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<< Cardiac Arrest: Current Concepts, Controversies, And Evidence

Emergency Department Evaluation

The First Minute

The ED evaluation begins with a brief history obtained from paramedics, witnesses, or family members. Quickly assess the adequacy of the airway, the presence of a pulse, and the nature of any electrical activity on the heart monitor.

If an endotracheal tube is in place, the clinician should check for proper tube location. While successful intubation rates may vary among locales, one study showed that up to 25% of all endotracheal tubes inserted by medics may be misplaced (17% in the esophagus, 8% in the hypopharynx).82 Many physicians simply listen for breath sounds bilaterally and the absence of gurgling sounds over the stomach; however, this method is fallible.83 The emergency physician can also visualize tube placement using direct laryngoscopy. While the reliability of this approach in a code situation remains unknown, it seems to be a reasonable approach. End-tidal CO2 using a capnograph or a colorimetric device can be extremely useful when the result is positive. While the presence of CO2 measured by an inline device strongly supports correct placement,84 in the arrested patient, a negative value may occur with either esophageal placement or proper endotracheal intubation. The lack of end-tidal CO2 during arrest may be due to poor perfusion of the lungs or decreased CO2 production despite CPR.85 An alternative method to confirm endotracheal tube placement that does not rely on perfusion involves the esophageal detector device. This device aspirates air from the endotracheal tube using a syringe or suction bulb.86 If the tube is in the  rachea, suction is easy and the air flows freely into the syringe. If the tube is in the esophagus (which collapses during suction), air return is negligible.87

The presence of a pulse should be assessed by palpation of a central artery, such as the carotid or femoral. Pulses may be checked with CPR stopped to evaluate return of circulation and during CPR to determine adequacy of compressions. Palpation of peripheral arteries is not reliable.88

 
History

Important information includes the circumstances and timing of the arrest and resuscitation in the field. Did the patient have any preceding symptoms of chest pain, palpitations, or dyspnea? Was the arrest witnessed, and if bystander CPR was performed, was it begun immediately? Importantly, how long has resuscitation been going on? And when was an AED or defibrillation applied? What further treatments did paramedics administer?

Events just prior to the arrest are of particular interest. Determine if there was potential exposure to inhaled, injected, ingested, or external toxins, or exposure to electricity, trauma, or drowning. A history of chest, abdominal, or head pain prior to the arrest may suggest the underlying etiology. In the appropriate clinical situation, ask about risk factors for pulmonary embolism, cardiac disease, or arrhythmia. The past medical history may play an important role in resuscitation, especially if the patient was taking known cardiotoxic drugs.

Physical Examination

The initial physical examination should focus on airway, breathing, circulation, and disability (neurologic examination). In the first several minutes, determine whether breath sounds are equal and bilateral during ventilation and whether there is a pulse during CPR. A deviated trachea, distended neck veins, and unilateral decreased breath sounds indicate a tension pneumothorax.

A secondary survey should also be performed during the course of the ED evaluation. The pupils will generally lose reactivity and dilate within four minutes of untreated arrest, but this may be reversed with adequate CPR.89 Fixed and dilated pupils during CPR portend a poor outcome, but this is not absolute.90 There may be multiple confounding factors such as the administration of epinephrine, dopamine, or other sympathomimetics that tend to dilate the pupils.91 Atropine in conventional doses causes slight pupillary dilation but does not abolish light reactivity.92

Distended neck veins may suggest an obstruction to blood flow often associated with tension pneumothorax, pericardial tamponade, or massive pulmonary embolism. The presence of a vascath or upper-extremity shunt suggests chronic renal failure and the possibility of hyperkalemia.

Diagnostic Testing

Laboratory Testing


A variety of ancillary tests can help diagnose potentially reversible causes of cardiac arrest. Recognize that the patient in full arrest derives little benefit from laboratory tests that require the traditional 30 minutes to process. However, certain point-of-care tests may be of some value. Serum glucose is frequently evaluated in patients who are known to be diabetic, but it is unclear whether someone who arrests from hypoglycemia could be resuscitated by sugar alone. Arterial blood gas measurements have limited utility during cardiac arrest because they don’t correlate with the mixed venous and tissue acid-base status.93 Electrolyte abnormalities are an important cause of or contributing factor in many cardiac arrests.94 Derangements of potassium, magnesium, and calcium are particularly important and may require emergent treatment—yet once again, treatment may be based on clinical suspicion (in the case of an arrested dialysis patient who had missed several dialysis sessions) rather than as a result of testing. A retrospective study that examined the utility of mandatory electrolyte measurements for inpatient cardiac arrest showed little clinical usefulness.95

Electrocardiagram And Chest X-Ray


The ECG may be helpful to diagnose electrolyte derangements in patients with impending arrest, but in one study the sensitivity of emergency physicians in diagnosing hyperkalemia above 6.5 mmol/L was only about 60%.96 Similarly, the diagnosis of serum calcium derangements based on the ECG QT interval has also been found to have limited utility.207 The post-arrest ECG is essential in the evaluation of MI and perhaps complex dysrhythmias.

