What did Henry Heimlich (1920-2016) discover?

A maneuver to help people who are choking on food to dislodge the food so they can breathe again. The maneuver is easiest with another person to help. They get behind the choking victim and put their arms around their abdomen. Then with a fist and the thumb pressed against the victim's belly, they do a thrust in and upward. The pressure of the air in the stomach applies force against the trapped food particle helping propel it out of the throat. Sometimes it takes a few tries. The maneuver can also be done to the self though it is a bit harder. Finding the back of a hard chair the victim can give themselves a Heimlich.

Henry Heimlich also invented a valve to help a person with a collapsed lung breathe.

https://en.wikipedia.org/wiki/Henry_Heimlich