Interpreting Lung Function Tests

Transcription

1 Interpreting Lung Function Tests

2 Interpreting Lung Function Tests A STEP-BY-STEP GUIDE Brigitte M. Borg, BAppSc, CRFS Deputy Head, Physiology Service Department of Allergy, Immunology and Respiratory Medicine Alfred Hospital and Monash University Melbourne, Victoria, Australia Bruce R. Thompson, BAppSc, CRFS, PhD, FANZSRS Professor and Head, Physiology Service Department of Allergy, Immunology and Respiratory Medicine Alfred Hospital and Monash University Melbourne, Victoria, Australia Robyn E. O Hehir, FRACP, PhD, FRCP, FRCPath Professor and Director Department of Allergy, Immunology and Respiratory Medicine Alfred Hospital and Monash University Melbourne, Victoria, Australia

3 This edition first published by John Wiley & Sons, Ltd. Registered office: John Wiley & Sons, Ltd, The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK Editorial offices: 9600 Garsington Road, Oxford, OX4 2DQ, UK The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK 111 River Street, Hoboken, NJ , USA For details of our global editorial offices, for customer services and for information about how to apply for permission to reuse the copyright material in this book please see our website at The right of the author to be identified as the author of this work has been asserted in accordance with the UK Copyright, Designs and Patents Act All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by the UK Copyright, Designs and Patents Act 1988, without the prior permission of the publisher. Designations used by companies to distinguish their products are often claimed as trademarks. All brand names and product names used in this book are trade names, service marks, trademarks or registered trademarks of their respective owners. The publisher is not associated with any product or vendor mentioned in this book. It is sold on the understanding that the publisher is not engaged in rendering professional services. If professional advice or other expert assistance is required, the services of a competent professional should be sought. The contents of this work are intended to further general scientific research, understanding, and discussion only and are not intended and should not be relied upon as recommending or promoting a specific method, diagnosis, or treatment by health science practitioners for any particular patient. The publisher and the author make no representations or warranties with respect to the accuracy or completeness of the contents of this work and specifically disclaim all warranties, including without limitation any implied warranties of fitness for a particular purpose. In view of ongoing research, equipment modifications, changes in governmental regulations, and the constant flow of information relating to the use of medicines, equipment, and devices, the reader is urged to review and evaluate the information provided in the package insert or instructions for each medicine, equipment, or device for, among other things, any changes in the instructions or indication of usage and for added warnings and precautions. Readers should consult with a specialist where appropriate. The fact that an organization or Website is referred to in this work as a citation and/or a potential source of further information does not mean that the author or the publisher endorses the information the organization or Website may provide or recommendations it may make. Further, readers should be aware that Internet Websites listed in this work may have changed or disappeared between when this work was written and when it is read. No warranty may be created or extended by any promotional statements for this work. Neither the publisher nor the author shall be liable for any damages arising herefrom. Library of Congress Cataloging-in-Publication Data Borg, Brigitte M. (Marianne), author. Interpreting lung function tests : a step-by-step guide / Brigitte Marianne Borg, Bruce Robert Thompson, Robyn Elizabeth O Hehir. p. ; cm. Includes bibliographical references and index. ISBN (pbk.) I. Thompson, Bruce R. (Robert), author. II. O Hehir, Robyn E. (Elizabeth), author. III. Title. [DNLM: 1. Respiratory Function Tests. WF 141] RC734.P dc A catalogue record for this book is available from the British Library. Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic books. Cover image: Courtsey of Professor Merryn Tawhai and Professor Bruce Thompson Typeset in 10/13pt Palatino by Laserwords Private Limited, Chennai, India

4 Contents About the authors, vii Forewords, ix Preface, xi Acknowledgement, xiii 1 General features of interpretation and report writing, 1 2 Spirometry, 13 3 Static lung volumes, 37 4 Carbon monoxide transfer factor: single breath method, 53 5 Tests of respiratory muscle strength, 79 6 Bronchial provocation tests, 99 7 The importance of quality tests, When the results do not fit the rules, 139 Glossary, 161 Index, 165 v

