Bronchial anatomy and single-lung ventilation in the pig

Purpose: To explore why two pigs died in the course of a study in which a double-lumen tube (DLT) was used to achieve single-lung ventilation, the bronchial anatomy of all six pigs involved in the study was examined at autopsy. Methods: Autopsy involved examination of the lungsin situ and subsequent dissection of the lung tissue from the lobular bronchi. Results: All six pigs were found to have an apical lobe (or lobular) bronchus arising from the trachea. In three it was on the right, as is usual in pigs, and in three, including the two that died, it was on the left. The mainstem bronchi to both lungs were short in all pigs, with major segmental bronchi arising just distal to the carina. Conclusion: The bronchial anatomy of the pig is such that the inflated cuffs of commercially available DLTs may cause partial or complete obstruction of the apical bronchi of one or both lungs, regardless of the side of the tracheal bronchus. The transmission of the resulting breath sounds across the narrow pig thorax can make auscultation unhelpful in assisting with optimal tube placement.Wolfgang G. Mouton, John Pfitzner, Justin R. Bessell, Guy J. Madder