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Correspondence The Need for Scientific Validation of Chest Thrust Data

To the Editor:

"Airway Obstructed by Foreign Material: The Heim- lich Maneuver," by Guildner et al (JACEP, September 1976) has l i t t l e scient if ic va lue in its p resen t form. Moreover, it has been used as a basis for recommending confusing and potential ly dangerous therapy for choking. These questions need to be answered:

1) With what degree of assurance can resul ts from volunteers a n e s t h e t i z e d w i th h a l o t h a n e , i n t u b a t e d , hypervent i la ted, and at f unc t i ona l r e s idua l capac i ty (FRC) be extrapolated to recommend therapy for victims of choking?

2) Isn ' t it expected from a considerat ion of the basic mechanics of breathing, tha t ches t ' th rus t s in a relaxed patient at FRC would be more efficient than abdominal thrusts? What results did they obta in at other lung vol- umes? Do they suggest tha t people choke only at FRC?

3) Does the enormous range of the results (eg, 90 to 920 cc were expressed from the chest with abdomina l thrusts in the s i t t ing position) indicate unacceptable var- iahility in the application of the th rus t or errors of meas- urement?

4) Were the abdominal thrus ts applied in the m a n n e r presently recommended by Heimlich, or were they given as a "squeeze with one hand grasping the wrist of the other" as the authors indicated in another communica- tion of the same results? 1

51 Would the biostat is t ician who helped with the ex- perimental design indicate how subject and exper imenter bias can be el iminated? Is the sample size adequate (six, or in some cases, four volunteers)? How m a n y thrus t s were given in each position? What was the var iabi l i ty of the results obtained by each rescuer? With data of such an enormous range, can "mean results" differing by such relatively small amounts be statistically signif icant - - as implied by the authors in their summary - - and what are the numer ica l values of this s tat is t ical significance?

6) As the authors realize (Hughes T: Computer ized Analysis of Dr. Henry J. Heimlich's Data on 536 Case Reports of the Application of the Heimlich Maneuver , written communicat ion to C. W. Guildner, July, 1976), there are over 400 people, inc lud ing many physicians, nurses, and paramedical personnel, who claim to have saved lives by the application of the Heimlich maneuve r Without cardiopulmonary resuscitat ion. The authors a s ~ sert, "We feel the e m e r g e n c y m a n a g e m e n t of an obstructed airway due to foreign mater ia l should not be

• thought of as an isolated technique, bu t ra ther should be integrated into the basic l ife-support conc.epts of car-

diopulmonary resuscitat ion." By this, do they mean tha t the public should not be t augh t the Heimlich m a n e u v e r unt i l they have learned basic cardiopulmonary resuscita- t ion (CPR)?

7) There is no discussion of the possible dangers of the chest thrust .

8) Why are four th rus t s (not the eight suggested by the American Nat ional Red Cross) recommended by the au- thors? When the vict im is horizontal, is the chest th rus t to be applied with the victim on his side with the rescuer lying behind him as in these experiments? Of what use is the abdominal t h rus t if, as the authors suggest, the chest thrus t is superior?

9) Are there e th ica l or medicolegal impl ica t ions of h u m a n exper imenta t ion of this na ture? Did a committee on h u m a n e xpe r i me n t a t i on consider tha t the r isks of these exper iments were justif ied?

Perhaps the chest t h rus t is more efficient t han the ab- dominal t h rus t in c lear ing obs t ruct ion due to food or foreign body. However, this paper in its present form does not establish this point and certainly should not be offered as the basis for recommending therapy for chok- ing. Since h u m a n exper imenta t ion on choking is difficult to perform, the present paper will be an extremely impor- t a n t con t r ibu t ion if, and only if, the quest ions raised above are answered to the satisfaction of accepted medi- cal and scientific s tandards . Without doubt, the authors have a responsibi l i ty to clarify the confusion resu l t ing from their good in tent ions .

Trevor Hughes, MB, ChB University of North Carolina Chapel Hill, North Carolina

REFERENCES

1. Guildner CW, Williams D, Subitch T: Airway obstructed by foreign material, emergency management, Exhibit E2, ANRC Conference on Emergency Relief of Airway Obstruction (Heim- lich Maneuver), October 27, 1975~ Washington, DC.

Chest Thrust and Heimlich Maneuver Need Further Study

To the Editor:

Emergency depar tment personnel rarely see the totally obstructed airway since this is a self-triaging lesion. But as more and more depar tments become involved in telem- etry and more efficient ambulance services deliver pa- t ients sooner, the emergency physician will encounter more of these problems_

The Heimlich maneuve r has signif icantly improved the field a r m a m e n t a r i u m in deal ing with this problem. It is

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easy to teach, has already been proven effective in a goodly n u m b e r of cases, but, as yet, has been unable to m a k e its way in to official r e c o m m e n d a t i o n s of the American Heart Association. 1

Gui ldner et al (JACEP, September 1976) have now recommended a modification of this maneuver . But, be- fore everyone changes technique, there are several ob- servations to be made. First, the experiment was carried out on only a small number of young heal thy subjects, none of whom had an airway obstruction. Second, it is not known whether sufficient pressures could be gener- ated in the emphysematous chest wall. Third, in field use, careful screening would have to be carried out to find the complication rate of broken ribs and possible sequelae. Approximately 30% of pat ients receiving CPR will sus ta in broken ribs and the technique recommended by Gui ldner et al may have this potential as well.

