Pediatric Pulmonary Disorders Overview Flashcards
embryonic stage of lung development
3-6 weeks
i. Outpouching of the foregut into the mesoderm and begin to branch - trachea, main stem, lobar and segmental bronchi are formed, lacking cartilage, smooth muscle or nerves
ii. Epithelium remains undifferentiated
iii. Mesenchyme tissue is important to guide this branching morphogenesis
iv. Vascular connections with the atria are established, pulmonary and bronchial vessels are not well formed
pseudoglandular stage of lung development
6-16 weeks
i. Continued branching of airways - Terminal bronchioles and primitive acinar structure are formed
ii. Epithelial cells start to differentiate
iii. Pulmonary vasculature develops parallel to bronchi and bronchioles
canalicular stage of lung development
16-26 weeks
i. Continued branching to the level of primitive alveolar ducts and acinar tubules
ii. Epithelial cell differentiation becomes increasingly complex
iii. Capillaries surround distal acinar tubules to form gas exchange region of the lung
iv. By end of stage, gas exchange can be supported after birth
saccular stage of lung development
26-36 weeks
i. Further growth of lung acini
ii. Continued capillary development
iii. Epithelial cells differentiated - Type I and II alveolar cells
alveolar stage of lung development
36 weeks onward
continued development of alveoli, can persist up until adolescent age
respiratory distress syndrome (RDS)
diagnosis progressive respiratory failure, characteristic chest radiograph, which demonstrates low lung volme and diffuse reticulogranular ground-glass appearance with air bronchograms
most often seen in premature infants
due to inadequate production of surfactant
bronchopulmonary dysplasia (BPD) or chronic lung disease of infancy
term given to infants who had RDS and continue to have airway and parenchymal abnormalities
if an infant is on oxygen at day 28, need to reassess oxygen need later in infancy
mild BPD
if < 32 weeks gestational age, breathing room air at 36 weeks post birth
if >/= 32 weeks gestational age, breathing room air at 56 days of life
moderate BPD
if <32 weeks gestational age, breathing <30% FIO2 at 36 age post birth
if >/= weeks gestational age, breathing <30% FIO2 at 56 days post birth
severe BPD
if < 32 weeks gestation, >30% FIO2 or positive pressure ventilation at 36 weeks post birth
if >/= 32 weeks gestation, >30% FIO2 or positive ventilation at 56 days post birth
factors that increase the risk of BPD
lower birth weight
lower gestational age
infections (both maternal and infant)
positive pressure ventilation, oxygen toxicity
antenatal steroids
accelearate morphologic development of Type I and II pneumocytes
recommended for women at risk of preterm delivery prior to 34 weeks gestation
congenital airway abnormalities
laryngomalacia
tracheo-bronchomalacia
tracheoesphageal fistula
congenital parenchymal abnormalities
pulmonary sequestration
congenital pulmonary airway malformation
congenital lobar emphysema
congenital vascular abnormalities
cascular ring/slings
pulmonary arteriovenous malformations
laryngomalacia
clinical presentation - stridor
omega shaped epiglottis
short aryepiglottic folds
prolapse arytenoids
diagnosis with bronchoscopy
surgical treatment if severe
tracheo-bronchomalacia
noisy breathing
etiology not ocmpletely known, but likely to be alterations of structural support
diagnose with bronchoscopy or expert oopinion
treatmen tis primarily supportive, but surgery can be done for more severe cases
tracheoesophageal fistula
drooling due to inability to swallow secretions
choking when attemting feeds, usually within the first 24 hours of life
caused by incomplete separation of the esophagus from the laryngotracheal tube
diagnose because of inability to pass gastric tube, also can use a radiographic evaluation
treatment involves surgical means
pulmonary sequestration
normal, non-functioning lung tissue with no connection to the bronchial tree
blood supply for sequestration is from the systemic circulation and most often the descending thoracic aorta or the abdominal aorta
three different types:
intralobar
extralobar
bronchopulmonary
intralobar:extralobar is 3:1
intralobar pulmonary sequestration
can be acquired through bronchial obstruction, pneumonia, parasitzation of pulmonary arteries
no lobar predominance
completely covered by normal lung tissue or by a segment of the visceral pleura of the lung lobe within which the sequestration occurs
equal among males and females
venous drainage via pulmonary veins
extralobar pulmonary sequestration
an accessory lung forms - covered in visceral pleura and spearated from the functioning lung
generally in the left lower lobe (80%)
about 10% below diaphragm
venous drainage is via systemic venous system (azygous or portal vein)
bronchopulmonary pulmonary sequestration
forgut malformation occurs when the abnormal lung tissue is connected to the gastrointestinal tract
congenital pulmonary airway malformation (CPAM)
previously called CCAM (cystic adenomatoid malformation of the lung)
heterogeneous group of congenital cystic and non-cystic lung masses characterized by extensive overgrowth of the primary bronchioles which are in communication with the abnormal bronchial tree lacking cartilage
25-30% of all congenital lung malformations
no lobar or side predominance - most frequently in lower lobes, and 85-90% in only one lobe
congenital lobar emphysema
overinflation and distention of one or more pulmonary lobes
caused by intrinsic or extrinsic bronchial narrowing with subsequent air trapping
hypoalveolar (< expected number of alveoli)
polyalveolar (> number of expected alveoli)
left upper lobe most frequently affected (rarely bilateral or multifocal)
