e3 109 Arena F, Dugowson C, Saudek C Salicylate induced hypoglycemia and ketoacidosis in a nondiabetic adult Arch Intern Med 1978; 138 1153 1154 110 Thundiyil JG, Kearney TE, Olson KR Evolving epidemi[.]
e3 109 Arena F, Dugowson C, Saudek C Salicylate-induced hypoglycemia and ketoacidosis in a nondiabetic adult Arch Intern Med 1978; 138:1153-1154 110 Thundiyil JG, Kearney TE, Olson KR Evolving epidemiology of drug-induced seizures reported to a poison control center system J Med Toxicol 2007;3:15-19 111 Willis B, Erickson T Drug- and toxin-associated seizures Med Clin North Am 2005;89:1297-1391 112 Reichert C, Reichert P, Monnet-Tschudi F, et al Seizures after single-agent overdose with pharmaceutical drugs: analysis of cases reported to a poison center Clin Toxicol 2014;52:629-634 113 Boehnert MT, Lovejoy Jr FH Value of the QRS duration versus the serum drug level in predicting seizures and ventricular arrhythmias after an acute overdose of tricyclic antidepressants N Engl J Med 1985;313:474-479 114 Foulke GE Identifying toxicity risk early after antidepressant overdose Am J Emerg Med 1995;13:123-126 115 Bailey B Glucagon in beta-blocker and calcium channel blocker overdoses: a systematic review Clin Toxicol 2003;41:595-602 116 Yuan TH, Kerns WP II, Tomaszewski CA, et al Insulin-glucose as adjunctive therapy for severe calcium channel antagonist poisoning Clin Toxicol 1999;37:463-474 117 Boyer EW, Duic PA, Evans A Hyperinsulinemia/euglycemia therapy for calcium channel blocker poisoning Pediatr Emerg Care 2002;18:36-37 118 Artman M, Grayson M, Boerth R Propranolol in children: safetytoxicity Pediatrics 1982;70:30-31 119 Love J, Sikka N Are 1-2 tablets dangerous? Beta-blocker exposure in toddlers J Emerg Med 2004;26:309-314 120 Aramaki Y, Uechi M, Takase K Comparison of the cardiovascular effects of intracellular cyclic adenosine 3' 5’-monophosphate (cAMP)-modulating agents in isoflurane-anesthetized cats J Vet Med Sci 2002;64:981-986 121 Love J, Leasure J, Mundt D A comparison of combined amrinone and glucagon therapy to glucagon alone for cardiovascular depression associated with propranolol toxicity in a canine model Am J Emerg Med 1993;11:360-363 122 Kerns W 2nd, Shroeder D, Williams C, et al Insulin improves survival in a canine model of acute b-blocker toxicity Ann Emerg Med 1997;29:748-757 123 Page C, Hacket LP, Isbister GK The use of high-dose insulin-glucose euglycemia in beta-blocker overdose: a case report J Med Toxicol 2009;5(3):139-143 124 Stellpflug SJ, Harris CR, Engebretsen KM, Cole JB, Holger JS Intentional overdose with cardiac arrest treated with intravenous fat emulsion and high-dose insulin Clin Toxicol 2010;48:227-229 125 Bismuth C, Gualtier M Hyperkalemia in acute digitalis poisoning: prognostic significance and therapeutic implications Clin Toxicol 1973;6:153-162 126 Mason D, Zelis R, Hughes L, et al Current concepts and treatment of digitalis toxicity Am J Cardiol 1971;27:546-559 127 Woolf AD, Wenger TL, Smith TW, et al Results of multicenter studies of digoxin-specific antibody fragments in managing digitalis intoxication in the pediatric population Am J Emerg Med 1991;9(2 suppl 1):16-20 128 Chan A, Isbister GK, Kirkpatrick CM, Dufful SB Drug-induced QT prolongation and torsades de pointes: evaluation of a QT nomogram QJM 2007;100: 609-615 129 Tzivoni D, Banai S, Schuger C, et al Treatment of torsade de pointes with magnesium sulfate Circulation 1988;77(2):392-397 130 Rumack B Acetaminophen hepatotoxicity: the first 35 years J Toxicol Clin Toxicol 2001;40:3-20 131 Keays R, Harrison PM, Wendon JA, et al Intravenous acetylcysteine in paracetamol induced fulminant hepatic failure: a prospective controlled trial Br Med J 1991;303:1026-1029 e4 Abstract: When a toxin is unknown, physical and analytic clues may help guide diagnosis and therapy A toxidrome is a constellation of signs associated with certain substances or groups of substances Recognition of a toxidrome can inform targeted investigation and treatment Attention should be particularly paid to vital signs, mental status, pupil size and reactivity, skin characteristics, bowel sounds, muscle tone, respiratory effort, and mucous membrane characteristics The presence of seizures may suggest certain toxins Similarly, abnormal diagnostic results, such as metabolic acidosis