Respiratory Disease in Infants and Children
Normal Development
- 4th week of gestation – lung bud appears
- 5th-20th week – lung buds continue to branch
- Pseudoglandular period (Weeks 6-16) – continuing bronchial branching; differentiation of certain cells
- Canalicular Period (Weeks 16-28) – period of acinar development, differentiation of type I & II pneumos
- Terminal Sac Period (Weeks 28 to term) – surfactant production
- Alveolar Period (34 weeks to 18-24 mths after birth) – true alveoli form and multiply
Congenital Malformations
- Hypoplastic lung
Ø usually accompanies other malformations
Ø unilateral hypoplasia – growth of one lung is restricted by intra- or extrathoracic compression
- usually associated with congenital diaphragmatic hernia
Ø Bilateral hypoplasia
- usually accompanies oligohydramnios due to renal aplasia, urinary tract obstruction, or other renal dysfunction.
Ø Resp. tract obstruction
Ø Pulmonary vascular abnormalities
Ø Anencephaly
- Anomalies of bronchial distribution
Ø usually part of CV malformation syndromes
Ø usually do not produce functional problems
- Pulmonary Sequestration (Four types)
1) Accessory lung
2) Foregut connection – the bronchial connection is to the foregut
3) Extralobar sequestration
Ø masses of pulmonary tissue separated from the main lung
Ø has own pleura
Ø usually has a systemic arterial blood supply with venous drainage to the azygous or portal
Ø True malformation
Ø More common than 1 & 2
4) Intralobar sequestration
Ø most common
Ø no communication with trachea or bronchi
Ø systemic blood supply
Ø usually posterior basal portion of lung
Ø susceptible to inflammation
Cystic Disease
- Bronchogenic
Ø The cyst wall is made up of bronchial mucosa separate from the tracheobronchial tree
Ø Found anywhere along the mediastinum
- Lymphangiectasis
Ø multiple small cystic spaces occur throughout the lung, occupying the pleura and septae
Ø can accompany HMD
Ø Three varieties
1) obstruction to pulmonary venous return
2) Idiopathic: localized to lung
3) Idiopathic: pulmonary and systemic
- Cystic adenomatoid malformation
Ø unilateral, usually
Ø numerous small cystic spaces lined by mucinous, “gastric-like” epithelium
Ø malformations of the kidney and heart frequent
Congenital Lobar Emphysema
- usually affects one lobe
- intact alveolar septae – represents hyperexpansion rather than true emphysema
- bronchus collapses allowing inhalation but not exhalation
Neonatal Pulmonary Disease
Hyaline Membrane Disease (HMD)
- Clinical
1) difficulty in air exchange shortly after birth
2) gasping inspiration, cyanosis, retraction of sternum and intercostal spaces, anoxia, hypercarboxia, exhaustion
- Infants at risk
Ø premies, diabetic mothers, c-section before 38 weeks, males>females, whites>blacks, second born of twins, neonatal asphyxia and precipitous delivery
- Morphology
1) abnormal expansion pattern
2) lungs: solid, moist, heavy, congested
3) Atelectasis is most severe at the periphery of the lobule
4) Dilated airways and collapsed air spaces
5) The Patent terminal bronchioles and alveolar ducts are lined by the hyaline membranes
6) Membranes may contain necrotic debris, desquamated epithelium, fibrin, serum proteins, and rarely bilirubin
- Usually does not appear before 4 hours of life
- After 24 hours, the alveolar lining cells regenerate and macs proliferate among the membranes
- REMEMBER O2 TOXICITY IS POSSIBLE
Ø High concentration of O2 for a day or two – toxic to the alveolar epithelium
Ø Leads to necrosis of respiratory epithelium, proliferation and degeneration of alveolar epithelial cell, fibroblastic thickening or alveolar septae
- HMD usually results from a LACK OF SURFACTANT which leads to pulmonary instability
Ø usually appears at 24-28 weeks gestation
Ø disappears with pulmonary edema and atelectasis
Ø hypoperfusion of the lung occurs because of vascular spasm which leads to shunting
Ø the resultant ischemia leads to outpouring of the transudate
Bronchopulmonary Dysplasia
- Essential Features/Causes of Bronchopulmonary Dysplasia
1) HMD or other lung injury
2) Premies more susceptible
3) Artificial ventilation
4) O2 therapy
Indistinctively divided phases/stages
Stage I Exudative, early reparative Acute; 1-3 days Hyaline Membranes
Atelectasis
Lymphatic dilatation
Stage II Subacute, fibroproliferative 4-10 days Necrosis
Alveolar repair
Hyperaeration
Stage III Transition 10-20 days Bronchiolar necrosis
Bronchiolitis obliterans
Alveolar cell
regeneration
Alveolar hist.
