A Call To Reconsider The Heimlich Experiment: Let's Scientifically Determine The Best Approach To Choking Victims

What should you do if you encounter someone choking on food?
If you ask someone on an American street  the likely answer will be to “perform a Heimlich maneuver.”
This is understandable because we frequently hear of celebrities performing or having performed on them a Heimlich maneuver and saving or being saved from choking to death. In addition, we have  descriptions of individuals relating their own stories of lives saved.
For example, in May of 2016, 96-year-old Dr. Henry Heimlich, widely credited as the inventor of the eponymous abdominal thrust procedure, made headlines around the world when he reportedly performed it on a fellow retirement home resident in Cincinnati.
Surprisingly, despite the widespread belief that the Heimlich maneuver is the scientifically-affirmed treatment of choice for choking victims, there is only anecdotal evidence for its effectiveness as well as its dangers and there is no scientific consensus on the best approach to a person who is choking or has foreign body airway obstruction (FBAO).

The Origins of The Heimlich maneuver

In 1972,  Heimlich writes in his autobiography “Heimlich’s Maneuvers“,  he came across a NY Times article  which revealed that the sixth leading cause of accidental deaths in the
US  was  choking on a foreign body, usually food ,and that 3900 individuals were dying from foreign body airway obstruction (FBAO) a year.
The typical scenario for these deaths was first described  in a 1963 JAMA report on 9 patients who suddenly collapsed at a dinner table and were subsequently pronounced dead on arrival to the emergency room. Death had been attributed to coronary artery disease but  at autopsy these victims were found  to have food obstructing their airways  (4 by steak, 2 by beef, one by ham and one by kippered herring). The author termed these sudden deaths in resturants “The Cafe’ Coronary.”
In 1972 there was no consensus on how to treat victims of the Cafe’ Coronary and Heimlich noted that the three options were

  1. Inserting a large-caliber hypodermic needle into the trachea or performing a tracheotomy
  2. Utilizing an instrument designed to remove the object from the throat
  3. Slapping choking victims on the back.

Noting the risks of option one, the impracticality of option two and the lack of scientific evidence to support option 3,  Heimlich pondered a better approach, one that would utilize the residual air in the victim’s lungs to forcefully expel the lethal food bolus “like the cork from a Champagne bottle.”

Pop Goes The Cafe’ Coronary

Heimlich first described his  namesake maneuver in an article in Emergency Medicine in June of1974 entitled “Pop Goes The Cafe Coronary.”

Standing behind the victim the rescuer puts both arms around him just above the belt line, allowing head, arms and upper torso to hang forward. Then, grasping his own right wrist with his left hand, the rescuer rapidly and strongly presses into the victim’ abdomen, forcing the diaphragm upward, compressing the lungs and expelling the obstructing bolus

Heimlich states in the 1974 article that the procedure was adapted from “experimental work “with four 38-pound beagles.
Although admitting that these results might not be duplicated in humans, he indicates that “there is certainly no risk in recommending that the procedure be tried in actual cafe’ coronary emergencies.”

“then, as experiences are reported, the method can be evaluated.”

Shockingly, Heimlich, in this article (subsequently picked up and promoted by the lay press) proposed to  all Americans that they begin an experiment on helpless choking victims to see if his newly developed idea was of any benefit.
He requests in the last lines of this monumental communication that Americans help him gather information from the experiment.
“Should you use, or learn of anyone else using, the Heimlich method by the way, please report the results either to EM or me.”

Flimsy Experimental Basis For Heimlich

Four 38 pound beagles-The experimental work supporting an unsupervised, unregulated national experiment on choking victims!
Below is the sum total of the description Heimlich provides for his experiments:

After being given an intravenous anesthetic, each dog was “strangled” with a size 32 cuffed endotracheal tube inserted into the larynx. After the cuff was distended to create total obstruction of the trachea, the animal went into immediate respiratory distress as evidenced by spasmodic, paradoxical respiratory movements of the chest and diaphragm. At this point, with a sudden thrust. I pressed the palm of my hand deeply and firmly into the abdomen of the animal a short distance below the rib cage, thereby pushing upward on the diaphragm. The endotracheal tube popped out of the trachea and, after several labored respirations, the animal began to breathe normally. This procedure was even more effective when the other hand maintained constant pressure on the lower abdomen directing almost all the pressure toward the diaphragm.

We repeated the experiment more than 20 times on each animal with the same excellent results When a bolus of raw hamburger was substituted for the endotracheal tube, it, too, was ejected by the same procedure, always after one or two compressions.

