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Clinical blood gases: Assessment & Intervention, 2nd edition.

While literally all of the major comprehensive respiratory therapy textbooks include chapters on blood gases, none goes into the depth and detail that a dedicated book on the subject could. But oddly, there have only been a few books devoted solely to blood gases ever written. One is Dr. Barry Shapiro's classic text and this is the other. This is the second edition of William Malley's text; his first was published in 1990. I am not going to compare the two. I don't even have a copy of the 1990 book. But what I want to know, when I review a book for this journal, is whether the book is well-suited for either students who are learning the topic as part of a structured educational program. Or is it well-suited for experienced practitioners who need a detailed source of reference? Or both? However, in this case, I'll also be asking if the book is a good choice for someone interested in setting up and managing a blood gas laboratory. A quick glance at the 2005 offering reveals a slick, good-looking textbook that is easy to read and easy to navigate. Many pages use a very attractive pink shading where emphasis is required and to enhance the read-ability of tables and charts. Most of the over 130 illustrations are crisp two-color line drawings (black on white with pink accent shading); a few are black and white photographs. All are clear and concise and do an excellent job of conveying their message.



The book has 523 pages divided into 16 chapters. The chapters are arranged into 6 different sections called "units." The units are: I -- Introduction to Blood Gases, II -- Technical Issues in Blood Gas Analysis, III -- Basic Physiology, IV -- Clinical Oxygenation, V -- Clinical Acid Base, and VI -- Noninvasive Techniques and Case Studies. This structure appears to be appropriate for guiding students through the nuances of blood gas while providing experienced clinicians with a facile guide for occasional reference.

Some of the chapters conclude with a number of exercises designed to test the reader's comprehensive and retention of key elements of the chapter. One of the exercises at the end of each chapter is named "Internet Work" and prompts the reader to use the Internet to discover the answer to specific questions or to find the Internet location(s) of various resources relating to blood gas analysis theory, equipment, or regulatory issues. If all these little pearls of information from the Internet were assembled into a complete list, with URLs, it would represent an impressive online guide to blood gas information. Many chapters also include a section called "NBRC Challenge" which lists a number of multiple choice questions typical of those that might be found on the Registry examination. The 16th and final chapter contains 14 detailed and informative arterial blood gas case studies covering all of the major blood gas acid-base disturbances indexed to specific clinical scenarios (e.g., narcotic overdose, diabetic ketoacidosis, COPD and cardiac disease and respiratory failure, among others).

At the content level, Chapter 1, Arterial Blood Gases, offers an excellent overview of the topic and ties up a lot of the loose ends that don't necessarily fit anywhere else. For example, it mentions normal ranges and explains why "normal" is a statistical concept rather than an absolute. Mention is made of the infection control implications of blood gas analysis, and the concept of needle safety, and examples of needle safety systems. Chapter 1 also has one of the best reviews of the pertinent arterial anatomy that I have seen in any publication. The chapter also discusses arterial puncture and catheterization techniques and describes pressurized arterial flush systems and the use of their stopcocks. Chapter 2 tackles the classic issues of blood gas and acid base nomenclature and classification. This is the kind of material one would expect in any book about blood gases. It is educational and handled well.

Chapter 3, Blood Gas Sampling Errors, is the first of three in the unit on Technical Issues. This chapter has an abundance of detail concerning sample acquisition, sample handling, preanalytical errors and errors introduced by temperature variability as well as anticoagulants. Chapter 4 covers Blood Gas Electrodes and Quality Assurance. There is a good basic overview of the physical principles of the various electrodes, how they work and how their accuracy is influenced. This leads to a discussion of quality control in which the applicable statistical concepts are explained. The terms "accuracy" and "precision" are defined and different types of error patterns are explained. I feel it is mandatory that practitioners understand and distinguish between these two qualities because I hear them misuse the term "accuracy" on an almost daily basis. Mention is made of Levey-Jennings charts and Westgard Rules but there is really no mention of how to use these tools in the context of day-to-day blood gas laboratory operation. The chapter also includes a useful, albeit generic, troubleshooting chart for the three basic electrode systems. This is the only chapter in which some of the hybrid blood gas systems, such as transcutaneous electrodes, continuous indwelling miniature electrodes and optical measurement systems are briefly explained, but there's a paucity of graphics to bolster the explanations. Likewise, merely four brief paragraphs are used to discuss Point-of-Care Testing which seems to be mostly concerned with the conceptual framework of POC application rather than the technology itself. Again, no photos or examples of devices were included. I would welcome more information and detail about the technology.

In the real world, patients do not always present with simple blood gas and acid-base patterns; some are challenging dilemmas. Chapter 5, Accuracy Check and Metabolic Acid-Bases Indices, addresses "the less frequent and more subtle technical nuances of blood gas classification and analysis," according to the author. This chapter demonstrates many of the real-world blood gas and acid-base situations that need to be evaluated for internal consistency and external incongruity.

Unit III -- Basic Physiology consists of Chapters 6 through 8 which cover, respectively, Oxygenation and External Respiration, Oxygen Transport and Internal Respiration, and Acid-Base Homeostasis. Likewise, Unit IV -- Clinical Oxygenation, consists of Chapters 9 through 11 covering Assessment of Hypoxemia and Shunting, Treatment of Hypoxemia and Shunting, and Hypoxia: Assessment and Intervention. Unit V -- Clinical Acid Base also consists of three chapters: Regulation of Acids, Bases and Electrolytes; Differential Diagnosis of Acid-Base Disturbances; and Mixed Acid-Base Disturbances and Treatment. The content of these chapters is included for comprehensiveness and the examples are appropriate although there is nothing here that can not be found in many other respiratory care texts.

There are two chapters in Unit VI -- Noninvasive Techniques and Case Studies. One is the aforementioned 16th chapter containing case studies and the other is Chapter 15, Noninvasive Blood Gas Monitoring. This information is very important and lends value to a book such as this, in my estimation, because of the growing dependence on noninvasive techniques for estimating arterial blood gases. How can we believe, trust and, indeed, accurately correlate noninvasive data to classical in vivo blood gas data without a thorough understanding of the equipment and the techniques? Thus, the chapter does an excellent job of explaining the principle of oximetry, spectrophotometry, co-oximetry, pulse oximetry, transcutaneous O2 and CO2 electrodes, and capnometry. Although most of the information is relatively concise, it is right on the money.

In summary, my biggest beef with this book is with respect to what it does not cover. Apparently the author did not set out to write a blood gas equipment book. Too bad. I believe the book would have been of much greater value if it had dropped a couple of the chapters devoted to treatment of acid-base and oxygenation disturbances and instead included information on how to set up and manage a blood gas laboratory. I believe that more information on equipment selection, examples of contemporary analyzers and devices, greater emphasis on regulatory issues (e.g., CLIA, state laboratory requirements, etc), and information concerning the new breed of analyzer that measures blood gases, acid-base status, electrolytes and metabolites would have rendered a book of even greater value and wider appeal. But don't get me wrong--this is an excellent book for what it covers and it is worth the money.

Reviewed by Michael McPeck RRT
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Author:McPeck, Michael
Publication:FOCUS: Journal for Respiratory Care & Sleep Medicine
Article Type:Book Review
Date:Mar 22, 2005
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