Bern Zumpano, M.D.- http://www.walkinginpower.org/books/spiritual_warfare_prayers.pdf -
PRAYER FOR SALVATION OF A DYING PERSON IN COMA
"I had occasion to meet...an Evangelist from India. He had told me a story of a study that he had done with a medical school professor who was a cardiologist or heart specialist. They had evaluated a series of, I believe, 39 patients who had heart problems and who were being resuscitated for cardiac arrest. During resuscitation, the Evangelist would lean over & call the person’s name, whispering and speaking in a low voice into the person’s ear on the belief that the person’s soul & spirit could still hear even though the body was unconscious due to brain coma. He told them to call upon the Name of Jesus, letting go of all unforgiveness toward those who hurt them & to repent of sin, & to keep calling the Name of Jesus. Surprisingly, some 19 patients were successfully resuscitated...
Later they were interviewed by the Cardiologist & the Evangelist. They were asked if they could recall what was going on during the resuscitation. All but 4 could recall separating from their body during the death experience and being pulled down into the ground. They said that they could not help themselves, nor could they resist.  They were able to hear the Evangelist’s voice commanding them to call the Name of Christ Jesus and to repent of sin and unforgiveness. Every person who did this reported that upon immediately cooperating, they felt an immediate pull in the upward direction, which continued in the upward direction. They, thereafter, found themselves in their physical bodies. The scripture says that all that call upon the Name of the Lord shall be saved. Since that time, I have made it a practice to pray over unconscious people no matter what the source of their problem is. Simply lean over the person’s ear and speak something like this in a normal voice:
'Satan, I bind you, the ruler spirits, & all spirits not of the Holy Spirit from (name of person) in the Name of Christ Jesus. I bind, and loose (disconnect) from (name of person) all of your opposition, hindrance, interference, & obstructions.
I curse & destroy your works in (name of person) & render them of no effect...all in Christ Jesus’ Name.'
'(Person's Name), in Christ Jesus’ Name I ask you to call the Name of Christ Jesus, right now in your thoughts and in your spirit, & tell Him that you are sorry for all of your sins & ask Him to forgive you.
Let go of any unforgiveness towards anyone & ask Jesus to forgive you for it. Ask Jesus to save you & He will, for the asking. Call the Name of Christ Jesus. Call the Name of Christ Jesus. Call the Name of Christ Jesus.
Tell Him that you are sorry for all of your sins. Call the Name of Christ Jesus to save you.'
When we stand-in-the-gap for a person in a coma, believing that we have received for him, we believe that someday, at home in glory with the Lord, we will meet that person face-to-face.
This is the kind of faith God asks of us.’’  (This last sentence is often prayed from a Catholic perspective.)

#199) Kat Kerr - Tell My People I Have Keys  source -
Shouts of Grace Church 4-24-2011 AM - http://www.christianforums.com/threads/kat-kerr-powerful-testimonies-of-heaven.7709517/page-8 - Alive_Again,  Dec 23, 2012
“There are too many testimonies, where people were dying & descending into Hell, & Christ caught them & said, ‘This person is praying for you. I have to give you a chance.’  He said, ‘Tell My people. I have keys.
I go into Hell when I want to, beyond the grave when I want to, & even at death if I want to.
My Word if you make a stand & you stand there for.  It says, If you abide in Me & My Words abide in you, you shall ask what you will, & it shall be done unto you.’ 
You make a stand in faith for your family members salvation.  The Word says, Your & your household MIGHT be saved? (NO.)  It says, Will be saved!  So if you’re standing for your family members salvation, guess what happens? God said there will be many people you’d thought would never make it to Heaven.
Even if they’re in comas, their spirit is awake.
He can go in the spirit to them, while they’re in a coma & speak to them.
If you’re with somebody in the hospital & they’re in that (coma), you preach the gospel to them. Their spirit can hear it. Because He has the keys.
He said, ‘They’re not hanging on some pretty hook in Heaven.’
He said, ‘I have them. They’re Mine. I paid a price, & I use them when I want to.’
So that’s some new revelation for you.
Why do you think He got the keys? He uses them, BUT He needs your words.
Your words produce power & weapons for Him to use against the enemy.
But He walked over to Satan after defeating all of the hierarchy. He stripped everything off of him, & 1 by 1, plucked those gemstones off of his being.  He (Satan) laid there in absolute, utter defeat.
Then He ascended back up through the tomb.  The stone was rolled away (from all our hindrances)."
Revealing Heaven on TN Radio (Kat Kerr) 1/2/2015 @  http://jesusstories.info
The human spirit and the soul are awake 24/7 & can choose/receive Jesus as saviour/healer when the body is in a coma.  (Thus, one can play hymns, read scripture, etc. & spirit/soul will hear that.)
Kerr, Kat - Throne Room Declarations - 2009 - www.revealingheaven.org
If any 1 person is standing the gap, God will honor His spoken word & not let it fall to the ground.
The individual (even if he is in a coma) is allowed a 2nd chance to choose Jesus as saviour.