This “experimental work” seems to have been sloppily done and would not have passed muster through a legitimate current day peer-reviewed scientific journal. It seems more like the observations of an 18th century  scientist than a 20th century one.
Here are a few of the red flags I see that suggest either these experiments weren’t really done or that they need to be repeated with better documentation or by an investigator who is unbiased as to the outcome.

  • The beagles are all exactly the same size
  • There are no measurements recorded. Of any kind.
  • Important data was not recorded: What anesthetic was utilized? What was the position of the animals? How long between experiments?. How many “more than 20 times” were the animals choked.? How big was the hamburger bolus?

Flimsy Experimental Work Embellished And Republished

A year later Heimlich was  apparently emboldened by reports of the successful application of his now namesake maneuver and his “special communication” ,published in JAMA, in October of 1975 reiterated his previous publication with a near identical description of the experiments on the four 38 pound beagles.
He added some more details to these experiments. For example, we learn the beagles were anesthetized, with thiamyial sodium given intravenously.
And he embellishes the method for choking the dogs

A cuffed, No. 32 endotracheal tube, the lumen plugged by a rubber stopper, was inserted under direct vision through the mouth into the larynx. The cuff was distended with 3 to 4 ml of air, causing total obstruction of the trachea, simulating a bolus of food caught in the human larynx. The animal immediately went into respiratory distress, as evidenced by spasmodic paradoxical respiratory move- ments of the chest and diaphragm.
At first, the rib cage was manually compressed in an attempt to increase the intrapulmonary pressure and expel the bolus. This procedure was unsuccessful. It was later realized that the compressibility of the lungs by this technique was inadequate due to the rigidity of the chest wall. Furthermore, any increase in intrapleural pressure would be dissipated by depressing the diaphragm.

Apparently realizing that he needed to provide some evidence that his abdominal thrusts were superior to chest compression He added to  his experimental description the following:

At first, the rib cage was manually compressed in an attempt to increase the intrapulmonary pressure and expel the bolus. This procedure was unsuccessful.

And adds a gratuitous explanation for the failure of the chest compression:

It was later realized that the compressibility of the lungs by this technique was inadequate due to the rigidity of the chest wall. Furthermore, any increase in intrapleural pressure would be dissipated by depressing the diaphragm.
Subsequently, I pressed the palm of my hand deeply and firmly upward into the abdomen of the animal a short dis- tance below the rib cage, thereby pushing against the dia- phragm. The endotracheal tube (bolus) popped out of the trachea.

Interestingly, there is no published, peer-reviewed paper verifying the research that Heimlich claims to have done in developing this procedure. And according to his son, Peter M. Heimlich, his father’s archives at a University of Cincinnati medical library include no documentation of the research on the beagles.


The Chest Thrust (Guildner Maneuver): A Superior Approach?

Two years later, Charles W. Guildner, an Everett, Washington anesthesiologist and American Heart Association (AHA) consultant, published the results of experiments he performed on six human volunteers which concluded that chest thrusts were  superior to abdominal thrusts in generating air flow out of the trachea and presumably more effective at clearing foreign bodies obstructing the airway of choking victims. Guildner’s results are supported by  a study by Audun Langhelle of Oslo, Norway, published in 2000 by the journal Resuscitation.
Langhelle compared peak airway pressure with standard chest compressions versus Heimlich maneuvers done by emergency physicians in cadavers with simulated complete airway obstruction in a randomized crossover design.  Mean peak airway pressure was significantly lower with the Heimlich maneuver than with the chest compressions.

Heimlich Markets and Bullies To Gain Prominence For His Maneuver 

Prior to 1976, the guidelines of the AHA and the American Red Cross (ARC)  recommended back blows as the best treatment for responding to a conscious choking victim. After a 1976 National Academy of Science conference on emergency airway management (at which Heimlich was an invited participant), both organizations adopted the following recommendations:

  1. Back blows (4)
  2. Manual thrust (4)
  3. If ineffective repeat back blows and manual thrusts until they are effective or until the victim becomes unresponsive.

Host Johnny Carson demonstrates the Heimlich maneuver on actress Angie Dickenson while Dr. Henry Heimlich watches on April 4, 1979..
For Heimlich, having his maneuver incorporated in US first aid guideliness only two years after he introduced it wasn’t enough. He then embarked on a ten-year media campaign he called “back blows are death blows” in which he accused the AHA and ARC of putting lives at risk because they continued to recommend that treatment.
In 1986, with support from Dr. C. Everett Koop, U.S. Surgeon General under President Ronald Reagan, Heimlich got his way. The AHA removed backblows from its guidelines and endorsed the Heimlich maneuver as the sole approach to the choking victim. The ARC followed suit.
Heimlich’s typical rhetoric on this issue can be found in a July, 1988 NY Times editorial where he extensively quotes Koop’s condemnation of back blows and states:

“The organizations and journals responsible for disseminating this medical error should advise Americans that the back slap, taught for more than a decade as a treatment for choking, causes death.”

