JEAN CARPERS'S Outlook article of April 22, "Beware the Back Slap If You're Choking to Death," is a good summary of Dr. Henry Heimlich's concerns about emergency care of the victim of airway obstruction. Her questions are well taken and deserve reply.

The method by which emergency care recommendations are made to the public is important, so the American Red Cross depends on an independent scientific review group assembled by the National Academy of Sciences.

One concern that scientists have is the diagnosis of choking. We know that certain presentations of convulsive disorders, stroke, heart attack or low blood sugar may appear to be choking to the onlooker, yet each of these conditions will not respond favorably to the Heimlich maneuver and requires other emergency techniques. For these and similar reasons, the National Academy of Sciences has chosen to recommend general emergency care princiles that are applicable to a wide variety of potentially lethal situations. The possibility always exists for missed or mistaken diagnosis. For this reason the method for dealing with the obstructed airway includes not only attempting to clear the airway but also head tilt methods for opening an airway, back blows, Heimlich abdominal thrusts, finger sweeps, methods for dealing with foreign objects and finally mouth-to-mouth ventilation.

To evaluate methods and compare them it may be necessary to use animal models. This Dr. Heimlich did in his beagle dogs and more recently Dr. Archer Gordon, UCLA Medical School, did in baboons. Although neither model is necessarily applicable to the human, the more expensive baboon was chosen because its airway, mechanics of breathing, etc., more closely represent the human than the dog. These experiments in the baboon indicated that for the smaller food object stuck in the airway, the Heimlich maneuver did successfully work, as did lower chest compression, back blows and the typical closed chest compression of cardiopulmonary resuscitation. For large objects, particularly meat, although the Heimlich maneuver is probably the most effective single technique, it was shown conclusively that the combination of back blows, Heimlich maneuver and finger sweeps was more effective than any single technique used exclusively.

To evaluate any of the available methods of treatment, one needs to know a number of things. If there are 2,000 to 4,000 food choking deaths annually in the United States, as is commonly reported, how many nonlethal choking attacks are there? We have reason to believe that there is a high proportion of nonlethal attacks which result in coughing and choking. If for every 50 or 100 attacks there is one death and if we apply any maneuver to the rest, we will obtain an inordinately high "save" rate.

We need to know the cases in which the Heimlich maneuver was apparently unsuccessful. Were these choking incidents, and, if so, involving large meat objects? Or were these other medical emergencies for which the Heimlich maneuver is inappropriate and ineffective?

Finally, we need to carefully examine the cases in which damage was done to the victim by well-meaning rescuers: those cases in which ribs were broken, or organs ruptured or other unfortunate sequels.

The Heimlich maneuver has been incorporated into the National Academy of Sciences' sequence of emergency maneuvers. There are no controlled studies, as yet, on the use of this sequenced method versus the Heimlich maneuver alone. Such studies would require careful protocols that take into account eyewitness accounts of how the situation developed and what was done, including time parameters and apparent and long-term results.

The burden of proof is on the proponent, not the cautious critic. We need more than testimonial letters. We need data. Let Dr. Heimlich set up such a study, monitor the results and report them in a refereed medical journal. This is one of the most accepted ways by which scientific questions should be answered - not by a popularity poll or vote.