A Primer of Anesthesia Rajeshwari Subramaniam
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2A Primer of ANESTHESIA: (For Undergraduates)
Editor Rajeshwari Subramaniam MD Professor Department of Anesthesiology and Intensive Care All India Institute of Medical Sciences New Delhi, India
Published by
Jitendar P Vij
Jaypee Brothers Medical Publishers (P) Ltd
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© 2008, Rajeshwari Subramaniam
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First Edition: 2008
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4To the Past, Present and Future Teachers of Anesthesiology
5Contributors 6Foreword
It is not often that a scientific treatise turns out to be a treat to discerning readers’ vision and mind. The editor, Rajeshwari Subramaniam, a former (and still claims to be!) student of mine for some years, has perfected such a piece of work here written so thoughtfully that it eliminates the need for an instructor to explain the contexts any further. The abundance of sensibly selected illustrations, most of them having an aura of originality, reveal the tremendous effort put in to offer a rational presentation of fundamentals. This promises to be an asset to both the postgraduate trainee in anesthesiology and the undergraduate who has an interest to become part of the specialty of anesthesia, pain management and resuscitation. Easy-to-understand sketches and illustrations and facts and vital figures of physiology and pharmacology are most valuable for the new inductee in the specialty. This instructive piece of work is spiced with original drawings and sketches, particularly in sections dealing with monitoring, vascular access, airway management, and the figures on fluid therapy. It is unique in the sense that it does not follow the conventional flow of material down the pages ‘system by system’ or ‘organ by organ’. Rather, the stress is on problems and ways to solve them intelligently, answering questions that all of us want to ask. This book is an asset to the learning process and provides sensible and rational explanations to unravel the issues that are challenges to the trainee, the trainer and the practitioner. I expect this to go far and wide and for a long time to come.
Em Prof VA Punnoose MD, FMCA
(Present) Dean of PG Studies, St.Stephen's Hospital
Former Head of Cardiothoracic Anaesthesia
All India Institute of Medical Sciences
Commonwealth (CFTC) Expert to the University of Ghana
Professor of Anaesthesiology
University Jos, Cardiac Anaesthesia
Fellow at Green Lane Hospital
New Zealand
I have witnessed the growth of anesthesiology as a specialty for more than last four decades and watched its change from an art form to a science based on the known principles of physiology and pharmacology. No other specialty has seen such a transformation in this short time. From an assistant and side-kick to a surgeon, the modern anesthesiologist has become a specialist in his/her own right. This period has also witnessed a widening of the prospects and range of clinical activities of anesthesiologists, covering preoperative evaluation and administration of anesthesia for postoperative pain management, and management of the critically ill surgical and medical patients on various life-support systems. This has prompted some of our colleagues to suggest the new name of “Perioperative Medicine” for the specialty.
The present role of anesthesiologists involves a number of functions, unknown to their predecessors. Anesthesiologists have to know and understand the clinical implications of the patient's disease and its effect on the conduct of anesthesia. In view of this, the knowledge base of an anesthesiologist has widened. Many of our young medical graduates find it difficult to get information of such breadth and ranging topics from a single source. In this context, this book, ‘A Primer of Anesthesia” will fulfill a great need for source material covering a whole lot of different subjects.
The authors have compiled a generous source of readily available information in a crisp and concise manner. The subjects covered have been divided into four main sections covering the preoperative period, intraoperative period, postoperative period and critical care which deals with all the major aspects of an anesthesiologist's day to day work schedule. Each chapter describes briefly, but clearly the essential theoretical details. Addition of a large number of illustrations, both photographs as well as line drawings, ensure that it is easily understandable even to a fresh medical graduate. The MCQs provided can help the reader check his/her grasp of the subject.
I would like to give full credit to Prof. Rajeshwari Subramaniam (who has been my student), for accepting this daunting challenge and producing a very readable treatise with support from each of the contributing authors. This book shall be of immense value not only to all those who aspire to become anesthesiologist, but also to fresh medical and surgical residents who find it difficult to get easily accessible information on important day to day patient care functions. It shall also be useful to a busy practitioner as a ready reference volume. I wish the authors well and hope that they shall start right away to prepare the next edition, and include at the end of each chapter a short bibliography for further reading, for those who are interested.
