Evaluation of effect of lung resection on lobar ventilation and perfusion using intrabronchial capnography

Intrabronchial capnography was applied in 11 lung cancer patients to investigate the effects of lobectomy on regional lung function. Spirometry and intrabronchial capnography were performed before surgery (PRE), and during the early (POST1, 19±5 POD) and late (POST2, 184±98 POD) postoperative periods. End-tidal carbon dioxide concentration (EtCO₂) and Smidt's velocity profile index (V-index) were calculated from each lobar capnogram obtained bronchoscopically. The V-index of lobes without cancer on the operated-on side increased after surgery (PRE, 10.7±5.0%; POST1, 14.3±9.4%, NS; POST2, 16.8±8.6%, p<0.05), while the V-index on the unoperated-on side decreased after surgery (PRE, 10.5±5.3%; POST1, 7.9±3.5%, p<0.05; POST2, 7.2±2.9%, p<0.05). EtCO₂ after surgery was lower on the operated-on side (POST1, 5.1±1.1%; POST2, 4.6±1.1%) than on the unoperated-on side (POST1, 5.4±0.9%, p<0.05; POST2, 5.0±0.9%, p<0.01). Since the V-index and EtCO₂ are compatible with the expiratory flow rate and the perfusion/ventilation ratio, respectively, we concluded that the air flow decreased on the operated-onside and increased on the unoperated-on side postoperatively and that perfusion on the operated-on side was more severely reduced than ventilation. These findings suggest that intrabronchial capnography is useful for assessing the ventilation and perfusion of the individual lobes as single units.