Patent Ductus Arteriosus ✅

Question 1

How is the patency of the ductus arteriosus maintained?

Answer 1

• High blood flow
• Hypoxia
• Locally derived prostaglandin E2D

Question 2

How does the ductus arteriosus of pre-term infants compare to term infants?

Answer 2

In pre-term infants, the ductal wall is thinner, the lumen is larger, and post-natal constriction does not wholly obliterate the lumen

Question 3

How is the incidence of functional PDA related to gestational age?

Answer 3

It is inversely proportional

Question 4

What are predisposing risk factors for PDA?

Answer 4

• RDS
• Sepsis
• Fluid overload

Question 5

In what direction is blood shunted across a PDA?

Answer 5

Left to right

Question 6

What does the left-to-right shunting through the PDA result in?

Answer 6

Increased pulmonary blood flow and higher venous return to the left atrium and left ventricle (high preload)

Question 7

What can the increased pulmonary blood flow in PDA result in?

Answer 7

• Pulmonary oedema
• Congestive cardiac failure
• Pulmonary haemorrhage
• Increased risk of bronchopulmonary dysplasia

Question 8

What does a haemodynamically significant PDA lead to?

Answer 8

Decreased systemic blood flow

Question 9

What does the decreased systemic blood flow caused by a haemodynamically significant PDA cause?

Answer 9

• Hypotension, especially diastolic
• Reduced gut and renal perfusion
• Metabolic acidosis

Question 10

What does a haemodynamically significant PDA causing diastolic hypotension in particular produce?

Answer 10

A wide pulse pressure

Question 11

What complications can arise from the reduced systemic perfusion caused by a haemodynamically significant PDA?

Answer 11

• Necrotising enterocolitis

- Intraventricular haemorrhage

Question 12

What do the clinical effects of PDA include?

Answer 12

• Tachypnoea
• Increased oxygen requirement
• Increased ventilatory requirement
• Extubation failure
• Apnoea
• Hepatomegaly from congestive heart failure
• Impaired weight gain

Question 13

What examination findings are present in PDA?

Answer 13

• Systolic or pansystolic murmur at left sternal edge
• Loud second heart sound
• Gallop rhythm
• Bounding pulses from wide pulses pressure
• Hepatomegaly from right heart failure

Question 14

When might the murmur be absent in PDA?

Answer 14

If the shunt is large

Question 15

Why is conservative management often appropriate in PDA in preterm infants?

Answer 15

In infants >1kg birth weight, 2/3 of PDA close spontaneously, and in infants <1kg 1/3 close spontaneously

Question 16

What does conservative management for PDA consist of?

Answer 16

Restricted fluid early on in first week

Question 17

What is the problem with fluid restriction in the management of PDA?

Answer 17

Prolonged fluid restriction may worsen systemic hypoperfusion

Question 18

What can be used for pharmacological closure of PDA?

Answer 18

• Indomethacin

- Ibuprofen

Question 19

How does pharmacological closure of PDA work?

Answer 19

By decreasing production of PGE2

Question 20

What is the first line agent for pharmacological closure of PDA?

Answer 20

Ibuprofen

Question 21

Why is ibuprofen the first line agent for pharmacological closure of PDA?

Answer 21

Indomethacin use is associated with more nephrotoxicity, NEC, GI haemorrhage, platelet dysfunction, and impaired cerebral blood flow

Question 22

What kind of drug is ibuprofen?

Answer 22

Non-selective cyclo-oxygenase inhibitor

Question 23

When are diuretics used in PDA?

Answer 23

Only in babies with heart failure

Question 24

Why are diuretics only indicated for babies with heart failure?

Answer 24

Because they may worsen systemic hypoperfusion and increased the renal production of prostaglandins, which may promote ductal patency

Question 25

What might be indicated if medical intervention for PDA fails?

Answer 25

Surgical ligation