CORRESPONDENCE

RobertF Percy, MD, FACC Departmentof Cardiology RobertL Wears, MD, FACEP Division of EmergencyMedicine Universityof Florida Health Science Center Jacksonville 1. Yryback DG: A conceptual model for output measures in costeffectiveness evaluation of diagnostic imaging. J Neuroradiol 1983;10:94-96. 2. Rifkin RD: Maximum S h a n n o n information content of diagnostic medical testing. Med Deeis Making 1985;5:179-190. 3. Fineberg HV, Scadden D, Goldman L: Care o f patients with low probability of acute myocardial infarction: Cost effectiveness of alternatives to coronary care unit admission. N Engl J Med 1984;310:1301-1307. 4. Wears RL, Li S, Hernandez JD, et al: How many myocardial infarctions should we rule out? Ann Emerg Med 1989;18:953-963. 5. Brush JE, Brand DA, Acamphora D, et al: Use of the initial electrocardiogram to predict in-hospital complications of acute myocardial infarction. N Engl J Med 1985;312:1137-1141. 6. Schroeder JS, Lamb I, Hu M: Do patients in whom myocardial infarction has been ruled out have a better prognosis after hospitalization t h a n those surviving infarction? N Engl J Med 1980;303:1-5. 7. Schroeder JS, Lamb IH, Harrison DC : Patients admitted to the coronary care unit f o r chest p a i n : High risk subgroups f o r subsequent cardiovascular death. Am J Cardiol 1977;39:829~32. 8. Herlitz J~ Hjalmarson A, Karlson BW, et al: Long term morbidity in patients where the initial suspicion of myocardial infarction was not confirmed. Clin Cardio11988;11:209214. 9. Fesmire FM, Percy RF, Wears RL: In-hospital outcome in patients with coronary artery disease in whom myocardial infarction has been ruled out (letter). N Engl J Med 1989;320:1423-1424. 10. Fesmire FM, Percy RF, Wears RL, et al: Risk stratification according to the initial electrocardiogram in patients with suspected acute myocardial infarction. Arch Intern Med 1989;149:1294 1297.

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~Rep~ Drs Fesmire, Percy, and Wears make some interesting points; however, their thesis is flawed by one major incorrect assumption. Their argument only holds if all patients with anterior chest pain who present to the emergency department have either acute myocardial infarction or cardiac ischemic pain. Unfortunately, only 26% of patients who present to EDs with anterior chest pain turn out to have chest pain of cardiac etiology.1 One large recent study of this issue revealed that of 4,770 such patients only 1,270 had a cardiac origin of their pain. 2 In view of this, the criticality of making clinical decisions in these patients arises not only from correctly diagnosing those patients whose pain is of cardiac origin and may need admission, but also correctly identifying those patients who do not have cardiac pain and who do not need to be in the hospital. If the latter group makes up 74% of all patients who present to the ED with anterior chest pain, and the overall diagnostic threshold specificity for overall admissions is 74%, 2 this would result in as many as 55 patients per 100 being incorrectly admitted to the hospital who do not have chest pain of cardiac origin. This event is clearly not positive at either the management or the societal level. Young et al reveal no evidence that the rapid CK-MB in any way is able to clearly differentiate between chest pain of cardiac and noncardiac etiology or that it reduces the number of patients admitted to the hospital with noncardiac chest pain. In view of this, the argument stands that overall reduction in admissions is a desirable end point, albeit that the ideal would be to singularly reduce the admissions of those patients who do not need admission with both cardiac and noncardiac chest pain. Other studies have not revealed the high complicaton rate in patients who have been ruled out for myocardial infarction. Again, the same stud# noted above2 documented a three-day complication rate of 16%

in patients with myocardial infarction, but a rate of 0.6% in patients without infarction.

William G Baxt, MD Departmentof EmergencyMedicine University of California San Diego Medical Center 1. Goldman L, Weinberg M, Weisberg M, et al: A computer-derived protocol to aid in the diagnosis of emergency room patients with acute chest pain. N Engl J Med 1982;307:588-596. 2. Goldman L, Cook i F , Brand DA, et al: A computer protocol to predict myocardial infarction in emergency department patients with chest pain. N Engl J Med 1988;318:797-803.

