TABLE 8.1 ANATOMIC AND PHYSIOLOGIC FEATURES IN CHILDREN PERTINENT TO LARYNGOSCOPY AND INTUBATION Anatomy • Size —airway structures are smaller and field of vision is narrower • Adenoidal hypertrophy is common in young children • Developing teeth —while young infants are edentulous, the underlying alveolar ridge contains developing tooth buds that are susceptible to disruption • Primary teeth in young children can be easily avulsed and/or aspirated • Tongue is large relative to size of oropharynx • Superior larynx —often referred to as “anterior,” the laryngeal opening in infants and young children is actually located in a superior position (in infants, the larynx is opposite C3–C4 as opposed to C4–C5 in adults) This makes the angle of the laryngeal opening with respect to the base of the tongue more acute and visualization more difficult • The hyoepiglottic ligament (connects base of tongue to epiglottis) has less strength in young children—thus, a laryngoscope blade in the vallecula will not elevate the epiglottis as efficiently as in an adult • The epiglottis of children is narrow and angled acutely with respect to the tracheal axis; thus the epiglottis covers the tracheal opening to a greater extent and can be more difficult to mobilize • The narrowest point occurs at the level of the cricoid cartilage Physiology • Lung —smaller and fewer alveoli, decreased gas exchange surface area, absent collateral channels of ventilation • Respiratory mechanics —the cartilaginous chest wall in children has poor elastic recoil and leads to increased compliance The closing volume (CV), the volume at which terminal bronchioles collapse as a result of extrinsic pressure exceeding intrabronchial pressure + elastic recoil forces is frequently higher than functional residual capacity (FRC), leading to a greater tendency for atelectasis and collapse • Cellular physiology —increased oxygen consumption in infants; prone to significant increase with physiologic perturbation (e.g., fever, hypothermia) • Cardiovascular —high vagal tone, greater tendency for bradycardia with hypoxia, laryngeal stimulation High-Flow Nasal Cannula High-flow nasal cannula (HFNC) devices deliver oxygen at rates that match or exceed patients’ inspiratory flow rates (up to as high as 60 L/min in adults), resulting in a higher concentration of oxygen (FiO2 ) due to limited entrainment of room air HFNC can deliver an FiO2 from 21% to 100%, with heated and humidified air being well tolerated Nasal cannulas come in sizes for neonatal, pediatric, and adult use The flow should be adjusted based on patient age ( Table 8.2 ) If adequate respiratory support can be achieved with HFNC devices, the need for sedation and risk of ventilator-associated pneumonia associated with endotracheal intubation and mechanical ventilation can be avoided In addition, HFNC devices may be better tolerated than face masks by pediatric patients because they are less constricting and permit speaking and feeding HFNC has an excellent safety profile, with only case-reportable complications related to barotrauma (pneumothorax, pneumomediastinum, pneumocephalus) TABLE 8.2 SUGGESTED FLOW RATES FOR HIGH-FLOW NASAL CANNULA (HFNC) Patient weight (kg) Starting flow (L/min) Maximum flow (L/min) 40 15–20 25–30 25–30 15 20 40 40–60 Noninvasive Ventilation NIV encompasses mechanical respiratory support without endotracheal intubation through either continuous positive airway pressure (CPAP) or bilevel positive airway support (BPAP) CPAP provides a constant distending airway pressure throughout the respiratory cycle BPAP provides two levels of pressure referred to as inspiratory positive airway pressure (IPAP) and expiratory positive airway pressure (EPAP) Breaths can be synchronized to spontaneous respiratory effort or delivered independently Both CPAP and BPAP can be delivered through a range of interfaces, including nasal cannula, nasal mask, full-face mask, or helmet Choosing an appropriate interface is often the greatest challenge in pediatrics Interfaces should be chosen balancing the desire to maximize comfort and compliance while ensuring minimal leak In addition to pressure, NIV can also deliver supplemental oxygen and inhaled therapies such as albuterol or racemic epinephrine Similar to HFNC, NIV can be used for either acute hypoxic or hypercarbic respiratory failure CPAP may be appropriate when hypoxemia is the primary indication Because it delivers higher mean airway pressures while offloading inspiratory effort, BPAP can be used for more severe hypoxemia and to address hypercapnia Multiple parameters can be titrated with NIV, including CPAP (typically 5- to 10-cm H2 O), EPAP and IPAP (typically to 10 cm H2 and to 22 cm H2 O, respectively), FiO2 , and backup ventilation rate for patients experiencing intermittent apnea or hypopnea If successful, NIV eliminates some complications related to intubation, such as laryngeal or