If choking is severe, you should begin by using the Heimlich maneuver, instructs the Mayo Clinic. The Red Cross also recommends a technique involving sharp blows to the back, but it is acceptable to use the Heimlich maneuver alone. If the patient falls unconscious, stop attempting the Heimlich maneuver, and lower the patient to the ground to begin CPR. If the blockage does not clear, call 911, and attempt the steps again.
To perform the Heimlich maneuver, stand behind the choking person, placing your arms around his waist and bending him forward, clenching one fist directly above his belly button, putting the other hand on top of the first, and pulling both arms sharply inward and upward at his stomach. Repeat this thrusting motion five times in a row before checking the choking person's airway again, according to the Mayo Clinic. In the event that the patient is pregnant or obese, it is necessary to move your arms up from the stomach to just above the lowest ribs.
If the patient is an infant younger than 1 year old, place him face down on the forearm, resting on the thigh, suggests the Mayo Clinic. From there, you should push firmly but gently on the middle of the back with the heel of your hand. If this does not dislodge the blockage, turn the infant face up and place two fingers on the infant's breastbone, giving five quick chest compressions. If the blockage clears but the infant does not resume breathing, begin infant CPR.
The Mayo Clinic recommends that you prepare for these situations by learning the Heimlich maneuver and CPR in a certified first-aid training course.