pediatric airway

Question 1

what structures differ in the pediatric airway?

Answer 1

• tongue
• laryngeal position
• epiglottis
• vocal cords
• subglottis

Question 2

describe the difference in the pediatric tongue

Answer 2

• proportionately larger
• increased risk of obstruction
• more difficult to move with laryngoscope

Question 3

describe the difference in the pediatric laryngeal position

Answer 3

• located at C3-C4 (more anterior than adult C4-C5)
• proximity of tongue to more superior larynx leads to a more acute angle to visualize glottis opening (*reason need to use straight blade)

Question 4

describe the difference in the pediatric epiglottis

Answer 4

• narrow
• horseshow shaped
• angled away from axis of the trachea
• stiff, thick, and can be hard to move
  (adult: flat, broad, parallel)

Question 5

describe the difference in the pediatric vocal cords

Answer 5

• more caudad attachment on anterior side
• adult more perpendicular to trachea
• angle causes more intubation difficulty

Question 6

describe the difference in the pediatric subglottis

Answer 6

• *most narrow part of infant airway at cricoid cartilage or area immediately below (adult’s is space b/w vocal cords called the rima glottides)
• harder to determine tube size
• laryngeal edema big problem

Question 7

describe the cricoid ring

Answer 7

• elliptical NOT round (can have significant leak but still be applying pressure on surrounding cricoid ring with round cuff)
• only complete, non-expandable tracheal ring (reason laryngeal edema so serious)

Question 8

how does 1 mm of edema affect the pediatric airway compared to an adult’s?

Answer 8

• infant tracheal diameter is 4 mm
• adult tracheal diameter is 8 mm
• *1 mm of circumferential edema causes 75% cross sectional decrease in the infant and only 44% decrease in the adult

Question 9

at what age does the pediatric airway reach adult proportions?

Answer 9

10-12

Question 10

describe the pediatric airway physiology

Answer 10

• infants: obligate nasal breathers; nasal obstruction can cause hypoxia
• adequate mouth breathing at 3-5 months
• larynx, trachea. and bronchi much more compliant, so more likely to become distended or obstructed
• loss of SV (with GA) can cause dynamic airway collapse
• vigorous crying can cause airway collapse
• caution with opiates and sedation (can cause life sustaining respiratory effort leading to severe hypoxia
• O2 consumption 2x higher than adults (compensation with faster respiratory rate)
• obstruction: increases O2 demand which causes tachypnea, eventual exhaustion, and respiratory failure (need to reintubate)

Question 11

describe obstruction during anesthesia for peds

Answer 11

• may be due to loss of airway muscle tone
• “sniffing” improves hypopharyngeal airway patency but does not significantly affect tongue position
• OSA: pharyngeal airway obstruction

Question 12

how is airway obstruction treated

Answer 12

• continuous positive airway pressure (CPAP)
• chin lift and jaw thrust
• lateral position; nasal/oral airways
• *most effective overall: jaw thrust

Question 13

what should be assessed for during the airway evaluation?

Answer 13

• URI: increased risk of laryngospasm, bronchospasm, edema (increased secretions and may already have swelling)
• snoring, noisy breathing: signs of big adenoids/tonsils, OSA
• croupy cough: can be sign of subglottic stenosis, foreign body
• inspiratory stridor: laryngomalacia (“soft larynx”; larynx collapses inward during inhalation causing obstruction; epiglottis flapping; sounds like hiccupping), laryngeal web (airway is blocked off by membrane like structure extending across laryngeal lumen; most are partial), foreign body
• hoarseness: edema/swelling of vocal cords, vocal cord palsy (paralysis) or papillomas (HPV; usually need GA for rigid bronch multiple xs a year)
• wheezing: can be d/t asthma, bronchitis, foreign body (if active, probably need to postpone esp if acute)

Question 14

what history can cause increased airway reactivity and possible difficult airway management?

