2010 Dr Azam's Notes in Anesthesiology – Second Edition PEDIATRIC ANAESTHESIA Dr. Mohammed Azam Danish Consultant Anesthesiologist & Critical Care Specialist www.DrAzam.com Dr Azam's Notes In Anesthesiology 2 0 10 -Second Edition Dr Azam’s Notes in Anesthesiology 2nd Edition Pediatric Anesthesia By Dr. Azam Consultant Anesthesiologist & Critical Care 2 www.DrAzam.com Dr Azam's Notes In Anesthesiology 2 0 10 -Second Edition PREFACE This book grew from notes first written in 2003 - 2004 for the students at the J J M Medical College in Davangere. There are many textbooks to choose from when preparing for the “Anesthesiology examination”. The candidate suffers not from the lack of information but rather from being inundated with it. The candidate then has the task of information sorting and data compression to memorize and utilize all this information. Graphic representation of data is an excellent form of data compression; figures or drawings are frequently asked about at the viva examination, particularly since the candidate’s understanding of a problem comes across most clearly when drawing a figure or a using a picture. Figures are also a good way of approaching a topic. I constructed parts of Dr Azam’s Notes in Anesthesiology for Postgraduate students when preparing for the Anesthesiology examination and later when preparing for tutorials. Dr Azam’s Notes is aimed primarily at trainees in Anesthesia though more experienced practitioners may find it useful as a refresher in recent concepts and advances Dr Azam’s Notes is not a substitute for the major anesthesiology text books but concentrates on principles of management of the most challenging anesthetic cases. The format is designed to provide easy access to information presented in a concise manner. I have tried to eliminate all superfluous material. Selected important or controversial references are presented as well as suggestions for further reading. Some relate more to basic principles, physiology, pharmacology, etc. – bookwork. Others are more practical in nature, discussing the principles of anesthetic techniques for certain high-risk situations. Dr Azam’s Notes have been created keeping the Postgraduate needs while preparing for the exams, and also help in his day to day practice. I am sure that Dr Azam’s Notes will not only help him to secure highest marks but also help him to gain knowledge to its full. 3 www.DrAzam.com Dr Azam's Notes In Anesthesiology 2 0 10 -Second Edition A NOTE TO THE READER Anesthesiology is an ever-changing field. Standard safety precautions must be followed, but as new research and clinical experience broaden our knowledge, changes in treatment and drug therapy may become necessary or appropriate. Readers are advised to check the most current product information provided by the manufacturer of each drug to be administered to verify the recommended dose, the method and duration of administration, and contraindications. However, in view of the possibility of human error or changes in medical sciences, neither the author nor the publisher nor any other party who has been involved in the preparation or publication of this work warrants that the information contained herein is in every respect accurate or complete, and they disclaim all responsibility for any errors or omissions or for the results obtained from use of the information contained in this work. Readers are encouraged to confirm the information contained herein with other sources. It is the responsibility of the licensed prescriber, relying on experience and knowledge of the patient, to determine dosages and the best treatment for each individual patient. Neither the publisher nor the editor assumes any liability for any injury and/or damage to persons or property arising from this publication. 4 www.DrAzam.com Dr Azam's Notes In Anesthesiology 2 0 10 -Second Edition DEDICATION Mohammed Shafiulla To , my father, my oxygen, companion, and best friend; for being my major pillar of support and making this vision a reality. Thank you for your continual sacrifices with boundless love and limitless gratitude for the sake of your children. I owe you a debt I , can never repay. I also would like to thank my mom (Naaz Shafi), my wife (Roohi Azam), my two lovely kids (Falaq Zohaa & Mohammed Izaan),for their support, ideas, patience, and encouragement during the many hours of writing this book my Collegues Dr Rajshekar Reddy & Dr Sachin for their support. Finally, I would like to thank my teachers. The dream begins with a teacher who believes in you, who tugs and pushes and leads you to the next plateau, sometimes poking you with a sharp stick called "truth." 5 www.DrAzam.com Dr Azam's Notes In Anesthesiology 2 0 10 -Second Edition Contributions 01. Dr. Rajshekar Reddy – UAE 02. Dr. Surendra – UAE 03. Dr. Nagaraj Chandy – Hubli 04. Dr.Kusuma – Bangalore 05. Dr Sachin Doijode – London 06. Dr Chandrashekar – Bangalore 07. Dr Sidhu – Bangalore 08. Dr Ravindra B K – Bangalore 09. Dr Harshavardhan – Mangalore 10. Dr Anil Kumar – Tamil Nadu 11. Dr Mashooda – Kerla 12. Dr Anusuya – Bangalore 13. Dr Sudhir – Bangalore 14. Dr Uma – Davangere 15. Dr Rajeev – UAE 16. Dr Surendra – UAE 17. Dr Shivananda – Shimoga 18. Dr Soujanya – Bangalore 19. Dr Aslam Faris – Kerla 20. Dr Nandakumar – Tamil Nadu 21. Dr Anuradha – Bangalore 22. Dr Arun G Pai – Kerla 23. Dr Geetha – Bangalore 6 www.DrAzam.com Table of Contents PREFACE .......................................................................................................................................................... 3 DEDICATION .................................................................................................................................................... 5 CHAPTER 1 - ANATOMY AND PHYSIOLOGY .................................................................................................... 12 CLASSIFICATION BY AGE: ........................................................................................................................................ 12 1) Body size: ................................................................................................................................................ 12 2) Airway anatomy: ..................................................................................................................................... 12 3) Respiratory physiology: ........................................................................................................................... 13 4) Cardiovascular system: ........................................................................................................................... 13 5) Hematology: ............................................................................................................................................ 14 6) Renal: ...................................................................................................................................................... 15 7) Hepatic: ................................................................................................................................................... 15 8) Body composition: ................................................................................................................................... 