Arterial Blood Gases Made Easy E-Book , livre ebook

Arterial Blood Gases Made Easy
Second Edition
Iain A M Hennessey MBChB (Hons) BSc (Hons) MMIS FRCS
Consultant Paediatric Surgeon and Clinical Lead for Innovation, Alder Hey Children's Hospital, Liverpool, UK
Alan G Japp MBChB (Hons) BSc (Hons) MRCP PhD
Consultant Cardiologist, Royal Infirmary of Edinburgh and St John's Hospital, Livingston, UK

Edinburgh London New York Oxford Philadelphia St Louis Sydney Toronto 2016
Table of Contents
Cover image
Title page
Copyright
Preface
Acknowledgements
Part 1 The ABG explained
1.1 Introduction
1.2 Pulmonary Gas Exchange: The Basics
Pulmonary Gas Exchange: Partial Pressures
Carbon Dioxide Elimination
Haemoglobin Oxygen Saturation (SO2)
Oxyhaemoglobin Dissociation Curve
Alveolar Ventilation and PaO2
1.3 Disorders of Gas Exchange
Hypoxia, Hypoxaemia and Impaired Oxygenation
Type 1 Respiratory Impairment
Type 2 Respiratory Impairment
Hyperventilation
Summary of Gas Exchange Abnormalities
1.4 Acid-Base Balance: The Basics
Maintaining Acid-Base Balance
Maintaining Acid-Base Balance
Disturbances of Acid-Base Balance
Compensated Acid-Base Disturbance
Mixed Acid-Base Disturbance
1.5 Disorders of Acid-Base Balance
Metabolic Acidosis
Metabolic Acidosis and the Anion Gap
Lactic acidosis
Diabetic ketoacidosis
Other forms of ketoacidosis
Metabolic Alkalosis
Respiratory Acidosis
Respiratory Alkalosis
Mixed Respiratory and Metabolic Acidosis
1.6 ABG Sampling Technique
Before Sampling
Radial Artery Sampling
After Sampling
1.7 When and Why Is an ABG Required?
1. To Establish a Diagnosis
2. To Assess Illness Severity
3. To Guide and Monitor Treatment
4. Venous Blood Gas Analysis
1.8 Common ABG Values
1.9 Making ABG Interpretation Easy
Assessing Pulmonary Gas Exchange
Interpreting Acid-Base Status
Appendix
Cases
Case 1
Case 2
Case 3
Case 4
Case 5
Case 6
Case 7
Case 8
Case 9
Case 10
Case 11
Case 12
Case 13
Case 14
Case 15
Case 16
Case 17
Case 18
Case 19
Case 20
Case 21
Case 22
Case 23
Case 24
Case 25
Case 26
Case 27
Case 28
Case 29
Case 30
Answers
Case 1
Case 2
Case 3
Case 4
Case 5
Case 6
Case 7
Case 8
Case 9
Case 10
Case 11
Case 12
Case 13
Why is the patient hypoxaemic?
Why does SaO2 appear to be normal?
Case 14
Case 15
Case 16
Case 17
Case 18
Case 19
Case 20
Case 21
Case 22
Case 23
Case 24
Case 25
Case 26
Case 27
Case 28
Case 29
Case 30
Index
Copyright

2016 Elsevier Ltd. All rights reserved.
No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Details on how to seek permission, further information about the publisher's permissions policies and our arrangements with organizations such as the Copyright Clearance Center and the Copyright Licensing Agency, can be found at our website: www.elsevier.com/permissions .
This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein).
First edition 2007
Second edition 2016
ISBN 9780702061905
International ISBN 9780702061912
British Library Cataloguing in Publication Data
A catalogue record for this book is available from the British Library
Library of Congress Cataloging in Publication Data
A catalog record for this book is available from the Library of Congress

