Lung Part 1 Flashcards
Cells in trachea/bronchus
Goblet cell
Seromucous gland
Cartilage
Cells in bronchiolus
Clara cell - exocrine cells
No cartilage, goblet cells or seromucous glands
Cells in alveolus
Type 1 pneumocyte (95%)
Type 2 pneumocyte (5%)
Lobule
Cluster of terminal bronchioles with attached acini
Acinus
Respiratory bronchiole and all attached alveolar ducts and alveolar sacs
Pulmonary hypoplasia
Common - 10% neonatal autopsy
Seen with fetal compression and with other anomalies
Tracheoesophageal Fistula
Most common form is blind ended proximal and distal end opening into trachea
Congenital foregut cysts
Mediastinal and hilar locations
Maldeveloped foregut, usually bronchogenic with respiratory epithelium
Not connected to the airways
Congenital Cystic Adenomatoid Malformation
CPAM
Hamartomatous lesion with abnormal bronchiolar tissue
Larger cysts have better prognosis because they aren’t associated with other congenital abnormalities
Bronchopulmonary Sequestrations
Areas of lung without normal connection to airways
Blood supply is from systemic arteries
Extralobar sequestrations
External to lung (thorax or mediastinum)
May have other congenital anomalies
Intralobar sequestrations
Within lung
Associated with recurrent local infection and/or bronchiectasis
Most likely an acquired lesion
Cause of respiratory distress in newborns
Excessive maternal sedation Fetal head injury Blood or amniotic fluid aspiration Intrauterine hypoxia from nuchal cord **Hyaline membrane disease
NRDS - Hyaline Membrane Disease
Rate inversely proportional to gestational age
Immaturity of lungs
Deficiency of pulmonary surfactant
Associated with male sex, maternal diabetes mellitus, multiple gestation and C-section before onset of labor
How does insulin effect surfactant
Inhibits secretion
How do glucocorticoids and thyroxine effect surfactant
Increase secretion
Lungs 20 weeks gestation
Glandular
Lungs 30 weeks gestation
Saccular
Lungs at term
Alveolar
Surfactant
From type II pneumocytes
Made of phospholipids and glycoproteins
Methods: ***Thin layer chromatography Flourescence polarization Foam stability index Lamellar body count
L/S ratio
Lung to surfactant ratio
>2 at term
1 at less than 32 weeks
Clinical presentation of RDS
Preterm and AGA Male sex, maternal DM, C-section Low APGAR May need resuscitation Then may do well for short time (< 1 hour) Become cyanotic Fine pulmonary rales (crackles) Reticulonodular/ground glass chest x-ray Oxygen therapy needed Death or recovery in 3 – 4 days
Not seen in still born
Clinical course of RDS
Administration of surfactant (<26-28 weeks)
Antenatal treatment with steroids (24-34 weeks)
Monitor amniotic fluid surfactant for lung maturity
Death now unusual
Recovery begins at about 4 days
Therapy with O2 carries risks:
Retinopathy of prematurity
Bronchopulmonary dysplasia
Bronchopulmonary Dysplasia
> 28 days of O2 therapy in infant > 36 weeks post-menstrual age
Alveolar hypoplasia and thickened walls
O2 decreases lung maturation
**Developmental arrest at saccular stage
Cystic fibrosis
Disorder in epithelial transport affecting fluid secretion in exocrine glands and the epithelial lining of the respiratory, gastrointestinal, and reproductive tracts
Viscid mucus
Autosomal recessive - cystic fibrosis transmembrane conductance regulator (CFTR) gene
Diagnostic criteria of CF
Phenotypic characteristics or family history or positive infant screen
AND