Answer 14

• pneumonia
• wheezing
• foreign bodies
• aspiration
• previous anesthesia problems
• environmental allergies (runny nose, sneezing; probably no need to postpone unless infection or complications)
• environmental tobacco smoke
• congenital syndromes

Question 15

what should the pediatric physical exam consist of?

Answer 15

evaluate and document:

• nasal flaring
• mouth breathing/snoring
• retractions (supra-, inter-, sub-costal)
• tachypnea
• mouth opening
• tongue
• dentition
• palate
• mandible
• syndromatic facial features
• *look up any unfamiliar syndromes to know anesthesia implications

Question 16

what diagnostic testing should be performed?

Answer 16

• if stable, CT or MRI is common
• probably wont do blood gas first (stick and crying will lead to possible increased airway obstruction)
• want to keep child CALM
• *intubation never delayed for diagnostics when severe hypoxia present
• *fiberoptic bronchoscopy for direct airway visualization

Question 17

describe proper pediatric airway management

Answer 17

• masking: sniffing position, mouth open, no pressure on soft tissue, hand on the bag (takes practice)
• oral airway during induction can decrease obstruction d/t tongue
• nasal airway for upper airway obstruction on emergence (needs to be big enough to get past the tongue
• *oral and nasal airway must fit properly (too small can worsen problem)

Question 18

describe intubation of pediatrics

Answer 18

• straight blade
• avoid inserting laryngoscope deep and “backing up”
• 3 axis theory: align mouth, oropharynx, and trachea (“sniffing” position)
• consider shoulder roll for infants to compensate foe large occiput (want it under shoulder to lift and allow head to fall back)

Question 19

what was the major risk of low volume, high pressure cuffs used in earlier years?

Answer 19

• post extubation laryngeal edema
• permanent scarring led to subglottic narrowing and stenosis
• usually used uncuffed in children up to 8 y/o

Question 20

what did studies later show about cuffed and uncuffed tubes in children newborn to 8 y/o?

Answer 20

• no difference in cuff vs. uncuffed ETT
• biggest risk factor of post extubation laryngeal edema:
• poorly fitted uncuffed ETT and repeat laryngoscopy (if chose the wrong size, had to get another and repeat)
• 35% of children

Question 21

describe ETTs and cuffs

Answer 21

• legal standardization requirement: Internal diameter (I.D.) only; (O.D.) vary
• uncuffed: if no air leak heard at 20-25 cm H2O, ETT should be changed to next half size smaller (have someone holding 20 cmH2O and someone listening at neck; if no leak or cant hold pressure, must change tube out)
• cuffed: inflate to minimal seal at 20 cm H2O (stop inflating cuff when stop hearing leak; gives minimal seal that allows ventilation)
• tracheal perfusion pressure est. to be 20 cmH2O, so want a leak around 20 cmH2O so cuff pressure not exceeding tracheal perfusion pressure
• controversy over cuffed ETTs in children

Question 22

describe MicroCuff ETTs

Answer 22

• ultra thin (10 microns) polyurethane cuff (softer, more pliable; less damage; molds to airway)
• tracheal sealing at lower pressure (less than 15 cmH2O)

Question 23

what are advantages of uncuffed ETTs?

Answer 23

-half size larger can be used

Question 24

what are disadvantages of uncuffed ETTs?

Answer 24

• poor guess (repeat laryngoscopy/intubation)
• manageable leak can become unmanageable with changing environment (position change, relaxant wears off, insufflation pressure, bronchospasm)
• leak gets huge with laparoscopic surgeries and bronchospasm
• EtCO2 and flow volume loops inaccurate (no plateau; surgery may require controlled EtCO2)

Question 25

what are advantages of cuffed ETTs?

Answer 25

• decreased repeat laryngoscopy
• decreased OR pollution
• decreased aspiration risk
• more accurate physiologic monitoring
• high PIP can be delivered
• ability to control cuff pressure

Question 26

what are disadvantages of cuffed ETTs?

