What does waking up mean?

I've been talking a lot about "waking him up".  I wasn't completely sure what that meant, though I thought it meant removing him from the respirator.  It doesn't.  At least not entirely.  It's a process, and Ill go through the process now.

The baby is currently on 5 medications.
Tracrium - This keeps the baby from moving around.
Dormicum - This is the sedative, keeps the baby sleeping.
Morphine - Obviously.  Helps Norman fly the friendly skies.
(Similar to Adrenaline) - He was on adrenaline until this morning.  Now they moved him onto something else (forget the name) which helps the heart muscles to pump.
Milk - He is starting to get his mother's milk on a regular basis.
Pishing Meds - The nurse explained that after heart surgery, babies have a hard time urinating on their own.  The baby is on medications to help him pish more.
So now what?  Basically, when they feel all his stats are good, meaning his blood pressure, heart rate, blood test results, o2 sats, temperature and urine are all looking good they will begin to to remove the tracrium medication and allow the baby to move around a little.
If his moving around is looking good, then they will begin the process of the respirator.  They let his lungs breathe a little, and let the respirator breathe a little less.  They play with it enough until they are completely satisfied that he can breathe on his own, and then they remove the respirator.  If i remember correctly, then they will remove the sedation and let him officially wake up.

When he was in post-op he had three tubes in him, they have removed one now.  Progress.

The current status as of right now is that they didn't like his recent blood work, and they ordered an ultrasound for his kidneys.  I asked why, and the nurse explained that it has to do with the output of the kidneys.  So we're ultrasounding now.