16 9) Nervous system: ...................................................................................................................................... 16 10) Thermoregulation: ................................................................................................................................ 16 CHAPTER 2 - APPLIED ASPECTS OF ANATOMY AND PHYSIOLOGY OF RELEVANCE TO PEDIATRIC ANESTHESIA ...................................................................................................................................................................... 19 CLASSIFICATION ACCORDING TO GESTATIONAL AGE: ..................................................................................................... 19 CLASSIFICATION ACCORDING TO BIRTH WEIGHT ........................................................................................................... 19 Airway: ........................................................................................................................................................ 19 Respiratory system: ..................................................................................................................................... 21 Control of breathing: ................................................................................................................................... 21 Postoperative apnea: .................................................................................................................................. 22 Cardiovascular system: ............................................................................................................................... 22 Physiological differences between neonatal and adult myocardium .......................................................... 25 Age-related changes in vital signs. .............................................................................................................. 25 Age related changes in TBW and its distribution ........................................................................................ 26 CHAPTER 3 - PHARMACOKINETICS AND PHARMACODYNAMICS OF ............................................................... 33 ANESTHETIC DRUGS IN PEDIATRICS ............................................................................................................... 33 Pharmacokinetics of drugs in children: ....................................................................................................... 34 Absorption of drugs: .................................................................................................................................... 34 Parenteral: .................................................................................................................................................. 35 CHAPTER 4 - PREANESTHETIC EVALUATION AND ........................................................................................... 46 PREMEDICATION IN PEDIATRICS .................................................................................................................... 46 CHAPTER 5 - PERIOPERATIVE FLUID AND ELECTROLYTE MANAGEMENT IN PEDIATRIC PATIENTS .................. 57 PHYSIOLOGICAL CONSIDERATIONS IN INFANTS AND CHILDREN ........................................................................................ 57 ELECTROLYTE PHYSIOLOGY IN INFANTS AND NEONATES ................................................................................................. 59 Table 1: Daily electrolyte requirements for Pediatric patients .................................................................... 60 Cardiovascular considerations in infants and neonates .............................................................................. 60 Determining fluid requirements .................................................................................................................. 60 Dr Azam's Notes In Anesthesiology 2 0 10 -Second Edition Table 2: Assessment of dehydration severity in neonates and infants ....................................................... 62 TABLE 3: MAINTENANCE FLUID REQUIREMENTS IN NEONATES ........................................................................................ 63 Table 4: Electrolyte composition of body fluids ........................................................................................... 64 Table 5: Composition of commonly used intravenous fluids in children ..................................................... 64 Maintenance fluid therapy .......................................................................................................................... 64 The fluids for maintenance therapy replace losses from two source: ......................................................... 64 Table 6: Replacement for third space and evaporative losses .................................................................... 66 Replacement of blood loss .......................................................................................................................... 67 Electrolyte imbalance in the perioperative period ...................................................................................... 68 CHAPTER 6 - MONITORING IN PEDIATRIC ANESTHESIA .................................................................................. 75 Table 2: Physiological limitations of pulse oximetry ................................................................................... 79 Table 3: Normal values of blood pressure according to age ....................................................................... 83 Table 4: Comparison of main stream and side stream capnography .......................................................... 90 Table 5: Interpretation of some capnographs ............................................................................................. 90 Train of four ................................................................................................................................................ 94 CHAPTER 7 - ANESTHETIC CONSIDERATIONS FOR SPECIALIZED SURGERIES PECULIAR TO PEDIATRIC AGE GROUP ........................................................................................................................................................... 98 I. CONGENITAL DIAPHRAGMATIC HERNIA ....................................................................................................... 98 Embryology ................................................................................................................................................. 98 Pathophysiology: ......................................................................................................................................... 98 Causes of hypoxemia: .................................................................................................................................. 99 Classification based on anatomical defect in the diaphragm: .................................................................. 100 Assessment of severity of pulmonary hypoplasia ..................................................................................... 