Peds Advanced Patho Flashcards
prematurity
birth before 37 weeks gestation
low-birth-weight
<2500 g
very-low-birth-weight
<1500 g
extremely-low-birth-weight
<1000 g
five anatomical structures in the airway that are different in pediatric patient versus adult
- tongue
- position of larynx
- epiglottis
- vocal folds
- subglottis
tongue in pediatric patient
- infant’s tongue relatively large in proportion to rest of the oral cavity
- contributes to easy obstruction of infant’s airway
- oral airway helps to relieve the obstruction
other differences in pediatric airway
- narrow nasal passages
- more secretions from salivary glands
- large tonsils and adenoids
position of larynx in pediatric patient
- higher (more cephalad) for neonates to 2 years of age
- larynx seems more anterior
- located C3-C4 infants (C4-5 adults)
- a straight laryngoscope blade more effectively lifts the tongue from the field of view
epiglottis in pediatric patient
- adult = flat and broad with axis parallel to trachea
- infant = more narrow, omega shaped and angled away fro the axis of the trachea
- often obstructs the view of the vocal cords and is more difficult to lift
vocal cords in pediatric patient
- infant’s vocal cords have a lower (caudad) attachment anteriorly versus posteriorly
- adult the axis of the vocal cords is perpendicular to the trachea
- can lead to difficult intubation with the tip of the ETT held up at the anterior portion of the folds
trachea in pediatric patient
- shorter than in adults
- infant 4-5 cm
rule of thumb for tube placement in peds
3x size of the tube
subglottic area in pediatric patient
- traditionally taught = this is the narrowest portion of the child’s airway
- recent studies = pediatric larynx is oblong shaped (like a football) and may be more narrow in the AP dimension but wider in the transverse dimension
prematurity and the airway
- small airways, such as those in prematurity, are predisposed to obstruction and difficulty with ventilation
- resistance to airflow inversely proportional to radius of 4th power (poiseuille’s law)
- ETT internal diameter smaller
- partial occlusion of ETT due to kinking or secretions GREATLY increases WOB for premie
- tight fitting ETT compresses tracheal mucosa and can cause damage/edema
diseases that narrow the airway
- subglottic stenosis
- tracheal stenosis
- tracheobronchomalacia
subglottic stenosis
- 90% of acquired subglottic stenosis are result of ETT and prolonged intubation
- often requires placement of smaller ETT
tracheal stenosis
-often occurs at carina and creates added resistance distal to ETT
tracheobronchomalacia
- intrathoracic airway collapses during exhalation
- PEEP and CPAP are helpful to stent open airway
when does surfactant production begin?
23-34 weeks gestation
-concentration of surfactant often inadequate until 36 weeks post-conception
lung maturation
- prenatal = alveoli are thick, fluid filled sacs that are deficient in surfactant and require GREAT pressures to expand
- structure and function of immature lungs predisposes infant to alveolar collapse and hypoxia
- leads to reduced lung volumes, decreased lung compliance, increased intrapulmonary shunting and V/Q mismatch
intercostal and diaphragmatic musculature in infants
- low numbers of type I muscle fibers (marathon muscles, slow twitch; do not develop adequate until > 6-8 months)
- chest wall more horizontal and pliable, minimal vertical movement so less room for lung expansion
- result = early fatigue and propensity for apnea
respiratory system in children
- changes occur from 8 mo-12 yo
- episodic respirs in utero
- passage through birth canal forces fluid out of lungs
- RR elevated in infant and small child
- O2 consumption 2-3x higher (6-10 mL/kg/min)
- Vt/kg remains constant throughout development
- decreased FRC and increased CC
- immature hypoxic and hypercapnic drives
respiratory control in children
- premies have biphasic ventilatory response to hypoxia
- initial = ventilation increases, but after several minutes, ventilation decreases and bradycardia/apnea may occur
- ventilatory response to hypothermia and CO2 is also decreased
- increased risk of hypoxia, hypercapnia, and apnea in post-op period because of these things combined with anesthesia
BPD
- bronchopulmonary dysplasia
- form of chronic lung disease that occurs in patients who have survived severe neonatal lung disease
- cause = uncertain
- most likely related to increased end-inspiratory lung volumes + frequent collapse and reopening of alveoli