Review Of The Literature Finds Abdominal Thrusts and Chest Compressions Equivalent

In 2005, the American Red Cross, after reviewing the scientific literature concluded that back blows, abdominal thrusts, and chest thrusts were equally effective for FBAO.

As a result, the ARC’s 2005 Guidelines for Emergency Care and Education essentially returned to their 1976-1985 recommndation to treat conscious, choking children and adults, now called “the five and five”: first perform 5 back blows; if that fails to remove the obstruction, proceed with 5 abdominal thrusts. If necessary, repeat the cycle.”
Heimlich, ever vigilant of the primacy of his maneuver, condemned this to the Cincinnati Enquirer in a 2013 interview.

Those recommendations “horrify” Heimlich. “There has never been any research saying the back slap saves lives,” he said. “We know the Heimlich maneuver works. So it comes down to a matter of life or death.”

Richard Bradley, MD writing in defense of this change on the Red Cross blog  in 2013 wrote:

A review of the scientific literature suggested that back blows, abdominal thrusts and chest compressions are equally effective. Additionally, the use of more than one method can be more effective to dislodge an object. These findings are consistent with those of international resuscitation societies.
The Red Cross certainly isn’t discounting the use of abdominal thrusts. But we include back blows, abdominal thrusts and chest compressions in our training because there is no clear scientific evidence to say that one technique is more effective than the others when treating a choking victim.
. “Additionally, the use of more than one method can be more effective to dislodge an object. These findings are consistent with those of international resuscitation societies.”

The AHA ‘s 2005  Adult Basic Life Support guidelines were published in Circulation recognizing that there was insufficient evidence to promote the Heimlich maneuver (like the ARC, now referring to it by the generic abdominal thrust) over back slaps or chest thrust

Chest thrusts, back blows/slaps, or abdominal thrusts are effective for relieving FBAO (Foreign Body Airway Obstruction) in conscious adults and children >1 year of age, although injuries have been reported with the abdominal thrust. There is insufficient evidence to determine which should be used first. These techniques should be applied in rapid sequence until the obstruction is relieved; more than one technique may be needed. Unconscious victims should receive CPR. The finger sweep should be used in the unconscious patient with an obstructed airway only if solid material is visible in the airway. There is insufficient evidence for a treatment recommendation for an obese or pregnant patient with FBAO.

Interestingly, the switch in recommendations and the change in terminology were likely influenced by Dr. Heimlich’s son investigative blogger Peter M. Heimlich. Research by Peter and his wife  Karen M. Shulman has  resulted in scores of exposes  in the lay press about what they term Dr. Heimlich’s “wide-ranging unseen history of fraud,” and is documented on their website: http://medfraud.info

The AHA Goes Back To The Heimlich

In 2010, the AHA guidelines revisited foreign body airway obstruction (FBAO) and gave the abdominal thrust priority again “for simplicity in training.”:

Although chest thrusts, back slaps, and abdominal thrusts are feasible and effective for relieving severe FBAO in conscious (responsive) adults and children ≥1 year of age, for simplicity in training it is recommended that abdominal thrusts be applied in rapid sequence until the obstruction is relieved. If abdominal thrusts are not effective, the rescuer may consider chest thrusts. It is important to note that abdominal thrusts are not recommended for infants <1 year of age because thrusts may cause injuries.

The 2015 AHA guidelines did not update  the 2010 FBAO recommendations

Scientific Support For The Heimlich

An abstract presented at the 2012 AHA meetings reviewed the scientific literature to answer the question:

For adults, either conscious or unconscious, with obstructed airway, does any specific resuscitation techniques compared to currently recommended techniques, lead to different outcomes?”

This review found only two studies provided significant evidence to support recommendations

  1. one fair quality LOE 3b study suggests that peak airway pressures developed by chest compressions are significantly higher than the pressure from abdominal thrusts
  2. 2. one poor quality LOE 4 study suggests that for conscious adults with an obstructed airway, abdominal thrusts generate higher peak airway pressures when delivered when the victim is supine as compared to seated and that back blows do not generate any significant change in airway pressure.

The final conclusion of this review:

Clearly, there is a dearth of evidence to support basic life support treatment guidelines for this important problem.