Adequate Training for Endotracheal Intubation To the Editor. We read with interest the paper by Stratton et al, "Prospective Study of Mannequin-Only Versus Mannequin and Human Subject Endotracheal Intubation Training of Paramedics" [December 1991;20:1314-1318]. The authors did an excellent job of ensuring adequate initial training in this crucial skill in their students but glossed over some principles of education that we think bear restating. The educational process is commonly divided into three parts. To properly perform a skill one must have an adequate knowledge base, be able to do the skill smoothly and efficiently, and have adequate effective preparation to carry out the skill in a real situation. In the context of endotracheal intubation adequate effective preparation would mean that the paramedic is not stopped from performing an appropriate intubation by fear of the procedure nor likely to perform an inappropriate one because of inadequate concern about its risks. Furthermore, the paramedic should not suffer undue psychologic harm from an unavoidable bad outcome. Knowledge is best developed in a didactic environment. Psychomotor skills are best learned on models. Effective training should take place in an environment that mimics the emotional content of

the real situation. Cadavers do not necessarily "feel" more realistic than mannequins in either the physical or emotional sense of the word. Both are merely models. The Joint Review Committee on Educational Programs for the Emergency Medical Technician Paramedic (JRC EMTP) has a policy ("Essential"), approved by all its sponsors, including the American Society of Anesthesiologists and the American College of Emergency Physicians, that after the mechanical skill is learned, the student should perform that skill on live human subjects. In most circumstances, this is done in the operating room under the guidance of an anesthesiologist. In this environment, adequate numbers of subjects can be managed, mistakes are quickly caught, and repercussions to the patient and student are minimized. This is, after all, the training we expect for physicians. It is incumbent on any training program to ensure that its graduates will be capable of performing critical skills in the real world. This requires supervised experience in situations that are close to these actually faced by practitioners. Experience in less realistic situations provides only a surrogate for proof of the ability to perform in a real situation. Unfortunately, few paramedic training programs are able to guarantee enough field intubations to adequately assess mastery of this skill by all graduates. Stratton et al have shown that if students receive an hour of didactic training and five 20-minute sessions of mannequin practice, an additional three cadaver intubations are not necessary to perform the simple mechanical skill of endotracheal intubation. This is hardly surprising. We disagree with the authors' implication that this is optimal, or even adequate, training for paramedics.

Mark Hauswald,MD, FACEP Departmentof EmergencyMedicine University of New Mexico Schoolof Medicine Albuquerque

ANNALS OF EMERGENCY MEDICtNE 21:9 SEPTEMBER1992

CORRESPONDENCE

GFTuohy,MD Departmentof Anesthesiology University of Missouri KansasCity Philip yon tier Heydt, IVIEd,RRT JRCEMTP Euless, Texas In Reply: I appreciate the interest in our paper. ) agree, intuitively, that the more exposure paramedics receive to various endotracheal intubation practice medalities, the more optimal will be their training in the procedure. I strongly suggest that endotracheal intubation practice on live people who are under general anesthesia is merely another model for intubation training. In no way does the controlled operating room environment and anesthetized patient mimic the emotional content or physical feel of an actual field emergency intubation. In our community, it is generally considered unethical for paramedics to practice endotracheal intubation on individuals undergoing general anesthesia without the individual's prior informed consent. This need for consent, as well as a potential for litigation, has seriously limited the ability to obtain operating room experience for our paramedics. Because of this, fresh human cadavers have been used for intubation training. Realistically, supervised endotracheal intubation instruction with a fresh human cadaver is little different from instruction using a freshly arfesthetized patient. During our mannequin practice sessions, each student received 2(} minutes of supervised, individual instruction while other students observed and participated. These practice sessions included teaching distracters to simulate the actual field setting leg, poor lighting, vomiting, trauma). One important point is that our paper addresses adult intubation and should not be considered when evaluatingpediatric intubation. Without any implicatons, our study supports the concept of using only mannequins and didactic sessions

SEPTEMBER 1992

21:9

for teaching the skill of adult endotracheal intubation to paramedics.

