Tracheal resection with primary anastomosis in cadavers: the effects of releasing maneuvers and length of tracheal resection on tension.

To determine the relationships among length of trachea resected, total tracheal length, and anastomotic tension when using various release maneuvers, we studied 10 adult human cadavers: 5 male and 5 female. The trachea was transected between rings 2 and 3. Precision, handheld spring tensiometers (Geneva Gage, LLC) were used to measure the tension required to approximate, and then overlap, the proximal segment relative to the distal segment, and the distal segment relative to the proximal segment after these maneuvers: no release, blunt dissection, neck flexion, suprahyoid release (SHR) without neck flexion, SHR with neck flexion, and right hilar release. After the tension measurements were recorded, the trachea was harvested and the total tracheal length was measured. Length-tension curves were plotted for both the superior and inferior tracheal segments after each release maneuver. The stiffness coefficient for the trachea and the resting load on the trachea following each release maneuver were calculated. An exponential length-tension relationship existed for the distal tracheal segment regardless of whether release maneuvers were performed. The proximal tracheal segment exhibited a linear length-tension relationship initially, but displayed an exponential relationship after SHR. We could resect 6.68 cm (range, 4.2 to 9.9 cm), 13.3 rings (range, 10 to 20 rings), or 65.5% (range, 42% to 100%) of the trachea without undue tension (<1,000 g) on the anastomosis. We conclude that various tracheal release maneuvers are effective in increasing the length of trachea that can be relatively safely resected. However, these maneuvers are not uniformly effective across subjects.