A Physiologic and Anatomic Study After Pulmonary Irradiation in Dogs

A 52 Week Report

¹ Departments of surgery and pathology, Harbor General Hospital, Torrance, Calif., and the UCLA School of Medicine, Los Angeles
² Department of Radiology, University of Wisconsin, Madison, Wisconsin

Physiologic and anatomic changes following unilateral pulmonary irradiation up to 6,000 rads in dogs were studied. Fractionate irradiation was given to the right lung of 11 dogs divided into three groups which received 2,000, 4,000 and 6,000 rads respectively. Differential bronchospirometry was serially performed at approximately four week intervals for one year. There was no significant change in the relative distribution of ventilation and oxygen uptake between the irradiated and the contralateral control lungs. Upon diversion of the entire cardiac output through the irradiated lung by temporary unilateral pulmonary artery occlusion, pulmonary artery pressure and left atrial pressure remained within normal limits. Thus, there was no suggestion of increased pulmonary vascular resistance as a consequence of irradiation. Neither adhesions nor abnormalities of the bronchial vessels were observed. The microscopic findings consisted of focal organized pneumonia which was found only in the 4,000 and 6,000 rads groups, and mild focal interstitial fibrosis plus focal vascular sclerosis found in representatives of each of the three groups. We conclude that no significant physiologic abnormalities following unilateral pulmonary irradiation up to 6,000 rads in dogs were demonstrated.