F ina l ly , the field worker as well as the emergency physician mus t be equipped with other techniques such as su rg ica l i n t r a c a t h e t e r c r i co thyro tomy should the obstruction persist.

Peter Rosen, MD

REFERENCES

1. Standards for cardiopulmonary resuscitation (CPR) and emergency cardiac care (ECC), American Heart Association - - Academy of Science - - National Research Council. JAMA 227:833-868, 1974.

Author's Reply

The American Hear t Association reference ment ioned by Dr. Rosen was published five months befbre Heimlich published his first description of the maneuver .

The Amer ican Hear t Association has acknowledged "the abdomina l thrus t" in their First Aid for Foreign Body Obstruction of the Airway, published in 1976. Dr. Heimlich has requested that his name not be used in connection with American Heart Association descriptive and teaching materials .

All of the maneuvers as described should be submit ted to careful ongoing study. The possible complications of all these procedures will evidence themselves as more expe- rience is gained_

Charles W. Guildner, MD Everett, Washington

need for breath interposit ion between cardiac compres. sion, early in tuba t ion is purported to pre~ent gastric as. pirat ion and inflation. 2 Two techniques for endotrach%l vent i la t ion have emerged.

Endo t r achea l i n t uba t i on , f ami l i a r in the operatiag room, has been used successfully by t ra ined paramedics since its conception. 1 The use of the esophageal oh. tura tor airway to obstruct the esophagus and ventilate the lungs, since first described in 1968, ~ has been e×te~. sively used by paramedics for the same purpose. Whih both methods have proponents, there is a lack of scion. t ific da ta t h a t c r i t i c a l l y a n a l y z e s the methods and evaluates them.

As the endotracheal route is uncri t ical ly accepted as ideal based on its use in the operat ing room, the sole at. guments agains t it have been directed at adequacy and f e a s i b i l i t y of t r a i n i n g a n d m a i n t a i n i n g sk i l l s 0~ paramedics, medical, and other personnel who use it. No data has been collected on the percentages of failure, delay in insert ion, inadver ten t esophageal entry, lung collapse and t r a u m a following its use in the field. Ac. complishing endotracheal en t ry may boost the ego of the operator, which may be counterproductive. Recent data 3 support the safety of the esophageal obturator airway in 29,000 insert ions al though a few instances of esophageal rupture 4 have been reported.

Complications following the use of any adjunct tend to reach the medical l i tera ture too readily and obfuscate the scientific evaluat ion of a procedure. The number of pa- t i en ts who have been successfully resusci ta ted under similar conditions by either or both procedures is not re- ported in relat ion to complications encountered. Data on insert ion time, incidence of false entry, inabi l i ty to intu- bate by ei ther route are largely anecdotal. The advan- tages of in tuba t ion over mouth- to-mouth resuscitation is stated as fact without figures. Equal ly vague and anec- dotal is the information available on the management of foreign body obstruction.

It is t imely and appropriate for a scientific body to set up mul t icentr ic studies based on comparable protocols for data collection to guide emergency airway manage- ment. The protocols need to carefully evaluate not merely complications, but the concept of cost/benefit ratio as it relates to each technique, who uses it and where the emergency occurs.

Options for Emergency Management of the Airway

T. A. Don Michael, MD, FACC, FACP, FRDP Bakersfield, California

To the Editor.

Since James Curry, in 1792,1 described the use of an esophageal ob tura tor to improve endotracheal vent i la- tion, a var ie ty of techniques have been described for emergency m a n a g e m e n t of the airway.

Cur ren t in teres t has centered around early in tuba t ion of the apneic , unconsc ious p a t i e n t . A p a r t from the theoret ical advan tages of cardiac massage faster t h a n 60/minute to optimize cardiac ou tput and obviate the

REFERENCES 1. Alvares H: Medic I, The Seattle Advanced AMA Medic Train- ing Program. Published in proceedings of National Standards for Emergency Care, 1973.

2. Don Michael TA, Lambert EH, Mehran A: Mouth to lung airway for cardiac resuscitation. Lancet 2:1329, 1968.

3. Don Michael TA, Archer G, Schoffermann J: Abstract pre- sented at American College of Cardiology Annual Scientific Meet-

. ing, Las Vegas. Am J Cardiol (to be published, March, 1977)-

4. -Polcher D, DeMeules J: Esophageal perforation following u s e of EOA. Chest 69:377.

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