Rôle of Respiratory Obstruction in “Neuropathic” Pulmonary Edema Following Vagotomy

Abstract

Reports by Weiser 1 and Farber 2 have suggested that pulmonary congestion and edema, fatal within a period of hours, are specific consequences of bilateral vagotomy in the rat, guinea pig, and rabbit. In the larger common laboratory animals (cat and dog) this is not the case. 3 , 4 , 5 This study was undertaken in an effort to determine the basis for this difference.

Doubly vagotomized rats and guinea pigs in which tracheotomy was first done were kept alive many hours longer than the longest survivals reported, 1 , 2 without evidence of pulmonary edema. Tracheotomy consisted of a simple transverse slit, handling of the trachea being avoided. The animals were fixed on their backs throughout the procedure to permit care of the wound. Cannulation, which would have circumvented this, was found unsatisfactory because of the difficulty in maintaining a free air-way. In spite of all precautions, tracheal secretions produced respiratory obstruction in a number of animals. Death with pulmonary congestion and edema followed shortly if effective steps were not taken to clear the air-way.

In a number of rats and guinea pigs, and in one rabbit, the right vagus was cut below the recurrent laryngeal nerve, the left being severed in the neck a number of days later. In the rat, paralysis of one vocal cord caused an obvious obstruction, the animal dying within thirty hours, many times the survival period observed in bilaterally vagotomized rats with both vocal cords immobilized. The lungs exhibited varying degrees of congestion and edema, as well as extensive pneumonic consolidation. Survival in the guinea pigs ranged from one to 22 days. Laryngeal obstruction was apparent in the short survivals.