DAVE MONTGOMERY: It's very important to identify a stroke quickly because the longer the brain is without oxygen, the higher the chance of permanent damage. We ask people to remember FAST, F-A-S-T, to spring into action. F stands for Face. Is there anything abnormal about the patient's face? Is their smile drooping? Is their eyelid drooping? A stands for Arms. Ask the person to raise their arms and observe if one of the arms is drooping. S stands for Speech. Listen to the speech carefully. Are they slurring their words? Ask them to repeat a very simple phrase, the grass is green. If they cannot repeat that phrase, the higher chance of stroke. And then T, if you see any of these things, Time is of the essence. Call 911 right away.