Prof HL Kaul MD, FRCA
Retired Head
Department of Anaesthesiology and Intensive Care
All India Institute of Medical Sciences
New Delhi, India
Anesthesiology is a rapidly expanding and vital specialty especially in India and other developing countries. There is an ever-increasing need for trained anesthesiologists to provide safe perioperative care to patients at primary health center (PHC) level to tertiary hospitals carrying out cardiac surgery, neurosurgery and organ transplantation.
Where do we begin?
For a start, it is important to attract more postgraduates to the specialty of anesthesiology. Unfortunately the present scheme of rotation provided to undergraduates is not long enough for the students to get familiar with anesthetic pharmacology, terminology, equipment and skills. Further, the students find themselves at sea in the world of the modern operating theatre and ICU equipped with hitech monitors and gadgets.
This book has been written with the primary aim of demystifying anesthesiology and presenting the necessary theory related to pharmacology, equipments and skills in an easy-to-understand manner.
It is hoped that better understanding of this subject at undergraduate level will lead to enhanced appreciation and motivation to pursue it as a career.
Rajeshwari Subramaniam
I gratefully acknowledge all the contributors to this book who devoted time from their busy schedules to write their chapters. I acknowledge with deep gratitude and humility my teachers (Late) Prof. NP Singh, Prof. VA Punnoose, (Late) Prof. GR Gode, Prof. HL Kaul and Prof. TS Jayalakshmi, who inculcated in me not only a sense of obligation to teach and practice evidence-based anesthesia, but also to treat patients with respect and compassion. Their dictum: “It is the enlightened who can enlighten”.
I acknowledge the vastness and majesty of this specialty without which no advancements in modern surgical technique would have been possible.
My family who encouraged this endeavour cannot be thanked enough.
I thank production staff of M/s Jaypee Brothers Medical Publishers (P) Ltd., New Delhi, for their patience for the numerous revisions and modifications I thrust upon them.
I would like to add that the photographs of ampoules/vials of drugs displayed in some of the chapters are those in common use and I have no financial gains from the manufacturers.
My special thanks to Dr. Sunil Chumber (Additional Professor, Dept. of Surgical Disciplines, AIIMS), who was the one who succeeded in motivating me to write this book.
If this book fulfils the expectation of its users I would give all credit to the contributors and I take the responsibility for errors, if any.
Last but not the least, I acknowledge my colleagues and students whose faith in me is amazing and humbling.
Numerous path-breaking advances have been responsible for taking the specialty of anesthesia to its pinnacle in today's practice. Although many are being mentioned here in chronological order. The tremendous progress of the science of anesthesia over the last 150 years can be attributed to the observation, dedication, motivation and perseverance of some extremely committed individuals. These individuals and their labor have resulted in unprecedented developments in the understanding of physiology, safe use of pharmacological agents, monitoring, pain control and provision of perioperative care to even the most compromised patients.
The word ‘anesthesia’ can be traced back to the Greek philosopher Dioscorides in the 1st century AD, who used it to describe the narcotic-like effects of the mandragora plant. Ancient civilizations used opium (from poppy), mandrake root, alcohol, coca leaves for phlebotomy, etc. to facilitate surgery. Nerve compression (to produce ischemia, shown in ) and cryoanalgesia (application of ice parallel to incision) were forms of regional anesthesia. In spite of these obviously meager and inadequate methods, records of trephinations and amputations can be found in medieval texts. However, modern surgery as we know it, was impossible due to poor understanding of disease, lack of asepsis and absence of reliable and safe anesthetic techniques.
As early as 1540–1550 Paracelsus noted the soporific effect of ether on chickens. In 1842 Crawford W Long and William E Clark, used ether for surgical removal of a sebaceous cyst. However, the first public demonstration of ether anesthesia that convinced the patient, the audience (and the surgeons!) was on 16th October 1846 at the Bullfinch amphitheater of the Massachusetts General Hospital, Boston by WTG Morton (). Ether's popularity and use spread rapidly through US and Europe. Incidentally, the word ‘anesthesia’, specifically used to denote the sleep-like state that makes painless surgery possible, was coined by Oliver Wendell Holmes, Professor of Anatomy at the Massachusetts General Hospital, soon after the first public demonstration by Morton.