For patients with return of spontaneous circulation, the chest x-ray may be helpful to assess a variety of findings, including the heart size, pulmonary inflation and congestion, and the location of various tubes and central lines, if any. During arrest the chest film is unlikely to be of much value. Tension pneumothorax is a clinical diagnosis, and using a chest film to determine endotracheal tube position can introduce lethal delays and misdiagnosis.

 
Echocardiography

Cardiac ultrasound has a number of uses in the setting of cardiac arrest. The most important for the emergency physician is to diagnose abnormal pericardial fluid and pericardial tamponade using transthoracic echocardiography.97 Tamponade can also be treated using ultrasound-guided pericardiocentesis.98 Transthoracic echocardiography can also assess for cardiac contractions in PEA. Evidence of organized cardiac contractions is termed pseudo-electromechanical dissociation and should prompt a search for reversible causes such as hypovolemia, pericardial tamponade, tension pneumothorax, or massive pulmonary embolism.99 If hypovolemia is suspected, ultrasound can be used to investigate the major abdominal vessels and to perform the FAST (focused abdominal sonography in trauma) examination to search for intraabdominal hemorrhage.100 Echocardiographic findings of disorganized myocardial contractions in the setting of presumed asystole suggest fine VF instead, and immediate defibrillation is indicated.101 For physicians with advanced echocardiographic skills, the cardiac ultrasound can evaluate the thoracic aorta and aortic valve as well as identify the presence of regional cardiac wall motion abnormalities. Transesophageal echocardiography (TEE) may be particularly useful for diagnosing thoracic aortic disease and pulmonary embolism.208 Despite the potential difficulty in obtaining an emergent TEE, this diagnostic modality may be considered, if available.

End-Tidal CO2 And Echocardiography

The presence of cardiac motion on ultrasound in patients in cardiac arrest is predictive of survival. In one study of 136 patients in cardiac standstill by echocardiography, none survived to leave the ED regardless of their initial cardiac rhythm.102 In another ED-based study, 11 of 41 patients (27%) with and two of 61 patients (3%) without sonographic evidence of cardiac activity during the resuscitation survived to hospital admission. However, cardiac ultrasound added no additional independent prognostic information to end-tidal CO2 measurements where a cutoff value of 16 mmHg was found to be optimal (all patients with a value lower than 16 mmHg died).103 It is interesting to note that all echocardiography in both of these studies was performed by emergency physicians, and the majority felt it was an easy procedure.103

In another prospective, observational study of 150 patients, investigators found that an end-tidal CO2 level of 10 mmHg or less after 20 minutes or more of CPR had a 100% sensitivity and specificity for death.104 The confidence intervals, however, were large.

 

 

