Preface

Notes About the New Digital Version

We're excited to bring you this new version of the book. A considerable amount of time and effort has gone into putting the book into its new format, and we're delighted to have it out there. We are making this digital version freely available under a Creative Commons (CC BY-NC 4.0) license to maximize its reach and impact. You can find full details on the License page.

Goal

The goal of Respiratory Physiology: A Clinical Approach is to provide a clear, clinically oriented exposition of the essentials of respiratory physiology for medical students, residents, nurses, and allied health professionals. We present the physiology in the context of a system to emphasize that the functions we associate with breathing depend on more than the lungs. This approach is essential for a complete understanding of the clinical problems that affect respiration and that lead to symptoms of shortness of breath.

Our goals are to present physiology in a clinically meaningful way, to emphasize that physiology is best understood within the context of an organ system, to demonstrate principles common to different systems, and to use an interactive style that engages and challenges readers.

Level

The level of the book is intended to fit a range of needs from students who have had no previous exposure to physiology to residents who are now in the thick of patient care but feel the need to review relevant physiology in a clinical context. We have drawn upon many years of experience teaching students, residents, and fellows in making decisions with respect to the topics emphasized and the clinical examples used to illustrate key concepts. The book is not intended as a comprehensive review of respiratory physiology nor is it designed for advanced, research-oriented physiologists. Rather, we have focused on issues that are most relevant for the care of patients while, at the same time, providing sufficient physiological detail to provide readers with the foundation to examine and analyze new data on these topics in the future.

Most of the concepts presented in the book are well established, and we do not burden you with reference lists for this information. When we present newer and, in some cases, more controversial issues, however, we do provide relevant primary source citations.

Content

The book begins with two chapters that serve to provide context for the study of respiratory physiology. In Chapter 1, we lay out the framework (controller, ventilatory pump, and gas exchanger) of the respiratory system upon which we will hang concepts and information in the succeeding chapters. In the process of building this framework, we also give you an opportunity to experience some of the interactive elements of the text that will be revisited in subsequent chapters. Chapter 2 focuses on functional anatomy, reviewing the essential elements of which the respiratory system is composed and linking the structure of these elements to their physiological role.

The next two chapters address what historically has been called "respiratory mechanics." Chapters 3 and 4 focus on the function of the ventilatory pump, first under conditions when there is no flow in or out of the lungs (statics) and then when the system is set in motion (dynamics). Chapter 5 centers on the gas exchanger and delineates essential principles necessary for an understanding of the factors that affect the movement of oxygen and carbon dioxide into and out of the blood.

Chapter 6 focuses on the controller, the neurological regulation of breathing. This is linked closely with the next two chapters, which provide an introduction to acid-base physiology and respiratory sensations. Although a complete understanding of acid-base physiology depends on knowledge of renal function, the respiratory system is a critical player in the body's response to alterations in pH, and diseases of the respiratory system are often the cause of acid-base abnormalities. The fundamentals of acid-base physiology are addressed in Chapter 7. Chapter 8 discusses the physiology of respiratory sensations.

This topic is not traditionally covered in introductory physiology texts, but we have included it because it forms the basis for an appreciation of the symptoms of breathing discomfort found in a variety of disease states. Much of the information provided in this chapter is derived from research conducted in the past 2 to 3 decades and is less well disseminated among practicing physicians than is the content in the remainder of the book. For this reason, we have provided a reference list at the end of this chapter.

We conclude with Chapter 9, exercise physiology, which integrates the materials from the entire book and demonstrates links between respiratory and cardiovascular physiology. This chapter may be challenging for you if you have not yet studied cardiovascular physiology, but it will provide you with an introduction to that system upon which you can build in the future.

Throughout the book, we draw heavily on clinical examples to emphasize concepts and to highlight how an understanding of normal physiological principles will help you understand pathological states. Beginning students will see the relevance of the material presented. Advanced students and residents will be able to use the book's clinical examples to understand the signs and symptoms of your patients and the rationales for therapeutic interventions.

Pedagogy

• Chapter outline: The outlines at the beginning of the chapters provide previews of the chapters and are useful study aids.
• Learning Objectives: Each chapter starts with a short list of learning objectives, which are intended to help you focus on the most critical concepts and physiological principles that are presented in the chapter.
• Text: The text is written in a conversational style that is intended to recreate the sense of participating in an interactive lecture. Questions are posed periodically to offer you opportunities to reflect on information presented and to try your hand at synthesizing and applying your knowledge to novel situations.
• Topic headings: Topic headings are used to delineate key concepts. Sections are arranged to present the material in easily digestible quantities as you move from simple to more complex physiology.
• Boldfacing: Key terms are boldfaced upon their first appearance in a chapter. Definitions for all boldfaced terms are found in the glossary.
• Thought Questions: Interposed within the text are Thought Questions that are designed to challenge you to use the material just presented in the text in a novel fashion. Many of these questions are posed in a clinical context to demonstrate the clinical relevance of the material as well. We encourage you to try these questions on your own before checking the answers that appear at the end of each chapter.
• Illustrations and Animated Figures: The figures have been developed to demonstrate the relationships between physiological variables, to illustrate key concepts, and to integrate a number of principles enumerated in the text. Many of the figures in this book are linked to interactive learning tools (called Animated Figures in the text and indicated by an icon) that will provide you with an opportunity to view a physiological principle in motion or to manipulate variables and see the physiological consequences of the changes. These animations and computer simulations permit you to work with the concepts and apply them in a range of circumstances. Our goal is that, with self-paced use of these interactive animations, you will gain a deeper, more intuitive understanding of the physiological principles discussed in each chapter.
• Tables and Quick Checks: Tables and Quick Checks provide summaries of information outlined in the text.
• "Putting It Together" sections: At the end of each chapter is a clinical case presentation that poses questions about physical findings, laboratory values, or diagnostic and therapeutic issues that can be answered with the physiological information presented in the chapter. These cases are designed to integrate material, to demonstrate the clinical relevance of the physiology, and to provide you with an opportunity to test yourself by applying what you have just learned in a new situation.
• Review Questions and answers: You can use the Review Questions at the end of each chapter to test whether you have mastered the material. For medical students, the USMLE-type questions should help you prepare for the Step 1 examination. Answers to the questions are presented at the end of the book, and include explanations that delineate why the choices are correct or incorrect.
• Search: A search function in the sidebar allows you to easily find material in the text.

In the final analysis, most people study physiology because it offers great insights into the workings of the human body. We have organized and presented the materials in this book in a way that we hope will allow you to achieve your individual goals while having some fun with a subject that continues to challenge and intrigue us.

Richard M. Schwartzstein, MD
Michael J. Parker, MD