1 Acknowledgements Thanks to all the registrars and junior doctors who have worked in my Department over the years for the opportunity they have given me to both teach and learn from them. Thanks to all those people who have said over the years, “You should write a textbook.” Now I can say that I have done so. Thanks to my colleagues for their comments and insightful feedback. Thanks to Barb Lindbergs for permission to use the Anaesthetic Machine check documents and for access to her costing spreadsheets. Lastly I would like to thank my wife who inspires and tolerates me. I welcome any comments, criticism or vitriol and they can be conveyed to me at [email protected] Lachlan Rathie Toowoomba April 2016 Disclaimer Every effort has been made to ensure the information contained within this book is accurate and correct; especially with regard to drug dosages. Despite this, errors may have been made and advances or changes in medical science and practice may render some information incorrect or incomplete. Current drug product information monographs are the most reliable source of prescribing information. 2 TABLE OF CONTENTS Setting the scene A bit about the structure of this book ....................................................................... 7 Why have I written this book? .................................................................................... 9 Common errors made by trainee anaesthetists ....................................................... 12 Curriculums.................................................................................................................. 13 What you should be able to do after a year ............................................................. 15 Resources ..................................................................................................................... 17 How to learn anaesthesia ........................................................................................... 21 Tools of the Trade Monitoring- all those pretty waveforms .................................................................. 25 The Electroencephalogram and Its Application to Anaesthesia .......................... 32 The Anaesthetic Machine .......................................................................................... 45 The White Stuff ........................................................................................................... 53 Thiopentone and Ketamine ...................................................................................... 63 Volatile Agents and Nitrous Oxide .......................................................................... 68 Muscle Relaxants and Reversal ................................................................................. 84 Analgesics, Antiemetics and Local Anaesthetics .................................................... 98 The Main Event Preoperative Assessment ......................................................................................... 108 Planning the Anaesthetic ......................................................................................... 127 The IV and drawing up drugs ................................................................................. 132 Induction of Anaesthesia ......................................................................................... 138 3 Maintenance of Anaesthesia .................................................................................... 144 Emergence ................................................................................................................. 151 How to do a spinal (& an epidural) ........................................................................ 156 Everything you should know about Propofol TCI .............................................. 168 Putting it all together- Example Cases ................................................................... 177 Special Situations Obstetric Anaesthesia ............................................................................................... 185 Paediatric Anaesthesia .............................................................................................. 201 The Obese Patient .................................................................................................... 209 A few words about endoscopy................................................................................ 218 Crises in a Nutshell Difficult Airway 101 ................................................................................................. 222 Hypoxia ...................................................................................................................... 236 Hypotension .............................................................................................................. 240 High Airway Pressure ............................................................................................... 243 Perioperative Medicine Studies you should probably know about ............................................................. 248 Antithrombotic Drug Management ....................................................................... 253 The bleeding patient and transfusion therapy ...................................................... 257 Making a Difference ................................................................................................. 268 Miscellany My Top Twenty Tips ................................................................................................ 276 The Cost of Things ................................................................................................... 277 4 Preparing for the Primary Examination ................................................................ 279 Pre-Questionnaire ..................................................................................................... 283 Initial Assessment of Anaesthetic Competence- example paper ....................... 285 Midyear Checklist for Meeting with Supervisor- JCCA ...................................... 288 My Other Books ....................................................................................................... 