The Heimlich maneuver: best technique for saving any choking victim's life. (1990)


Henry J. Heimlich, MD, ScD Edward A. Patrick, MD, PhD

Postgraduate Medicine, 87:6,38-53, May 1, 1990.

Preview
The Heimlich maneuver, introduced in 1974, has been declared "the best rescue technique in any choking situation." Why, then, are backslaps and chest thrusts still being taught? The authors relate the tragic delays by first aid organizations in informing the public about the dangers of these methods and explain why the Heimlich maneuver is the only effective, safe, and scientifically sound procedure for saving the lives of all choking victims.

The Heimlich maneuver has saved thousands of lives since it was introduced 16 years ago.1-9 It has been adopted by the lay public as well as medical authorities throughout the world. However, pockets of resistance exist, and backslaps and chest thrusts continue to be used to treat choking victims, even though these methods have been proven ineffective and have caused deaths.4-16 This article provides scientific and historical facts to justify use of the Heimlich maneuver in treating all choking victims.

How the controversy started
Since 1854, authorities have consistantly warned of the danger of using backslaps in removing foreign bodies in the airway.17-29 Despite these warnings and a lack of scientific evidence supporting the use of backslaps, the American Red Cross (ARC) and the American Heart Association (AHA) for many years taught that backslaps are the treatment of choice for choking.30-35

In June 1974, Heimlich1 first described the use of subdiaphragmatic pressure to save a choking victim's life. Three months later, editors of the Journal of the American Medical Association designated this method the Heimlich maneuver.2

In the following 10 years, the ARC and AHA continued to recommend backslaps as the treatment of choice for choking.36-38 To avoid any association with injuries and death caused by backslaps, Dr. Heimlich denied the ARC and the AHA the use of his name, and they substituted the incorrect terms "abdominal thrust" and "chest thrust."

Finally, in 1985, Surgeon General C. Everett Koop39 issued the following declaration:

Millions of Americans have been taught to treat persons whose airways are obstructed by a foreign body by administering back blows, chest thrusts, and abdominal thrusts. Now they must be advised that these methods are hazardous, even lethal. A back slap can drive a foreign object even deeper into the throat. Chest and abdominal thrusts, because they refer to blows to unspecifed locations on the body, have resulted in cracked ribs and damaged spleens and livers, among other injuries...

The best technique in any choking situation is the Heimlich Maneuver. I urge the American Red Cross, the American Heart Association, and all those who teach first aid to teach only the Heimlich Maneuver. Manuals, posters, and other materials that recommend treating choking victims with slaps and thrusts should be withdrawn from circulation...

The Heimlich Maneuver is safe, effective, and easily mastered by the average person. It can be performed on standing or seated victims and on persons who have fallen to the floor. It can be performed on children and even on oneself.

Surprisingly, the Surgeon General's warning against backslaps,chest thrusts, and abdominal thrusts has never been mentioned or cited by the ARC or the AHA.

The 1985 National Conference on Cardiopulmonary Resuscitation (CPR) and Emergency Cardiac Care (ECC) sponsored by the ARC and AHA, dropped the recommendation for use of backslaps, abdominal thrusts, and chest thrusts for relieving airway obstruction by a foreign body and recommended use of subdiaphragmatic abdominal pressure for choking persons of all ages. As a result, Dr. Heimlich permitted the ARC and the AHA to use the term "Heimlich maneuver," and this term appears in the ARC and AHA standards and guidelines published in 1986.40 However, contrary to the recommendation of the 1985 conference, the ARC and AHA standards and guidelines eliminated the Heimlich maneuver for choking infants under 1 year of age and recommended only back blows and chest thrusts for this age-group.

The 1986 standards and guidelines also recommend use of the Heimlich maneuver to expel water (a foreign body) from a near-drowning victim, with the victim placed in the prone position and the face turned to one side. But, illogically, this procedure is preceded by mouth-to-mouth ventilation, which has proven ineffective while the lungs are flooded with water. Mouth-to-mouth ventilation is not appropriate until the water has been removed. Patrick41 proved the Heimlich maneuver evacuates water and debris from the lungs. The scientific basis for the Heimlich maneuver as the first step in saving near-drowning victims was recently described.42

Controversy over recommendations on choking in infants
At the closing session of the 1985 conference on CPR and ECC, Roger D. White, MD, chairman of the panel on choking, was asked his committee's opinion as to whether the risk of liver laceration in infants may be greater with the "abdominal thrust" (Heimlich maneuver) than with the chest thrust. Dr. White replied, "We felt that we were unable to identify any definite evidence that the abdominal thrust would be any riskier in infants..."43 The panel's opinion was based on the many documented case reports of infants who were saved by the Heimlich maneuver and on the well-established scientific evidence for expelling an object by that method.

