Tracheal Replacement: A Scoping Review.

 To summarize patient characteristics and outcomes for the historical and current methods of long-segment tracheal replacement in humans.  A single reviewer screened the abstracts and full texts using Covidence for file management. Studies published in English that reported human subjects with circumferential or near-circumferential (>270 degrees) cervical tracheal replacements were included. Articles with subjects treated with primary anastomosis alone, retracted articles, abstracts, expert opinion articles, and conference presentations were excluded.  A total of 32 articles were included in the review reporting 156 cases of long-segment tracheal replacement including synthetic (alive at 1-8 years  = 6/64), regenerative medicine (dead at 15 days-55 months  = 4, not reported  = 6), cadaveric tracheal allograft (alive at 5 months-10 years  = 32/38), aortic allograft (alive at 6-85 months  = 12/16), free tissue transfer (alive at 6-108 months  = 13/21), allotransplantation (alive at 6-24 months  = 5/8), and vascular composite allograft (VCA) (alive at 20 months  = 1/1).  Silicone and Marlex prostheses have poor long-term outcomes. The cadaveric tracheal allograft can only replace near-circumferential tracheal defects and is therefore limited to benign tracheal pathology. Inadequate structural support plagues the aortic allograft and often requires numerous invasive procedures and maintenance of an intraluminal stent. A lack of mucociliary clearance exists in all methods of tracheal replacement except cadaveric tracheal allograft and VCA and can cause fatal mucous plugging and chronic pulmonary infections. VCA and allotransplantation require long-term immunomodulation therapy.