100 TRACHEOOESOPHAGEAL FISTULA ............................................................................................................. 103 Risk categorizations .................................................................................................................................. 104 Spitz classification ..................................................................................................................................... 104 TOF types: Cross and Vogt classification ................................................................................................... 104 PATHOPHYSIOLOGY ............................................................................................................................................. 105 Clinical presentation and diagnosis:.......................................................................................................... 105 ANESTHETIC CONSIDERATIONS: .............................................................................................................................. 106 Anesthetic technique ................................................................................................................................. 107 FOREIGN BODY REMOVAL FROM AIRWAYS ................................................................................................... 108 Pathophysiology: ....................................................................................................................................... 108 Four types of obstruction and their effects ............................................................................................... 109 CHAPTER 8 - LAPAROSCOPIC SURGERIES IN CHILDREN ................................................................................ 114 PHYSIOLOGICAL CHANGES ..................................................................................................................................... 114 PNEUMOPERITONEUM (PNP) ............................................................................................................................... 114 OTHER MEANS FOR PNEUMOPERITONEUM ............................................................................................................... 115 Intra-abdominal Pressure (IAP) ................................................................................................................. 115 Positioning ................................................................................................................................................. 115 Cardiovascular effects ............................................................................................................................... 115 Respiratory effects .................................................................................................................................... 116 8 www.DrAzam.com Dr Azam's Notes In Anesthesiology 2 0 10 -Second Edition Neurologic effects ..................................................................................................................................... 116 Endocrinal effects ...................................................................................................................................... 117 Anesthetic management Preoperative evaluation .................................................................................... 117 Premedication ........................................................................................................................................... 117 Monitoring ................................................................................................................................................ 117 Induction of Anesthesia ............................................................................................................................. 117 Perioperative care ..................................................................................................................................... 118 Postoperative care .................................................................................................................................... 118 Pain management ..................................................................................................................................... 118 Use of laryngeal mask airway (LMA) ........................................................................................................ 118 CHAPTER 9 - PYLORIC STENOSIS ................................................................................................................... 121 SIGNS AND SYMPTOMS:........................................................................................................................................ 121 Anesthetic management: .......................................................................................................................... 121 Postoperative management: ..................................................................................................................... 122 CHAPTER 10 - PEDIATRIC AMBULATORY SURGERY PERIOPERATIVE CONCERNS........................................... 124 PREOPERATIVE FASTING ....................................................................................................................................... 124 Table 5: Laryngeal mask airways .............................................................................................................. 124 CHAPTER 11 - REGIONAL ANAESTEHSIA IN PEDIATRIC PATIENTS ................................................................. 128 THE ADVANTAGES OF RA ARE: ............................................................................................................................... 128 INDICATIONS ...................................................................................................................................................... 128 Contra indications ..................................................................................................................................... 128 Common regional analgesia techniques ................................................................................................... 128 Caudal block .............................................................................................................................................. 128 CHAPTER 12 - COMPLICATIONS FOLLOWING GENERAL ANESTHESIA IN PEDIATRIC PATIENTS...................... 136 A. COMPLICATIONS DUE TO PREMATURITY ............................................................................................................... 136 A. IMPAIRED THERMOREGULATION ......................................................................................................................... 136 CAUSES OF HYPOTHERMIA: ................................................................................................................................... 136 B. APNOEA ........................................................................................................................................................ 137 c. Respiratory distress syndrome ............................................................................................................... 