Choking Treatment Recommendation in Australia/New Zealand/UK

In the resuscitation guidelines of medical organizations in Australia and New Zealand, the Heimlich maneuver is warned against as unproven and  to be avoided due to “life-threatening complications” associated with its use. Instead, first aid authorities in those countries recommend first performing a series of backblows followed by, if necessary, a series of chest thrusts, the treatment studied by Guildner (1976) and Langhelle (2000).
The Resucitation Council of the United Kingdom recommends the following for choking victims:

  1. Encourage to cough
  2. Give back blows (up to 5). Support the chest with one hand and lean the victim well forwards so that when the obstructing object is dislodged it comes out of the mouth rather than goes further down the airway.Give five sharp blows between the shoulder blades with the heel of your other hand
  3. Give abdominal thrusts.

Heimlich Maneuver: Time For A Reconsideration 

Thus, it is clear the Heimlich maneuver was recommended by Henry Heimlich for general usage without any human clinical studies to support its safety and efficacy. With Heimlich’s aggressive promoting of the technique it became the recommended way to treat choking conscious individuals despite experimental evidence showing it inferior to chest thrusts and no controlled human trials to support its safety and effectiveness.
Australia and New Zealand, countries free of Heimlich’s influence, do not recommend the Heimlich maneuver for choking victims.
It is entirely possible that chest thrusts are a safer and more effective maneuver for removing foreign bodies from choking victims. Since Dr. Heimlich died in December, 2016 perhaps the organizations that teach CPR can reevaluate their recommendations in this area without fear of public shaming or retribution.
Given the uncertainty in the treatment of choking victims and the number of deaths a national trial comparing chest thrusts versus abdominal thrusts as the initial procedure should be initiated as soon as possible.
Skeptically Yours,
N.B. In Part Two of this analysis of the Heimlich maneuver we will review the evidence of the harm the Heimlich maneuvers have done over the years.


3 thoughts on “A Call To Reconsider The Heimlich Experiment: Let's Scientifically Determine The Best Approach To Choking Victims”

  1. I have no dog (beagle or otherwise) in the fight over what the best approach is for helping choking victims. But I will tell you that the Heimlich maneuver has saved my life three times.
    The first time happened a few years ago at a work bbq. Some of the meat served was of poor quality, containing a great deal of connective tissue. I have always had a tendency to wolf my food – take large mouthfuls and swallow without chewing sufficiently. When the large lump of meat in my mouth proved recalcitrant to my chewing efforts, I tried to swallow it and it stuck in my throat. I was helpless and confused – I had no idea what to do having never experienced this situation before, but fortunately when another person familiar with the Heimlich spotted my distress, he applied it and was immediately successful in dislodging the bolus in my throat.
    The second and third times happened while I was alone at home. You would think after the first time I would have learned my lesson, but I initially attributed that incident primarily to the poor quality of the meat. I have now learned that I can no longer swallow bigs lumps of food safely and must cut things like meat into smaller pieces, put less in my mouth, and chew thoroughly before swallowing.
    But back to these latter two incidents: had I not had the first experience, I would not have known what to do. After that incident, I knew how to interpret the symptoms, and I read up on the Hemlich and learned how to do a self-Heimlich, by pressing my upper abdomen over the back of a chair or the edge of a table, etc. This is what saved me in those cases.
    So my point is that in developing a technique to help choking victims, it is essential to consider the case where the victim is alone and needs to self-apply the technique. And for this situation the technique needs to be simple and easily memorized as the victim will have precious little time before lapsing into unconsciousness.

  2. A similar situation happened to me at a lunch meeting several years ago. While at lunch, I observed an older lady choking on a lodged piece of food that, obviously, was too large to go down. As a result, she started choking and was starting to turn cyanotic.
    I employed the Heimlich maneuver and, lo and behold, out came the piece of food she was trying to swallow.
    Whatever the method chosen to be used, I think it’s a great one if the food/object/etc is dislodged and the individual recovers from the ordeal!
    The Heimlich was the one I was experienced with and it was what worked!
    Were there other techniques that would have worked? Most likely! But, were they used? No, they were not!
    Enough said!

  3. Many years ago I accompanied my son’s nursery school class to a performance of Nutcracker. One of the teachers passed out hard candy to keep the kids quiet. A child two seats down from me suddenly made a strange noise, and I realized he was choking. I grabbed the kid, flipped him upside down and slapped him on the back. The candy fell out, and he was fine. (Yes, I realize this is impractical for choking victims who are too big to easily hold upside down, but it may be reasonable for kids.)


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