Pulmonary Hypertension and Respiratory Distress Syndromes

Question 1

What is pulmonary hypertension? What is it characterized by? What is seen on histology?

Answer 1

High pressure in the pulmonary circuit (mean arterial pressure > 25 mm Hg. Characterized by atherosclerosis of the pulmonary trunk, smooth muscle hypertrophy of pulmonary arteries and intimal fibrosis. Plexiform lesions are seen with severe, long-standing disease.

Question 2

How does pulmonary HTN present? What does it lead to?

Answer 2

Presents with exertional dyspnea or right-sided heart failure. Leads to right ventricular hypertrophy with eventual cor pulmonale.

Question 3

Which population is primary pulmonary HTN seen in? What mutation is involved? What does it cause?

Answer 3

Young adult females. Some familial forms are related to inactivating mutations of BMPR2, leading to proliferation of vascular smooth muscle.

Question 4

What causes secondary pulmonary HTN?

Answer 4

Due to 1. Hypoxemia (COPD and interstitial lung disease) 2. increased volume in the pulmonary circuit
3. recurrent pulmonary embolism.

Question 5

What is acute respiratory distress syndrome (ARDS)? What does it cause?

Answer 5

Diffuse damage to the alveolar-capillary interface. Leakage of protein rich fluid leads to edema that combines with necrotic epithelilal cells to form hyaline membranes in alveoli.

Question 6

What are the clinical features of acute respiratory distress syndrome (ARDS)?

Answer 6

1. Hypoxemia and cyanosis with respiratory distress - due to thickened diffusion barrier and collapse of ar sacs
2. White out on chest x-ray

Question 7

What cells are damaged in acute respiratory distress syndrome (ARDS)? What causes the damage?

Answer 7

Activation of neutrophils induces protease and free radical mediated damage of type I and II pneumocytes.

Question 8

What cells are damaged in acute respiratory distress syndrome (ARDS)? What causes the damage?

Answer 8

Activation of neutrophils induces protease and free radical mediated damage of type I and II pneumocytes.

Question 9

How is acute respiratory distress syndrome (ARDS) treated? What might complicate recovery?

Answer 9

Ventilation with positive end-expiratory pressure. Complicated by interstitial fibrosis; damage and loss of type II pneumocytes leads to scarring and fibrosis.

Question 10

What is the pathogenesis of Neonatal Respiratory Distress Syndrome?

Answer 10

Respiratory distress due to inadequate surfactant levels. Lack of surfactant leads to collapse of air sacs adn formation of hyaline membranes.

Question 11

What is the role of surfactant and what cells make it? What is the major component?

Answer 11

Surfactant decreases surface tension in the lung, preventing collapse of alveolar air sacs after expiration. It is made by type II pneumocytes. Phosphatidylcholine (lecithin) is the major component.

Question 12

What is the role of surfactant and what cells make it? What is the major component?

Answer 12

Surfactant decreases surface tension in the lung, preventing collapse of alveolar air sacs after expiration. It is made by type II pneumocytes. Phosphatidylcholine (lecithin) is the major component.

Question 13

What is Neonatal Respiratory Distress Syndrome associated with?

Answer 13

1. Prematurity
2. Caesarian section delivery (due to lack of stress induced steroids which increase surfactant synthesis during vaginal delivery)
3. Maternal diabetes (Insulin increases surfactant production)

Question 14

How is lung maturity screened? When does surfactant production begin and when do adequate levels reach? What indicates adequate surfactant production?

Answer 14

Ratio of amniotic fluid lecithin to sphingomyelin is used to screen for maturity. Phosphatidylchline (Lecithin) levels increase when surfactant is produced while sphongomyelin remains constant. Surfactant production begins at 28 weeks. Adequate levels are not reached until 34 weeks. A ratio >2 indicates adequate surfactant production

Question 15

What is the pathogenesis of Neonatal Respiratory Distress Syndrome?

Answer 15

Respiratory distress due to inadequate surfactant levels. Lack of surfactant leads to collapse of air sacs adn formation of hyaline membranes.

Question 16

How is lung maturity screened? When does surfactant production begin and when do adequate levels reach? What indicates adequate surfactant production?

Answer 16

Ratio of amniotic fluid lecithin to sphingomyelin is used to screen for maturity. Phosphatidylchline (Lecithin) levels increase when surfactant is produced while sphongomyelin remains constant. Surfactant production begins at 28 weeks. Adequate levels are not reached until 34 weeks. A ratio >2 indicates adequate surfactant production

Question 17

What are the clinical features of Neonatal Respiratory Distress Syndrome?

Answer 17

1. Increased respiratory effort after birth, tachypnea with use of accessory muscles and grunting
2. Hypoxemia with cyanosis
3. Diffuse granularity of the lung on x-ray

Question 18

What complications are created by Neonatal Respiratory Distress Syndrome?

Answer 18

1. Hypoxemia which increases the risk for persistence of patent ductus arteriosus and necrotizing enterocolitis
2. Supplemental oxygen increases the risk for free radical injury. Retinal injury leads to blindness, lung damage leads to bronchopulmonary dysplasia.