Fig. 1: Nerve compression
John Snow (), a physician, pioneered the use of ether in England. He was fascinated by anesthesia and designed a number of vaporizers for safe and controlled administration of ether, and was one of the most sought-after and famous anesthetists. Chloroform was introduced a year later.20
Fig. 2: Public demonstration of ether
Fig. 3: John Snow
It owed its popularity to Sir James Simpson, an obstetrician, who eventually became a practicing anesthetist. He used it extensively to alleviate pain during labor. The administration of chloroform by Sir John Snow to Queen Victoria for the birth of her eighth child, Prince Leopold (and subsequently, Princess Beatrice) served to heighten the fame of both obstetric analgesia and chloroform.
Joseph Clover (1825-1882) succeeded Snow in London as a practising anesthetist. Due to his impeccable technique he was much sought after by surgeons. He had, to his credit, more than 7000 chloroform anesthetics without a single fatality. It is interesting to note that Clover was the first physician to monitor the pulse (see photograph: ), color and respiration under anesthesia and the first physician to administer ‘jaw thrust’ and ‘chin-lift’ maneuvers to relieve airway obstruction during anesthesia. Chloroform use rivaled that of ether in the 1850's-1860's. The first reported anesthetic death was associated with chloroform anesthesia. The patient was a young girl named Hannah Greener. Its popularity waned gradually due to its tendency to cause arrhythmias, respiratory depression and hepatotoxicity. The report of the Chloroform Commission in 1864 signaled the beginning of the end of chloroform and it was virtually out of use by the Ist World War.
Ether was revived in the 1870's in England and its rival in anesthetic practice at this stage was cyclopropane.21
Fig. 4: Joseph Clover
Since both were combustible and explosive, the arrival of halothane in the 1960's (and intravenous anesthesia, mentioned below) was welcomed by all operation theater personnel. Halothane was soon followed by methoxyflurane, enflurane and isoflurane. These agents possessed more useful clinical profiles and were not explosive. Further, precision vaporizers were available by this time, the anesthesia ‘machine’ had evolved, with breathing circuits. Desflurane and sevoflurane are the latest fluorinated anesthetics, introduced in the 1990's.
Intravenous anesthesia gained impetus only after the syringe and needle were invented by Alexander Wood in 1855 (). Chloral hydrate was used as a hypnotic in 1872. Numerous intravenous barbiturates were synthesized and tried in the late 1800's and early 1900's. However, only thiopentone sodium, reported simultaneously by Ralph Waters and J.S.Lundy in 1934 has stood the test of time. It is still the most widely used intravenous induction agent and remains the gold standard for any new non-narcotic anesthetic drug. Ketamine, synthesized in 1962 has specific uses and advantages. Di iso propyl phenol (Propofol) synthesized in 1984 is rapidly gaining popularity as a reliable and short acting intravenous agent.
Fig. 5: Alexander Wood and the syringe
The necessity for maintaining an unobstructed airway in war casualties undergoing facio-maxillary procedures was the impetus to the development of tracheal intubation. Sir Ivan Magill () and Sir Stanley Rowbotham were both proficient in blind nasal intubations before the invention of the laryngoscope. Sir William Macewen, a Scottish neurosurgeon, is credited with the performance of the first endotracheal intubation in 1880. Sir Robert Macintosh () was the other pioneer in airway management and the most commonly used laryngoscope is named after him.22
Fig. 6: Sir Ivan Magill
Fig. 7: Sir Robert Macintosh
It was by trial and error that a variety of endotracheal equipment was evolved and has perfected to the present day; it is difficult to imagine that sick and injured patients underwent surgery and anesthesia without protection of the airway just a century ago, compared to the availability of present-day gadgets like the fiberoptic laryngoscope and other sophisticated airway equipment.
The credit for discovering the local anesthetic properties of cocaine and using it for ophthalmic anesthesia goes to Karl Koller in 1884. Subsequently Sir William Halstead, the renowned surgeon, used cocaine for nerve blocks and infiltration. Although August Karl Gustav Bier performed the first spinal anesthetic () in 1898, it was to be nearly 35 years before lumbar epidural analgesia was demonstrated by Pages and Dogliotti in 1932. The advantages and safety of spinal and epidural anesthesia made these techniques very popular. The use of other regional anesthetic techniques like brachial plexus block and stellate ganglion block also became widespread, due to the development of less toxic drugs, improved knowledge of pharmacokinetics and availability of nerve stimulators and imaging techniques.
