Abstract
Problem
The endoscopic management of tracheal stenosis remains ineffective, despite advances in dilation and resection techniques. The vascular literature reveals improved patency rates of stenosis with cryodilation compared to balloon angioplasty. The proposed mechanism is a decrease in collagen deposition with cryotherapy. Similarly, tracheal cryotherapy maintains the cartilaginous framework of the airway while minimizing collagen deposition. The objective of this study is to compare collagen deposition in tracheal injuries dilated with room temperature versus subfreezing temperature balloons.
Methods
Six New Zealand White rabbits underwent endoscopic tracheal injury with a nylon brush. At 3 weeks post injury, dilation was performed by a balloon inflated with either room temperature saline (n=3), or nitrous oxide to −10 °C, (n=3). Rabbits were sacrificed at 2 and 4 weeks post dilation. Segments of injured trachea were histologically examined for collagen and graded as none, mild, moderate, or severe.
Results
Collagen deposition at 2 weeks post dilation was graded as moderate to severe in all specimens. In the 4 week post dilation tracheas, marked differences in collagen deposition were noted. While the trachea dilated at room temperature was graded as moderate to severe, the cryoballoon dilated trachea showed minimal to no collagen deposition. Despite the observed differences in collagen deposition, sub-mucosal thickness differed between specimens by an average of 0.2 mm.
Conclusion
This preliminary study suggests that dilation with balloon cryotherapy decreases collagen deposition in the injured airway.
Significance
Long-term patency of immature tracheal stenosis may be improved with the addition of subfreezing temperatures to endoscopic dilation techniques.
Support
A grant was provided by Boston Scientific, Inc. in the form of money and supplies.
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