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The Effects of Maldistribution on the Uptake and Distribution of Inert Gases in the Human Lung Ferruh Erturk Iowa State University

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The Effects of Maldistribution on the Uptake and Distribution of Inert Gases in the Human Lung Ferruh Erturk Iowa State University Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1977 The effects of maldistribution on the uptake and distribution of inert gases in the human lung Ferruh Erturk Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Chemical Engineering Commons Recommended Citation Erturk, Ferruh, "The effects of maldistribution on the uptake and distribution of inert gases in the human lung " (1977). Retrospective Theses and Dissertations. 5867. https://lib.dr.iastate.edu/rtd/5867 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. INFORMATION TO USERS This material was produced from a microfilm copy of the original document. While the most advanced technological means to photograph and reproduce this document have been used, the quality is heavily dependent upon the quality of the original submitted. The following explanation of techniques is provided to help you understand markings or patterns which may appear on this reproduction. 1.The sign or "target" for pages apparently lacking from the document photographed is "Missing Page(s)". If it was possible to obtain the missing page(s) or section, they are spliced into the film along with adjacent pages. This may have necessitated cutting thru an image and duplicating adjacent pages to insure you complete continuity. 2. When an image on the film is obliterated with a large round black mark, it is an indication that the photographer suspected that the copy may have moved during exposure and thus cause a blurred image. You will find ja good image of the page in the adjacent frame. 3. When a map, drawing or chart, etc., was part of the material being photographed the photographer followed a definite method in "sectioning" the material. It is customary to begin photoing at the upper left hand corner of a large sheet and to continue photoing from left to right in equal sections with a small overlap. If necessary, sectioning is continued again — beginning below the first row and continuing on until complete. 4. The majority of users indicate that the textual content is of greatest value, however, a somewhat higher quality reproduction could be made from "photographs" if essential to the understanding of the dissertation. Silver prints of "photographs" may be ordered at additional charge by writing the Order Department, giving the catalog number, title, author and specific pages you wish reproduced. 5. PLEASE NOTE: Some pages may have indistinct print. Filmed as received. University Microfilms International 300 North Zeeb Road Ann Arbor, Michigan 48106 USA St. John's Road, Tyler's Green High Wycombe, Bucks, England HP10 8HR 77-25,981 ERTURK, Ferruh, 1949- THE EFFECTS OF MALDISTRIBUTION ON THE UPTAKE AND DISTRIBUTION OF INERT GASES IN THE HUMAN LUNG. Iowa State University, Ph.D., 1977 Engineering, chemical XGFOX UniVGrSity Microfilnfis, Ann Arbor, Michigan 48106 The effects of maldistribution on the uptake and distribution of inert gases in the human lung by Ferruh Erturk A Dissertation Submitted to the Graduate Faculty in Partial Fulfillment of The Requirements for the Degree of DOCTOR OF PHILOSOPHY Department: Chemical Engineering and Nuclear Engineering Major: Chemical Engineering Approved: Signature was redacted for privacy. Work Signature was redacted for privacy. Signature was redacted for privacy. For the Graduate College Iowa State University Ames, Iowa 1977 ii TABLE OF CONTENTS Page NOMENCLATURE iv INTRODUCTION 1 LITERATURE 5 The Maldistribution Problem - Its Significance and Consequences 8 MODEL DEVELOPMENT 35 Influence of Recirculation 42 Effect of Maldistribution 53 The Washout Technique 63 One-Compartmental Approach 64 Effect of Discontinuous Breathing 66 Combined Effect of Time and Venous Return During Intermittent Respiration 70 EXPERIMENTAL MEASUREMENTS 73 Experimental Procedure 75 Method of Analysis 78 Effect of Intermittent Breathing on the Washout Curves ^3 RESULTS AND DISCUSSION 87 Effect of Intermittent Respiration and Venous Return 88 One Compartmental Approach 90 Serial Dead-space Comparison of Sinusoidal and Stepwise Methods ^6 Page Investigation of Other Possible Models 98 CONCLUSIONS 110 RECOMMENDATIONS 113 BIBLIOGRAPHY 114 ACKNOWLEDGMENTS 121 APPENDIX 122 iv NOMENCLATURE Roman AR amplitude ratio of the expired and inspired inert gas partial pressures f ratio of dead space/tidal volume g 1-f h fraction of gas flow rate to a compartment P partial pressure of inert traces p fraction of blood flow to a compartment 0 blood flow rate, mls/min S degree of ventilation/perfusion maldistribution (spread parameter) S' saturation t time, min. V volume, mis V air flow rate, mls/min. Greek X partitition coefficient, dimensionless w angular frequency of the inert gas wave, rad/min. T time constant, sec. Subscripts A