology*; D012123:Pulmonary Ventilation / Q000502:physiology*; D012756:Sheep
D010206:Papain