Stabbed in the back

In my current WIP I have a scene where a man falls backwards into a chair in which a broken mirror had been placed; a large shard of glass stabs him in the back. I intend it to be fatal.

Would he have time to register shock? Would he have time to scream, or even grimace? Would he start spitting up blood?

I can think of a movie scene where someone was killed by a jagged piece of glass in a falling window sash, but the afterlife was a main plot theme and we see his reaction after he's dead.

In the scene, a mirror is placed in a chair in a dimly lit room and the person shoots it. He's then disarmed and tossed into the chair by the person he thought he had shot.

Later, he gets up and a large shard of glass that was in the mirror frame falls forward, so it's at about a forty-five degree angle. Then he's tossed back into the chair.

I'm picturing a piece of glass that's angled, sharp, and about eight inches wide at the base.