The Pediatric Airway

Objective: Students will be able to:
Explain the operational significance of the following selected pediatric characteristics.

1. Young infants have relatively less oxygen reserve (greater oxygen consumption), so hypoxemia occurs relatively more rapidly. Skill in bag and mask ventilation of infants is valuable.

2. There is a large range of pediatric patient sizes: 500 grams to 100 kilograms. A universal "pediatric cart" thus needs to be bigger and hold much more equipment than an "adult cart."

3. Airway sizes may vary unpredictably among pediatric patients of same age and weight. So one ought have more equipment available: at least 3 different sized endotracheal tubes.

The appropriate uncuffed ETT size may be determined by the following formula (age in years):
4 + (1/4)(age)
Subtract 0.5 for the appropriate size cuffed ETT
E.g.: 4-year-old: uncuffed ETT size = 4 + (1/4)4 = 5, so
cuffed ETT size = 4.5
The appropriate depth of ETT insertion (Lau et al, 2006):
Over one year of age:
oral: 13 + (1/2)age
nasal: 15 + (1/2)age
Infants (weight in kg):
oral: 8 + (1/2)(weight)
nasal: 9 + (1/2)(weight)

4. Some pediatric patients and their airways are small, and resistance to air flow is inversely proportional to the fourth power of the radius of the airway. One mm of concentric edema in a newborn trachea (radius approximately 2 mm) increases resistance about 16 times.

5. Young pediatric patients are less likely than their adult counterparts to be completely cooperative. Consideration must frequently be given to local anesthesia, sedation and general anesthesia with or without muscle relaxants.

6. There are anatomic differences between the infant and the adult upper airway:
• Infant larynx:
  • More superior in neck
    
  • Epiglottis shorter, angled more over glottis
    
  • Vocal cords slanted: anterior commissure more inferior
    
  • Larynx cone-shaped: narrowest at subglottic cricoid ring
    
  • Softer, more pliable: may be gently flexed or rotated anteriorly
    
• Infant tongue is relatively larger.
  
• Infant head is relatively larger: naturally flexed in supine position. Extension of head may result in tracheal extubation; while flexion may lead to main stem intubation.

7. Young infants (less than approximately 2-3 months) are obligate nose breathers.

8. The infant upper airway is relatively more sensitive to inhalational agents; more prone to collapse. Oral airways may be quite useful and should always be available.

9. Infants may suffer from congenital vascular rings and slings (and other congenital cardiovascular things) that negatively effect their airway and breathing.

10. Young children (especially 12-24 months of age) have a relative propensity to aspirate foreign bodies (food, coins).

11. DL may be impossible in:
Syndromes with micrognathia (small mandibular space): Pierre Robin "sequence"
• Stickler's syndrome (progressive myopia, glaucoma, stiff joints, and, in one third, micrognathia)
  
• velocardiofacial syndrome
  
• fetal alcohol syndrome
  
• isolated micrognathia (20% of cases)
  
Syndromes with limited atlanto-occipital extension:
• Klippel-Feil (fusion of c-spine)
  
• Goldenhar's (may also have mandibular hypoplasia)
  
• arthrogryposis
  

12. Life-threatening infections:
• croup
  
• epiglottitis
  
• retropharyngeal abscess
  
• bacterial tracheitis
  

13. Gastroesophageal reflux is quite common in infants. It is generally benign and resolves spontaneously. There is some debate over how much is abnormal and just how to accurately quantitate it. For infants felt to have significant reflux, acid aspiration prophylaxis, for example with metoclopramide and/or H2-blockers, may be considered.

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