Fluid, Electrolyte, Metabolic and Respiratory Acid-Base Management

Fluid, Electrolyte, Metabolic and Respiratory Acid-Base Management A Vimala MBBS MD DM (Nephrology) FRCP (Lond) Professor of Nephrology Dr SMCSI Medical College Karakonam, Thiruvananthapuram Consultant Nephrologist Dr Govindan’s Hospital Thiruvananthapuram, Kerala, India Formerly Vice Principal Medical College Kottayam, Kerala, India E-mail: [email protected] Foreword

MA Muthusethupathi

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Dedicated to My beloved parents Sri P Padmanabha Iyer and Smt Avadai Ammal & My esteemed teacher Professor VC Mathew Roy

Contributors A Vimala MBBS MD DM (Nephrology) FRCP (Lond) Professor of Nephrology Dr SMCSI Medical College Karakonam, Thiruvananthapuram Consultant Nephrologist Dr Govindan’s Hospital Thiruvananthapuram, Kerala, India Formerly Vice Principal Medical College Kottayam, Kerala, India G Krishnakumar MD (Gen Med) DA EDIC FRCP Physician and Intensivist Dr Govindan’s Hospital Thiruvananthapuram, Kerala, India R Kasi Visweswaran MD DM FRCP Professor and Head Department of Nephrology Pushpagiri Medical College Thiruvalla Senior Consultant Nephrologist Ananthapuri Hospital Thiruvananthapuram, Kerala, India

Foreword Ever since Claude Bernard formulated the concept that maintenance of the constancy of the internal environment (milieu interior) is the ‘condition of free life’, the central importance of the kidneys as a regulator of body fluid volume and composition has become increasingly studied and appreciated. Nephrologists with significant help from the internists have logically become the experts in the field of Fluid, Electrolyte and Acid-Base Disorders. Because of the mathematical and physicochemical equations and formulae involved in its understanding, many doctors have put off this field of medicine, which, by common consent, has been considered a ‘difficult’ topic to teach and more difficult to practice at the bedside. In actual fact, however, most of these Fluid, Electrolyte and Acid-Base problems are fairly easy to understand if one starts with some basic principles of chemistry and physiology. Correct understanding and application of these principles in practice lead to gratifying results for our patients, many of whose lives can thus be saved. I feel that this topic by itself is quite interesting and intellectually challenging. What more can one ask in the field of study—beneficial to many and fascinating in its complexity? Professor A Vimala is one of the brightest, conscientious and hard-working teachers and practitioners of Nephrology in our country today. Her commitment and teaching skills are truly extraordinary. It is fortunate indeed that she has chosen to write a book on this exciting topic for the benefit of all the students and teachers of medicine. This book begins by describing the principles of Fluid and Electrolyte Physiology and goes on to discuss the various disorders encountered in practice. Section 2 describes an approach to Acid-Base disorders, starting with physiological

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Fluid, Electrolyte, Metabolic and Respiratory Acid-Base Management

principles and goes on to discuss the various disorders in a simple and easy-to-understand manner. My friend and esteemed colleague Professor R Kasi Visweswaran has contributed the chapters on Potassium abnormality and Metabolic Alkalosis which bears his hallmark of erudition and clarity. I must mention that the text is interspersed with practical, clinical examples which go a long way in making this book more interesting and lively. A section on the interpretation of Arterial Blood Gas studies has been included so that the readers of the book can learn the logical practical approach to Acid-Base problems in actual clinical practice. One chapter on the Stewart approach to acid-base makes the text up-to-date regarding some important new advances in this field. It is a commendable effort. Dr G Krishnakumar, a dedicated intensivist, has tried his level best to make this complex chapter simple. He also has made a succinct presentation on respiratory acidosis, alkalosis and ventilator management, which is a model of clarity. I congratulate the author, Professor A Vimala for her praiseworthy effort in bringing a book, which should serve generations of medical students and young nephrologists. I hope it may also serve to attract more young physicians to this fascinating field of study. This book is one of those really useful manuals which must be read, chewed, digested and assimilated, so that it can be easily and naturally applied in clinical practice to help a large number of patients. May this book enjoy a great success that it so richly deserves!

