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September 30, 1950


JAMA. 1950;144(5):412. doi:10.1001/jama.1950.02920050052023

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To the Editor:—  An excellent résumé of diagnostic procedures employed in the clarification of pulmonary lesions discovered by mass roentgenographic survey recently appeared in The Journal (143:943 [July 15] 1950). Among the specific diagnostic procedures described, attention was directed to the use of the Valsalva maneuver in the visualization of arteriovenous shunts in the lungs. This procedure was described as an attempted inhalation while holding the nose and mouth. The resulting increased negative pulmonary pressure causes increased vascularity of the lung, aiding in visualization of the area of the shunt.The physiological mechanism involved is correct; however, the maneuver described is actually the Müller procedure. In Valsalva's experiment (forced expiration with the glottis closed), the intra-alveolar pressure increases and the pulmonary vascularity decreases. In Müller's experiment (forced inspiration with the glottis closed), the intra-alveolar pressure decreases and the pulmonary vascularity increases. The importance of these procedures and the resultant

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