New clinically applicable method for visualizing adjacent lung segments using an infrared thoracoscopy system

Objective Our objective was to attempt a clinical trial of segmentectomy using the infrared thoracoscopy system after intravenous injection of indocyanine green. Patients and Methods A total of 8 patients with lung lesions were investigated (5 with primary lung cancer, 2 with metastatic lung tumor, and 1 with inflammatory change). All were scheduled to undergo segmentectomy and had been confirmed to have no allergy to iodine or indocyanine green. Informed consent was obtained from all patients. We identified the dominant pulmonary artery supplying the target segment using reconstructed computed tomography images. The dominant pulmonary artery of the target segment was ligated, and after we had observed the lung using the infrared thoracoscopy system after intravenous injection of indocyanine green (3.0 mg/kg), and marked the white-to-blue transitional zone by electrocautery, we performed segmentectomy. Results Average operation time was 150 ± 62.1 minutes, and bleeding volume was 68.8 ± 30.5 mL. Under infrared thoracoscopy, the area with a normal blood supply became stained blue 13 seconds after injection of indocyanine green. Maximum staining intensity was attained 28 seconds after dye injection, and the observation duration was 3.5 minutes. A well-defined color zonation was observed in all patients. We had enough time to mark it. No complications attributable to infrared thoracoscopy after intravenous injection of indocyanine green were encountered. Conclusions Infrared thoracoscopy with indocyanine green makes it possible to identify the target lung segment easily and quickly without the need for inflation. This method will be especially useful for cases associated with severe emphysema or when surgery offers a limited view, as is the case with video-assisted thoracic surgery.