Proliferation
Hyperaeration
Stage IV Chronic, fibroproliferative 1 month Honeycombing
Peribronchial musc.
Hyper
Atelectasis
Alveolar hist.
proliferation
Tortuous lymphatics
Arterial medial hyper.
- Complications of BPD
Ø Patent ductus arteriosus
Ø Intrapulmonary shunts
Ø Right Ventricular Hypertrophy
Ø Pulmonary interstitial Emphysema
Ø Pneumothorax
Ø Pneumomediastinum
Ø Deficient alveolar development
Pneumonia
- 20% of neonatal deaths
Portal of Entry and associated manifestations
- Transplacental (congenital)
1) TORCH agents, syphilis, listeria monocytogenes
2) Usually part of a generalized disease
- Ascending Infection (congenital)
1) aspiration of infected amniotic fluid
2) frequently follows prolonged period after ruptures membranes
- Intrapartum acquired pneumonia
1) common organisms – coliform or Group B strept
2) can resemble HMD microscopically
- Late onset pneumonia
1) usually environmental organisms
2) strept, coliform organisms
Pulmonary Hemorrhage
- usually accompanies other disease
Ø HMD
Ø Pneumonia
Ø Cerebral hemorrhage
- Massive Pulmonary Hemorrhage
Ø intraalveolar hemorrhage
Ø RDS and acute lung collapse presentation
Ø Unknown etiology (O2 therapy implicated)
Meconium aspiration
- may occur in meconium stained infants
- distal airways obstructed by masses of meconium, mucus, bile, squamous epi cells
- can enhance bacterial growth
Cystic Fibrosis
- the most common fatal metabolic disorder in childhood
- also known as fibrocystic disease of the pancreas, mucoviscidosis
- disorder of exocrine glands
- LUNG INVOLVEMENT IS THE MOST COMMON CAUSE OF DEATH
Basic Defect
- abnormal transport of cellular Cl-
- reduced trypsin content in gut
- deletion of PHE at chromosome 7q DF508. (MOST COMMON)
Clinical Presentation
- autosomal recessive, congenital, familial
- 2% of the population are carriers
- Malabsorption
- Neonatal intestinal obstruction (Meconium Ileus)
- Pre-natal testing available
- Chronic bronchopulmonary disease, cor pulmonale
- Nasal polyps
- Obstructive biliray cirrhosis
- Rectal prolapse
Clinical Laboratory Findings in CF
- Elevated Na, Cl content of sweat ( occurs with virtually all mutations )
Ø sweat test conducted at > 3 months of age
Ø false negatives are common
- Increased viscosity and diminished trypsin from the intestinal content
- Most common mutation chromosome 7qD508. (over 500 known mutations)
- Genetic screening picks up about 50-70%
Morphology
- Pancreas
Ø inspissitation, cyst formation, scarring
Ø exocrine pancreas involved
Ø fatty replacement as you age
- Intestine
Ø meconium ileus
Ø affects 10% of patients with CF
Ø rectal prolapse
Ø peptic ulcer incidence increased
- Respiratory tract
Ø MAJOR CAUSE OF DEBILITY AND DEATH
Ø Recurrent infections
Ø Bronchiectasis with bacterial colonization (usu. Pseudomonas)
Ø Abnormal salt concentration in the mucus layer – may explain proneness to infection
Ø Nasal polyps
- Hepatobiliary
Ø inspissated secretions in bile ducts
Ø obstructive biliary cirrhosis
- Reproductive System
Ø discontinuity in vas deferens
Ø MALES – USUALLY INFERTILE
Ø Sweat glands appear structurally normal
Tags: Alveolar Period, Anencephaly, Bilateral hypoplasia, Bronchopulmonary Dysplasia, Canalicular Period, Congenital Lobar Emphysema, Congenital Malformations, Cystic Disease, cystic fibrosis, Hyaline Membrane disease, Hypoplastic lung, Idiopathic, Lymphangiectasis, Meconium aspiration, Neonatal Pulmonary Disease, Pseudoglandular stage, Pulmonary Hemorrhage, Pulmonary Sequestration, Terminal Sac Period, unilateral hypoplasia
