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Research Article Free access | 10.1172/JCI105654
Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana
Department of Surgery, Indiana University School of Medicine, Indianapolis, Indiana
Heart Research Center, Indiana University School of Medicine, Indianapolis, Indiana
*Received for publication 18 April 1967 and in revised form 5 July 1967.
Reported in part at the 1966 meeting of the American Society for Clinical Investigation, Atlantic City, N. J.
This study was supported in part by research grants H-6228, H-9243, and H-4080 from the National Heart Institute, U. S. Public Health Service and in part by the Indiana Heart Association.
Address requests for reprints to Dr. Walter J. Daly, Department of Medicine, Indiana University Medical Center, 1100 W. Michigan Street, Indianapolis, Ind. 46207.
Find articles by Daly, W. in: JCI | PubMed | Google Scholar
Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana
Department of Surgery, Indiana University School of Medicine, Indianapolis, Indiana
Heart Research Center, Indiana University School of Medicine, Indianapolis, Indiana
*Received for publication 18 April 1967 and in revised form 5 July 1967.
Reported in part at the 1966 meeting of the American Society for Clinical Investigation, Atlantic City, N. J.
This study was supported in part by research grants H-6228, H-9243, and H-4080 from the National Heart Institute, U. S. Public Health Service and in part by the Indiana Heart Association.
Address requests for reprints to Dr. Walter J. Daly, Department of Medicine, Indiana University Medical Center, 1100 W. Michigan Street, Indianapolis, Ind. 46207.
Find articles by Waldhausen, J. in: JCI | PubMed | Google Scholar
Published October 1, 1967 - More info
22 anesthetized dogs were given a barium sulfate suspension intravenously in a dose sufficient to double mean pulmonary artery pressure. 10 sec breath-holding carbon monoxide diffusing capacity (DLCO10) was measured before and after this standard embolization in each dog. No post-embolic decrease in DLCO10 was observed. In the study of this apparent paradox, it was found that the potential for further increase in DLCO10 during exercise remained after embolization. During rest prolongation of breath holding to 60 sec decreased CO absorption significantly more in the embolized than in the nonembolized dogs. While DLCO10 was not affected by standard barium embolization, oxygen diffusing capacity was clearly decreased. The bronchial collateral circulation did not participate in preventing a DLCO10 decrease after embolization since surgical interruption of the bronchial circulation did not alter the response to barium. Microscopic examination of lung sections taken after standard embolization showed plugging of precapillary vessels in the 40-50 μ range. These studies suggest that acute precapillary embolic obstruction of vessels of this size interferes remarkably little with CO absorption over short periods of time, probably because of continued CO absorption in portions of the capillary net distal to the sites of impaction. The remarkable anastomotic nature of this capillary network with multiple sources of access possibly provides the anatomic basis for this observation. This study demonstrates a clear dissociation between acute changes in pulmonary vascular resistance and DLCO10—both during rest and exercise.
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