Bronchoscopic assessment of bronchial anastomosis by visualizing local circulation status-index of hemoglobin (IHb) imaging.

BACKGROUND: Healing of airway anastomosis is largely affected by local circulation. Index of hemoglobin (IHb) imaging is a color enhancement technique that clarifies local circulation in the gastrointestinal endoscopic field. In this study, we investigated the relationship between bronchoscopic assessment of bronchial anastomosis using IHb mode and occurrence of anastomosis-related complications. METHODS: IHb was calculated by logarithmic transformation for each pixel of the electronic endoscopic images and expressed by colors of red, green, and blue. The distribution of each color area was automatically calculated by the summation of pixels. A preliminary experiment spraying vasodilator on swine was performed to confirm the relationship between bronchial mucosal circulation and the IHb image. Forty consecutive patients who underwent bronchoplasty were divided into retrospective training and prospective validation cohorts, and anastomosis-related complications and IHb images were analyzed. RESULTS: The IHb images immediately and accurately reflected the mucosal changes in the animal experiment. Among 25 cases in the retrospective training cohort, 6 cases experienced complications, with significantly lower red and higher blue values in IHb observed (P=0.03 and P=0.01, respectively). A receiver operating characteristic (ROC) curve for IHb red and blue distributions revealed the thresholds to differentiate cases with complications as 89.2 and 109.0, respectively. An analysis of the prospective validation cohort revealed that IHb blue on POD 7 was a potentially reliable predictor of complications, with 60.0% sensitivity and 90.0% specificity. CONCLUSIONS: IHb mode of bronchoscopy may be useful for assessing the local circulatory condition of bronchoplasty, which can predict anastomosis-related morbidity.