Permanent tracheostomy for long-term respiratory studies.

Background: We describe a modified surgical technique for permanent, anterior tracheal-wall stoma for chronic, repeat respiratory studies in trained, conscious dogs. These cannula-free tracheostomies require minimal daily maintenance, permit repeat intubation with endotracheal tubes modified for airflow respiratory measurement, and facilitate up to 6 h continuous administration of aerosol agents during long-term or repeat respiratory studies.

Methods: In 20 dogs, during a 30 to 40 min procedure, portions of tracheal rings 2-4 were removed to create an oval stoma, approximately 2 x 1 cm. The dermis was secured to the transected cartilage and tracheal mucosa in such a manner that skin covered the sternohyoid muscles and grew-in flush with the tracheal mucosa at the stomal opening. Stomas were cleaned daily, and fur was clipped weekly around the stomal site. No other maintenance procedures or environmental modifications were needed. Animals breathed through both the stoma and the upper airway and barked normally.

Results: Stomas remained viable in long-term animals (n = 4) ongoing for 70.3 +/- 32.2 mo (mean +/- SEM), with an ongoing maximum of 126 mo. Postmortem examinations were performed on shorter-term animals (n = 16) sacrificed at 16.7 +/- 7.3 mo. Thirteen showed no appreciable tracheal stenosis and three showed <10% stenosis at the level of the stoma. Histopathological examination of the stomal opening and surrounding tissue revealed minimal chronic inflammation and no evidence of necrosis or infection.

Conclusions: During long-term respiratory studies, this practical and dependable tracheal stoma provides a means for examining acute and chronic effects of environmental and pathophysiological influences on the respiratory system of conscious dogs.