5 About the authors Ms Brigitte M. Borg Brigitte Borg has a Bachelor of Applied Science (Medical Biophysics and Instrumentation) and is a Certified Respiratory Function Scientist. Brigitte is the Deputy Head of the Physiology Service, Allergy, Immunology and Respiratory Medicine at The Alfred, Melbourne. She is responsible for the day-to-day management of a busy lung function laboratory that encompasses clinical, research and education in its core activities. Brigitte has actively participated in the training of advanced trainees in lung function interpretation over many years and has been on the faculty of the American Thoracic Society s postgraduate course for the Interpretation of Lung Function since Brigitte s research interests are twofold: quality of measurement of lung function and oxygen therapy. Professor Bruce R. Thompson Professor Bruce Thompson, B. App. Sci, CRFS, PhD, FANZSRS, is the Head of the Physiology Service within the Department of Allergy, Immunology and Respiratory Medicine, Alfred Hospital and Central Clinical School, Monash University. After graduating with a degree in Physiology and Electronics, he completed a PhD examining the effects of ventilation heterogeneity on gas transfer factor. Prof. Thompson is the head of one of the largest pulmonary function laboratories in Australia and combines a very active research programme. Prof. Thompson s research interest centres on the structure and function of the small airways, and he also has a very keen interest in quality of pulmonary function measurements. He is a member of the Global Lung Initiative T L CO taskforce. Finally, his contribution to respiratory research and laboratory measurement was recognised in 2011 when he was awarded the ANZSRS research medal (Fellowship). vii

6 viii About the authors Professor Robyn E O Hehir Professor O Hehir, FRACP, PhD, FRCP, FRCPath, is Professor and Director of the Department of Allergy, Immunology and Respiratory Medicine, Alfred Hospital and Central Clinical School, Monash University. After graduating in Science (Microbiology, Biochemistry and Physiology) and then in Medicine at Monash University and Alfred Hospital, Melbourne, Australia, she completed her clinical postgraduate training at Royal Brompton Hospital and the University of London, specialising in both Allergy and Clinical Immunology and Respiratory Medicine. Professor O Hehir conducts an active programme combining clinical care, clinical and experimental research and education. She is an Editor of the international journal Clinical and Experimental Allergy and has a strong interest in translational medicine.

7 Forewords Tell me and I forget, teach me and I may remember, involve me and I learn. Benjamin Franklin Franklin realised that effective teaching occurs when one involves the learner in his or her own education. We all have had memorable learning experiences when our teachers presented us with learning material or activity that was more germane to our jobs and activities. Yet scant attention has been paid to the teaching of the interpretation of lung function tests. In contrast to the vast number of books on ECG interpretation, try finding a decent book of PFT interpretation! This book is exceptional and singular. The book is divided into eight chapters. Five of the chapters cover the five standard pulmonary function tests widely used by most lung function laboratories worldwide. However, three of the chapters deal with, first, a general approach to interpretation of lung function tests and then their report writing. The latter is the most helpful treatment I have ever seen on the topic. Next, there is a complete chapter devoted to test quality. Lastly, and perhaps uniquely, is Chapter 8 devoted to unusual test results that cause difficulties in interpretation, for example, patients with borderline results. Again, this is totally unique material. However, the best part of this book is the number and quality of the case studies, and the best part of these is the presence of complete interpretations. Oh, what I would have given to have this book the first day I sat down with a stack of PFT results! If you spent the time on the cases, then you would make Ben Franklin proud. So take a deep breath and turn the page! Charles G. Irvin, Ph.D. University of Vermont Burlington, Vermont ix