Dr Professor MA Muthusethupathi

Formerly: Professor and Head, Department of Nephrology Madras Medical College and Government General Hospital Chennai, India

Preface We medical professionals, like professionals in many other fields, are often circumscribed by our circumstances—gaps in research, exposure and the resultant understanding available at our disposal. In hindsight, we often wish we had the knowledge or the perspective at a specific point in time that could have helped us approach and resolve a case better. Of course, every generation of dedicated professionals tries to contribute its own bit by drawing on its own exposure to the latest in medical advancements and specific medical cases. We have tried to do our bit too through this book. As doctors with years of medical experience, we have been fortunate enough to have got a closer look at a variety of cases and medical scenarios. These experiences, while shaping our own perspectives and knowledge, have also enabled us to understand the different approaches taken by the medical professionals to specific case management. They have also made us wonder at better alternatives. Three specific areas that we have observed closely have been fluid therapy, electrolyte and ventilator management in intensive care. These areas, while being an important aspect in the treatment of any condition, have also been throwing some unique challenges at us. Right from the basics of fluid electrolyte abnormalities, fluid therapy, and analysis of pulmonary physiology to the analysis of respiratory acid-base, interpretation of ABG, maintenance of H+ ion balance and much more, there is often the need for a comprehensive approach. This book is an attempt to look at some such aforementioned situations and seeks to offer a better understanding and approach through specific case studies and examples. We have drawn on a number of cases that we have personally come across and attended to and also on notes

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and observations gathered over the years of professional experience. We have also included details of the treatment given in each case. The idea is to offer some perspectives to young medical professionals so that they are better equipped to decide on the right approach to treatment, especially in the intensive care stage. So, we hope that postgraduate students, young medical professionals and others will benefit from our hindsight and take a judicious approach to handling intensive care patients. A Vimala

Acknowledgments A venture of this kind owes its origins to many factors, not the least of them being the people who shape our perspectives and push us towards greater goals. I would first like to thank Professor MA Muthusethupathi, Former Professor and Head, Department of Nephrology, Madras Medical College, Chennai, India for being there for me as a mentor and giving me the right professional inputs. The same may be said of Professor S Krishnakumar, Former Professor of Nephrology, Medical College, Thiruvananthapuram, India, whom I would like to thank for guiding me professionally. I must also say that this book would have remained a mere dream had it not been for the help of a few people who ought to be mentioned here. From sowing the seeds of the idea to giving the right dose of inspiration and supporting through valuable suggestions and other help, there have been many people who were the driving force behind this book. I express my sincere gratitude to Professor R Kasi Visweswaran and Dr G Krishnakumar for contributing important chapters to this text. First, a big thanks to Professor K Lalitha, Consultant Gynecologist, SUT Hospital, Thiruvananthapuram, for being the motivation behind this book. I would also like to thank Dr Godwin, Dr Murali and Dr Jigy Joseph, who were of invaluable help, without which this book would have been impossible. Also, a special thanks to all my dear students, the ones who keep my professional spirit alive. They were of great help during the course of writing this book. An initiative of this kind needs a focused direction of energy and commitment, which is possible only with a strong family support. And I must say I have been fortunate in this regard. I would like to thank my brother and sisters, brothersin-law, sister-in-law and my nieces and nephews—Shalini,

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Vivek, Gowri, Sharanya, Ananth and Nandini, all of whom supported me immensely as I threw myself into this book. I acknowledge my patients for whom it is a privilege to care. My sincere appreciation also goes to Shri Jitendar P Vij (Group Chairman), Mr Ankit Vij (Managing Director) and Mr Tarun Duneja (Director-Publishing) of M/s Jaypee Brothers Medical Publishers (P) Ltd, New Delhi, India for their support in this project. Last, but not the least, I would like to thank the team at Jaypee Brothers Medical Publishers, New Delhi and at Kochi Branch for being instrumental in bringing out this book.

Contents Section 1—Fluid and Electrolyte Abnormalities 1. Physiological Principles, Composition and Distribution of Parenteral Fluids 3 A Vimala Milestones in the Development of Fluid Therapy 3 Milestones in the Development of Parenteral Solutions 3 2. Fluid Therapy in Pathological States 20 A Vimala Abnormalities in ECF Volume 20 Early Goal-Directed Therapy 28 Indications 28 Objectives of Early Goal-Directed Therapy 29 3. Sodium Homeostasis and Renal Regulation of Sodium 35 A Vimala Renal Handling of Sodium 36 Control of Proximal Tubular Sodium Reabsorption 36 4. Hyponatremia 42 A Vimala What Causes Hyponatremia? 43 Clinical Features of Hyponatremia  53 Hyponatremia with Normal ECF Volume (Euvolemic Hyponatremia) 64 Criteria to Diagnose SIADH (Bartter and Schwartz) 66 Hyponatremia in Special Situations 76 TURP Syndrome 78 Exercise-associated Hyponatremia (EAH) 81 Potomania (excessive beer ingestion) 83 In Neonates and Children  84 Complications of Rapid Correction  85 5. Hypernatremia 89 A Vimala What is Hypernatremia? 89

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