Effects of hyperbaric oxygen on the rat neurogenic pulmonary edema

Neurogenic pulmonary edema was induced in rats by bilateral cervical vagotomy. One hour after surgery, 25 animals were placed in an experimental hyperbaric chamber and allowed to breathe oxygen at 1.8 absolute atmospheres for 325 min. Vagotomized controls (N = 25) breathed atmospheric air. Twenty-four h after vagotomy, arterial blood samples were obtained and the lungs removed. Lungs were weighed wet and dry and lung indexes were calculated for each animal by dividing lung wet weight and dry weight by total body weight. There was no statistical difference in total lung weight or total water among groups. However, the dry lung index was about 20% lower in oxygen-treated animals than in controls. There was no difference between hyperbaric oxygen-treated animals and non-vagotomized normal animals, but vagotomized air-breathing controls differed significantly from non-vagotomized animals (P less than 0.05). These results strongly suggest a slower formation of pulmonary edema in the hyperbaric oxygen-treated group.