PATENT DUCTUS ARTERIOSUS By Nicole Stevens PATENT DUCTUS

PATENT DUCTUS ARTERIOSUS By: Nicole Stevens

PATENT DUCTUS ARTERIOSUS • Patent Ductus Arteriosus is a functional connection between the pulmonary artery and the descending aorta. • In the fetus the DA allows blood to be diverted away from the pulmonary artery (the high resistance pulmonary circulation) to the descending aorta (the low resistance systemic circulation) • The duct remains open due to the prostaglandin supply coming from the placenta. • The DA protects the lungs from circulatory

PATENT DUCTUS ARTERIOSUS • After the birth the baby’s lungs expand as they begin to take breaths. • Pulmonary resistance decreases and the oxygen levels in the blood rise causing the DA to constrict. • Sometimes the DA doesn’t constrict and the baby is left with a PDA. • This can be due to lack of oxygen or an increase in the amounts of prostaglandin. • Sometimes the PDA will functionally close but will

PATENT DUCTUS ARTERIOSUS • It is approximately 10 mm in diameter • Functional closure occurs between 12 hours and 4 days of age in healthy term babies • Structural closure takes between 2 to 6 weeks

PATENT DUCTUS ARTERIOSUS • It is common in premature infants • Serious concern as the pulmonary artery is not getting enough blood for the lungs to function effectively • It can cause worsening RDS and an escalation in the respiratory support that is required • Diagnosed on ECHO

PATENT DUCTUS ARTERIOS PDA in the preterm infant: q There is nothing wrong with the heart, the PDA just doesn’t close and usually causes a left to right shunt q The tissue is immature; the fetal haemoglobin has a higher affinity for oxygen (doesn’t release it as easily) q The lower the gestational age the greater the risk of PDA q VLBW infants will have up to 50 – 60% chance of a PDA

PATENT DUCTUS ARTERIOSUS PDA in the term infant: q If there is pulmonary hypertension (numerous causes for this, eg. meconium aspiration, infection) the blood shunts right to left through the PDA q Deoxygenated blood that should be going to the lungs goes back to the body, this causes hypoxia and acidosis, which causes vascular smooth muscle to constrict, and the end result can be persistent fetal circulation (without the

PATENT DUCTUS ARTERIOSUS q When trying to determine if shunting of blood is occuring across a PDA you may be asked to measure pre and post ductal oxygen saturations q Pre ductal Sa. O 2 are measured on the right hand/wrist, and post ductal Sa. O 2 can be measured on any of the other limbs, usually a difference of 10% or more is considered significant and may be caused by shunting of blood across a PDA q The arteries that supply part of the brain, and right arm, branch off the aorta prior to where

• • • PHYSIOLOGICAL EFFECTS of a PDA Pulmonary oedema Poor perfusion Bounding pulses Swinging saturations Desaturations Renal compromise Heart murmur Congestive cardiac failure Mottled or pale

TREATMENT OF PDA If a neonate is symptomatic of an existing PDA they may require treatment q Chemical treatment: Indomethacin (usually given IV but oral route can be used, althought to be not as effective) (Note: there is currently a world-wide shortage of indomethacin as its production has stopped, in the near future an alternate drug may be used) q If chemical treatment fails surgical treatment

INDOMETHACIN • First line treatment • Urea & Creatinine are checked before commencing Indomethacin to ensure normal renal function before commencement of the drug. • Platelets are also checked to ensure normal range • 3 daily doses of 200 mcg/kg at 2200 hrs • Side Effects include impairment of renal function, reduce platelet aggregation, GI

NURSING RESPONSIBILITIES FOR INDOMETHACIN • • • Monitor urine output Daily Urinalysis BP monitoring Observe for bleeding and or NEC Contraindicated in infants with recent IVH and NEC

KEEPING A PDA OPEN • Some cardiac abnormalities are considered “duct-dependent”; these can be cyanotic or acyanotic • Duct-dependent defects can be related to pulmonary flow (for example pulmonary stenosis or pulmonary atresia); or related to systemic flow (for example hyperplastic left heart or transposition of the greater arteries) • If there is a definite or suspected diagnosis of a cardiac abnormality, that is duct dependent, a prostaglandin infusion is the treatment of choice (a synthetic version of the hormone that