290 5 Setting the scene An assortment of textbooks from the author's personal collection 6 A bit about the structure of this book This book is arranged into seven sections. The first section endeavours to explain why I have written this book. It outlines the existing deficits in the textbook literature, the shortcomings in trainee knowledge I have witnessed firsthand and the errors that have resulted. The two curriculums pertaining to anaesthetic training in Australia are briefly described as well as their practical implications. I have listed what skills and attributes that are both likely and necessary to be gained after a year of anaesthetic practice. The best available resources are reviewed to inform practitioners of their value to the learner anaesthetist and perhaps help you decide whether to buy any of them for your personal library. Finally are some thoughts about how to learn anaesthesia. The second section, ‘Tools of the Trade’, gives some detailed core information about the integral tools of our profession- namely our equipment with a focus on the anaesthetic machine and patient monitors and the drugs with a focus on the important anaesthetic drug classes. A common theme in the book is to expressly focus on pragmatic but core knowledge that is required to conduct anaesthesia safely but is lacking or hard to find in conventional learning resources. At the end of some of the chapters in this section and the next four are up to three separate items. The first of these are selected references. These are not exhaustive or definitive but references I feel worthy of reading in their own right by the junior anaesthetist. The second item comprises challenge questions relating to the content in the preceding chapter or chapters. The answers are on the following page. Some of these will even challenge your consultant! The third component that follows some chapters I collectively term ‘light relief’ and contains items of a humorous/ cynical/ sarcastic nature. The third and largest section of this book I have dubbed ‘The Main Event’. This relates to the actual conduct of anaesthesia and is further subdivided into chapters relating to preoperative assessment, planning and giving the anaesthetic. There is a detailed chapter about propofol TCI, a subject whose practical application is a lot better realized than an understanding of its theoretical foundation. Lastly is a section outlining in a stepwise fashion the anaesthetic management of some common cases. To an extent this synthesizes information from earlier chapters and applies it to example cases. The emphasis is very much on giving a practical and common sense foundation to what we do every day in the operating theatre. I believe you should critically appraise and be able to justify your practice and this section attempts to do just that. The next section relates to the two main specialty areas of anaesthetics that all generalist anaesthetists practise in- namely obstetrics and paediatrics. Again common errors and deficits are addressed as well as practical considerations for safe practice. A chapter is devoted to the most significant challenge of our professional lives- obesity. Finally are some thoughts about the commonest procedures performed that require anaesthetic services, namely endoscopy. The fifth section relates to crisis management. There are many good resources on this subject (including one I wrote) so I have restricted this section to the three commonest crises encountered intraoperatively: hypoxia, hypotension and high airway pressures. Airway crises 7 feature prominently in the anaesthesia canon so the section commences with a discussion regarding difficult airway management. The next section relates to aspects of perioperative medicine. This is a very large component of contemporary anaesthetic practice and I have restricted myself to the more common issues that anaesthetists have to deal with on a daily basis. This is an element of practice which is informed to a degree by an evidence base. Consequently I have tried to highlight the important studies of relevance as well as making the trainee anaesthetist aware of the multiple situations where there is a lack of quality evidence to inform practice. My personal perspective on how we as anaesthetists can make a difference to important perioperative outcomes is succinctly outlined. Finally, in the aptly titled ‘Miscellany’ section is an assortment of topics. A list of the cost of commonly used anaesthetic drugs and consumables is included for your consideration. Cost efficiency is an important attribute of the contemporary anaesthetist. Most anaesthetists in their first year are contemplating if not studying for the primary exam so my personal thoughts about how to tackle this life defining event are included for your consideration. An example of the IAAC (Initial Assessment of Anaesthetic Competence) exam I give my trainees is reproduced. This serves as an indicator of the level of knowledge you should possess after approximately six months on the job. Lastly, if you enjoy my ‘light relief’ items there’s a blurb about my two ‘other’ books most of the items came from: The Anaesthetist’s Companion and The Cynical Anaesthetist. 8 Why have I written this book? My predominant anaesthetic interest pertains to educating the next generation of anaesthetists. My credentials that demonstrate this are my role as the Supervisor of Training (SOT) of anaesthetic trainees in a large regional hospital. I am also a primary examiner for the College of Anaesthetists. Prior to becoming an anaesthetist I was a rural general practitioner (GP) in South Western Queensland and completed a Fellowship with the College of General Practitioners as well as a Graduate Diploma in Rural General Practice and a Diploma in Obstetrics and Gynaecology. My first real exposure to anaesthesia was my advanced skills year of anaesthetics that I did as a component of my rural GP training. I essentially decided to pursue anaesthesia as a career because I enjoyed giving anaesthetics more than consulting. I also like the academic and professional challenges that the specialty provides. I became an examiner because it appeals to the academic snob in me and because I consider it the defining element of our training and it reflects the high level of training that Australasian anaesthetists receive. I am inherently biased but I think Australasian anaesthetists are the best in the world and I want to contribute to maintaining that proud record. I am a bit of a textbook junkie and have accrued quite a large collection over the years. The vast majority of texts are an expensive disappointment. Common themes of disappointment are outlined below:  Overt American or UK flavour  Out of date  Can’t find ‘exam’ answer  Inadequate explanation of fundamental concepts  Unreadable, boring, dry  Nothing ‘new’  Patchy coverage of topics  No practically useful information The last disappointment detailed above is the biggest crime- the answers to practical questions regarding how to anaesthetize the patient I have in front of me are invariably not found in books. Try and find in a textbook the answer to the following questions:  What are the criteria for extubation?  What is the intubating dose of rocuronium in a patient who weighs 150kg?  How do I interpret a post tetanic count?  How long does the patient have to be off Rivaroxaban/ Dabigatran/ Prasugrel before I can do a spinal?  Do platelets/ FFP need to be ABO compatible?  How do I manage a LMA with a leak?  What’s the point of giving Midazolam on induction?  Should I use a cuffed tube in a 4 year old?  When do I cancel a kid with an URTI?  How do I intubate someone without muscle relaxants? 9