137 d. Retinopathy of prematurity ................................................................................................................... 137 e. Periventricular - intraventricular haemorrhage .................................................................................... 138 B. Complications due to congenital anomalies ......................................................................................... 138 a. Congenital heart disease ....................................................................................................................... 138 Intracardiac shunts: .................................................................................................................................. 139 CHAPTER 13 - POSTOPERATIVE PAIN MANAGEMENT IN PEDIATRIC PATIENTS ............................................ 146 PAIN ASSESSMENT IN CHILDREN ............................................................................................................................. 146 A. QUESTION THE CHILD ....................................................................................................................................... 147 Problems and contraindications to Pediatric PCA ..................................................................................... 154 Adverse effects of PCA in the pediatric population ................................................................................... 154 CHAPTER 14 - NEONATAL ASPHYXIA ............................................................................................................ 159 9 www.DrAzam.com Dr Azam's Notes In Anesthesiology 2 0 10 -Second Edition CHAPTER 15 - PLACENTAL TRANSFER OF DRUGS OF ANESTHETIC IMPORTANCE .......................................... 162 NARCOTICS: ....................................................................................................................................................... 162 INHALATION AGENTS: ............................................................................................................................... 163 CHAPTER 16 - NEONATAL RESUSCITATION ................................................................................................... 167 NEONATAL RESUSCITATION EQUIPMENT: ..................................................................................................... 167 Resuscitation trolley: ................................................................................................................................. 167 Apgar score: .............................................................................................................................................. 168 PULMONARY RESUSCITATION: ...................................................................................................................... 170 Tracheal intubation: .................................................................................................................................. 170 TRACHEAL SUCTIONING: ....................................................................................................................................... 170 VENTILATION: .................................................................................................................................................... 170 CARDIOVASCULAR RESUSCITATION: .............................................................................................................. 171 UMBILICAL VESSEL CATHETERIZATION: ..................................................................................................................... 171 CORRECTION OF ACIDOSIS: ............................................................................................................................ 171 HYPOVOLEMIA: .............................................................................................................................................. 171 CHAPTER 17 - MENINGOMYELOCELE ........................................................................................................... 176 SIGNS AND SYMPTOMS:........................................................................................................................................ 176 ASSOCIATED CONGENITAL ANOMALIES: ................................................................................................................... 176 Anesthetic management: .......................................................................................................................... 177 CHAPTER 18 - HYDROCEPHALUS ................................................................................................................. 180 CLASSIFICATION: ................................................................................................................................................. 180 CONGENITAL CAUSES OF OBSTRUCTIVE HYDROCEPHALUS............................................................................................. 180 Signs and symptoms: ................................................................................................................................. 180 DIAGNOSTIC TESTS: ............................................................................................................................................. 181 TREATMENT: ...................................................................................................................................................... 181 ANESTHETIC MANAGEMENT: ................................................................................................................................. 181 CHAPTER 19 - DOWN SYNDROME / TRISOMY 21 ......................................................................................... 184 CHARACTERISTICS: .............................................................................................................................................. 184 CHAPTER 20 - TEMPERATURE REGULATION IN INFANTS .............................................................................. 186 EFFECTS OF HYPOTHERMIA: ................................................................................................................................... 186 CHAPTER 21 - NONSHIVERING THERMOGENESIS (NST) ................................................................................ 187 MECHANISM: ..................................................................................................................................................... 187 CHAPTER 22 - FETAL HEMOGLOBIN .............................................................................................................. 188 CHAPTER 23 - LOBAR EMPHYSEMA .............................................................................................................. 189 PNEUMONECTOMY ............................................................................................................................................. 189 SIGNS AND SYMPTOMS:........................................................................................................................................ 189 Anesthetic management: .......................................................................................................................... 189 10 www.DrAzam.com