An Instrument for Dynamic Vital Capacity Measurements1

Journal/Book: Reprinted from SCIENCE October 26 1951 Vol. 114 No.2965 pages 444-446. 1951;

Abstract: Thorndike Memorial Laboratory Second and Fourth Medical Services (Harvard) Boston City Hospital and Department of Medicine Harvard Medical School; Thoracic Surgery Service Physiology Laboratory Sanatorium Division Mattapan; and Department of Surgery Boston University School of Medicine Boston Massachusetts 1This investigation was supported (in part) by research grants from the National Institutes of' Health USPHS; from the Committee on Medical Research and Therapy of the American Trudeau Society Medical Section of the National Tuberculosis Association ; and from the Foundation for the Study and Treatment of Thoracic and Related Diseases. The vital capacity has been used for the clinical evaluation of pulmonary function for more than 100 years without any modification (1). It is recognized that this test cannot give any indication of defects of distribution or diffusion of gases. Even now however it is widely employed in efforts to evaluate ventilatory function concerned with the. exchange of air between the outside atmosphere and the lungs. The use of the vital capacity in this connection is based an the misconception that the effectiveness of ventilation is solely dependent an the stroke volume or the amount of air that can be moved by a single maximal effort of all the muscles of respiration (2). Interest in applied clinical pulmonary physiology has been greatly stimulated during the past 20 years by the rapid advances in thoracic surgery and phthisiotherapy. During this time it has been increasingly apparent that the effectiveness of ventilation depends not so much an the single stroke volume as on the volume of air that can be moved per unit of time. A number of investigative methods including maximum breathing capacity high-speed recording spirometry air-velocity studies and alveolar pressure determinations have been developed to evaluate this time-volume relationship. These methods because of the complexity and expense of the apparatus and the trained personnel required have been largely reserved for the laboratory engaged primarily in research. The vital capacity therefore continues to be the most widely and most frequently used test of pulmonary function with consequent frequent misjudgment of the degree of pulmonary insufficiency. ...

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