Ever since I entered the medical profession as a student and then again as a post graduate in surgery, I was confused when it came to topics like Fluids, Electrolytes, Acid Base Balance and Critical Care. Every book available seemed to write differently and everything became vague after a few days of reading. I found out to my relief that it was not just me who felt like that! It was during my residency days in surgery that I started reading a lot on these topics and also began to get a hang of physiology as applied to bedside management. It was during this time in 1996 that I attended the lectures of Mr M O Wright, a renowned Professor of Physiology at Edinburgh and was greatly inspired by him. At that time, I was keenly taking classes on these topics for undergraduate and post graduate students. I began to compile my notes and was soon offered to teach these in the famous and sought after Overseas FRCS PG Course organised by Mr P K Datta in 1999 and the journey has continued ever since. This “Handbook on Critical Care and Fluid Management” is a product of more than a decade’s compilation of my notes supplemented by knowledge from my teachers, textbooks and research papers. The whole idea is to make these topics easily understandable to the clinician in the ward and aid a resident or a duty doctor to manage a critical patient with ease and reasoning. I have 8 Handbook on Surgical Physiology deliberately refrained from writing in text book like paragraphs and kept information in easy to read points. There are ample flow charts, schematic diagrams and tables to help for easy understanding. This book should also find use for MBBS students, MS, MD and DNB postgraduate students and for doctors writing for various PG entrance examinations as well as MRCS/FRCS/USMLE candidates. Lastly, I wish to thank my dear father Dr J L Gupta, who has been the guiding force at all times and provided me with the enthusiasm to complete this work. I would be most grateful for suggestions, comments and constructive criticisms from readers for use in future editions.