<s>[INST] context: PDA in preterm neonate

In previous explanations I have explained that chances of spontaneous closure of PDA are higher in premature infants as there is no structural abnormality. However, you should keep in mind that this fact is true when we are comparing the spontaneous closure of PDA between term and pre-term neonate. Overall, the percentage of spontaneous closure of PDA in preterm neonate is very low. To avoid confusion, I am explaining following facts in brief :-



Normal neonate :- Ductus arteriosus closes functionally within about 15 hours of birth.
FDA in term (mature) neonate :- The persistence of ductus arteriosus beyond 24 hours after birth is considered as PDA in term neonate. Spontaneous closure of PDA does not usually occur because PDA results from structural abnormality.
FDA in pre-term (pre-mature) neonate :- The ductus arteriosus in pre-term neonate is not as responsive to increased oxygen content as it is in term neonate. However, there is no structural abnormality.


Chances of spontaneous closure are very less (compared to normal term neonate).
Chances of spontaneous closure are more than the term-neonate with PDA. However, in premature neonate, where hypoxic pulmonary disease is common place, the ductus being sensitive to hypoxia, remains open.


So, it is very unlikely that spontaneous closure of PDA will occur in pre-term neonate. But chances are more when compared to term neonate with PDA (not nonnal term neonate in which ductus arteriosus closes within 15 hours of birth).

Manifestations of PDA in pre-term neonate

Apnea for unexplained reasons in an infant recovering from RDS;
A hyperdynamic precordium, bounding peripheral pulses, wide pulse pressure, and a continuous or systolic murmur with or without extension into diastole or an apical diastolic murmur, multiple clicks resembling the shaking of dice;
Carbon 'oxide retention;
Increasing oxygen dependence;
X-ray evidence of cardiomegaly and increased pulmonary vascular markings; and
Hepatomegaly


Increased pulmonary blood flow and compromised ventricular function accompanying dropping pulmonary resistance in the setting of a P A is a significant risk factor for pulmonary hemorrhage.
The greatest risk factor for NEC is prematurity. Any etiology which leads on to hemodynamic or hypoxic insult predisposes to NEC. PDA is common in preteen infants and it definitely causes hemodynamic stress and is a risk factor for development of NEC. [/INST] question: Preterm baby with PDA, which is the least idly findings? | options: A: CO2 washout B: Bounding pulses C: Pulmonary hemorrhage D: Necrotising enterocolitis | answer: A </s>