A canine model was used to determine the feasibility of preoperative, angiographic staining of bowel segments. Because methylene blue (MB) is contraindicated in patients with glucose-6-phosphate dehydrogenase deficiency or unstable hemoglobins, two alternate dyes, isosulfan blue (lymphazurin) and fluorescein were also studied. These three dyes were injected into 27 different mesenteric arterial branches in seven dogs following transfemoral catheterization. The duration of staining was evaluated over periods ranging from hours to 14 days, and pathologic sections were obtained to detect possible toxic effects. MB staining adequate for surgical resection persisted consistently up to 6 hours. Isosulfan blue and fluorescein produced adequate staining for only 30 to 60 minutes. Toxic mucosal changes were noted in four of 12 segments harvested within hours of the injection of MB and in none of the five MB injected segments harvested at four or 14 days. These changes varied greatly from focal regions of superficial necrosis to more generalized regions of transmucosal necrosis. All of the segments injected with isosulfan blue or fluorescein were free of histologic damage. It is concluded that the duration of staining produced by MB is sufficiently long to allow injection at angiography rather than at surgery. This allows decreased catheter time, and more importantly, precludes the possibility of interval catheter displacement. However, its clinical use should be viewed with some caution until its safety is established by further investigation. Isosulfan blue and fluorescein appear as alternate injectables, particularly for patients in whom MB is contraindicated. Because of their relatively short staining durations, injections with these agents should be made during surgery after angiographic catheter placement, although this method risks interval catheter dislodgement.
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