"Mommy, why do I have to take sildenafil three times a day?"
Because, honey, it helps to lower the pressure in your pulmonary arteries--the vessels that bring blood from your heart to your lungs.
She stops and thinks, not quite grasping it, so I ask: Do you know what pressure is, DQ?
I gently poke her arm and ask: Do you feel that? That is light pressure.
I then pressed harder: That is harder pressure.
Now, I want you to think about the hose you use for your sprinkler. When the water is off, it lays there and you can squeeze it right?
But when we turn on the water, the hose gets hard.
It is the pressure from the water pushing on the hose that makes it hard.
I pressed on her arm again.
The same thing happens in your arteries that carry blood to your lungs. They are very small, but your body is so big that you still need a lot of blood to keep your body going. All of that blood needs oxygen. So as your heart tries to push all that blood to your lungs through the small arteries, the pressure gets really hard.
I let that sink in for a moment, then press on her arm again (not hard, but enough that it could be felt).
What would happen if I pressed on your arm with this pressure for a long time?
"It would hurt me, Mommy. I would have a booboo."
Yes. What would happen in your lungs if we let the high pressure in your arteries continue?
"I would have booboos inside."
Yes, honey, you would. Sildenafil helps to lower the pressure and that is why you have to take it three times a day.
She didn't say much else, but from the look of her face, my Dancing Queen understood what I was saying. My sweet little 6 year old lost a little more of her innocence.