Increased NaCl in sweat or 2 CFTR mutations or abnormal nasal ion transport
Treatment of CF
Pancreatic insufficiency - oral pancrelipase
Vitamin deficiency - ADEK
Pulmonary disease - percussion, bronchodilators, mucolytic agents, antibiotics, hypertonic saline, ibuprofen
Liver transplants
Apparent Life Threatening Event
Infants resuscitated from ALTE are at increased risk of future respiratory death
Have prolonged apnea and diminished response to hypercarbia and hypoxia
Often premature or mechanical disorders
Not considered SIDS
Atelectasis in neonate
Collapsed lung
Incomplete expansion
Atelectasis in adult
Acquired collapsed lung
Resorption (obstruction) - Mediastinal shift toward involved lung
Compression (external pressure like tension pneumo) - Mediastinal shift away from involved lung
Contraction (secondary to fibrosis) - irreversible
Atelectasis at risk for
Infection
Hemodynamic pulmonary edema
Most common **Left sided heart failure Basal lower lobes **Heart failure cells Secondary infections Chronic leads to brown induration of lung (fibrosis)
Microvascular injury pulmonary edema
Increased permeability - infection (pneumonia), injury (direct or indirect)
**Can lead to ARDS
Acute lung injury
Acute onset of dyspnea
Hypoxemia
Bilateral infiltrates
**Absence of Primary left-sided heart failure
Cause of acute lung injury
Numerous Injuries include: Congestion Surfactant disruption Atelectasis Pulmonary edema
May progress to ARDS, DAD or AIP
Acute ARDS
Shock Lung = Acute Alveolar/Lung Injury Patients with severe disease Diffuse damage to alveolar capillary walls (inflammatory mediators -> neutrophil migration) **Secondary loss of surfactant Microthrombi
Infectious cause of ARDS
Sepsis
Pulmonary infection
Gastric aspiration
Physical injury cause of ARDS
Mechanical trauma/head injury
Contusions, drowning, burns, embolism, radiation
Inhaled irritants causing ARDS
Oxygen, smoke, gas/chemicals
Chemical injury causing ARDS
Paraquat
Reperfusion injury after transplant
Can lead to ARDS
50% of ARDS caused by
Sepsis
Pulmonary infection
Gastric aspiration
Trauma
Clinical presentation of ARDS
Patients are already ill
Profound dyspnea, tachypnea, cyanosis and respiratory failure
Diffuse bilateral infiltrates on xray
High mortality - permanent damage
Histology of ARDS
Collapsed alveoli
Hyaline membranes
Histology of lung recovering from ARDS
Lots of inflammatory cells, fibroblasts and collagen
Atypical type II pneumocytes
Acute interstitial pneumonia
Similar to ARDS but NO causative disorder
Acute respiratory failure following an illness
Obstructive chronic lung disease
Limit rate of flow
FEV1/FVC ratio low
Due to resistance at any level:
Emphysema, chronic bronchitis, bronchiectasis, asthma
Restrictive chronic lung disease
Low TLC and RV
Nearly normal flow rates
FEV1/FVC ratio low but levels are low
Chest wall disorders, obesity, ARDS, interstitial fibrosis, pneumoconioses
Chronic bronchitis
Bronchus Gland hyperplasia and hypersecretion Airway inflammation Caused by inhaling irritants Productive cough
Bronchiectasis
Bronchus dilation and scarring
Persistant infections
Productive cough
Asthma
Bronchus
Reversible obstruction
SM hyperplasia, extra mucus and inflammation
Episodic wheezing and cough
Emphysema
Acinus Airspace enlargement and wall destruction Overinflation Smoking Dyspnea
Small-airway disease, bronchiolitis
Bronchiole inflammation and scarring
Caused by irritants
Cough and dyspnea
Centriacinar/centrilobular emphysema
Caused by smoking!!