Fig. 8: August Bier and amputation under spinal anesthesia
The advent of muscle relaxants into the realm of clinical anesthetic practice in 1942 heralded another milestone. Relaxants have not only facilitated tracheal intubation but also tremendously improved surgical access and facilitated prolonged ventilation especially in the ICU. Opiates, which had been out of favor due to their potential to cause respiratory depression, now made a comeback as means of controlled ventilation were available. Lundy's concept of ‘balanced anesthesia’ introduced in the 1940's consisted of administration of thiopentone, nitrous oxide, muscle relaxant and an opiate, (usually meperidine) and still finds favor with most anesthesiologists. After the 1970's, synthetic opiates like fentanyl and sufentanil have become popular. Understanding of opiate receptors and availability of opiate antagonists have increased safety of opioid use.
In the 150 years following the clinical demonstration of ether anesthesia, anesthesiology has developed by unprecedented leaps and bounds. The role of the anesthesiologist is not only to provide for pain-free surgery and postoperative recovery, but as a primary care giver in the perioperative period. Thus it is the anesthesiologist's responsibility to (a) assess and evaluate the patient's preoperative condition, especially with respect to comorbid illnesses, (b) to optimize the condition whenever possible and 23(c) to provide a continuum of intensive monitoring and care till physiological stability is achieved.
Anesthesia care is also required beyond the confines of the operating theater in the cardiac catheterization laboratory, the lithotripsy room, CT scan and MRI suites, for electro-conclusive therapy and in the gastrointestinal endoscopy room, to name a few areas.
The anesthesiologists' skill in airway management, instituting invasive monitoring, working familiarity with advanced technology (blood gas analyzers, monitors, ventilators) and thorough knowledge of physiology, pharmacology, and cardio respiratory medicine, makes them a natural choice to manage ICUs.
Pain clinics are another example of units serviced by anesthesiologists to evaluate and treat acute and chronic pain. Measures ranging from oral non-steroid anti-inflammatory drugs (NSAIDs) to interventional pain management involving complex procedures like radio-frequency lesioning of the spinal cord and surgical implantation of intrathecal morphine delivery systems are carried out in pain clinics.
The teaching of cardiopulmonary resuscitation has also been the prerogative of anesthesiologists due to their constant association with the cardiopulmonary system, skill in intravenous access and airway management. They not only train post-graduates of the specialty but other members of the hospital staff and public. They are an integral part of the casualty (emergency) medical services and maintain check on equipment handled in its environs, and the emergency operation theater.
This wide role of the anesthesiologist is unfortunately still not known to the public at large, who perceive them as some kind of evanescent semi skilled technicians who administer a sleeping drug to the patient and disappear. This concept is changing with the wide recognition and necessity of trained anesthesiologists all over the world. It would be no exaggeration to state that advances in surgery would not have been possible in the absence of trained anesthesia personnel familiar with hemodynamic monitoring, airway management in routine and difficult situations, vascular access, use of intravenous fluids, respiratory critical care, and provision of analgesia. Quite justifiably, anesthesia has been quoted as “modern medicine's greatest gift to humanity.” For those of you who have not had an opportunity to visit Morton's memorial in Boston () the famous insciption engraved on it is presented below:
Fig. 9: William Thomas Green Morton and his memorial
“Inventor and Revealer of Inhalation Anesthesia:
Before Whom, in All Time, Surgery was Agony;
By Whom, Pain in Surgery was Averted and Annulled;
Since Whom, Science has Control of Pain.”
Need we say anything more in praise of this subject?
This textbook is designed to take undergraduate students on a ‘guided tour’ of the specialty of anesthesia. Its contents are aimed at teaching the basic principles, pharmacology, physiology, physics involved in anesthetic practice, as well as skills required to manage patients’ airway, knowledge of which will enrich them as future physicians no matter which specialty of medicine they choose to join; it will highlight how anesthesia has woven itself into virtually every specialty.
Welcome to the world of anesthesia!