8 x Forewords The lung is a highly complex organ whose access is difficult. Detection of abnormalities is largely dependent on measuring indices of lung function and imaging, other methods require invasive procedures such as bronchoscopy and tissue biopsy. Understanding how an organ with so many dichotomous components works to maintain the life-giving oxygenation and rid the body of carbon dioxide has been an enormous challenge. However, huge progress has been made in establishing structure function relationships of the lung as an integrated complex organ and its implications when these are affected by a disease leading to an informative list of tests that can precisely identify diagnoses. However, as with any test, interpretation depends on a clear understanding of lung physiology in health and disease, limitations of surrogate markers reflecting function and the possible pitfalls of over-interpretation. Although there have been many publications that deal with various aspects of this journey, there has not been a resource that enables the clinicians to easily interpret lung function measures in their entirety. Brigitte Borg, Bruce Thompson and Robyn O Hehir have achieved this remarkably well in their practical book Interpreting Lung Function Tests: A Step-by-Step Guide by explaining how the different tests of lung function are optimally undertaken, their implications for disease diagnosis and, importantly, how results should be reported, their clinical interpretation and limitations. A particularly valuable resource provided by this unique publication is a series of well-illustrated cases illustrating how far the tests can be interpreted to aid in diagnosis and evolve over the life course. The book is presented in an easily accessible format making it essential reading for all those delivering an effective pulmonary function service and respiratory physicians who utilise these tests for patient benefit. Such a concise and easily readable book will be of great value to those who both undertake and utilise lung function testing, especially those in training. Stephen T Holgate CBE, DSc, MD, FRCP, FRCPath, FMed Sci. Faculty of Medicine Southampton University, UK

9 Preface In the healthcare setting, the purpose of performing a lung function test is to provide information to assist clinical decision-making and management strategies. The current expectation is that those working in the field of respiratory medicine will be able to interpret physiological measurements of lung function. The inspiration for this book arose from our local need for a resource to educate our advanced trainee physicians specialising in respiratory medicine in interpretation and reporting of lung function. What started as a local guideline developed into a book as the guideline was expanded to include the many aspects and considerations in reporting common lung function tests. Illustrative cases were also incorporated to close the gap between theory and practice in interpretation and report writing. Theaimsofthisbookareasfollows: To provide a teaching/reference tool for writing reports for lung function tests routinely performed in adults in clinical practice. To provide the reader with the skill to interpret and write a concise and informative report. To provide a uniform report format that can be used by multiple personnel reporting lung function tests within a service to promote consistency in reporting style. There are many different tests of respiratory function, and it was not our objective to cover them all in this practical book. We have included the tests that are routinely performed in lung function laboratories, namely Spirometry, Static Lung Volumes, Gas Transfer Factor, Bronchial Provocation Tests, and Tests of Respiratory Muscle Strength. Similarly, we have chosen to focus on the lung function assessment of adults although some of the concepts equally apply to paediatrics. We have utilised published literature to inform the interpretation strategies suggested in this book. In cases where published data are unavailable, we have formed interpretative strategies based on expert opinion. xi

10 xii Preface Assumptions The assessment of lung function is multifaceted. This book is not intended to be a technical manual on test performance or quality assurance nor a compendium of respiratory pathophysiology. In order to interpret lung function assessments, however, knowledge of these aspects is required and it is assumed that those using this book: have a general understanding of respiratory physiology related to lung function assessment; recognise and understand the standard parameters of lung function measurement (e.g. FEV 1,TLC); understand the importance of appropriately chosen reference values and the limitations of reference sets. To keep it simple, the cases in Chapters 2 to 6 assume the following: Testing equipment used in the assessment of lung function has been properly maintained, calibrated and is part of a regular quality assurance programme to ensure the accuracy and precision of the device. Results include corrections for body temperature and water vapour pressure as required. Reference values used are appropriate to the subject for the case. Tests were performed according to published standards. Tests are of good quality and are a valid representation of the subject s true lung function. The cases in Chapters 8 and 9, however, are not straightforward, but the issue is identified. Our hope is that this book is of use in assisting individuals and laboratories to establish a consistent interpretative and/or reporting strategy that is, as far as possible, evidence based. Enjoy! Brigitte Borg Bruce Thompson Robyn E O Hehir

11 Acknowledgement We would like to thank our families and colleagues for their support throughout the writing of this book. Brigitte, Bruce and Robyn xiii