  1. * American Heart Association. International Guidelines 2000 for cardiopulmonary resuscitation (CPR) and emergency cardiac care (ECC). Circulation 2000;102[Suppl I]:I1-I384. (Consensus guidelines)
  2. de Latorre F, Nolan J, Robertson C, et al. European Resuscitation Council Guidelines 2000 for Adult Advanced Life Support. A statement from the Advanced Life Support Working Group and approved by the Executive Committee of the European Resuscitation Council. Resuscitation 2001;48(3):211-221.(Consensus guidelines)
  3. Cline D, Welch K, Cline L, et al. Physician compliance with advanced cardiac life support guidelines. Ann Emerg Med 1995;25:52-57. (Retrospective case series; 207 patients)
  4. Sanders AB, Berg RA, Burress M, et al. The efficacy of an ACLS training program for resuscitation from cardiac arrest in a rural community. Ann Emerg Med 1994;23(1):56-59. (Retrospective; 64 patients)
  5. Pepe PE, Abramson NS, Brown CG. ACLS—does it really work? Ann Emerg Med 1994;23(5):1037-1041. (Review)
  6. Stratton S, Niemann JT. Effects of adding links to “the chain of survival” for prehospital cardiac arrest: a contrast in outcomes in 1975 and 1995 at a single institution. Ann Emerg Med 1998;31(4):471-477. (Comparative; 240 patients)
  7. * van Walraven C, Stiell IG, Wells GA, et al. Do advanced cardiac life support drugs increase resuscitation rates from in-hospital cardiac arrest? The OTAC Study Group. Ann Emerg Med 1998;32(5):544-553. (Prospective; 773 patients)
  8. Camp BN, Parish DC, Andrews RH. Effect of advanced cardiac life support training on resuscitation efforts and survival in a rural hospital. Ann Emerg Med 1997;29(4):529-533. (Retrospective)
  9. * Stiell IG, Wells GA, Hebert PC, et al. Association of drug therapy with survival in cardiac arrest: limited role of advanced cardiac life support drugs. Acad Emerg Med 1995;2(4):264-273. (Observational cohort; 529 patients)
  10. Cummins RO, Chamberlain DA, Abramson NS, et al. Recommended guidelines for uniform reporting of data from out-ofhospital cardiac arrest: the Utstein style. Ann Emerg Med 1991;20:861-874. (Consensus guidelines)
  11. Valenzuela TD, Spaite DW, Meislin HW, et al. Case and survivaldefinitions in out-of-hospital cardiac arrest. Effect on survival rate calculation. JAMA 1992;267:272-274. (Case series; 372 patients)
  12. Cone DC, Jaslow DS, Brabson TA. Now that we have the Utstein style, are we using it? Acad Emerg Med 1999;6:923-928.
  13. * Stiell IG, Wells GA, DeMaio VJ, et al. Modifiable factors associated with improved cardiac arrest survival in a multicenter basic life support/defibrillation system: OPALS study phase I results. Ann Emerg Med 1999;33:44-50. (Observational cohort study; 5335 patients)
  14. American Heart Association. Introduction to the International Guidelines 2000 for CPR and ECC: A consensus on science. Circulation 2000;102[Suppl I]:I1-I11. (Review)
  15. Myerburg RJ, Kessler MK, Castellanos A. Sudden cardiac death— structure, function, and time—dependence of risk. Circulation 1992;85 [suppl I]:I2-I10. (General review)
  16. Gillum RF. Sudden cardiac death in Hispanic Americans and African Americans. Am J Public Health 1997;87:1461-1466. (Retrospective, observational; 8194 patients)
  17. Becker LB, Han BH, Meyer PM, et al. Racial differences in the incidence of cardiac arrest and subsequent survival. N Engl J Med 1993;329:600-606. (Prospective cohort; 6451 patients)
  18. * Valenzuela TD, Roe DJ, Nichol G, et al. Outcomes of rapid defibrillation by security officers after cardiac arrest in casinos. N Engl J Med 2000;343:1206-1209. (Prospective cohort; 105 patients)
  19. Weaver WD, Hill D, Fahrenbruch CE, et al. Use of the automatic defibrillator in the management of out-of-hospital cardiac arrest. N Engl J Med 1988;319:661-666. (Unrandomized; 504 patients)
  20. Becker LB, Ostrander MP, Barrett J, et al. Outcome of CPR in a large metropolitan area—where are the survivors? Ann Emerg Med 1991;20:355-361. (Cohort; 3221 patients)
  21. * Eisenberg MS, Mengert TJ. Cardiac resuscitation. N Engl J Med 2001;344:1304-1313. (General review)
  22. Cummins RO, Eisenberg MS, Hallstrom AP, et al. Survival of outof- hospital cardiac arrest with early initiation of cardiopulmonary resuscitation. Am J Emerg Med 1985;3:114-119. (Retrospective cohort; 1297 patients)
