The mechanical stability under load of tracheal anastomoses after various phases in vivo

Objective: The objective of our study was to postoperatively examine the mechanical stability under load of tracheal anastomoses over different periods in time and to compare these with native tracheae. Study Design: A randomized experimental study on animals. Method: We performed tracheal anastomoses on sheep with three different suturing techniques and different resection lengths (3,6, and 9 cm): These anastomoses were subjected to a breaking test at different intervals in vivo (1, 2, 4, 8, and 24 wk) and compared with the tracheae of healthy sheep. Results. After 1 week in vivo, the anastomosis itself tore off from the remaining trachea under tension, regardless of the suturing technique used and the length of resection. With all animals that survived for a longer period, the trachea broke a greater distance away from the anastomosis. The necessary breaking forces were only minimally lower than those required for breaking healthy tracheae and the difference is statistically insignificant. When all operated tracheae are combined and the forces compared with native tracheae, this reveals that the operated tracheae are significantly more stable (P = .015) and present a lower longitudinal elasticity (P = .004). Conclusion: During the first postoperative days, the stability under load of tracheal anastomoses is slightly lower than that of healthy trachea. This difference is, however, far from those values that can be measured intraoperatively on tracheal anastomoses. Thus, supplementary measures for the mechanical protection against suture line separation do not seem necessary.