Watching the public rush to aid victims in the aftermath of the Boston Marathon bombings, I took the best action I could from the safety of my couch: I Googled “how to tie a tourniquet.”

As it turns out, a tourniquet fashioned by a bystander like myself could do more harm than good. However, there are some highly effective—and downright simple—ways regular people can provide a lifeline in a medical crisis, be it at home or in public. We asked a panel of Denver-based ER docs what we should all know, just in case.

Stop Uncontrolled Bleeding

FA1Whether it’s a mass casualty incident like a bomb explosion or a simple household accident, controlling bleeding doesn’t require a medical degree; all it takes is two hands. Find the source of the bleeding, grab a piece of cloth (or not), and press down hard, with your entire body weight. If the victim tells you it hurts, you’re doing it right. With enough pressure, the bleeding should stop.

» With a puncture wound or any kind of impalement (like a tree branch in the gut), leave the implement in place until EMS arrives.

» When broken bones are the cause of blood loss, stabilize the wound. “Don’t try to straighten the break because that could cause more bleeding,” says Dr. Mischa Haroutunian, an emergency physician at Saint Joseph Hospital.

» If you’ve cut yourself slicing potatoes for dinner and you’re wondering if you need stitches, here’s how to know. Go to the ER if: it’s a gaping wound or it won’t stop bleeding after 15 minutes of direct pressure.

Use CPR and AED for Sudden Cardiac Arrest

FA2Colorado has Good Samaritan laws that protect bystanders providing CPR or using an automated external defibrillator (AED) from civil lawsuits. Besides, “if they don’t have a pulse, you can’t hurt them,” says Dr. Dylan Luyten, associate medical director for the emergency department at Swedish Medical Center and EMS medical director for HealthOne.

» CPR: If a victim is nonresponsive and without a pulse, kneel over him and begin delivering two-handed compressions to the breastbone—push hard, as fast as you can. Mouth-to-mouth breathing isn’t necessary. With immediate CPR, chances of surviving sudden cardiac arrest triple, and there’s very little downside to trying.

» AED: If you’re in a public building, like an airport, chances are it has an AED. Doctors say this device couldn’t be easier to operate, mostly because it’s made to be used by the untrained. If necessary, turn the machine on and listen for the audio instructions. The internal computer will determine if the current is needed and, if so, how much to deliver. Then proceed, just like on TV.

Recognize symptoms of a Stroke

FA3The most important tool set for helping a stroke victim is the ability to spot the signs and use the telephone to call 911. Quick administration of medication by health-care professionals can impact a patient’s outcome. A recent study found that stroke victims who received clot-busting drugs within three hours of symptom onset were less likely to experience permanent disability.

» Know the signs. The acronym to remember is FAST:

Face—Is one side drooping?

Arms—Can the patient raise his arms normally or is one dropping downward?

Speech—Is the patient slurring his words or unable to speak?

Time—If you observe any of these signs, call 911 immediately.

Should I Help?

When faced with a medical emergency, push aside your fears and step in. Bystanders often waste precious minutes looking for someone else to help. Call 911, and then get busy.

“Don’t assume someone else is more qualified to help than you are,” says Dr. Whitney Barrett, an ER doc and assistant professor at the University of Colorado Hospital. “Sometimes just being the closest person to an injury makes you the most qualified.”