  23. Bachman JW, McDonald GS, O’Brien PC. A study of out-ofhospital cardiac arrests in northeastern Minnesota. JAMA 1986;256:477-483. (Retrospective cohort; 512 patients)
  24. Westfal R, Reissman S, Doering G. Out-of-hospital cardiac arrests: an 8-year New York City experience. Am J Emerg Med 1996;14:364- 368. (Retrospective case series; 481 patients)
  25. De Maio VJ, Stiell IG, Wells GA, et al. Cardiac arrest witnessed by emergency medical services personnel: descriptive epidemiology, prodromal symptoms, and predictors of survival. Ann Emerg Med 2000;35:138-146. (Prospective cohort; 610 patients)
  26. Cohn EB, Lefevre F, Yarnold PR, et al. Predicting survival from inhospital CPR: meta-analysis and validation of a prediction model. J Gen Intern Med 1993;8:347-353. (Meta-analysis, retrospective case series)
  27. Parish DC, Dane FC, Montgomery M, et al. Resuscitation in the hospital: differential relationships between age and survival across rhythms. Crit Care Med 1999;27:2137-2141. (Retrospective case series; 2394 patients)
  28. Herlitz J, Bang A, Ekstrom L, et al. A comparison between patients suffering in-hospital and out-of-hospital cardiac arrest in terms of treatment and outcome. J Intern Med 2000;248:53-60. (Retrospective, prospective cohort; 1200 patients)
  29. Di Bari M, Chiarlone M, Fumagalli S, et al. Cardiopulmonary resuscitation of older, inhospital patients: immediate efficacy and long-term outcome. Crit Care Med 2000;28:2320-2325. (Retrospective case series; 245 patients)
  30. Kannel WB, Thomas HE. Sudden coronary death: the Framingham study. Ann N Y Acad Sci 1982;382:3-21. (Review)
  31. Huikuri HV, Castellanos A, Myerburg RJ. Sudden death due to cardiac arrhythmias. N Engl J Med 2001;345:1473-1482. (Review)
  32. Zipes DP, Wellens HJ. Sudden cardiac death. Circulation 1998;98:2334-2351. (Review)
  33. Salida WI, Natale A. Ventricular tachycardia syndromes. Med Clin North Am 2001;85:267-304. (Review)
  34. Wolfe CL, Nibley C, Bhandari A, et al. Polymorphous ventricular tachycardia associated with acute myocardial infarction. Circulation 1991;84:1543-1551. (11 patients)
  35. White RD, Wood DL. Out-of-hospital pleomorphic ventricular tachycardia and resuscitation: association with acute myocardial ischemia and infarction. Ann Emerg Med 1992;21:1282-1287. (Case report)
  36. Zareba W, Moss AJ, Schwartz PJ, et al. Influence of genotype on the clinical course of the long-QT syndrome. N Engl J Med 1998;339:960-965. (Cohort; 1378 patients)
  37. De Boer S. Die physiologie und pharmakologie de Flimmerns. Ergeb Physiol 1923; 21:1.
  38. Lown B. Electrical reversion of cardiac arrhythmias. Br Heart J 1967;29:469-489. (Retrospective cohort)
  39. Link MS, Wang PJ, Pandian N, et al. An experimental model of sudden death due to low-energy chest-wall impact (commotio cordis). N Engl J Med 1998;338:1805-1811. (Prospective animal study)
  40. Weaver WD, Cobb LA, Dennis D, et al. Amplitude of ventricular fibrillation waveform and outcome after cardiac arrest. Ann Intern Med 1985;102:53-55. (Cohort; 394 patients)
  41. Callaham M, Braun O, Valentine W, et al. Prehospital cardiac arrest treated by urban first-responders: profile of patient response and prediction of outcome by ventricular fibrillation waveform. Ann Emerg Med 1993;22:1664-1677. (Prospective cohort; 265 patients)
  42. Brown CG, Dzwonczyk R. Signal analysis of the human electrocardiogram during ventricular fibrillation: frequency and amplitude parameters as predictors of successful countershock. Ann Emerg Med 1996;27:184-188. (Retrospective, observational; 55 patients)
  43. Callaway CW, Sherman LD, Scheatzle MD, et al. Scaling structure of electrocardiographic waveform during prolonged ventricular fibrillation in swine. Pacing Clin Electrophysiol 2000;23:180-191. (Animal study)
  44. Callaway CW, Sherman LD, Mosesso VN, et al. Scaling exponent predicts defibrillation success for out-of-hospital ventricular fibrillation cardiac arrest. Circulation 2001;103:1656-1661. (Retrospective, observational; 75 patients)
  45. Kloeck WG. A practical approach to the etiology of pulseless electrical activity: A simple 10-step training mnemonic. Resuscitation 1995;30:157-159.
