Endoscopic use of fibrin adhesives - Problems when injecting through long catheters

When used endoscopically fibrin adhesives are injected through twin-lumen c atheters, which can reach up to 180 cm in length. Because fibrinogen soluti ons have a high viscosity, significant delivery forces are necessary, resul ting in discomfort for the operator. Therefore, the two predominant fibrin sealants were characterized with respect to their viscosity and the force n eeded for their injection. Viscosity was determined at 18 degrees C, 25 deg rees C, and 37 degrees C in a micro-Ostwald viscosimeter. Additionally, the maximum forces needed for injection through a 27-cm and a 160-cm catheter were determined at 25 degrees C in an Instron materials testing machine. Co mpared with preparation A the viscosity of preparation B was 8.0-34.5 times higher at 18 degrees C, 4.6-13.8 times higher at 25 degrees C and 3.1-6.4 times higher at 37 degrees C. In consequence, the delivery forces were 1.5- 2.5 times (27 cm probe) and 3.4-4.5 times (160 cm probe) the values determi ned for preparation A. For preparation B a maximum load of 3.8 kg was neces sary for injection. Assuming that different adhesive preparations have the same effect, a preparation of lower viscosity seems to be more suitable for use via long catheters than a preparation of high viscosity.