Stability and safety of transbronchial dye mixture for preoperative localization in a porcine model.

Objective: For thoracoscopy, the usefulness of a dye mixture of indigo carmine and Lipiodol for localizing lung lesions has been reported. However, little is known about the stability and safety of this dye mixture injected on the visceral pleura through a bronchoscope.

Methods: Porcine models were divided into three groups according to the detection time of the dye mixture: group A with a detection time of 4 h; group B, 8 h; and group C, 24 h. A dye mixture of indigo carmine and Lipiodol (0.5 mL each) was sprayed onto the visceral pleura both in the ventral and dorsal regions via a spray catheter.

Results: Twelve markings were created on the visceral pleura of the porcine lung (six ventral and six dorsal) in the six porcine models. At predetermined detection times, all 12 dye markings (100%) were visible on the visceral pleura. The mean longest diameter of the dye marking in the ventral and dorsal regions was 18.8 mm and 24.3 mm, respectively. In groups B and C, pathological changes in the lymphatic system, such as lymphatic dilatations, were found; minimal changes were found in group B, however, these changes with oval-shaped lymphatic cysts and Lipiodol accumulation, were more evident in group C.

Conclusions: The dye mixture of indigo carmine and Lipiodol had reliable stability and visibility. In terms of safety, it may be necessary to check the dye mixture on the lung surface within 8 h.