tracheal injury or ventilator-associated pneumonia, as well the risks associated with sedation and neuromuscular blockade NIV should not be used in patients requiring immediate endotracheal intubation, or those with impaired mental status or requiring airway protection Relative contraindications include facial injury, upper gastrointestinal bleeding, untreated pneumothorax, and significant or escalating vasopressor support Most children, with appropriate coaching and provider patience during initiation, will tolerate NIV though some require anxiolysis or sedation Beyond the potential for failure of NIV, the significant complications include barotrauma, aspiration, and hemodynamic instability due to decreased venous return Minor complications include skin breakdown, eye irritation, nasal mucosal trauma, and gastric distention APPROACH TO ENDOTRACHEAL INTUBATION Rapid sequence intubation (RSI) is the favored approach when advanced airway management is required in pediatrics RSI can optimize intubating conditions and results in higher intubation success rates than sedation alone approaches In brief, RSI involves the near simultaneous administration of a sedative and neuromuscular-blocking agent (NMBA) to render a patient unconscious and immobile, with blunted natural airway reflexes In pure RSI, bag mask ventilation is not performed to avoid gastric insufflation and increased risk of aspiration in patients presumed not to be fasted Modified or controlled RSI differs in that it includes the delivery of gentle positive pressure breaths following medication administration to prevent hypoxia or hypercarbia during apnea Sedation-only intubation may be preferred in cases of upper airway obstruction or in cases where a difficult airway is predicted, and maintaining spontaneous respiration and airway patency is deemed prudent ( Fig 8.1 ) RSI is generally considered to be a controlled series of steps starting with preparing for the procedure and ending with management following placement The steps are often described as the Ps: preparation, preoxygnenation, pretreatment/preoptimization (i.e., adjunctive therapies), paralysis with induction, positioning, placement of the endotracheal tube, and finally postintubation management The key components of RSI are reviewed in the sections that follow EQUIPMENT Anticipating the need for increasing airway support and having necessary advanced airway equipment available are critical An oxygen supply source, devices for passive oxygen delivery, and a resuscitation bag and mask are needed for preparation as well as during advanced airway management procedures Monitoring equipment including capnography should be available For advanced airway management, oral and nasal airways, endotracheal tubes (ETTs), stylets, and traditional laryngoscope blades and handles and/or a videolaryngoscope in the appropriate size for the patient should be available To facilitate preparation, the mnemonic “SOAP ME” (suction, oxygen, airway equipment, positioning, monitors and meds, end-tidal CO2 monitor and equipment) can be used Alternatively, centers are increasingly using preintubation checklists to assure appropriate equipment, personnel resources, and medications are available Endotracheal Tubes Both cuffed and uncuffed ETTs are available for use in pediatrics Historically, uncuffed tubes were preferentially used in young children to allow use of the maximal tube size that would be accommodated by the anatomic narrowing at the level of the subglottis More recent bronchoscopic and radiolographic data (airway CT and MRI) suggest that the pediatric airway may by more elliptically shaped at this level rather than circumferentially narrowed In addition, newly designed cuffed pediatric ETTs are manufactured with balloons that are low profile and moved distally on the tube to avoid laryngeal structures when appropriately positioned Use of these new cuffed tubes has been shown to decrease the need for tube exchange secondary to inappropriate sizing, with no increase in postextubation stridor, need for racemic epinephrine, or long-term complications Pediatric Advanced Life Support (PALS) guidelines as well as the anesthesia literature now support that, beyond the newborn period, cuffed ETTs are equally as safe as uncuffed tubes In addition, cuffed tubes are favored in ... CT and MRI) suggest that the pediatric airway may by more elliptically shaped at this level rather than circumferentially narrowed In addition, newly designed cuffed pediatric ETTs are manufactured... ventilation can be avoided In addition, HFNC devices may be better tolerated than face masks by pediatric patients because they are less constricting and permit speaking and feeding HFNC has an... full-face mask, or helmet Choosing an appropriate interface is often the greatest challenge in pediatrics Interfaces should be chosen balancing the desire to maximize comfort and compliance while