Heimlich maneuver

Abdominal thrusts, also known as the Heimlich Maneuver (after Henry Heimlich, who first described the procedure in a June 1974 informal article entitled "Pop Goes the Cafe Coronary", published in the journal Emergency Medicine). Edward A. Patrick, MD, PhD, an associate of Heimlich, has claimed to be the uncredited co-developer of the procedure. Heimlich has objected to the name "abdominal thrusts" on the grounds that the vagueness of the term "abdomen" could cause the rescuer to exert force at the wrong site.

Performing abdominal thrusts involves a rescuer standing behind a patient and using their hands to exert pressure on the bottom of the diaphragm. This compresses the lungs and exerts pressure on any object lodged in the trachea, hopefully expelling it. This amounts to an artificial cough.

Due to the forceful nature of the procedure, even when done correctly it can injure the person on whom it is performed. Bruising to the abdomen is highly likely and more serious injuries can occur, including fracture of the xiphoid process or ribs.
Source: http://en.wikipedia.org/wiki/Heimlich_maneuver#Abdominal_thrusts