alveolar a arterial B blood V c end-capillary D dead space E expired i inspired j tissue compartment j L lung 0 value at t=0 T tidal or tissue V venous or tissue V mixed venous 1 compartment 1 2 compartment 2 1 INTRODUCTION The lungs are the vital organs of higner animals and man, in which gas-blood exchange takes place to supply the oxygen demand of the internal respiratory system, and to remove the carbon dioxide produced by the same system. Thus, optimal molecular concentrations of oxygen and carbon dioxide are maintained in each cell. The respiratory and circulatory systems of the higher animals provide a combination of physical diffusion, transport and reversible chemical reac­ tions to maintain this optimal level. The diffusion process occurs across the microscopic spaces between the blood and the pulmonary alveoli or the peripheral cells. The gas molecules are transported between the lungs and the body tissues via the blood circulation in physical solution as in the case of oxygen and carbon dioxide in chemical combina­ tion with blood constituents. The functional elements of the gas-blood exchange in the lung are the alveoli. A normal adult male inhales about 500 ml of air per breath (tidal volume) at rest, with an average breathing frequency of about 12 per minute. Not all of the air entering the lung is "effective", however, due to the dead space contributed by the conducting airway which consists of pharnyx, larnyx, trachea, the two bronchi which further subdivide into branchioles, until the blind pouches. 2 the alveoli, are reached. In a normal adult male, this "anatomic" dead space occupies a volume of about 150 ml, causing an inefficient gas exchange amounting approximate­ ly to 30%. It is not until the alveoli, which amounts to about 300 million in numbers, are reached, that gas exchange takes place. This is only the "anatomic" side of the picture, however. As elucidated by Seagrave (48) and Kinne (25), there are principal gradients which contribute to ineffective gas transfer. The first gradient is the expired breath-mixed alveolar gradient which is due to the anatomic dead space, the second is the mixed alveolar-end-capillary gradient which results from impeded diffusion and/or maldistribution and which may be termed as due to "physiological dead space" or an "equivalent shunt". The third gradient is the end- capillary blood-arterial yradient which results froia "venous admixture" or "anatomic shunt". The aim of this work is to develop a descriptive and experimental model of maldistribution, which contributes to the second gradient mentioned above. The maldistribution prob­ lem has long been known, and several methods, including the graphical analysis of Riley and Cournand (43), and radio­ isotope scanning methods (8, 61) were used. The graphical procedure is laborious, however, because of the inter- 3 dependency and nonlinearity of the O2 and CO2 dissociation curves, and the fact that diffusion impairment plays a sig­ nificant role. This was taken into account by the graphical analysis of King and Briscoe (22), and computer routines were developed by Kinne and Seagrave (26), to reduce the labor requirement for this method. Radioisotope methods on the other hand, give V/0 on a topographic basis only, without considering inequality in neighboring regions. To overcome the complications introduced by and COg, various inert gas techniques were used (10, 50, 57). In this work inert gas will be defined as a gas which is not chemically reactive like ©2 and COg, and which obeys Henry's Law and therefore has linear solubility relations. Thus, they are quanti­ tatively recoverable from the body at any time. Thus, this uptake and elimination relationship may be described with relatively simple physical laws, which are applicable to most of the anesthetic agents used in anesthesiology. The work of Wagner et al. (56), which recovered continuous V/0 distributions by means of numerical techniques from retention (excretion)-solubility distributions using multiple inert gas infusion, was a considerable improvement for the detection of maldistribution, as it gave a continuous V/Q distribution, although it has some drawbacks from a mathematical point of view, as described by Olszowka (33). 4 The determination of lung perfusion by the frequency- response method (49), offered considerable promise, being noninvasive and simple, although not as exact as the continuous method of Wagner et al. (56). It was observed that this method could be used to determine maldistribution. Preliminary experiments using the frequency-response tech­ nique showed that a one-compartment homogeneous lung model describes the healthy lung satisfactorily and that the effect of recirculation may be neglected with a suitable choice of inert gas and frequency. This investigation was then extended with more sophisticated equipment using multiple inert gas washout technique simultaneously with the frequency response technique, which gave a better picture of mal­ distribution models in healthy subjects.
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