Prematurity (Raf)

Question 1

What are epidemiologic risk factors for RDS?

Answer 1

• GA
• gender (males worse than females)
• ethnicity (worse for whites than african American)
• antenatal steroids (which have decreased incidence and severity of RDS)
• maternal insulin

Question 2

What is the typical clinical presentation of RDS?

Answer 2

Early onset respiratory distress by 4 hours, worst at 24-36 hours, improved at 36-48 hours
(endogenous surfactant production starts at 24 hours)

Question 3

What are the CXR manifestations of RDS?

Answer 3

• Low lung volumes
• Diffuse ground glass (reticulonodular)
• Air bronchograms

Question 4

Pathologic features of new BPD?

Answer 4

• Fewer, larger and simplified alveoli
• Fewer arteries, but dysmorphic
• Less regional heterogeneity
• Rare airway epithelial lesions
• Mild airway smooth muscle thickening
• rare fibroproliferative changes

Question 5

Pathologic features of old BPD?

Answer 5

• heterogeneous: alternating atelectasis with hyperinflation
• severe airway epithelial lesions
• market airway smooth muscle hyperplasia
• extensive diffuse fibroproliferation
• hypertensive remodelling of pulmonary arteries
• decreased alveolarization and surface area

Question 6

Definition for BPD?

Answer 6

• Need for oxygen >21% for at least 28 days
• Time point for assessment:
  <32 weeks: assess at 36 weeks or discharge, whichever is sooner
• > 32 weeks: assess at 56 days or discharge, whichever is sooner
  (need to go with sooner since the patient will be discharge, so need to classify before discharge)
• Mild: no oxygen
• Moderate: <30% fiO2
• Severe: >30% fiO2 +/- PPV/CPAP

Question 7

Why are old and new BPD different?

Answer 7

Old BPD: infants were born in late saccular stage. Lung injury was due to hyperoxia, ventilator induced lung injury, inflammation, infection
New BPD: mid to late cannalicular stage, mainly due to aberrant lung development. With antenatal steroids, surfactant and gentl ventilation, less old BPD.

Question 8

Properties of chyle?

Answer 8

• Chylothorax = accumulation of lymphatic fluid in the pleura
• Lymph generally drains into thoracic duct
• Sudan IIIn stain positive for fat globules
• Triglycerides >1.1 mmol/L
• High lymphocyte content (>80%)
• sterile
• fat content higher than plasma
• electrolytes, BUN, glucose similar to plasma
• meets the criteria for an exudate

Question 9

Differential diagnosis of neonatal chylothorax?

Answer 9

• congenital: Down’s, Noonan, Turner
• Hydrops fetalis
• Injury to thoracic duct - either congenital (eg. birth trauma), post operative
• congenital lymphatic abnormality - eg. lymphangiectasis, lymphangioma
• Increased central venous pressure pressure - eg. post fontan, thrombosis of SVC
• Chylothorax in general: lymphoma, teratoma, neuroblastoma, TB, histoplasmosis, sarcoid

Question 10

If neonatal chylothorax is not improving with conservative management, what are next investigations?

Answer 10

• Lymphangiography to localize a site of lymphatic leak
• CT scan - may see thickened interlobular septa with lymphangiectasia, but can’t visualize lymphatics on CT scn (I’m not sure if this finding is specific to lymphangiectasia)

Question 11

Lymphangioma versus lymphangiomatosis versus lymphangiectasia?

Answer 11

Lymphangioma: abnormal proliferation of lymphatic vessels, forming a cyst
Lymphangiomatosis: multiple lymphangiomas, which can be in lung, liver, spleen, mediastinum
Lymphangiectasia: dilated lymphatic channels, which impair drainage. Can be primary or secondary (due to increased venous back pressure such as in heart failure or portal hypertension