with increased anion gap or electrocardiographic abnormalities, may give a clue to the ingested toxin and its treatment Key words: poisoning, toxidrome, acetaminophen, antidote, metabolic acidosis, cardiotoxin, neurotoxin SECTION XIV Pediatric Critical Care: Anesthesia Principles in the Pediatric Intensive Care Unit 127 Airway Management, 1510 128 Anesthesia Effects on Organ Systems, 1535 129 Anesthesia Principles and Operating Room Anesthesia Regimens, 1544 130 Malignant Hyperthermia, 1560 131 Neuromuscular Blocking Agents, 1567 132 Sedation and Analgesia, 1583 133 Tolerance, Dependency, and Withdrawal, 1611 134 Pediatric Delirium, 1617 135 Procedural Sedation for the Pediatric Intensivist, 1624 1509 127 Airway Management CHINYERE EGBUTA, E ALEXIS BRAGG, AND SAPNA R KUDCHADKAR PEARLS • • Safe management of the critically ill child’s airway requires a comprehensive understanding of the anatomic and physiologic changes that occur from birth through adolescence, advance recognition of congenital and acquired airway abnormalities, appreciation of the pathophysiologic consequences of airway manipulation, and preparation for airways that are potentially difficult to manage Laryngoscopy and intubation are potent physiologic stimuli that are associated with severe discomfort, profound cardiovascular and cerebrovascular changes, and increased airway reactivity The accurate assessment and safe management of the airway are the most essential first steps in providing effective care for a critically ill child These steps require that the practitioner understand the anatomic and physiologic changes that occur from birth through adolescence, recognize congenital and acquired airway abnormalities, appreciate the pathophysiologic consequences of airway manipulation and underlying disease processes, and prepare for airways that may potentially be difficult to manage Anatomic Considerations Configuration of a child’s airway changes dramatically from birth to adulthood (Fig 127.1) The nose is the site of nearly half of the total respiratory resistance to airflow at all ages The infant’s nose is short, soft, and flat, with small, nearly circular nares The nasal valve, the narrowest portion of the nasal airway, is approximately cm proximal to the alar rim in newborns and measures only about 20 mm2.1,2 By months, the dimensions of the nares have nearly doubled, but they are still easily occluded by edema, secretions, or external pressure Although an infant is perhaps not as much the obligate nose breather as commonly assumed, signs of airway obstruction frequently develop when the infant’s nose is obstructed.3,4 In infancy, the mandible is small and the basicranium (which provides the roof of the nasopharynx) is flat, creating a small oral cavity Over the years of its development, the jaw grows primarily inferiorly and anteriorly, with the mandibular ramus increasing in height and width The posterior portion of the basicranium develops a progressively more rounded configuration through childhood, which results in a larger nasal airway to meet the need for increased airflow These anatomic changes provide a chamber for the resonance of adult speech 1510 • • • Recognizing a difficult airway and preparing to manage it are essential to preventing potentially lethal complications of intubation The approach to intubation must be tailored to specific circumstances, including full stomach, elevated intracranial pressure, cervical spine injury, and upper airway obstruction Alternative approaches to airway management—such as the laryngeal mask airway, cricothyrotomy, retrograde intubation, tracheostomy, and video laryngoscopy—may be lifesaving Under normal conditions, the genioglossus muscle and other muscles of the pharynx and larynx help maintain airway patency Both tonic and phasic inspiratory activity synchronized with phrenic contraction have been noted in animal and human studies In particular, the genioglossus increases the dimensions of the pharyngeal airway by displacing the tongue anteriorly.5 In the infant and young child, the tongue is large relative to the surrounding bony structures and the cavities they form Relatively little displacement is possible at any time Therefore, loss of tone caused by sleep, sedation, or central or peripheral nervous system dysfunction