Contrary to the findings of the 1985 conference, however, the 1986 standards and guidelines40 express concern for potential intra-abdominal injury resulting from use of the Heimlich maneuver in infants younger than 1 year of age and recommended the combination of back blows and chest thrusts in this age group.

There are absolutely no known scientific data or published reports that chest thrusts or backslaps can help save or have saved a choking infant. In fact, all known published scientific evidence indicates that backslaps and chest thrusts are ineffective, hazardous, and often fatal.5-15

Why chest thrusts should not be used
The technique of chest thrusts has no scientific basis and, along with backslaps and abdominal thrusts, was cited by Surgeon General Koop as being "hazardous, even lethal."39

Chest thrusts produce substantially less effective energy to expel a foreign body from the airway than does the subdiaphragmatic Heimlich maneuver.3-7,12,44 The diaphragm provides more than 80% of respiratory exchange; the intercostal muscles provide only 20%.45 A study at Johns Hopkins Medical Institutions proved that intrathoracic pressure resulting from chest thrusts is dissipated by depression of the diaphragm.46 The effective energy to expel a foreign body is, therefore, significantly diminished.

According to the 1980 standards and guidelines,36 the chest thrust used in CPR and in choking are identical. The vulnerability of an infant's chest makes the complications of chest thrusts particularly ominous. In a review of the medical literature on chest thrusts,44 Heimlich summarized the data47-54 concerning injuries and result in fatalities:

Regardless of considerations as to the effectiveness, chest thrusts were abandoned because of the voluminous literature reporting injuries and deaths resulting from chest thrusts used for cardiopulmonary resuscitation. When one performs a chest thrust, it is impossible to know, especially in the case of a child, at what pressure the chest will be crushed. Reports of injuries following chest thrusts include damaged liver, heart, spleen, and lungs. A most significant report confirming these accidents came from the Mayo Clinic.

Heimlich cited two studies of complications occuring with chest thrusts. In the first, Paaske and associates5254 warned that chest thrusts can cause liver lesions, particularly in children, because their small size makes positioning of the pressure difficult. These investigators reported severe liver damage in a 3-year-old and a 9-year-old. reported an autopsy series of 323 persons who died after receiving CPR. In 90% of the cases, chest thrusts were performed by physicians, and 80% were performed in a hospital. Chest thrusts resulted in rib fractures in 44% of cases (21% being bilateral), and in two thirds these injuries were a significant factor in the clinical course. Sternal fractures occurred in 22% of cases and heart lesions in 13%. A liver lesion occurred in a 13-year-old child. In 17% of cases, the various lesions resulting from chest thrusts were severe enough to be a contributory cause of death. In the second study cited by Heimlich, Thaler and Krause

According to Heimlich's review,44 the ARC and the AHA became aware of crushed-chest injuries following chest thrusts and therefore replaced human subjects with mannequins when teaching CPR. The precordial thump (a thrust on the sternum with the fist), which had been routinely used in CPR, was abandoned following reports that it bruised the heart, resulting in cardiac arrhythmia and death. This injury occured even when the heart had been previously healthy.

Add to these facts the absence of any known report of an infant being saved from choking by chest thrusts, and the need to immediately discontinue such treatment is clear.

Why backslaps should not be used
Despite the Surgeon General's warning39 that backslaps are hazardous, even lethal, the ARC and AHA continue to teach backslaps for use in choking infants younger than 1 year of age.40 Posters and other instructional materials that advocate backslaps have not been withdrawn, and the millions of people who have received instruction in the technique of backslaps have not been informed that this is dangerous and has been recalled. There continue to be reports of the use of backslaps on choking victims who became worse before finally being saved by the Heimlich maneuver. Because of a lack of warning about backslaps, the public is being misdirected.

Backslaps were advocated by the ARC and AHA for many years before and after the introduction of the Heimlich maneuver. Consultants to these organizations55-61 were taken by surprise when the Heimlich maneuver was introduced and persisted in defending the backslap, even though their studies were flawed.55-62 Heimlich8,13-1610 and Hughes,11 among others, reported on a lack of scientific evidence supporting the backslap. Proponents of the backslap blamed the Heimlich maneuver for complications of resuscitation that in fact were caused by CPR and traumatic intubation,47-54,63 unrelated to the Heimlich maneuver.64 continued to stress that there was no scientific evidence to support the backslap and that the ARC and AHA deliberately ignored scientific evidence supporting the Heimlich maneuver. Gibbons

Research supports the Heimlich maneuver
Scientific experiments as well as clinical studies have proved that backslaps are not effective and are dangerous.

