Evaluating the in vitro adhesive strength of biomaterials. Biosimulator for selective leak closure.

AIMS: Surgical measures always involve problems of hemostasis and tissue management. Tissue sealing can be carried out in this case, with knowledge of the adhesive strength of liquid and fleece-bound sealing being of great clinical relevance. By employing a leak closure model, it has been possible to perform in vitro standardized technological-biomechanical experiments on a biomembrane mounted in a pressure chamber (biosimulator). FINDINGS: Liquid sealing (fibrin gluing: 4.1 hPa, photopolymerisate: 82.9 hPa) offers minimal and maximal adhesive strengths. Fleece-bound sealing does not depend on the carrier material and is always more stabile than pure liquid sealing, whereby systems that must be coated "on the spot" (prepare-to-use: 22.3-25.3 hPa) exhibit significantly lower adhesive strength (p < 0.0001) than a biodegradable collagen system, which is ready-to-use thanks to its fibrinogen-based coating (TachoComb H). Practicability, effectiveness and efficiency are further advantages of ready-to-use systems. CONCLUSIONS: The biosimulator, presented here, is flexible in terms of its application for tissue management and it enables reproducible, economic and ecological evaluation of repair systems, e.g. tissue sealings.

Innovative minimally invasive pediatric surgery is of therapeutic value for splenic injury.

BACKGROUND/PURPOSE: Until now, minimally invasive surgery (MIS) has not had any therapeutic status for operable splenic trauma, because reliable sealing of larger defects is not possible with general techniques. METHODS: Fleece-bound sealing allows rapid, large-area sealing of erosions and defects, so that with the aid of an MIS applicator system (AMISA), this method of tissue management can be transferred to MIS. RESULTS: An in vitro evaluation showed that liquid fibrin sealing (FS) exhibits incomplete selective leak closure and low adhesive strength (4.1 hPa) and is not suitable for challenging surfaces. Fleece-bound sealing (ready-to-use v. prepare-to-use) showed reliable sealing and higher adhesive strength for collagen fleeces that are ready coated with fibrinogen-based sealant (TachoComb H; Nycomed, Linz, Austria) compared with various carrier systems that had to be impregnated on the spot (prepare-to-use; 50.2 v 23 hPa; P <.0001). Between October 1993 and October 2001, 19 of 87 children with splenic rupture were treated with the AMISA system (AMISA + TachoComb H) (21.8%), and 3 of these children had multiple trauma. The operation was indicated because of circulatory instability despite adequate volume replacement therapy. Splenic repair always was possible with the AMISA system, a changeover and splenectomy was not necessary, and the postoperative course was complication free. The mean stay in the hospital was 9.2 days. CONCLUSIONS: The AMISA system efficiently expands the indications for emergency laparoscopy and can be used successfully in emergency laparoscopy for splenic rupture management.