PREVIOUS EXPERIMENTAL work, which has been partially confirmed in the human, has demonstrated the pathological physiology of pulmonary atelectasis.1,2 At times, the clinical picture of pulmonary atelectasis is observed with high fever, tachycardia, and a rapid respiratory rate, as well as decreased breath sounds and chest movement on the involved side, but the radiological examination has been negative. This clinical observation stimulated the experimental investigation of the period of time that elapsed between obstruction of the bronchus and radiological appearance of pulmonary atelectasis. At the same time, the effect of changing the gas in the alveoli beyond the obstruction from room air to 100% oxygen was observed.
The experimental animals were mongrel dogs of both sexes weighing 20 to 40 lb. Anesthesia was induced with intravenous hexobarbital, 15 mg/lb. Bronchial obstruction was produced in one group of 21 animals by insertion of cotton plugs into one of the