Question

In utero, a fetus's Pulmonary Vascular Resistance (PVR) is higher than it's Systemic Vascular Resistance (SVR) because the lungs are not inflated and the pulmonary capillary bed is collapsed and constricted. Normally, after birth with the onset of lung inflation, a newborn infant's PVR decreases. Persistent Pulmonary Hypertension of the Newborn (PPHN) occurs when, after birth, a newborn infant's PVR remains equal to or higher than it's SVR.

A 5 day old infant who is experiencing PPHN also has the defect identified by the asterisk * in the picture below.

Based on this information, select all of the following that are true about the pathophysiology of the infant's condition. You may select more than one answer.

SCV = Superior Vena Cava, Ao = Aorta, PT = Pulmonary Artery Trunk, RPA = Right Pulmonary Artery, LPA = Left Pulmonary Artery

a. Administering supplemental oxygen may worsen the pulmonary hypertension

b. The patient will have pulmonary edema due to pulmonary over-circulation

c. Blood flow may shunt right to left causing hypoxemia

Answer 1

Persistent pulmonary Hypertension in newborn infant is a syndrome characterised by sustained elevation of pulmonary vascular resistance associated with normal or low systemic vascular resistance.

*This abnormal process will leads to extra pulmonary shunting from right to left across patent ductus arteriosus,patent ductus arteriosus and patent foramen ovale and aross the patent foramen ovale.This shunting will results in mixing up of oxygenated and deoxygenated blood results in hypoxemia.

*Due to persistent pulmonary hypertension of newborn the blood is forced away from the lungs due to the high-blood pressure in the arteries that go to the lungs.Due to the shunting in the patent ductus arteriosus and patent foramen ovale resulting in pulmonary over circulation and the net effect is pulmonary oedema.

*In case of persistent pulmonary Hypertension there is a increased or elevation of pulmonary vascular resistance in the infants.our main goal is to reduce the resistance of the arteries relax the arteries by administering supplemental oxygen to the infant.This will promote the pulmonary vascular relaxation.The main physiology behind the administration of supplemental oxygen is to improve the oxygen levels in the blood,thus relax the blood levels in the lungs and maintain a normal blood pressure of the infant.

Here we can say that the pathophysiology of Persistent Pulmonary hypertension for the infant are option 'b' and option 'c'