With several engineering research groups conducting promising preclinical studies of new types of grafts, physician surgical expertise will be required for clinical translation, so that these advances may reach patients safely and effectively. A successful tracheal graft will require both the thoughtful and deliberate fabrication of a functional replacement conduit, as well as skilled surgical techniques and patient postoperative care. The complex problem of airway reconstruction is ripe for advancement through collaboration between clinicians and engineers.
Overview of evolution of long-segment tracheal repair methods over time. Nonetheless, the ideal tracheal replacement, which functions reliably in the long term, remains out of reach.įIG. Graft designs have improved over time with advancing material fabrication techniques, surgical procedures, and understanding of tracheal mechanics and physiology, which have generally led to increasing patient survival. For more than a century, clinicians have bridged these defects in critically ill patients using a variety of tracheal replacement grafts ( Fig. Large tracheal defects may be caused by cancer, trauma, infection, and congenital or acquired stenosis. The first long-segment circumferential repair of the trachea occurred in 1898 and was performed by Bruns, who used a “trachea cannula” of unspecified material to replace 10 tracheal rings in a patient, who went on to live with the repair for 5 years. 1 Long-segment tracheal defects, typically defined as being over 5 cm long in adults and shorter segments in children, are particularly difficult to address given the poor blood supply of the trachea, constant exposure of the airway lumen to the environment, and complex mechanical demands on the tissue. The first reported case of tracheal repair in a human was by Koenig in 1896, using a two-step operation to graft a piece of rib and connective tissue across a tracheal fistula. Tracheal damage has posed a significant challenge to clinicians for decades due to inherent difficulties attendant to any surgical intervention on the airway. In conclusion, we synthesized top clinical care priorities and design criteria to inform and inspire collaboration between engineers and clinicians toward the development of a functional tracheal replacement graft. Finally, we briefly summarize recent preclinical work in tracheal graft development. We further quantified graft-related causes of mortality, revealing failure modes that have been resolved, and those that remain a hurdle, such as graft mechanics. This method involves transplanting a cadaveric tracheal allograft that is first prevascularized heterotopically in the recipient. Our analysis of maximum clinical follow-up, as a proxy for graft performance, revealed that the Leuven protocol has a significantly longer clinical follow-up time than all other methods of airway reconstruction. Distinct trends emerge in the types of grafts used over time, including repair using autologous fascia, rigid tubes of various inert materials, and pretreated cadaveric allografts. To better understand the challenges facing this field today, we have consolidated all published reports of engineered tracheal grafts used to repair long-segment circumferential defects in humans, from the first in 1898 to the most recent in 2018, totaling 290 clinical cases. The development of a tracheal graft to replace long-segment defects has thwarted clinicians and engineers alike for over 100 years.
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