Patent Ductus Arteriosus ✅ Flashcards
How is the patency of the ductus arteriosus maintained?
- High blood flow
- Hypoxia
- Locally derived prostaglandin E2D
How does the ductus arteriosus of pre-term infants compare to term infants?
In pre-term infants, the ductal wall is thinner, the lumen is larger, and post-natal constriction does not wholly obliterate the lumen
How is the incidence of functional PDA related to gestational age?
It is inversely proportional
What are predisposing risk factors for PDA?
- RDS
- Sepsis
- Fluid overload
In what direction is blood shunted across a PDA?
Left to right
What does the left-to-right shunting through the PDA result in?
Increased pulmonary blood flow and higher venous return to the left atrium and left ventricle (high preload)
What can the increased pulmonary blood flow in PDA result in?
- Pulmonary oedema
- Congestive cardiac failure
- Pulmonary haemorrhage
- Increased risk of bronchopulmonary dysplasia
What does a haemodynamically significant PDA lead to?
Decreased systemic blood flow
What does the decreased systemic blood flow caused by a haemodynamically significant PDA cause?
- Hypotension, especially diastolic
- Reduced gut and renal perfusion
- Metabolic acidosis
What does a haemodynamically significant PDA causing diastolic hypotension in particular produce?
A wide pulse pressure
What complications can arise from the reduced systemic perfusion caused by a haemodynamically significant PDA?
- Necrotising enterocolitis
- Intraventricular haemorrhage
What do the clinical effects of PDA include?
- Tachypnoea
- Increased oxygen requirement
- Increased ventilatory requirement
- Extubation failure
- Apnoea
- Hepatomegaly from congestive heart failure
- Impaired weight gain
What examination findings are present in PDA?
- 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
When might the murmur be absent in PDA?
If the shunt is large
Why is conservative management often appropriate in PDA in preterm infants?
In infants >1kg birth weight, 2/3 of PDA close spontaneously, and in infants <1kg 1/3 close spontaneously
What does conservative management for PDA consist of?
Restricted fluid early on in first week
What is the problem with fluid restriction in the management of PDA?
Prolonged fluid restriction may worsen systemic hypoperfusion
What can be used for pharmacological closure of PDA?
- Indomethacin
- Ibuprofen
How does pharmacological closure of PDA work?
By decreasing production of PGE2
What is the first line agent for pharmacological closure of PDA?
Ibuprofen
Why is ibuprofen the first line agent for pharmacological closure of PDA?
Indomethacin use is associated with more nephrotoxicity, NEC, GI haemorrhage, platelet dysfunction, and impaired cerebral blood flow
What kind of drug is ibuprofen?
Non-selective cyclo-oxygenase inhibitor
When are diuretics used in PDA?
Only in babies with heart failure
Why are diuretics only indicated for babies with heart failure?
Because they may worsen systemic hypoperfusion and increased the renal production of prostaglandins, which may promote ductal patency
What might be indicated if medical intervention for PDA fails?
Surgical ligation