SamuelJ Stratton, MD, FACEP LosAngeles CountyDepartmentof Health Services EmergencyMedical ServicesAgency Paramedic TrainingInstitute Torrance, California

Augmented Carotid Massage To the Editor. Each time I read an article on a new pharmacologic method for treatment of paroxysmal supraventricular tachycardia {PSVT), I do so with chagrin. The editorial "Calcium Pretreatment to Prevent VerapamilInduced Hypotension in Patients With SW" [January 1992;21:68] left me disappointed. Although it is primarily a review of the literature on the subject and focuses on the correct dosage and preparation of calcium, its tone seems to lend credence to the idea of using a second drug to prevent a potential adverse effect of a first drug in the treatment of PSVT. Nonpharmacologic means often can be used to terminate the majority of cases of PSVT.1,2 Although the above statement may appear fatuous, the fact is that the use of carotid massage for the termination of PSVT has become a lost art, particularly since the introduction of verapamil,3 the modernist's panacea for PSVT. Carotid massage was described as a technique for use in paroxysmal tachycardia early in the 20th century, ~ but in modern textbooks seems to get relegated to the category of "honorable mention." In 1980, Waxman et aH studied patients with known PSVT and the effects of respiration and body position on termination of induced episodes of PSVT. They found that such episodes were more likely to be terminated if the patient was in a head-down (Trendelenburg) position and also in the deep inspiration portion of the respiratory cyc)e. Concurrently, the same lead author (with others) reported on the use of "vagal techniques" for the termina-

ANNALS OF EMERGENCY MEDiCiNE

tion of PSVT.2There was no report, however, on the use of such measures in combination. Prior to the Waxman studies, I was an advocate of carotid massage and had experienced fair success with it for termination of PSVT. After the publication of the Waxman articles, however, I expanded my method as follows: I. After examination, including auscultation of the carotid arteries, carotid pressure is applied (while observing the cardiac monitor) first on one side, and then, if not successful, on the other side. The patient should be flat in the supine position; usually no more than five seconds of pressure is applied at one time. 2. If the above does not terminate the episode, the patient is placed in a Trendelenburg position of about -10 ° and instructed to take a full inspiration, full expiration, and again full inspiration that is held briefly. This in itself will convert some patients to normal sinus rhythm. 3. If not effective, then carotid massage is carried out in the Trendelenburg position after the respiratory maneuvers described above have been completed. 4. If not effective, then pharmacologic methods are used. I have been using the above technique, which I term augmented carotid massage, regularly since 1981, and have used it in 100 to 200 patients with excellent results. There have been no instances of ensuing dysrhythmia (beyond the few seconds of transient bradycardia that may be seen with all modalities) or hypotensien. Importantly, there have been no instances of cerebral ischemia, transient or otherwise. Also, there have been no instances of recurrence, as is common with adenosine. Although I have not collected the data, I believe that at least 60% of all patients with PSVT have converted to normal sinus rhythm with the above-described, nonpharmacoiogic method. I have used it successfully in pregnant individuals in whom the administration of any drug might be potentially harmful to the developing fetus. A

fringe benefit of such use is that a certain percentage of patients thought to have PSVT instead have atrial flutter with 2:1 atrioventricula block but the P waves are not easily visible due to the rapid ventricular rate (usually about 150}. The use of carotid massage increases the atrioventricular block and allows the P waves to be seen, the correct diagnosis to be made, and a course of inappropriate therapy to be avoided. ) have always prided myself in being a clinician, and have tried to adhere to the doctrine of primum non nocere. I believe the conversion of PSVT is clearly an area where no drug is frequently better than one or two drugs, and where something new is not necessarily something better.

Paul R Pomeroy,MD, FACEP EmergencyDepartment St Mary Hospital Livonia, Michigan 1. Waxman MB, et al: Effects of respiraton and posture on paroxysmal sapraventricular tachycardia. Circulation 1980;62:1011-1020. 2. Waxman MB, et al: Vagal techniques for termination of paroxysmal supraventricular tachycardia. Am J Cardiol 1980;46:655-664. 3. Sung R J, Etser B, McAUister RG:

Intravenous verapamil for termination of re-entrant supraventricular tachycardias. Ann Intern Med 1980;93:682-689. 4. Cohn AE, Fraser RF: Paroxysmal tachycardia and the effect of stimulation of the vagus nerves by pressure. Heart 1913-14;5:93-108.

In Reply: I appreciate Dr Pomeroy's insightful response to the editorial authored by Dr Hargarten and myself. The point of the editorial, however, was not to discuss management options for PSVT, but to discuss the use of calcium once the decision to use verapamil is made. It is assumed that before the use of pharmacologic management, all other conservative means have been exhausted (eg, Valsatva, carotid massage, or even cold water immersion of the face if one is so bold). Few physicians, I'm afraid, are as aggressive as Dr Pomeroy with the

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