Resp - Path (Neonatal respiratory distress syndrome, ARDS, & Obstructive vs. Restrictive lung disease)

Question 1

What is the pathogenesis of neonatal respiratory distress syndrome?

Answer 1

Surfactant deficiency –> increased surface tension –> alveolar collapse

Question 2

What amniotic fluid finding is predictive of neonatal respiratory distress syndrome?

Answer 2

A lecithin:sphingomyelin < 1.5 in amniotic fluid is predictive of neonatal respiratory distress syndrome.

Question 3

For what condition does neonatal respiratory distress syndrome increase the risk, and why?

Answer 3

Persistently low O2 tension –> risk of PDA

Question 4

What are 2 conditions that can be caused by therapeutic supplemental O2 for neonatal respiratory distress syndrome?

Answer 4

Therapeutic supplemental O2 can result in retinopathy of prematurity and bronchopulmonary dysplasia.

Question 5

What are 3 risk factors for neonatal respiratory distress syndrome?

Answer 5

Risk factors: (1) prematurity (2) maternal diabetes (due to increased fetal insulin) (3) C-section delivery (decreased release of fetal glucocorticoids)

Question 6

What causes maternal diabetes to be a risk factor for neonatal respiratory distress syndrome?

Answer 6

maternal diabetes (due to increased fetal insulin [which decreases surfactant synthesis])

Question 7

What causes C-section delivery to be a risk factor for neonatal respiratory distress syndrome?

Answer 7

C-section delivery (decreased release of fetal glucocorticoids [which would normally increase surfactant synthesis])

Question 8

What is the treatment for neonatal respiratory distress syndrome before birth versus during infancy?

Answer 8

Treatment: maternal steroids before birth; artificial surfactant for infant

Question 9

What are 7 causes of acute respiratory distress syndrome?

Answer 9

May be caused by (1) trauma (2) sepsis (3) shock (4) gastric aspiration (5) uremia (6) acute pancreatitis (7) amniotic fluid embolism

Question 10

What is the pathophysiology behind acute respiratory distress syndrome?

Answer 10

Diffuse alveolar damage –> increased alveolar capillary permeability –> protein-rich leakage into alveoli and noncardiogenic pulmonary edema (normal PCWP).

Question 11

What membranous change occur as a result of acute respiratory distress syndrome?

Answer 11

Results in formation of intra-alveolar hyaline membrane

Question 12

What causes the initial damage in acute respiratory distress syndrome?

Answer 12

Initial damage due to release of neutrophils substances toxic to alveolar wall, activation of coagulation cascade, and oxygen-derived free radicals.

Question 13

What can be seen on CXR in patients with acute respiratory distress syndrome?

Answer 13

Near-complete opacification of the lungs with obscured cadiomediastinal silhouette

Question 14

What 2 histological findings are characteristic of acute respiratory distress syndrome?

Answer 14

Alveolar fluid (clear, frothy) and thickened hyaline membranes (pink)

Question 15

What is the FEV1/FVC in the following contexts: (1) Normal (2) Obstructive (3) Restrictive?

Answer 15

(1) 80% (2) < 80% (3) >= 80%

Question 16

Create 3 separate graphs of FEV1 and FVC for each of the following contexts: (1) Normal (2) Obstructive (lung disease) (3) Restrictive (lung disease). X axis is Time in sec and Y axis is Lung volume in L.

Answer 16

See p. 607 in First Aid 2014 for graphs at the bottom of the page

Question 17

How do obstructive and restrictive lung volumes compare to normal?

Answer 17

Obstructive lung volumes > normal (increased TLC, increased FRC, increased RV); Restrictive lung volumes < normal

Question 18

What changes occur with FEV1 and FVC in obstructive versus restrictive lung disease? How are those changes similar, and how they different?

Answer 18

In both obstructive and restrictive, FEV1 and FVC are reduced. In obstructive, however, FEV1 is more dramatically reduced compared to FVC, resulting in a decreased FEV1/FVC ratio