PREP 2021 Flashcards
What is persistent pulmonary hypertension of the newborn?
-PVR remains elevated after birth
-Prevents normal transition from fetal circulation to extrauterine circulation
Describe the flow of blood in a fetus?
-Oxygenated placental blood from umbilical vein into ductus venosus and caval circulation
-Majority of blood entering RA shunted across PFO by Eustachian valve to left heart and out to body
-Most of blood that enters RV and MPA goes R-L across ductus (because lungs are filled with amniotic fluid and not inflated the resistance to blood flow through pulmonary circulation is very high)
What causes closure of the ductus arteriosus and foramen ovale after birth?
-Pressures in pulmonary circulation decrease dramatically
-Results in less R-L shunting across PFO and PDA and leads to closure
What happens to the resistance in the pulmonary circulation in PPH?
It doesn’t drop- leads to pulmonary HTN
What is the reason for resistance in the pulmonary circulation failing to fall in PPHN?
-Not entirely understood
-Elevated vascular tone
-Abnormalities in the pulmonary vascular bed
-Pulmonary hypoplasia
-Some combination
What is the result of PPHN in the newborn?
-R-L shunting at PFO/PDA
-Hypoxemia that is minimally responsive to O2
What needs to be ruled in cases of suspected PPHN?
Cyanotic CHG like TAPVR
What is the general management strategy in PPHN?
-Reduce O2 demand (sedation)
-Increase PBF (optimize lung inflation, reduce PVR, treat underlying issues- infection, meconium aspiration, cardiac dysfunction, etc)
*Severe cases, may need ECMO until PVR improves
What is the fastest-onset therapy to quickly reduce PVR?
iNO
What is the Class I recommendations for reduction of PVR to prevent ECMO in PPHN in term or neat-term neonates with PPHN?
iNO
What type of medication is bosentan?
Endothelin receptor antagonist (pulmonary vasodilator)
How long does it take for bosentan to have effect?
5 hours (given enterally)
True or False: Bosentan is a treatment option for PPHN?
False- takes too long to have effect
What type of medication is Iloprost?
Inhaled (nebulized) prostacyclin analog
How long until iloprost reaches peak effect?
5 minutes (in inhaled form)
What are 2 ways that iloprost can be given?
Inhaled (nebulized)
IV
What are some problems with IV iloprost?
-Potential for systemic hypotension
-VQ mismatch
What are some problems with inhaled/nebulized iloprost?
-Irritate airways (because of carrier)
-Dosing less consistent because of loss into the nebulizer system
What is a Class IIb recommendation for refractory PPHN that doesn’t respond to iNO?
Inhaled iloprost
MOA sildenafil?
Phosphodiesterase 5 inhibitor
MOA milrinone?
Phosphodiesterase 3 inhibitor
True or False: Milrinone and sildenafil may be used to reduce PVR in an ill neonate with PPHN?
True
What are potential unwanted side effects of milrinone and sildenafil?
Lower systemic BP
When can sildenafil reach peak effect for lowering PVR?
Within 1-2 hours of administation