Upper Airway

Upper Airway

1. Neonates are obligate nose breathers due to weak oropharyngeal muscles and increased compliance of the pharynx, larynx, and bronchial tree. Their nares are relatively narrow, and a significant fraction of the work of breathing is needed to overcome nasal resistance. Occlusion of the nares by bilateral choanal atresia or tenacious secretions can cause complete airway obstruction; however, some infants will convert to mouth breathing. Placement of an oral airway, a laryngeal mask airway, or an endotracheal tube may be necessary to reestablish airway patency during sedation or anesthesia.
2. Infants have relatively large tongues, which can make mask ventilation and laryngoscopy challenging. A recent study called tongue size into question and found the tongue to be proportional in children aged 1 to 12. Clinically, the tongue can easily obstruct the airway if excessive submandibular pressure is applied during mask ventilation.
3. Infants and children have a more cephalad glottis (C3 vertebral level in premature infants, C4 in infants, and C5 in adults) and a narrow, long, angulated epiglottis, which can make laryngoscopy difficult.
4. In infants and young children, the narrowest part of the airway is at the cricoid cartilage (recent studies have questioned this; see suggested readings), rather than at the glottis (as in adults). An endotracheal tube that passes through the cords may still be too large distally.
5. Deciduous teeth erupt within the first year and are shed between ages 6 and 13 years. To avoid dislodging a loose tooth, it is safest to open the mandible directly, without introducing a finger or appliance into the oral cavity. Loose teeth should be documented on the preoperative evaluation. In some instances, unstable teeth should be removed before laryngoscopy. Parents and patients should be informed of this possibility in advance.
6. Airway resistance in infants and children can be increased dramatically by subtle changes in an already small-caliber system. Even a small amount of edema can significantly increase airway resistance and cause airway compromise.