Heimlich. The word is at once terrifying and utterly reassuring. It conjures up fear, flailing, the face turning blue as an olive takes a wrong turn.

At the same time, it speaks of competence, a plan, a scientifically proven method to send that olive sailing right back into its gin. A toast — to Heimlich!

Or, maybe not.

Unbeknownst to most of the public, both the American Heart Association and the American Red Cross have demoted Dr. Henry Heimlich’s famous maneuver. They no longer recommend it as the first treatment for choking victims.

It’s not that the maneuver is considered dangerous, or even ineffective. It’s just that, when faced with someone choking, those organizations want you first to try five old- fashioned back slaps, nice and hard, right between the shoulder blades. Only if those whacks don’t work are you supposed to try five “abdominal thrusts.”

Yes, that’s what they’re called now. Even the name “Heimlich” has been ejected from this maneuver, like a chunk of half-chewed brisket.

“Medicine does change,” the spokesman for the American Red Cross in Greater New York, Mike Virgintino, said. This new protocol, dubbed “Five-and-Five,” was adopted a little more than a year ago, after a review of the scientific literature on choking. “New lessons have been learned,” he said.

What lessons, exactly? Could it be we just spent 20 years doing exactly the wrong thing?

It certainly doesn’t seem that way. Most everyone knows someone who was saved by the Heimlich Maneuver. From Ronald Reagan to Nicole Kidman to, just last month, a boy on Staten Island, folks keep getting that big hug from behind and out flies the angel of death.

There was even that great story about a woman who attended a baseball game up near Buffalo in 1999 and saw an 11-year-old hit in the chest by a bat. He went into cardiac arrest and she saved him with CPR. Then, last year, she was at a restaurant and started choking. The dishwasher ran out and performed the Heimlich Maneuver. He saved her life — just as she had saved his, seven years earlier. It was that early brush with death that had convinced the young man to learn First Aid.

What the Red Cross has learned about First Aid is that, despite all those Heimlich successes, back slaps are every bit as effective — and possibly easier to remember. The last thing the agency wants is for would-be rescuers to waste time wondering which method to try first, so it pretty much arbitrarily ordered the techniques one, two, and three (no. 3 is chest compressions).

What’s weird is that suddenly there are three perfectly acceptable techniques. I grew up with the belief that back slaps were verboten — the First Aid equivalent of bonking a drowning man on the head with a cement life preserver. No, an American Red Cross spokeswoman, Pamela King, said: Back slaps were always part of the protocol — in Europe.

Choke me with a foie gras sandwich. They were? Then how’d they get such a bad rap over here?

Their infamy seems to have been promoted by the guy whose name was not back slap. The guy whose name was (and still is — he’s 87) Heimlich.

Back blows are “death blows,” Dr. Heimlich declared long and loud as he lobbied for his maneuver’s acceptance 30 years ago. In 1985, Surgeon General C. Everett Koop endorsed this view, dubbing backslaps “hazardous.” After that, only the Heimlich Maneuver was considered kosher.

What most people don’t realize, Dr. Heimlich’s son, Peter Heimlich, said, is that “Koop was an old friend of my father’s, and he did it as a buddy favor.”

Now, truth be told, son Peter spends a lot of his time contacting journalists about his father’s alleged transgressions. But it is also true that back slaps have come back from First Aid purgatory.

For his part, Dr. Heimlich still believes backslaps are “bad therapy,” his spokesman, Bob Kraft, said.

What a pickle. Here in New York, the health department is considering the new guidelines and may eventually replace the disturbing fish-bone posters (which themselves replaced the more disturbing choking person posters). The Red Cross, meanwhile, is trying to get the word out through press releases and educational seminars.

Until then, people will probably keep using Heimlich. Whether that means the doctor himself deserves a pat on the back — or a slap — is up the air.

And with any luck, so is the olive.