  46. Martin DR, Gavin T, Bianco J, et al. Initial countershock in the treatment of asystole. Resuscitation 1993;26:63-68. (Retrospective; 194 patients)
  47. Pepe PE, Levine RL, Fromm RE, et al. Cardiac arrest presenting with rhythms other than ventricular fibrillation: Contribution of resuscitative efforts toward total survivorship. Crit Care Med 1993;21:1838-1843. (Prospective cohort; 2404 patients)
  48. Herlitz J, Ekstrom L, Wennerblom B, et al. Predictors of early and late survival after out-of-hospital cardiac arrest in which asystole was the first recorded arrhythmia on scene. Resuscitation 1994;28:27-36. (Cohort; 1222 patients)
  49. Cummins RO, Austin D Jr. The frequency of “occult” ventricular fibrillation masquerading as a flat line in prehospital cardiac arrest. Ann Emerg Med 1988;17:813-817. (Cohort; 127 patients)
  50. Kellermann A, Hackman B, Somes G. Predicting the outcome of unsuccessful prehospital advanced cardiac life support. JAMA 1994;270:1433-1436. (Retrospective case series; 758 patients)
  51. Bonin M, Pepe P, Kimball K, et al. Distinct criteria for termination of resuscitation in the out-of-hospital setting. JAMA 1993;270:1457- 1462. (Prospective cohort; 1461 patients)
  52. Lewis L, Ruoff B, Rush C. Is emergency department resuscitation of out-of-hospital cardiac arrest victims who arrive pulseless worthwhile? Am J Emerg Med 1990;8:118-120. (Cost analysis)
  53. Cummins RO, Ornato JP, Thies WH, et al. Improving survival from sudden cardiac arrest: the “chain of survival” concept: a statement for health professionals from the Advanced Cardiac Life Support Subcommittee and the Emergency Cardiac Care Committee, American Heart Association. Circulation 1991;83:1832- 1847. (Review)
  54. Herlitz J, Ekstrom L, Wennerblom B, et al. Type of arrhythmia at EMS arrival on scene in out-of-hospital cardiac arrest in relation to interval from collapse and whether a bystander initiated CPR. Am J Emerg Med 1996;14:1-5. (Cohort; 1737 patients)
  55. Thompson RG, Hallstrom AP, Cobb LA. Bystander-initiated cardiopulmonary resuscitation in the management of ventricular fibrillation. Ann Intern Med 1979;90:737-740. (Cohort; 316 patients)
  56. De Maio VJ, Stiell IG, Spaite DW, et al. CPR-only survivors of outof- hospital cardiac arrest: implications for out-of-hospital care and cardiac arrest research methodology. Ann Emerg Med 2001;37:602- 608. (Observational cohort; 24 patients)
  57. Rudikoff MT, Maughan WL, Effron M, et al. Mechanisms of blood flow during cardiopulmonary resuscitation. Circulation 1980;61:345-352. (Animal study)
  58. Kern KB, Sanders AB, Raife J, et al. A study of chest compression rates during cardiopulmonary resuscitation in humans. Arch Intern Med 1992;152:145-149. (Unblinded cross-over trial; 23 patients)
  59. The American Heart Association in collaboration with the International Liaison Committee on Resuscitation. Guidelines 2000 for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Part 6: advanced cardiovascular life support: section 4: devices to assist circulation. Circulation 2000;102(8 Suppl):I105-I111. (Review)
  60. Arntz HR, Agrawal R, Richter H, et al. Phased chest and abdominal compression-decompression versus conventional cardiopulmonary resuscitation in out-of-hospital cardiac arrest. Circulation 2001;104:768-772. (Randomized; 50 patients)
  61. * Sack JB, Kesselbrenner MB, Bregman D. Survival from in-hospital cardiac arrest with interposed abdominal counterpulsation during cardiopulmonary resuscitation. JAMA 1992;267:379-385. (Randomized; 103 patients)
  62. Mateer JR, Stueven HA, Thompson BM, et al. Pre-hospital IAC-CPR versus standard CPR: paramedic resuscitation of cardiac arrests. Am J Emerg Med 1985;3:143-146. (Randomized; 291 patients)
  63. Sack JB, Kesselbrenner MB. Hemodynamics, survival benefits, and complications of interposed abdominal compression during cardiopulmonary resuscitation. Acad Emerg Med 1994;1:490-497. (Review)
  64. * Hallstrom A, Cobb L, Johnson E, et al. Cardiopulmonary resuscitation by chest compression alone or with mouth-tomouth ventilation. N Engl J Med 2000;342:1546-1553. (Randomized; 520 patients)
  65. Eisenberg MS, Copass MK, Hallstrom AP, et al. Treatment of outof- hospital cardiac arrests with rapid defibrillation by emergency medical technicians. N Engl J Med 1980;302:1379-1383. (Beforeand- after study; 154 patients)
