Alberta does indeed have a good samaritan law, called the Emergency Medical Aid act.
http://www.canlii.org/en/ab/laws/sta...000-c-e-7.html
Basically, if you provide assistance to someone in an emergent situation you are not liable for hurting or killing them unless it can be proved that you were grossly negligent.
That said, you are not legally required to provide help either, so you can stand there and watch someone die if you like.
There are always things to consider if you find yourself in a situation like this. Blood, saliva, and vomit present a risk of contracting HIV or other diseases, and you could be putting yourself at considerable risk in providing first aid. I would hope that most people would choose to help out if they could, but be smart about it.