Most common
Upper lobes - bronchiole
Panacinar/panlobular emphysema
Anti-trypsin or smoking
Lower lobes - alveolus and duct
Distal acinar/paraseptal emphysema
May be bullous and cause spontaneous pneumothorax in young adults
Associated with previously damaged lung
Irregular/paracicatrical emphysema
Common and focal
Asymptomatic with scarring
Emphysema pathophysiology
Proteolytic digestion of alveolar walls **Neutrophil-secreted elastase Free radicals inhibits the antiprotease Associated with alpha-1 antitrypsin deficiency **Made worse with smoking
Clinical presentation of emphysema
Airspaces enlarge and then collapse - expiration is difficult
Barrel chest, dyspnea, wheezing
Low FEV1 (bronchiole collapse and fibrosis), high TLC and RV
**Pink puffer
**Bullous emphysema and pneumothorax
Acidosis
Compensatory hyperinflation
Loss of adjacent tissue but no wall destruction
Obstructive overinflation
Trapped air
1) object causing obstruction
2) collaterals feeding around obstruction -> life threatening
(pores of kohn, canals of Lambert)
3) congenital -> lack of cartilage
Interstitial emphysema
Any air in the interstitium
Chronic bronchitis
3 months of productive cough/year for 2 consecutive years
SMOKING
Hypersecretion
Increased Reid index
Bronchiolitis obliterans in small airways
Secondary infections, cor pulmonale, dyspnea on exertion
**Blue bloaters
Reid index
Thickness of glands/thickness of wall
Increased - glands are enormous
Asthma
Episodic, partially reversible bronchoconstriction
Recurrent wheezing/breathlessness/chest tightness and cough
**Can progress to acute severe asthma and death
Increasing incidence, cause not always found
Atopic asthma
Type 1 hypersensitivity
Tendency to develop IgE antibodies
Bronchial SM constricts in reaction to inflammatory mediators
Nonatopic asthma
Associated with infections and air pollutants
Infection lowers vagal response -> bronchospasm
Common cause of drug induced asthma
Aspirin
Increase leukotriene production -> leukotrienes favor bronchoconstriction
Asthma morphology
Overinflated lungs Airway remodeling: Goblet cell hyperplasia Subbasement membrane fibrosis Eosinophilic inflammation Muscle hypertrophy
Charcot-Leyden Crystals
Asthma (or allergic diseases)
Eosinophilic
Curschmann Spiral
Asthma
From shed epithelium
Bronchiectasis
Permanent dilation
Tissue destruction secondary to infection
Dyspnea, orthopnea and rarely severe hemoptosis but foul smelling sputum
Associated with cystic fibrosis, obstruction, infections
Chronic inflammation, sequestration, transplant rejection, and aspergillus
Chronic interstitial lung disease
X-ray reticulonodular or ground glass
Restrictive -> decreased TLC and RV
Dyspnea, tachypnea, cyanosis, end-inspiratory crackles
End stage -> honeycomb lung
Can lead to pulmonary HTN and cor pulmonale
Fibrosing CILD
Usual interstitial pneumonia Nonspecific interstitial pneumonia Crytogenic organizing pneumonia CTD Pneumoconiosis Drugs Radiation
Granulomatous CILD
Sarcoidosis
Hypersensitivity
Eosinophilic pneumonias
Other CILD
Pulmonary alveolar proteinosis
Pulmonary Langerhans cells histiocytosis
Lymphoid interstitial pneumonia
Smoking related CILD
Desquamative
Bronchiolitis associated
Idiopathic pulmonary fibrosis
Usual interstitial pneumonia Repeated injury to alveolar wall Type 1 death Type 2 hyperplasia Inflammation with Th2
**Smoking
Pathogenic mechanism leading to idiopathic fibrosis?
Increased signaling through the PI3K/AKT pathway -> activated fibroblasts
Clinical presentation of idiopathic pulmonary fibrosis
Dyspnea, dry cough, hypoxemia with cyanosis, digital clubbing
Mean survival < 3 years
Only treat with transplant
Pathology of idiopathic pulmonary fibrosis
Repeated cycles of alveolitis
Predominently subpleural/interlobar and lower lobe
Honeycomb lung
Nonspecific interstitial pneumonia
Dyspnea and cough for several months
Better prognosis, not as sick as UIP
