Pediatric Airway Anatomy and Differences

Pediatric Airway Anatomy

• Pediatric head is proportionally larger than the rest of the body compared to adults
• Nose is smaller compared to the trachea in infants, who are obligate nose breathers at birth
• Tongue is larger in proportion to mouth size in children, potentially obstructing the airway

Airway Differences

• Airway shape is funnel-shaped in pediatrics, becoming cone-shaped in adults later in development
• Larynx is higher relative to the c-spine in children than adults, located at C3-C4
• Vocal cords in children attach lower on the anterior trachea than in adults, and slant forward and down
• Cricoid cartilage is the narrowest part of the pediatric airway, and the epiglottis has an omega shape in children, which is larger and stiffer than in adults

Infant Airway Considerations

• Miller blades are recommended for direct lifting of the epiglottis in infants

• Mainstem bronchi are narrower and shorter in infants compared to adults

• Mainstem bronchi divide more equally

• Infant airways are smaller in diameter, resulting in higher airway resistance

• Infants show a lower tolerance to edema , high metabolic rate, and decreased response to hypercapnia if ventilation increases

• Comparison of respiratory parameters:

  • Infant FRC is half of TLC
  • Infant RR is 25-50
  • Infant Vt is 6-8 ml/kg

• Pediatric closing volume is higher than in adults

• Pediatric FRC is closer to Vt, meaning smaller range of optimal oxygenation

• Pediatric oxygenation can decrease faster

• In infants, several factors including hypoxia, hypercarbia, acidosis, and high Hct can increase pulmonary vascular resistance (PVR)

• Similar factors in adults cause the opposite effect, decreasing PVR

• CO depends on heart rate (HR) due to fixed stroke volume (SV)

• Airway evaluation should consider recurrent pneumonia/respiratory infections as a possible indicator of frequent aspiration, and also note pre-existing conditions

Aspiration and Airway Issues

• Aspiration can occur due to incompetent larynx, GERD, TEF (tracheo-esophageal fistula), and tracheobronchial fistula
• Presence of URI can increase the risk of airway edema and associated conditions.
• Environmental factors, such as allergies or secondhand smoke, can exacerbate airway reactivity
• Conditions such as microtia (deformed ears), can cause increased risk of difficult airway management
• Positioning during mask ventilation of neonates should maintain normal head and neck alignment, however neck extension can be performed in older pediatric cases
• Nasopharyngeal airways (NPAs) are typically avoided in children due to increased risk of trauma due to hypertrophied adenoids
• Oral airway placement should account for tongue size, which is larger relative to the oropharynx in children, which will cause a block to airway flow
• The insertion of a mask can cause laryngospasm if performed during stage 2 (insertion)
• Minimizing pressure during mask ventilation is crucial to prevent airway collapse
• Laryngospasm needs careful assessment to determine whether to use LMA or Intubation
• Other airway issues include conditions like atlantoaxial instability (with or without subluxation), hypoplastic mandible, protruding tongue, Pierre-Robin sequence, and Treacher-Collins syndrome

Ventilation and Intubation Considerations

• Physiologic PEEP is 4-5
• Avoiding oxygen/N2O before 44 weeks of age to mitigate retinopathy of prematurity
• Extubation can be performed in an awake or deep state and have different advantages or disadvantages based on preference
• Considerations should be given to patient condition if non-protected airway is needed, as a non-protected airway puts patient in greater risk for aspiration
• Different airway obstruction causes can arise based on location (above vs below larynx), and may affect respiratory sounds
• Difficult procedures need well-considered use of airway devices to avoid possible complications
• Various airway syndromes such as choanal atresia and clef lip/palate can all result in a need for airway intervention

Additional Considerations

• Proper cuff pressure (20 cmH2O) and proper size consideration for endotracheal intubation (ETT) are critical
• Use of an appropriate intubation technique ( Miller or MAC) is essential depending on age range of patient
• Nasally intubation is preferable if possible, and using PCP mode if needed
• Consider physiological PEEP to assist with ventilation
• Avoid unnecessary instrumentation and procedures in the nasal cavity
• Various congenital conditions can affect the airway, requiring earlier consideration/preparation