Figure 2: These images (A, B, c and D) show the process of delivering 10% methylene blue to human skin using the double catheter with the extrusion port for 20 hours at an average rate of 0.6 ul/min. The liquid flows in the lumen between the internal and external tubes and is released at the exit site. The original functionality of the internal catheter (i.e. peritoneal catheter or other) is maintained and not affected by this process. In the second row, histological analysis showed focal disruption in the epidermis accompanied by minimal focal epidermal necrosis as seen on image E. Visible on F is the overall area affected by the dye, reaching a depth of about 1mm and indicated by an arrow. Overall, the changes in this sample were minimal to mild and there was no significant epidermal or dermal damage.