by gnomey

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what are the 3 reasons that neonates and infants have less efficient ventilation?
1. weak intercostal and diaphragmatic musculature d/t decrease in Type I fibers
2. horizontal and more pliable ribs
3. protuberant abdomen
why do neonate/infant lungs have a decreased lung compliance?
small and limited number of alveoli
why do neonate/infant have increase chest wall compliance?
they have a cartilaginous rib cage
what causes CW collapse during inspiration and relatively low residula lung volumes at expiration?
cartilaginous rib cage and small and limited amount of alveoli
why do neonates and infants become hypoxic faster than adults with loss of airway?
1. disproportionately smaller store of intapulmonary oxygen to use during apnea
2. increased O2 consumption
what does hypoxia and hypercapnia do to respiratory effort in neonate/infant?
depress respiration
what is the narrowest part of the airway in children < 5 years of age
cricoid cartilage, compared to adults where it is the glottis
Is FRC in the infant based on dynamic or passive factors? explain?
FRC is based on dynamic factors. It is set by a cessation of exhalation at a lung volume that is in excess of its relaxation volume. D/t a decrease in eleastic recoil of the chest and smaller recoid presure of the lung

This means that the apenic lung volume is less than the FRC in an infant.
why can't closing volume be measured in young children?
Up to age 5 the elastic recoil pressure is to low to measure the closing volume
what is the factor affecting pulmonary diffusion capacity that changes most in childhood?
surface area of the alveolar-capillary membrane
how is height and diffusing capacity related?
diffusing capacity increase with height, which is related to lung growth
is the alveolar-arterial oxygen difference higher/lower in neonates than adults? y
it is higher, d/t smaller surface area and thicker alveolar-capillary membrane
what is the permanent shunt fraction in infants compared to adults
infants: 10-20% of CO
adults: 2-5% of CO
infant response to increase PaCO2?
activation of central chemoreceptor in medulla cause increase tidal volume and rate. just like adults
what is the reaction to sustained hyoxia in preterm infants?
they have a return to baseline resp, then progress to ventilatory depression. this reverses after a certain age to the normal response
When is the Hering-Breuer reflex operative? what is it?
It is working within first few weeks of life

It causes apnea with hyperinflation of lung
what is periodic breathing
typical breathing pattern seen in newborns where there are pauses in ventilation for 5-10 seconds, then burst of resp activity
when is periodic breathing pathologic?
1. periods of apnea > 20 sec
2. bradycardia
what is rate of O2 consumption in infants?
2 that of adults, and causes a double in minute ventilation
what is the difference between size of tongue in infant vs adult
the tongue is larger in proportion to rest of oral cavity in infant
where is the larynx located in the infant
at level of C3-C4
the larynx being higer in the infant descreases the distances between what parts of the oropharynx
decreases distances between the tongue, hyoid bone, epiglottis, and roof of the mouth
describe the epiglottis of an infant?
narrower, omega shaped (oval) , and angled away from axis of trachea
how are the vocal cord placement difference in infants
they are attached lower (caudad) anteriorly than posteriorly
when do the cricoid and thyroid cartilages reach adult proportion?
at 10-12 years of age, eliminating both the angulation of vocal cords and narrow subglottic area
what are two main differences between forced glottic closure and laryngospasm?
Laryngospasm has:
1. Inspiratory effort that longitudinally seperates the vocal from the vestibular folds
2. Neither the thyroarytenoid (intrinsic) nor the thyrohyoid muscle contract

These two things allow upper portion of larynx to be partially open during mild spasm to cause Inspiratory Stridor
what benefit does performing a jaw thrust do for a laryngospasm?
it causes longitudinal separation of the base of tongue, epiglottis,a nd aryepiglottic folds from the vocal cords
what type of breathers are infants, oral/nasal?
They are nasal breathers. caused by:
1. immature coordination between resp efforts and oropharyngeal motor/sensory input
2. Tongue rests against roof of mouth during quiet respiration
when do infants begin to breath through mouth more often?
3-5 months, as result of caudad movement of larynx and maturation of oropharyngeal coordination
what is the O2 consumption in preterm and fullterm infants?
preterm 3x more than adults
fullterm 2x more than  adults
where is most of the resistance to airflow in infants?
in the bronchial and small airways d/t decrease in radius. only 25% of resistance is from nasal passages, compared to 60% in adults
what is the cause of airway obstruction during anesthesia in infants?
primarily related to loss of muscle tone in the pharyngeal and laryngeal structures rather than obstruction of tongue resting on posterior pharyngeal wall

Most airway obstruction is at level of soft palate and the epiglottis
how do you improve improvement d/t obstruction of airway by hypopharyngeal structures?
sniffing position (atlanto-occipital  extension with anterior displacement of cervical spine)
what happens if an oral airway is too long or too short?
too short- may rest on base of tongue forcing it posteriorly against the roof of the mouth

too long- tip may push the epiglottis into the glottic aperature, or tip may imping on uvular causing swelling and obstruction
what is the appropriate length of an OPA? NPA?
OPA- measure from corner of mouth to just cephalad to angle of mandible

NPA- measure from nares to angle of mandible
how is cervical spine displaced anteriorly?
by placing a folded blanket or pillow beneath the occiput
why is it unnecessary to elevate the head in infants and young children?
usually the head doesn't need to be elevated because the occiput is large in proportion to the trunk, this causes a natural anterior cervical displacement
what size of ETT will a child with Down's syndrome usually require?
a tube smaller than anticipated
when is a ETT too large?
if there is no leak around the cough at 20-25 cm H2O PIP.

IF this happens use a tube half size smaller
what is the reason behind having an air leak at 20-25cm H2O PIP?
that is believed to be the approximate capillary pressure of the adult tracheal mucosa. thus higher pressure will increase risk of ischemia to mucosa
what is a forumla for selecting the appropriate cuffed/uncuffed ETT?
cuffed tube:
ID (mm)= (age/4)+3

uncuffed tube
ID (mm)= (age/4)+3.5
what is the length of trachea (vocal cords to carina) in neonate/infant?
What is the appropriate ETT insertion distance for children?
newborn- 10cm
1 yearold- 11cm
2 year old- 12 cm
>2 (age/2)+ 12cm
what should be the first step in troubleshooting a persistent change in SpO2 in an intubated child?
investigate the cause and reassess the position of the ETT
What are factors associated with post-intubation croup? (8)
1. no air leak at >25 cm H2O PIP
2. position changes perioperatively
3. position other than supine
4. multi attempts at intubation
5. traumatic intubation
6. 1-4 years of age
7. coughing on ETT
8. previous hx of croup
treatment of post-intubation croup? (3)
1. humidified mist
2. nebulized epinephrine
3. Decadron
what is the major cause of acquired subglottic stenoses?
90% are result of endotracheal intubation, particularly prolonged intubation.

How does acquired subglottic stenosis develop?
1. ischemic injury secondary to lateral wall pressure from ETT
2. edema, necrois, and ulcerations develop
3. within 48 hours, granulation tissue begins to form within these ulcerations
4. scar tissue forms, resulting in narrower airway
what is a significant risk factor for using an LMA classic in pediatric case?
Malpositioning has been reported to cause gastric air insufflation in children 3-11 undergoing PPV with PIP above 17 cm H2O
in what type of pediatric patient has an LMA been advocated to use to prevent respiratory compromise?
advocated for use in ped pt with increased risk of bronchial airway reactivity
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