  66. Herlitz J, Bang A, Holmberg M, et al. Rhythm changes during resuscitation from ventricular fibrillation in relation to delay until defibrillation, number of shocks delivered and survival. Resuscitation 1997;34:17-22. (Cohort; 1216 patients)
  67. Weaver WD, Cobb LA, Copass MK, et al. Ventricular defibrillation— a comparative trial using 175-J and 320-J shocks. N Engl J Med 1982;307:1101-1106. (Randomized; 249 patients)
  68. Keener JP, Lewis TJ. The biphasic mystery: why a biphasic shock is more effective than a monophasic shock for defibrillation. J Theor Biol 1999;200:1-17. (Theoretical study)
  69. Bardy GH, Marchlinski FE, Sharma AD, et al. Multicenter comparison of truncated biphasic shocks and standard damped sine wave monophasic shocks for transthoracic ventricular defibrillation. Circulation 1996;94:2507-2514. (Blinded, randomized; 294 patients)
  70. * Schneider T, Martens PR, Paschen H, et al. Multicenter, randomized, controlled trial of 150-J biphasic shocks compared with 200- to 360-J monophasic shocks in the resuscitation of out-of-hospital cardiac arrest victims. Circulation 2000;102:1780-1787. (Randomized; 115 patients)
  71. Tang W, Weil MH, Sun S. Low-energy biphasic waveform defibrillation reduces the severity of postresuscitation myocardial dysfunction. Crit Care Med 2000;28 [Suppl]:N2222-2224. (Review)
  72. Marenco JP, Wang PJ, Link MS, et al. Improving survival from sudden cardiac arrest: the role of the automated external defibrillator. JAMA 2001;285:1193-1200. (Structured review)
  73. The American Heart Association in collaboration with the International Liaison Committee on Resuscitation. Guidelines 2000 for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Part 4: The automated external defibrillator: key link in the chain of survival. Circulation 2000;102 (8 Suppl):I60- I76. (Review)
  74. Gundry JW, Comess KA, DeRook FA, et al. Comparison of naive sixth-grade children with trained professionals in the use of an automated external defibrillator. Circulation 1999;100:1703-1707. (Controlled; 37 subjects)
  75. White RD, Asplin BR, Buglioso TF, et al. High discharge survival rate after out-of-hospital ventricular fibrillation with rapid defibrillation by police and paramedics. Ann Emerg Med 1996;28:480-485. (Retrospective cohort; 84 patients)
  76. Page RL, Joglar JA, Kowal RC, et al. Use of automated external defibrillators by a U.S. airline. N Engl J Med 2000;343:1210-1216. (Cohort; 200 patients)
  77. Eisenberg MS, Moore J, Cummins RO, et al. Use of the automatic external defibrillator in homes of survivors of out-of-hospital ventricular fibrillation. Am J Cardiol 1989;63:443-446. (Unblinded; 97 patients)
  78. Kaye W, Mancini ME, Giuliano KK, et al. Strengthening the inhospital chain of survival with rapid defibrillation by first responders using automated external defibrillators: training and retention issues. Ann Emerg Med 1995;25:163-168. (Prospective cohort; 140 subjects)
  79. Niemann JT, Cairns CB, Sharma J, et al. Treatment of prolonged ventricular fibrillation: Immediate countershock versus high-dose epinephrine and CPR preceding countershock. Circulation 1992;85:281-287. (Animal study)
  80. * Cobb LA, Fahrenbruch CE, Walsh TR, et al. Influence of cardiopulmonary resuscitation prior to defibrillation in patients with out-of-hospital ventricular fibrillation. JAMA 1999;281:1182- 1188. (Before-and-after study; 1117 patients)
  81. Niemann JT, Cruz B, Garner D, et al. Immediate countershock versus cardiopulmonary resuscitation before countershock in a 5- minute swine model of ventricular fibrillation arrest. Ann Emerg Med 2000;36:543-546. (Animal study; 31 swine)
  82. Katz SH, Falk JL. Misplaced endotracheal tubes by paramedics in an urban emergency medical services system. Ann Emerg Med 2001;37(1):32-37. (Prospective, observational; 108 patients)
  83. Linko K, Paloheimo M, Tammisto T. Capnography for detection of accidental oesophageal intubation. Acta Anaesthesiol Scand 1983;27(3):199-202. (Comparative; 20 patients)
  84. Ornato JP, Shipley JB, Racht EM, et al. Multicenter study of a portable, hand-size, colorimetric end-tidal carbon dioxide detection device. Ann Emerg Med 1992;21(5):518-523. (Prospective,multicenter; 227 patients)
