And now to a medical breakthrough tonight in the treatment of asthma, a condition that touches so many american families. Nearly 25 million people suffer from it, more than 2.5 million americans have a severe form, life threatening. A new study out finds a new treatment providing benefits that last years. Abc's chief medical editor dr. Richard besser with the tool that will help save lives. I can't breathe. Reporter: This is what it sounds like. I'm going to die. Reporter: Gasping, wheezing. It's a severe asthma attack. What you are hearing is the struggle to pull air into the lungs. Through airwaves that have spasmed closed. Shyla knows those symptoms all too well. Wearing this mask nearly every day. Wheezing has always been a normal breath sound for me. I've tried every medication. Constantly going to the emergency room with attacks. I was pretty much a hermit. Reporter: Desperate patients and a new solution. A surgical tube with four tiny wires. It's called thermal bronchoplasty. The tube is guided down into the lungs. There, the four wires zap excess muscle from around the air wave. By releasing bursts of heat, about the same temperature as a cup of coffee. It's the only nondrug asthma therapy approved by the fda. Doctors around the country are seeing remarkable results. After the procedure, 78% fewer emergency room visits. Knowing that we have another way to attack asthma and have another tool in our tool box is extremely exciting. Reporter: Here is an airway before the treatment. It's almost entirely closed. And here's one after. This is a one-time treatment and it's very effective and safe. Reporter: Shyla had it done last year. She's still taking some medications, but -- it is a miracle. I never thought there would be a day where I would be able to breathe without, you know, wheezing or having to, you know, stop myself and catch my breath. Reporter: And for karen? No more mask. Breathing easier. Something they'd almost forgotten. Besser is here now. And this gives new hope to people with extreme asthma. And this is the device right here? Reporter: Yeah, it's really incredible. This little wire. They snake it down into your lungs, squeeze the trigger and apply heat and in a few seconds, you're all done. Because the heat is moving the muscle out of the way? Reporter: That's right. No longer a blockage. Air flows very well. But it's not for everybody. It's for the severe patients who don't respond to medicine. It's giving them amazing hope.