This preview shows pages 1–2. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: A NEW METHOD FOR MEASURING AIRWAY RESISTANCE IN MAN USING A BODY PLETHYSMOGRAPH: VALUES IN NORMAL SUBJECTS AND IN PATIENTS WITH RESPIRATORY DISEASE' By ARTHUR B. DuBOIS, STELLA Y. BOTELHO, AND JULIUS H. COMROE, JR. (From the Department of Physiology and Pharmacology, Graduate School of Medicine, University ofPennsylvania,Philadelphia, Pa.) (Submitted for publication October 17,1955;accepted December 5,1955) Satisfactorymethods,utilizing measurements of transthoracicortranspulmonary pressureand air- flow, are now available for determining "non- elastic"pulmonaryresistance. However,thenon- elasticpulmonary resistancehas two components, tissue resistance and airway resistance, and no valid direct method is available for measuring either of these components separately in man. Since airway resistance isthe ratio of alveolar pressure duringflowtoairflow,airwayresistance alonecouldbemeasurediftherewereamethodfor determiningalveolarpressure during flow. This report presents a new method foraccomplishing thismeasurement, and gives data for airway re- sistance obtained in normal subjects and in pa- tients withrespiratorydisease. Of previous attempts to measure airway re- sistance, one ofthe earliestwas the painstaking studybyRohrer (1) who made anatomicalmeas- urements on thetracheobronchialtreeofahuman lung post mortem and calculated the cumulative resistance to airflow of the entire system using Poiseuille'slawand turbulencetheory. The first important experimental study of pulmonary re- sistance in the living animal was made by von Neergaard and Wirz who, in 1927 (2), analyzed intrapleuralpressure intotwo major components, "dynamic" (which is essentially resistive) and "static" (whichispredominantlyelasticinnature). This approachmadeitpossibletoobtainvaluesfor totalpulmonary resistance, though notforairway resistance alone. Bayliss and Robertson (3), reasoning that airway resistance, but not tissue resistance, would vary with the viscosity of the gases breathed, ventilated isolated animal lungs with gases of different density and viscosity; 1 These studieswere aided (inpart) by a contract be- tween the Office of Naval Research, Department of the Navy, and the University of Pennsylvania, NR 112-323. from the changes inpressure and volume during artificialventilationwith differentgases,theycal- culated the fraction of non-elastic pulmonary re- sistanceattributabletoairway resistance. Studies based upon the revised principle of utilizingsev- eraldifferentgas mixturesofdifferentdensityand viscosityhave been carried out more recently in man by Fry, Ebert, Stead, and Brown (4) and McIlroy, Mead, Selverstone, and Radford (5) who made thepointthatgas combinationswhich haveequal kinematicviscositiesshouldbeselected....
View Full Document
This note was uploaded on 09/26/2010 for the course BME 403 at USC.