Adult respiratory distress syndrome (ARDS) involves diffuse damage to the alveolar epithelium and capillaries resulting in progressive respiratory failure unresponsive to oxygen treatment. It has numerous causes including shock, sepsis, trauma, and infections. On x-ray, ARDS appears as bilateral diffuse widespread lung opacity. Respiratory distress syndrome of the newborn (also called hyaline membrane disease) occurs most commonly in preterm infants and those with maternal diabetes or multiple births. It results from a deficiency of surfactant causing atelectasis and hyaline membrane formation. Pulmonary embolism occurs when blood clots most often from the legs travel to the lungs. While most emboli do not cause infarction, large embol

1. Respiratory Distress SyndromesRespiratory Distress Syndromes
Adult respiratory distress syndrome (ARDS)Adult respiratory distress syndrome (ARDS)
 It is also known as diffuse alveolar damage (DAD), shock lungIt is also known as diffuse alveolar damage (DAD), shock lung
DefinitionDefinition::
Diffuse damage of alveolar epithelium and capillaries, resulting inDiffuse damage of alveolar epithelium and capillaries, resulting in
progressive respiratory failure that is unresponsive to oxygenprogressive respiratory failure that is unresponsive to oxygen
treatment.treatment.

2. Causes:Causes:
 shock,shock,
 sepsis,sepsis,
 trauma,trauma,
 gastric aspiration,gastric aspiration,
 radiation,radiation,
 oxygen toxicity,oxygen toxicity,
 pulmonary infections and many others.pulmonary infections and many others.

3. X-ray:X-ray: bilateral diffuse widespread lung opacitybilateral diffuse widespread lung opacity

4. MorphologyMorphology
 Gross: heavy, stiff, noncompliant lungsGross: heavy, stiff, noncompliant lungs
 Micro-Micro-
Interstitial and intra-alveolar edema,Interstitial and intra-alveolar edema,
Interstitial inflammation,Interstitial inflammation,
loss of pneumocytes(alveolar cells),loss of pneumocytes(alveolar cells),
hyaline membrane formation(neonatal respiratory distress )hyaline membrane formation(neonatal respiratory distress )


5. Respiratory distress syndrome of the newbornRespiratory distress syndrome of the newborn
Also known as hyaline membrane disease of newbornsAlso known as hyaline membrane disease of newborns
Associated withAssociated with
i. Prematurity (gestational age of <28 weeks has a 60% incidence)i. Prematurity (gestational age of <28 weeks has a 60% incidence)
ii. Maternal diabetesii. Maternal diabetes
iii. Multiple birthsiii. Multiple births
iv. C-section deliveryiv. C-section delivery
Defect: deficiency of surfactantDefect: deficiency of surfactant

6. MorphologyMorphology
 Atelectasis andAtelectasis and hyaline membrane formahyaline membrane forma

7. Pulmonary emboli (PE) and pulmonary infarctionPulmonary emboli (PE) and pulmonary infarction
 Most (90-95%) pulmonary emboli arise from deep vein thrombosisMost (90-95%) pulmonary emboli arise from deep vein thrombosis
(DVT) in the leg(DVT) in the leg
 Only 10% of pulmonary emboli cause infarctionOnly 10% of pulmonary emboli cause infarction
 Infarcts usually occur in patients with underlying cardiopulmonaryInfarcts usually occur in patients with underlying cardiopulmonary
diseasedisease
 Gross: wedge-shaped, hemorrhagic infarctionGross: wedge-shaped, hemorrhagic infarction
ComplicationsComplications
i. Large emboli (saddle emboli) may cause sudden deathi. Large emboli (saddle emboli) may cause sudden death
ii. Septic emboli may result in a pulmonary abscessii. Septic emboli may result in a pulmonary abscess

8. Pulmonary hypertensionPulmonary hypertension
Definition: increased pulmonary artery pressure, usually due toDefinition: increased pulmonary artery pressure, usually due to
increased vascular resistance or blood flowincreased vascular resistance or blood flow
EtiologyEtiology
i. COPD and interstitial disease (hypoxic vasoconstriction)i. COPD and interstitial disease (hypoxic vasoconstriction)
ii. Multiple ongoing pulmonary emboliii. Multiple ongoing pulmonary emboli
iii. Mitral stenosis and left heart failureiii. Mitral stenosis and left heart failure
IV. Congenital heart disease with left to right shunts (ASD,VSD,PDA)IV. Congenital heart disease with left to right shunts (ASD,VSD,PDA)
v. Primary (idiopathic)v. Primary (idiopathic)
PathologyPathology
i. Pulmonary artery athlerosclerosisi. Pulmonary artery athlerosclerosis
ii. Small artery medial hypertrophy and intimal fibrosisii. Small artery medial hypertrophy and intimal fibrosis
iii. Pulmonary arteriopathyiii. Pulmonary arteriopathy
Complication: right ventricular hypertrophy ~ failure (cor pulmonale)Complication: right ventricular hypertrophy ~ failure (cor pulmonale)