pediatric airway Flashcards
1
Q
what structures differ in the pediatric airway?
A
- tongue
- laryngeal position
- epiglottis
- vocal cords
- subglottis
2
Q
describe the difference in the pediatric tongue
A
- proportionately larger
- increased risk of obstruction
- more difficult to move with laryngoscope
3
Q
describe the difference in the pediatric laryngeal position
A
- 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)
4
Q
describe the difference in the pediatric epiglottis
A
- narrow
- horseshow shaped
- angled away from axis of the trachea
- stiff, thick, and can be hard to move
(adult: flat, broad, parallel)
5
Q
describe the difference in the pediatric vocal cords
A
- more caudad attachment on anterior side
- adult more perpendicular to trachea
- angle causes more intubation difficulty
6
Q
describe the difference in the pediatric subglottis
A
- *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
7
Q
describe the cricoid ring
A
- 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)
8
Q
how does 1 mm of edema affect the pediatric airway compared to an adult’s?
A
- 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
9
Q
at what age does the pediatric airway reach adult proportions?
A
10-12
10
Q
describe the pediatric airway physiology
A
- 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)
11
Q
describe obstruction during anesthesia for peds
A
- 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
12
Q
how is airway obstruction treated
A
- continuous positive airway pressure (CPAP)
- chin lift and jaw thrust
- lateral position; nasal/oral airways
- *most effective overall: jaw thrust
13
Q
what should be assessed for during the airway evaluation?
A
- 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)
14
Q
what history can cause increased airway reactivity and possible difficult airway management?
A
- 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
15
Q
what should the pediatric physical exam consist of?
A
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
16
Q
what diagnostic testing should be performed?
A
- 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
17
Q
describe proper pediatric airway management
A
- 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)
18
Q
describe intubation of pediatrics
A
- 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)
19
Q
what was the major risk of low volume, high pressure cuffs used in earlier years?
A
- post extubation laryngeal edema
- permanent scarring led to subglottic narrowing and stenosis
- usually used uncuffed in children up to 8 y/o
20
Q
what did studies later show about cuffed and uncuffed tubes in children newborn to 8 y/o?
A
- 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
21
Q
describe ETTs and cuffs
A
- 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
22
Q
describe MicroCuff ETTs
A
- ultra thin (10 microns) polyurethane cuff (softer, more pliable; less damage; molds to airway)
- tracheal sealing at lower pressure (less than 15 cmH2O)
23
Q
what are advantages of uncuffed ETTs?
A
-half size larger can be used
24
Q
what are disadvantages of uncuffed ETTs?
A
- 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)
25
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
26
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
27
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
28
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
29
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
30
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)
31
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
32
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
33
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)
34
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
35
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