PRESSURE-TIME CURVES VERSUS ENERGY MODEL -- A major cause of past and present confusion about backslaps is the erroneous belief that pressure removes a foreign body. In 1975, Gordon55 compared the pressure and flow of airway gas produced in response to backslaps with that produced by the Heimlich maneuver. Typical results are shown as a plot of gas pressure versus time. Gordon presented his findings in 1975 at the National Research Council of the National Academy of Sciences joint meeting with the National Red Cross, and subsequently he and his colleagues distributed them elsewhere.57-62,65 They argued that the pressure curves show a higher peak pressure for backslaps than for the Heimlich maneuver in expelling foreign bodies. Consequently, backslaps continue to be advocated for choking infants65,66 without any scientific justification.

Also at the National Research Council conference in 1975, Patrick67 presented a paper showing the fallacy of Gordon's conclusion that pressure alone removes a foreign body. Citing standard physics principles, Patrick explained that energy is required to remove a foreign body5-7,12,67,68 and that energy results from pressure acting over time. He showed that energy directed to move a foreign body is proportional to the area within the pressure-time curve (for a segment of time concerned). The hatched area under the upward (positive) backslap pulse is negligible compared with the hatched area under the prolonged curve produced by the Heimlich maneuver. Therefore, the energy produced by a backslap is insignificant compared with that produced by the Heimlich maneuver. In fact, the upward (positive) impulse of the backslap (hatched area) produces considerably less energy than the downward (negative) curve (solid area) that follows; thus, the effect of backslap energy is to direct the foreign body toward the lungs, tighter into the airway.

The Heimlich maneuver delivers more than seven times the kinetic energy to a foreign body than does the backslap, and the maneuver always propels the object toward the mouth, away from the lungs (see appendix A). Whatever the type of obstructing foreign body -- food, water, sewage, or seaweed -- the energy model applies. To force the material out of the airway, energy must be delivered with a force vector toward the mouth. The energy model proves that the backslap is ineffective and dangerous, and this conclusion applies to persons of all ages, including infants under 1 year of age.69

Proponents of the backslap do not cite the energy studies by Patrick5-7,12,67,68 and Fink.70 Consequently, Gordon's flawed interpretation of the pressure-time curves has been copied and repeated.56-62 Even the 1985 and 1988 emergency medicine study guides71,72 justify the use of backslaps by indicating that they produce an instantaneous increase in airway gas pressure. Thus, practicing physicians and researchers have been misdirected by flawed research which incorrectly concluded that gas pressure alone removes a foreign body.

OUTCOME ANALYSIS -- Outcome analysis, pioneered by Patrick,68,73 involves using examples (eg, of choking cases) to learn the probability of outcomes for different treatments. Patrick analyzed 1,432 confirmed choking cases,7,9 and his results were verified by William Studden, professor of statistics at Purdue University.74 The results showed that the probability of an undesirable outcome (ie, loss of consciousness or death) was nearly four times higher if backslaps were used before the Heimlich maneuver or in place of it. The calculations and further details are found in appendix B.

AHA DATA -- A 1979 study directed by Redding compared AHA data on backslaps, chest thrusts, and the Heimlich maneuver.59-61 The original AHA data, requested by Purdue University for analysis, were accompanied by a written reply from Royce J. Britton,75 chief of the section on ECC of the AHA, which included the following:

These [AHA] data must be used with extreme care. There [is] no standard methodology or controls, the sample is relatively small, self-selected and probably tends to exclude attempts resulting in death. In addition, we found the data difficult to interpret, particularly when multiple types of treatments were attempted. In such cases, we attributed "success" to the treatments so labeled on the questionnaire, usually the last one attempted. However, one might question whether earlier treatments contributed to the success attributed to the last treatment. All treatments appear to have been employed with some degree of success. Beyond that, the data should be treated as being no more than somewhat suggestive due to the limitations noted above [emphasis added].

Despite the AHA rejection of their own data, supporters of backslaps60,61 continued to refer to Redding's study as evidence that backslaps are superior to the Heimlich maneuver and omitted reference to Patrick's scientific papers.5-7,9,12,67,68

YALE UNIVERSITY SCHOOL OF MEDICINE RESEARCH -- Day and associates76,77 used a body plethysmograph to obtain a graph of pressure curve versus time for simulated airway resistances. Backslaps produced an average peak pressure of 11.5mm Hg with a pulse duration of 0.01 second. The Heimlich maneuver produced an average peak pressure of 21 mm Hg with a pulse duration of 70 seconds. Thus, compared with the Heimlich maneuver, the backslap produces insignificant energy; this confirms Patrick's energy model.

Day and associates76,77 also studied the movement of a ball bearing in a tube. The ball, free to move in the tube, simulates a partial obstruction. In four adult subjects, many backslaps caused either no movement of the ball or movement of only 2 to 3 in. The Heimlich maneuver drove the ball vigorously to the end of the tube. A complete obstruction was simulated with five ball bearings placed in a vertical column in the tube. Backslaps did not lift two balls, while the Heimlich maneuver always vigorously lifted two, three, or four balls.

