Trapped mountaineer records video before facing choice of cutting own arm off or death

Mountaineer Aron Ralston was forced to make a life-changing decision during his solo expedition of the Bluejohn Canyon in southeastern Utah in 2003.

Aged just 27 at the time, his arm became trapped after a boulder pinned his right wrist to the side of the canyon wall.

He was then faced with the horrifying choice of cutting his arm off or to die without intervention.

Watch below:

The American spent five days sipping his small amount of remaining water along with slowly eating his two burritos, all while repeatedly trying to slip out his arm.

Despite three days of trying to remove the boulder (360kg), Ralston made the call to amputate the mid section of his forearm to escape.

After implementing tourniquets and superficial cuts to his forearm, on the fourth day, he realised that he didn't really have the tools available to do so.

On day five he ran out of food and began to drink his own urine.

He then carved his name, date of birth and presumed date of death into the sandstone canyon wall, and videotaped his last goodbyes to his family.

"It's 3:05 on Sunday. This marks my 24-hour mark of being stuck in Blue John Canyon. My name is Aron Ralston," he said in the video.

Ralston said goodbye to his family. (NBC)

"My parents are Donna and Larry Ralston, of Englewood, Colorado. Whoever finds this, please make an attempt to get this to them. Be sure of it. I would appreciate it."

However, all of a sudden, he began hallucinating and had a vision of himself playing with a future child while missing part of his right arm.

Ralston said this gave him the belief that he would make it.

Living to tell the tale, he explained: "I said to myself, 'Here we go, Aron. You're in it now,' and I took my knife.

"At first I still had the larger blade out and I held it up against my arm and started pushing into it.

"I couldn't get the knife to sink in, so I switched over and pulled out the smaller blade. With the smaller blade I started the amputation because the smaller blade was still sharp."

Ralston cut through the top later of skin and saw an artery, at which point he realised he hadn't attached the tourniquet that he'd made from the insulated lining of his water bottle.

"I put the tourniquet on and I was bleeding down the wall and I severed the artery," he recalled.

Ralston lived to tell the story. (Mark Davis/WireImage)

"I took the pliers side of the knife and used that to twist and rip until the tendon gave way."

This continued for about an hour until he got to the nerve, which he knew would be the most painful part of the amputation.

He told the camera: "I was looking at the nerve, this little strand of spaghetti running through my arm and I had to take the knife.

"I felt the fire... like sticking my arm into a pot of liquid metal.

He had to cut into it again and this time the fire sensation redoubled and went all the way up to his shoulder. However, once he'd cut through it, that was it and he was free.

He was rescued four hours after amputating his arm.

The story of Aron Ralston, was the real-life inspiration behind 2010 movie 127 Hours.