Volume reduction surgery impairs immediate postoperative pulmonary function in canine emphysema.

RATIONALE

In severe pulmonary emphysema, lung volume reduction surgery (LVRS) improves pulmonary function over a 2-yr period in selected patients. However, the changes in lung function and maximal flow (Vmax) occurring immediately postoperatively are not clear and may contribute to the high morbidity observed. In the present study, we used a chronic canine model of upper lobe emphysema to address this question.

METHODS

Bilateral upper lobe emphysema was produced by the intrabronchial administration of papain. Measurements were made before and immediately after LVRS was performed. A vacuum-assisted surgical system (VALR Surgical System; Spiration, Redmond, WA) that deploys a compression sleeve over portions of the disease tissue was used to produce LVRS. Changes in Vmax were interpreted in terms of the wave-speed theory of flow limitation in which a pressure sensor was placed into the airway to determine the site of limitation and intrabronchial pressures.

RESULTS

In the emphysema group, total lung capacity postemphysema increased to approximately 20% above the preemphysema value, whereas Vmax was reduced as compared with a control group. After LVRS, tidal respiratory compliance and Vmax decreased, whereas lung elastic recoil and frictional resistance increased in both the emphysema and control groups as compared with presurgery.

CONCLUSION

The acute effect of LVRS leads to an impairment in lung mechanical properties. These changes could contribute to ventilatory complications, including the difficulty of weaning patients from mechanical ventilation and the mortality observed from this procedure.