In addition, Day and associates76,77 used an accelerometer to measure force on a mass simulating airway obstruction with a foreign body. A metal ball was placed above the glottis in a plastic model in the supine position. A backslap did not move the ball, while a gentle blow downward to the shoulder moved the ball toward the mouth. An accelerometer was then taped externally to a volunteer's neck, and with back blows, acceleration toward the lungs was recorded. The investigators postulated that a whiplike movement caused the metal ball to accelerate toward the lungs. These results further confirm Patrick's earlier conclusion that the backslap drives a foreign body toward the lungs.

At the 1985 conference on CPR and ECC, Day76 compared the work of Patrick with that of Redding and the AHA:

Dr Patrick . . . has done what is in my opinion the most carefully done analysis and certainly the largest and best analyzed series of anecdotes. There is another paper by Dr Redding who used data supplied to him, I believe, by the American Heart Association. . . . Redding himself said these data were so sloppily collected that they should not be submitted to computer analysis. My contention is that if you have data that is sloppy then it shouldn't be analyzed. They should not draw a conclusion from it. But a conclusion was drawn. The conclusion was drawn that sometimes back blows work.

This statement by Day and the written statement by Britton75 agree with our assessment of the AHA data. We conclude that the AHA data are not scientifically useful. Yet, these data continue to be used by AHA consultants59-61 to support the use of backslaps over the Heimlich maneuver.

Summary and conclusion
The American Red Cross (ARC) and the American Heart Association (AHA) advocated backslaps, chest thrusts, and abdominal thrusts for 10 years after the Heimlich maneuver was introduced in 1974. Even after the Surgeon General in 1985 declared these methods to be "hazardous, even lethal," the ARC and the AHA continue to recommend backslaps and chest thrusts for infants under 1 year of age. ARC and AHA instructional materials that advocate use of these methods have not been recalled, and the public has not been warned of the dangers.

One cause of the confusion about backslaps is the flawed belief that gas pressure alone removes a foreign body. In addition, there is lack of understanding that compared with the Heimlich maneuver, the backslap produces an insignificant amount of energy required to expel an object from the airway. In fact, the energy produced by the backslap drives the foreign object in the wrong direction, toward the lungs, while the energy produced by the Heimlich maneuver drives the object away from the lungs, toward the mouth.

Backslaps and chest thrusts should be publically recalled as a treatment for choking infants before further deaths and injuries occur. The Heimlich maneuver is the best rescue technique for treating choking victims of all ages.

References
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Historical insights on choking
The first significant work on airway obstruction was A Practical Treatise on Foreign Bodies in the Air Passages, published in 1854, Samuel D. Gross, MD, professor of surgery at the University of Louisville. The book contains a critical analysis of 200 cases selected from the world literature or known personally by Gross. His brilliant description of the insidious nature of the problem was evident in the following remarkable statement:

How many persons have perished, perhaps in an instant and in the midst of a hearty laugh, the recital of amusing anecdote, or the utterance of a funny joke, from the interception at the glottis of a piece of meat, a crumb of bread, a morsel of cheese, or bit of potato, without a suspicion on the part of those around, of the real nature of the case! Many a coroner's inquest has been held on the bodies of the victims of such accidents, and the verdict rendered that they had died by the visitation of God, when the actual cause of death lay quietly and unobserved at the door of the windpipe of the deceased.

Gross urged immediate tracheostomy for airway obstruction or an aspirated foreign body, followed by insertion of an instrument the lining of the trachea, or the use of errhines (medication applied to the nasal membranes to induce sneezing or to cause spasms of coughing) in the hope of expelling the foreign body through the tracheostomy opening or the spae between the vocal cords.

In a number of the cases reported by Gross, the expressions used were repeated verbatim over a century later by choking victims who had been saved by the Heimlich maneuver. For example, a foreign body was ejected with such force that it "flew across the room." Yet, when Heimlich first described his data in 1974, many questioned the validity of patients' descriptions and considered the reports exaggerated.

On the basis of his meticulous analysis, Gross concluded that the victim of an aspirated (or impacted) foreign body should never be inverted, should never be slapped on the back, and should never be finger-probed, because of the risk of increasing the impaction.

More than 100 years after Gross's observations, a study from the renowned Chevalier Jackson Clinic in Philadelphia, 28 based on 6,000 case studies of choking from 1912 through 1973, stated that the rescuer:

The report concluded that "a blow on the back" and an "attempt to remove the foreign body with the finger" can force a foreign body into the larynx.

In 1973, Dr Heimlich began investigations that eventually led to the rescue technique that bears his name. Former US Surgeon General C. Everett Koop, in 1985, declared that the Heimlich maneuver should be the only method used to relieve an airway obstruction by a foreign body. He warned that improvisation could be extremely dangerous or lethal. Dr Heimlich's brilliant insight should put a final perspective on the problem of choking.

Milton H. Uhley, MD