Constant rate intravenous infusion of indocyanine green leading to high fluorescence intensity in infrared thoracoscopic segmentectomy

Objectives: The purpose of this study was to determine whether or not fluorescence could be increased by administering indocyanine green at a constant rate, thus stabilizing its blood concentration. Methods: In 20 consecutive patients undergoing segmentectomy, the dominant pulmonary arteries were ligated, blocking blood in the target segment. Fluorescence intensity was then observed using different indocyanine green administration methods under infrared thoracoscopy. Intravenous administration of indocyanine green, via a syringe pump at a rate of 12.5 mg/min, was defined as the constant rate group. The bolus group was defined by a 5-mg indocyanine green rapid intravenous injection. The fluorescence intensity was compared at the time of maximum fluorescence and 2 minutes after fluorescence initiation. Results: At maximum staining, the fluorescence intensity of the normal blood flow area was brighter in the constant rate group (median, 184.2; interquartile range, 170.2-200.1) compared with the bolus group (median, 1223; interquartile range, 87.3-1447; P = .0003). The fluorescence of the normal blood flow was retained even after 2 minutes. There was no difference in the fluorescence intensity of the ischemic segments. Conclusions: The constant rate method showed brighter and better fluorescence than the bolus injection, without an increase in the dose. The contrast between adjacent segments was clear, facilitating the differentiation of the areas.