Sort of, though not so directly as like doing CPR or anything. My friend in college, hadn't heard from her since a party on Friday night. It was Saturday evening and her parents called me because she had been weird over the phone and they knew something was up. I agreed to check on her, went with my boyfriend to her apartment.

When we got there, she was stumbling, walking into things, slurring her speech, insisting she was still drunk, asking what we were doing there. It was now past 6pm on Saturday and she thought it was still Friday night after the party. I realized half her face wasn't moving and I knew she was having a stroke.

I called an ambulance, and after she went I called her parents; they would have to fly across the country to our school.

The 911 operator and the parametics were skeptical (she was an otherwise mostly healthy 21 year old with some blood sugar problems occasionally), but I was right. It was a stroke. We found out later that she had the stroke in the van on the way home from the party. The driver thought she was drunk, and so did her roommate when she got home. She went to bed and in the morning her roommate left while she was still asleep. The ambulance didn't arrive until almost 16 hours after she had the initial stroke. Doctors told us that if we had been even an hour later, some of the damage could have been irreversible. She also suffered several more, much smaller strokes within the first few hours of being admitted to the hospital. I shudder to think what would have happened if her parents hadn't called, or worse - if we had visited and not recognized the signs or taken her word that she was drunk.

I definitely saved her quality of life, and my actions led to getting her help before her situation become more urgently life-threatening, but luckily the situation was not so dire at the exact moment we found her that I literally saved her life all by myself.