Pediatric Pulmonary Disorders Overview

Question 1

embryonic stage of lung development

Answer 1

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

Question 2

pseudoglandular stage of lung development

Answer 2

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

Question 3

canalicular stage of lung development

Answer 3

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

Question 4

saccular stage of lung development

Answer 4

26-36 weeks

i. Further growth of lung acini
ii. Continued capillary development
iii. Epithelial cells differentiated - Type I and II alveolar cells

Question 5

alveolar stage of lung development

Answer 5

36 weeks onward

continued development of alveoli, can persist up until adolescent age

Question 6

respiratory distress syndrome (RDS)

Answer 6

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

Question 7

bronchopulmonary dysplasia (BPD) or chronic lung disease of infancy

Answer 7

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

Question 8

mild BPD

Answer 8

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

Question 9

moderate BPD

Answer 9

if <32 weeks gestational age, breathing <30% F_IO2 at 36 age post birth

if >/= weeks gestational age, breathing <30% F_IO2 at 56 days post birth

Question 10

severe BPD

Answer 10

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

Question 11

factors that increase the risk of BPD

Answer 11

lower birth weight

lower gestational age

infections (both maternal and infant)

positive pressure ventilation, oxygen toxicity

Question 12

antenatal steroids

Answer 12

accelearate morphologic development of Type I and II pneumocytes

recommended for women at risk of preterm delivery prior to 34 weeks gestation

Question 13

congenital airway abnormalities

Answer 13

laryngomalacia

tracheo-bronchomalacia

tracheoesphageal fistula

Question 14

congenital parenchymal abnormalities

Answer 14

pulmonary sequestration

congenital pulmonary airway malformation

congenital lobar emphysema

Question 15

congenital vascular abnormalities

Answer 15

cascular ring/slings

pulmonary arteriovenous malformations

Question 16

laryngomalacia

Answer 16

clinical presentation - stridor

omega shaped epiglottis

short aryepiglottic folds

prolapse arytenoids

diagnosis with bronchoscopy

surgical treatment if severe

Question 17

tracheo-bronchomalacia

Answer 17

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

Question 18

tracheoesophageal fistula

Answer 18

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

Question 19

pulmonary sequestration

Answer 19

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

Question 20

intralobar pulmonary sequestration

Answer 20

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

Question 21

extralobar pulmonary sequestration

Answer 21

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)

Question 22

bronchopulmonary pulmonary sequestration

Answer 22

forgut malformation occurs when the abnormal lung tissue is connected to the gastrointestinal tract

Question 23

congenital pulmonary airway malformation (CPAM)

Answer 23

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

Question 24

congenital lobar emphysema

Answer 24

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)

Question 25

vascular rings/slings

Answer 25

presents with trouble swallowing, stridor, respiratory distress, recurrent pneumonia, or apnea

caused by developmental abnormality of the aortic arch system, which leads to the compression of the esophagus and trachea

diagnosed using barium swallow

types include sling (aberrant left pulmonary artery, aberrant right subclavian artery), ring (double aortic arch), or things (other variants)

Question 26

pulmonary artery malformations

Answer 26

abnormal connection between arteries and veins

clinical presentation of pulmonary hemorrhage or hemoptysis or hypoxia

diagnosis is chest radiograph and angiography

treatment is embolization

Question 27

hereditary hemorrhagic telangectasia (HHT)

Answer 27

genetic illness associated with AVMs caused by mutations in the genes for activin receptor like kinase (ALK1), endoglin (ENG), or SMAD4

patients can have telangectasias of the nose, mouth, and hands, and AVMs can be found in the lung, gastrointestinal tract, and brain

Question 28

factors that decrease risk of BPD

Answer 28

antenatal steroids

surfactant treatment

nutritional support

ventilator management