Answer 26

• requires vigilant cuff pressure monitoring, especially with N2O (manometer should be standard)
• need to keep pressure down and monitor/control cuff pressure
• must downsize by 1/2 size with cuffed ETTs, but downsize can cause problem with really small sizes and spontaneous breathing

Question 27

when is appropriate intraop use of cuffed ETTs safe and advantageous for infants?

Answer 27

> or equal to 3 kg

*need more evidence, so used uncuffed ETTs in infants less than 3 kg

Question 28

what is appropriate use of ETTs?

Answer 28

• appropriate size: uncuffed, if no air leak at 20-25 cmH2O change to next 1/2 size smaller; *cuffed, use 1/2 smaller than uncuffed size and *inflate to minimal seal at 20 cmH2O
• cuff pressure: measure the cuff leak accurately; monitor and control pressure throughout the case (esp. with N2O!)
• should routinely use cuff pressure manometers

Question 29

what should be considered with N2O use with cuffed ETTs in young children?

Answer 29

• small changes in cuff volume lead to large changes in cuff pressure
• most required adjustments during N2O administration: 1st 105 min, post-intubation
• best to avoid N2O with cuffed ETTs in children OR if N2O to be used, control and document cuff pressure every 15 minutes for the 1st 2 post-intubation hours

Question 30

how should ETT size be chosen in children?

Answer 30

• 1000 gm.: 2.5 uncuffed
• 1000-2500 gm.: 3.0 uncuffed or cuffed
• newborn- 6 mths: 3.0 cuffed
• 6 mths- 1 yr.: 3.5 cuffed
• 1 yr.- 18 mths: 4.0 cuffed
• 18mths- 2 yrs.: 4.0-4.5 cuffed
• > 2 yrs.: age yr. + 16/ 4 for uncuffed (*use 1/2 size smaller for cuffed)

Question 31

how is insertion distance determined in children?

Answer 31

• less than 1 kg: 6 cm
• less than 2 kg: 9 cm
• full-term: 10 cm
• 1 yr: 11 cm
• 2 yr: 12 cm
• (age in yrs/2) + 12
  ex: 6 y/o = 15 cm

Question 32

what are complications associated with intubation in children?

Answer 32

post extubation laryngeal edema/croup

• treat with steroids (decadron), nebulized racemic epi, humidified O2
• subglottic stenosis: 90% d/t ETT, esp. prolonged intubation or poorly fitted (cuffed or uncuffed)
• mucosal pressure from ETT cause edema, fibrotic scarring
• scar tissue shrinks down opening, permanently narrowed subglottic airway

Question 33

describe laryngeal tracheal reconstruction

Answer 33

-shared airway technique with surgeon working above trach with trimmed oral rae ETT or around nasal ETT
-may be done in one procedure or staged
A) stenotic area resected
B) costal or auricular cartilage grafted to trachea
*high risk; large air leaks
*must have tracheostomy if don’t already
-post-op ICU, ventilated and paralyzed 5-7 days
-back to OR for GA/extubation/DLB (direct laryngoscopy and bronchoscopy)

Question 34

describe LMAs in pediatrics

Answer 34

• frequent use for GA
• only for spontaneous ventilation (never put any LMA on vent)
• should meet criteria for safe mask management
• works well with pressure support
• peak inspiratory pressure (PIP) must stay low to avoid abdominal insufflation/regurgitation
• sizing based on pt. wt.
• remove deep with children d/t coughing and gagging; leave cuff inflated to pull pooled secretions out too

Question 35

describe difficult airway techniques in pediatrics

Answer 35

• LMA
• glidescope, stylet wands, bullard
• LMA assisted fiberoptic
• retrograde wire
• ENT available (rigid bronch, trach)
• cricothyrotomy (thyroid gland covers this cartilage)
• no relaxant until airway secured
• document: ease of mask ventilation, ease of intubation, special maneuvers (what worked and what didn’t), grade of laryngeal structures