  85. Garnett AR, Ornato JP, Gonzalez ER, et al. End-tidal carbon dioxide monitoring during cardiopulmonary resuscitation. JAMA 1987;257(4):512-515. (Prospective; 23 patients)
  86. Jenkins WA, Verdile VP, Paris PM. The syringe aspiration technique to verify endotracheal tube position. Am J Emerg Med 1994;12(4):413-416. (Prospective; 90 patients)
  87. Marley CD Jr, Eitel DR, Anderson TE, et al. Evaluation of a prototype esophageal detection device. Acad Emerg Med 1995;2(6):503-507. (Prospective; 51 patients)
  88. Brealey S, Shearman CP, Simms MH. Peripheral pulse palpation: an unreliable physical sign. Ann R Coll Surg Engl 1992;74:169-171. (Prospective, observational; 5 patients)
  89. Zhao D, Weil MH, Tang W, et al. Pupil diameter and light reaction during cardiac arrest and resuscitation. Crit Care Med 2001;29:825- 828. (Animal study; 15 swine)
  90. Steen-Hansen JE, Hansen NN, Vaagenes P, et al. Pupil size and light reactivity during cardiopulmonary resuscitation: A clinical study. Crit Care Med 1988;16:69-70. (Observational cohort; 231 patients)
  91. Ong GL, Bruning HA. Dilated fixed pupils due to administration of high doses of dopamine hydrochloride. Crit Care Med 1981;9:658-659. (Case series; 5 patients)
  92. Goetting MG, Contreras E. Systemic atropine administration during cardiac arrest does not cause fixed and dilated pupils. Ann Emerg Med 1991;20:55-57. (Prospective, observational; 49 patients)
  93. Weil MH, Rackow EC, Trevino R, et al. Difference in acid-base state between venous and arterial blood during cardiopulmonary resuscitation. N Engl J Med 1986;315:153-156. (Case series; 16 patients)
  94. American Heart Association. International Guidelines 2000 for cardiopulmonary resuscitation (CPR) and emergency cardiac care (ECC). Part 8: Advanced challenges in resuscitation, Section 1: Life-threatening electrolyte abnormalities. Circulation 2000;102[Suppl I]:I217-I222. (Consensus guidelines)
  95. Eisenberg MJ. Electrolyte measurements during inhospital cardiopulmonary resuscitation. Crit Care Med 1990;18:25-28. (Observational cohort; 99 patients)
  96. Wrenn KD, Slovis CM, Slovis BS. The ability of physicians to predict hyperkalemia from the ECG. Ann Emerg Med 1991;20:1229- 1232. (Retrospective, observational cohort; 220 patients)
  97. Plummer D, Heller M. Cardiac applications. In: Heller M, Jehle D, eds. Ultrasound in Emergency Medicine. 1st ed. Philadelphia: W.B. Saunders; 1995:126-134. (Textbook chapter)
  98. Tsang TS, Enriquez-Sarano M, Reeman WK, et al. Consecutive 1127 therapeutic echocardiographically guided pericardiocenteses: clinical profile, practice patterns, and outcomes spanning 21 years. Mayo Clin Proc 2002;77:429-436. (Case series; 977 patients)
  99. Varriale P, Maldonado JM. Echocardiographic observations during in hospital cardiopulmonary resuscitation. Crit Care Med 1997;25:1717-1720. (Case series; 18 patients)
  100. Hendrickson RG, Dean AJ, Costantino TG. A novel use of ultrasound in pulseless electrical activity: the diagnosis of an acute abdominal aortic aneurysm rupture. J Emerg Med 2001:21:141-144. (Case report; 1 patient)
  101. Amaya SC, Langsam A. Ultrasound detection of ventricular fibrillation disguised as asystole. Ann Emerg Med 1999;33:344-346. (Case report; 1 patient)
  102. Blaivas M, Fox JC. Outcome in cardiac arrest patients found to have cardiac standstill on the bedside emergency department echocardiogram. Acad Emerg Med 2001;8:654-657. (Cohort; 169 patients)
  103. Salen P, O’Connor R, Sierzenski P, et al. Can cardiac sonography and capnography be used independently and in combination to predict resuscitation outcomes? Acad Emerg Med 2001;8:610-615. (Case series; 102 patients)
  104. Levine RL, Wayne MA, Miller CC. End-tidal carbon dioxide and outcome of out-of-hospital cardiac arrest. N Engl J Med 1997;337:301-306. (Prospective cohort; 150 patients)
  105. Paradis NA, Martin GB, Rivers EP, et al. Coronary perfusion pressure and the return of spontaneous circulation in human cardiopulmonary resuscitation. JAMA 1990;263:1106-1113. (Prospective cohort; 100 patients)
  106. Paradis NA, Martin GB, Rosenberg J, et al. The effect of standardand high-dose epinephrine on coronary perfusion pressure during prolonged cardiopulmonary resuscitation. JAMA 1991;265:1139- 1144. (Prospective cohort; 32 patients)
