Accumulation of/inability to clear secretions
Progressive destruction of the normal lung architecture
Clinical manifestations:
Chronic cough, green/yellow sputum, dyspnea
Breath indicative of active infection
Crepitation/crackles base of the lung 
Complications:
Emphysema
Secondary amyloidosis
Emphysema
Permanent enlargement of alveoli accompanied by destruction of alveolar walls without
obvious fibrosis
Etiology:
COPD (main reason)
Pathophysiology:
Loss of elastic recoil
Dilation and combining air spaces reduces surface area for oxygen exchange
Ruptured alevoli
Clinical manifestations
As in other COPD
Labored breathing
Barrel chest
*Respiratory Tract Infections
Pneumonia:
Discussed in detail in LUSL2036
Pathophysiology:
– Acute inflammation; accumulation of neutrophils & macrophages, inflammatory mediators, congestion, exudate release, etc.
– Consolidation (inflamed, thickened and scarred airway)
Tuberculosis
Discussed in detail in LUSL2036
Pathophysiology:
– Chronic inflammation, tubercle formation, caseous necrosis
Acute bronchitis
Acute inflammation of the bronchi
Commonly follows a viral infection of upper resp tract
Similar symptoms to pneumonia but does not demonstrate pulmonary consolidation and chest infiltrates
Obstructive Sleep Apnea
Partial or complete upper airway obstruction during sleep
Etiology:
Adenotonsillar hypertrophy is the most common cause.
Pharyngeal web = hyperplasia tissue that blocks the nasopharynx.
At night the nasopharynx relaxes → high CO2 so patient wakens abruptly to temporarily correct breathing pattern (fix apnea).
Pathophysiology:
Mild, moderate, severe based on AHI (apnea-hypopnea index)
Disruption of normal ventilation and sleep patterns
Oxidative stress
– The cells get tired. The endothelium releases NO to dilate the vessels to help with O2
Hypercoagulability and CV complications
Clinical Manifestations and Diagnosis:
Snoring and labored breathing during sleep
Daytime sleepiness
Chronic mouth breathing
Sleep studies (Polysomnography)
Sleep questionnaires:
– Berlin and *STOP-Bang
Pulmonary Vascular Disorders
Pulmonary Embolism (PE)
Occlusion within pulmonary vascular bed by clot (thrombus, embolus), fat/air bubble, amniotic fluid droplet 
Etiology and Pathophysiology:
Deep vein thrombosis (DVT) in the lower limb
Virchow triad
Hypoxemia, low oxygen saturation
Perfusion is affected, not ventilation
Clinical manifestations and evaluation:
Dyspnea, chest pain on inspiration
Tachycardia, cyanosis, hypotension 
Lab and radiology:
Elevated D-dimer
CT & pulmonary angiography
Doppler US
Pulmonary Hypertension
Elevation of pressure in pulmonary vasculature
Pressure > 20 mm or elevation by 5-10 mm Hg above normal
Etiology & classifications:
Primary pulmonary hypertension (Idiopathic)
Pulmonary hypertension due to left heart disease
– E.g. mitral valve
Pulmonary hypertension due to lung disease/hypoxia
– E.g. COPD
Pulmonary hypertension due thrombo-embolic disease
– E.g. lung clots
Clinical manifestations:
Dyspnea
Fatigue
Dizziness
Complications:
▪ RT ventricular failure
▪ Cor Pulmonale:
– RV enlargement/failure secondary to pulmonary hypertension
Malignancies of the Respiratory Tract
Lung (bronchogenic) cancer
Etiology & risk factors:
Cigarette smoking: most common cause (heavy smokers 20 x > risk than nonsmokers)
Environmental or occupational risk factors e.g. asbestos, radon
Types:
Non-small cell carcinoma:
– Squamous cell carcinoma
– Adenocarcinoma
– Large cell carcinoma
Small cell carcinomas:
– Highly malignant
– Can arise outside lungs (prostate, cervix, LN)
– Can be hormone secreting (paraneoplastic)
Selected Pulmonary Function Disorders in Children – Chapter 27
Cystic Fibrosis
Etiology & Pathophysiology:
Autosomal recessive- mutations in transmembrane conductance regulator (CFTR) gene
– Damages the chloride channels that helps make the mucus, this reduces the water, so the mucus is now thick
Multisystem disease
Exocrine or mucus-producing glands secrete abnormally thick mucus
In the lungs, thick secretions obstruct the bronchioles and predispose to chronic lung infections
Chronic inflammation leads to hyperplasia of goblet cells, bronchiectasis, pneumonia, hypoxia, fibrosis, etc.
Upper Airway Obstruction with Croup
Croup:
– URT infection causing barking like cough
One cause of stridor (noisy breathing) (others are fb.)
Acute laryngotracheobronchitis:
– Children from 6 months to 5 years
– Commonly caused by a virus (influenza, or RSV)
– Usually occurs after an episode of rhinorrhea, sore throat, low-grade fever
– URT inflammation → obstruction → stridor (~70% narrowing)
– Life-threatening 
*Acute Epiglottitis
Severe, rapidly progressive, life-threatening infection of the epiglottis and surrounding area
Historically caused by Haemophilus influenzae type B
– 80%-90% decreased incidence due to HIB vaccination
Manifestations:
High fever
Irritability
Sore throat
Inspiratory stridor/ muffled voice
Severe respiratory distress
Aspiration Disorders
Etiology and pathophysiology:
Aspiration of foreign bodies
– In children, ages of 1-3
– Any foreign substance: food, meconium (neonates), secretions (salivary or gastric), or environmental
– Inflammation of the lung tissue (aspiration pneumonitis)
Lung damage depends on volume and pH of aspirate
Leading cause of death in children specially, neurologically compromised
Clinical Manifestations:
Coughing
Choking
Gagging
Wheezing
Symptoms depend on size/ nature of the foreign body
Respiratory distress syndrome (RDS) of newborn
Etiology & Pathophysiology:
Prematurity & lack of adequate surfactant
Primarily a disease of preterm infants
Widespread atelectasis, respiratory distress, and pulmonary hypertension
Clinical manifestations:
Tachypnea
Expiratory grunting
Nasal flaring
Dusky skin 