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