is more likely to allow the tongue to relax into the posterior pharynx and cause upper airway obstruction in young children than it is in older patients The infant larynx is high in the neck at birth, with the epiglottis at the level of the first cervical vertebra and overlapping the soft palate This approximation of structures, in combination with the relatively large tongue and small mandible, contributes to the vulnerability of infants and young children to airway obstruction By months, the epiglottis has moved to about the level of the third cervical vertebra and is separate from the palate The epiglottis continues to descend to its adult position at about the fifth or sixth cervical vertebra by early adolescence The infant epiglottis is soft and omega shaped, in contrast with the more rigid, flatter adult structure, and has greater potential to occlude the airway For many years, standard teaching has been that both the immature larynx and trachea differ greatly from the mature structures However, modern imaging techniques, including bronchoscopy, computed tomography scanning, and magnetic resonance imaging, provide evidence that contradicts previous dogma.6–8 The immature larynx is roughly cylindrical, not funnel shaped, similar to the straight vertical column seen in adults Although the CHAPTER 127 Airway Management Infant 1511 Adult Inflammation 0.5 Newborn 18 months A B r R (normal) R (inflamed) 1 16 0.01 0.03 C ETT Circular airway Air leak fairly reliably reflects small enough ETT in a circular airway ETT Elliptical airway D ETT Mucosal compression/ischemia by ETT in spite of air leak Gently inflated cuff occludes air leak without mucosal compromise • Fig 127.1 Characteristics of the pediatric airway (A) Changes in mandibular shape from infancy through adolescence (B) The epiglottis is initially cephalad in infancy and then descends throughout childhood. (C) Edema has a much greater effect on airway resistance in the young child than it does later in life. (D) Contrary to traditional teaching, imaging indicates that the infant and young child’s airway is slightly elliptical in shape and its narrowest portion is at the vocal cords, as in adults The elliptical shape raises questions about the value of an air leak in selecting the correct endotracheal tube (ETT) size; a leak may be present even in the presence of mucosal compression and ischemia A gently inflated cuff seals the airway more effectively, but close monitoring of cuff pressure is necessary The cricoid is the most rigid segment and may be most at risk of injury E, Epiglottis; P, palate; r, relative radius of the trachea; R, relative airway resistance narrowest part of the young child’s airway was previously thought to be at the level of the cricoid cartilage, studies show that, as in adults, it is at or just below the vocal cords Nonetheless, the cricoid is more rigid than other areas of the airway and vulnerable to injury At all ages, the trachea is slightly elliptical in crosssection, with the anteroposterior diameter slightly greater than the transverse diameter These newer findings have important implications for endotracheal intubation and will be discussed later The internal dimensions of the trachea in a newborn are approximately one-third those of an adult, and absolute resistance to airflow is higher in newborns than in older children and adults The most important factor determining resistance (R) is the radius (r) of an airway (Poiseuille’s law: R is proportional to l/r4); therefore, small changes in airway diameter in infants or young children as a consequence of edema or secretions have a far greater effect on resistance than similar changes in larger patients (see Fig 127.1C) ... with the epiglottis at the level of the first cervical vertebra and overlapping the soft palate This approximation of structures, in combination with the relatively large tongue and small mandible,... young children to airway obstruction By months, the epiglottis has moved to about the level of the third cervical vertebra and is separate from the palate The epiglottis continues to descend to its... will be discussed later The internal dimensions of the trachea in a newborn are approximately one-third those of an adult, and absolute resistance to airflow is higher in newborns than in older