Notices
Knowledge and best practice in this field are constantly changing. As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary.
Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein. In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility.
With respect to any drug or pharmaceutical products identified, readers are advised to check the most current information provided (i) on procedures featured or (ii) by the manufacturer of each product to be administered, to verify the recommended dose or formula, the method and duration of administration, and contraindications. It is the responsibility of practitioners, relying on their own experience and knowledge of their patients, to make diagnoses, to determine dosages and the best treatment for each individual patient, and to take all appropriate safety precautions.
To the fullest extent of the law, neither the publisher nor the authors, contributors, or editors, assume any liability for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein.
Content Strategist: Laurence Hunter
Content Development Specialist: Helen Leng
Project Manager: Louisa Talbott
Designer: Christian Bilbow
Illustration Manager: Amy Naylor
Illustrator: Graeme Chambers; Jade Myers of Matrix and Vicky Heim



Printed in China
Last digit is the print number: 9 8 7 6 5 4 3 2 1
Preface
If you've taken the time to open Arterial Blood Gases Made Easy , you must believe that arterial blood gases (ABGs) are important, but not entirely straightforward.
We certainly agree on the first point: ABG analysis now plays an indispensable role in the assessment and management of patients with a huge range of acute medical and surgical problems. On the second point, we hope our book can be of assistance.
For this second edition of Arterial Blood Gases Made Easy we have remained true to our original principles of avoiding extraneous detail and focusing on the aspects of ABG analysis that are practical and useful. In this spirit we have been sparing with our additions to Part 1 of the book but have added 5 new clinical scenarios to Part 2 and included a new video showing how to obtain an arterial sample. We continue to believe that many medical and nursing students, junior doctors and specialist nurses will benefit from a clear, concise guide to performing and interpreting ABGs.
Iain A M Hennessey
Alan G Japp
Acknowledgements
We are indebted to Dr J K Baillie for his advice, suggestions and constructive criticism. We would also like to thank Heather Milne for allowing us to film her wrists for the demonstration video. Finally, we are grateful to Laurence Hunter and Helen Leng for their unfailing support and patience.
Part 1
The ABG explained
Outline

1.1 Introduction
1.2 Pulmonary Gas Exchange: The Basics
1.3 Disorders of Gas Exchange
1.4 Acid-Base Balance: The Basics
1.5 Disorders of Acid-Base Balance
1.6 ABG Sampling Technique
1.7 When and Why Is an ABG Required?
1.8 Common ABG Values
1.9 Making ABG Interpretation Easy
1.1
Introduction
Arterial blood gas (ABG) analysis refers to the measurement of pH and the partial pressures of oxygen (O 2 ) and carbon dioxide (CO 2 ) in arterial blood. From these values we can assess the state of acid-base balance in blood and how well lungs are performing their job of gas exchange .
Already there are questions: What is meant by acid-base status ? What is a partial pressure ? Why do they matter? It helps to break things down.
Part 1 of this book is designed to answer these questions. We start with a few pages covering the basic essentials of respiratory and acid-base physiology: please do not skip them! If you understand these core concepts, the rest will follow seamlessly. Part 1 also explains how, when, and why to obtain an ABG sample, before concluding with a simple step-by-step guide for interpreting ABG data.
Part 2 then allows you to put all of this into practice with a series of case scenarios involving ABG analysis. You may already have a method for interpreting ABGs but we urge you to try our system (set out in Section 1.9 ) that offers a logical, methodical and consistent way of approaching ABGs. By seeing how this system can identify all of the major patterns of ABG abnormalities, we hope you will gain the necessary confidence to apply it in clinical practice.
1.2
Pulmonary Gas Exchange
The Basics
Our cells use oxygen (O 2 ) to generate energy and produce carbon dioxide (CO 2 ) as waste. Blood supplies cells with the O 2 they need and clears the unwanted CO 2 . This process depends on the ability of our lungs to enrich blood with O 2 and rid it of CO 2 .
Pulmonary gas exchange refers to the transfer of O 2 from the atmosphere to the bloodstream (oxygenation) and CO 2 from the bloodstream to the atmosphere (CO 2 elimination).
The exchange takes place between tiny air sacs called alveoli and blood vessels called capillaries . Because they each have extremely thi