There's thousands of "must-have" apps on the market, but there’s one that really is changing lives. In fact, it's helping save them.

One September day, Dr. Matt Gittinger was relaxing with his computer and a cup of coffee in his Queen Anne home. It was his day off from the emergency department at Harborview

“Only difference was I was in pajamas instead of nicer clothes,” said Dr. Gittinger. “And I heard a random noise from my cell phone that I had never heard before, actually.”

The noise was Pulse Point – a phone app that notifies people when CPR is needed in a nearby public place. Those who are trained in CPR, and have downloaded the app, are alerted when medics are dispatched to an emergency in their immediate area.

“It was the first time I'd ever heard it, looked down and the location was just a couple blocks down the street, down the hill here,” said Dr. Gittinger. “I told my wife I was going to be going, took off and started running.”

Down several sets of stairs, on the side of busy Aurora Avenue, Doug Stine was in cardiac arrest.

His colleagues had pulled over and were trying to help him after he'd collapsed in their work truck. When they called 9-1-1, dispatchers activated Pulse Point, and here came an emergency department doctor to the rescue.

“[I] Basically was doing compressions right here, on the side of the hill,” said Dr. Gittinger.

Medics arrived and took over. Dr. Gittinger hopped in the ambulance and went along to Harborview.

“A couple of my colleagues looked at me and said ‘What are you doing here?’” said Dr. Gittinger. “And ‘Why are you wearing shorts and a t-shirt in the middle of the day with your hair looking like that?’”

But Dr. Gittinger's patient has no complaints.

“For him to take time out of his busy schedule to help somebody else, that's amazing,” said Stine.

After a few days in the hospital, and a defibrillator implanted in his chest, Doug Stine got to go home, with no damage other than sore ribs.

“If we can get people to start CPR before the fire department or medics can get there, that's an extra minute, two, three minutes of time, that blood is circulating and infusing somebody's brain,” said Dr. Gittinger. “I think it’s absolutely great technology and I really encourage anybody that has been formally trained in CPR to get the app.”

Both men are big believers in the power of Pulse Point.

“Today's my 13th wedding anniversary,” said Stine. “I'm able to spend time with my children and my nieces and nephews and see them grow up.”

This grateful family man is alive and well thanks to a phone app and expert care from a hero in pajamas.

The Red Cross of King County honored Dr. Gittinger as a hero for his actions.