Clinical trial of new methods for identifying lung intersegmental borders using infrared thoracoscopy with indocyanine green: comparative analysis of 2- and 1-wavelength methods.

OBJECTIVES: Infrared thoracoscopy is a new method of identifying lung intersegmental borders. This study compared the efficacy of 2- and 1-wavelength infrared thoracoscopy.

METHODS: A total of 30 consecutive patients who underwent segmentectomy were evaluated by these methods (2-wavelength method, 10 patients; 1-wavelength method, 20 patients). We ligated the dominant pulmonary artery and then observed the lung using an infrared thoracoscope after indocyanine green (ICG) intravenous injection. The 2-wavelength infrared thoracoscope irradiation and detection were conducted at 940 and 805 nm, respectively, and the images were projected based on the difference of the two reflected wavelengths. ICG absorbs 805 nm wavelength light, and the ICG distribution area appears blue against a white background. On the other hand, the 1-wavelength infrared thoracoscope irradiation and detection were conducted at 780 and 830 nm, respectively. The area stained with ICG shows fluorescence.

RESULTS: In the 2-wavelength method, 3.0 mg/kg of ICG was administered, and a well-defined white-to-blue border was observed in 9 of 10 patients. The staining duration was 220 (interquartile range, 187-251) s. In the 1-wavelength method, 0.5 mg/kg of ICG was administered, and a well-defined border between areas with or without fluorescence was observed in 19 of 20 patients. The staining duration was 370 (interquartile range, 296-440) s, which was significantly longer than the staining duration with the 2-wavelength method (P = 0.0001).

CONCLUSIONS: Infrared thoracoscopy is useful for detection of intersegmental borders. The dose of ICG for the 1-wavelength method was less than that for 2-wavelength method, and the duration of staining was longer.