  107. American Heart Association. International Guidelines 2000 for cardiopulmonary resuscitation (CPR) and emergency cardiac care (ECC). Part 6: Advanced cardiovascular life support, Section 7: Algorithm approach to ACLS emergencies. Circulation 2000;102[Suppl I]:I136-I165. (Consensus guidelines)
  108. Callaham M, Barton CW, Kayser S. Potential complications of high-dose epinephrine therapy in patients resuscitated from cardiac arrest. JAMA 1991;265:1117-1122. (Retrospective cohort; 68 patients)
  109. Callaham M, Madsen CD, Barton CW, et al. A randomized clinical trial of high-dose epinephrine and norepinephrine vs standarddose epinephrine in prehospital cardiac arrest. JAMA 1992;268:2667-2672. (Randomized, double-blind; 816 patients)
  110. Brown CG, Martin DR, Pepe PE, et al. A comparison of standarddose and high-dose epinephrine in cardiac arrest outside the hospital. N Engl J Med 1992;327:1051-1055. (Randomized, doubleblind; 1280 patients)
  111. Stiell IG, Hebert PC, Weitzman BN, et al. High-dose epinephrine in adult cardiac arrest. N Engl J Med 1992;327:1045-1050. (Randomized, double-blind; 650 patients)
  112. * Gueugniaud PY, Mols P, Goldstein P, et al. A comparison of repeated high doses and repeated standard doses of epinephrine for cardiac arrest outside the hospital. N Engl J Med 1998;339:1595- 1601. (Randomized, double-blind; 3327 patients)
  113. Vandycke C, Martens P. High dose versus standard dose epinephrine in cardiac arrest—a meta-analysis. Resuscitation 2000;45:161-166. (Meta-analysis)
  114. McCrirrick A, Kestin I. Haemodynamic effects of tracheal compared with intravenous adrenaline. Lancet 1992;340:868-870. (Randomized crossover trial; 12 patients)
  115. Niemann JT, Stratton SJ, Cruz B, et al. Endotracheal drug administration during out-of-hospital resuscitation: where are the survivors? Resuscitation 2002;53:153-157. (Retrospective cohort; 596 patients)
  116. Bleske BE, Billi JE. Comparison of adrenergic agonists for the treatment of ventricular fibrillation and pulseless electrical activity. Resuscitation 1994;28:239-251. (Review)
  117. Lindner KH, Prengel AW, Brinkmann A, et al. Vasopressin administration in refractory cardiac arrest. Ann Intern Med 1996;124:1061-1064. (Case series; 8 patients)
  118. Morris DC, Dereczyk BE, Grzybowski M, et al. Vasopressin can increase coronary perfusion pressure during human cardiopulmonary resuscitation. Acad Emerg Med 1997;4:878-883. (Case series; 10 patients)
  119. Lindner KH, Dirks B, Strohmenger HU, et al. Randomised comparison of epinephrine and vasopressin in patients with outof- hospital ventricular fibrillation. Lancet 1997;349:535-537. (Randomized, double-blind; 40 patients)
  120. * Stiell IG, Hebert PC, Wells GA, et al. Vasopressin versus epinephrine for inhospital cardiac arrest: a randomised controlled trial. Lancet 2001;358:105-109. (Randomized, blinded; 200 patients)
  121. American Heart Association. Guidelines 2000 for cardiopulmonary resuscitation and emergency cardiovascular care. Part 6: advanced cardiovascular life support, Section 5: Pharmacology I: Agents for arrhythmias. Circulation 2000;102[Suppl I]:I112-I128. (Consensus guidelines)
  122. Harrison EE. Lidocaine in prehospital countershock refractory ventricular fibrillation. Ann Emerg Med 1981;10:420-423. (Retrospective; 116 patients)
  123. Weaver WD, Fahrenbruch CE, Johnson DD, et al. Effect of epinephrine and lidocaine therapy on outcome after cardiac arrest due to ventricular fibrillation. Circulation 1990;82:2027-2034. (Unblinded, randomized; 199 patients)
  124. Herlitz J, Ekstrom L, Wennerblom B, et al. Lidocaine in out-of-hospital ventricular fibrillation. Does it improve survival? Resuscitation 1997;33:199-205. (Retrospective cohort; 1212 patients)
  125. Nowak RM, Bodnar TJ, Dronen S, et al. Bretylium tosylate as initial treatment for cardiopulmonary arrest: randomized comparison with placebo. Ann Emerg Med 1981;10:404-407. (Randomized, double-blind; 59 patients)
  126. Olson DW, Thompson BM, Darin JC, et al. A randomized comparison study of bretylium tosylate and lidocaine in resuscitation of patients from out-of-hospital ventricular fibrillation in a paramedic system. Ann Emerg Med 1984;13:807- 810. (Randomized, unblinded; 91 patients)