pediatric airway Flashcards
what structures differ in the pediatric airway?
- tongue
- laryngeal position
- epiglottis
- vocal cords
- subglottis
describe the difference in the pediatric tongue
- proportionately larger
- increased risk of obstruction
- more difficult to move with laryngoscope
describe the difference in the pediatric laryngeal position
- 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)
describe the difference in the pediatric epiglottis
- narrow
- horseshow shaped
- angled away from axis of the trachea
- stiff, thick, and can be hard to move
(adult: flat, broad, parallel)
describe the difference in the pediatric vocal cords
- more caudad attachment on anterior side
- adult more perpendicular to trachea
- angle causes more intubation difficulty
describe the difference in the pediatric subglottis
- *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
describe the cricoid ring
- 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)
how does 1 mm of edema affect the pediatric airway compared to an adult’s?
- 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
at what age does the pediatric airway reach adult proportions?
10-12
describe the pediatric airway physiology
- 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)
describe obstruction during anesthesia for peds
- 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
how is airway obstruction treated
- continuous positive airway pressure (CPAP)
- chin lift and jaw thrust
- lateral position; nasal/oral airways
- *most effective overall: jaw thrust
what should be assessed for during the airway evaluation?
- 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)
what history can cause increased airway reactivity and possible difficult airway management?
- 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
what should the pediatric physical exam consist of?
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
what diagnostic testing should be performed?
- 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
describe proper pediatric airway management
- 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)
describe intubation of pediatrics
- 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)
what was the major risk of low volume, high pressure cuffs used in earlier years?
- post extubation laryngeal edema
- permanent scarring led to subglottic narrowing and stenosis
- usually used uncuffed in children up to 8 y/o
what did studies later show about cuffed and uncuffed tubes in children newborn to 8 y/o?
- 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
describe ETTs and cuffs
- 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
describe MicroCuff ETTs
- ultra thin (10 microns) polyurethane cuff (softer, more pliable; less damage; molds to airway)
- tracheal sealing at lower pressure (less than 15 cmH2O)
what are advantages of uncuffed ETTs?
-half size larger can be used
what are disadvantages of uncuffed ETTs?
- 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)
what are advantages of cuffed ETTs?
- decreased repeat laryngoscopy
- decreased OR pollution
- decreased aspiration risk
- more accurate physiologic monitoring
- high PIP can be delivered
- ability to control cuff pressure
what are disadvantages of cuffed ETTs?
- 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
when is appropriate intraop use of cuffed ETTs safe and advantageous for infants?
> or equal to 3 kg
*need more evidence, so used uncuffed ETTs in infants less than 3 kg
what is appropriate use of ETTs?
- 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
what should be considered with N2O use with cuffed ETTs in young children?
- 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
how should ETT size be chosen in children?
- 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)
how is insertion distance determined in children?
- 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
what are complications associated with intubation in children?
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
describe laryngeal tracheal reconstruction
-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)
describe LMAs in pediatrics
- 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
describe difficult airway techniques in pediatrics
- 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
