Cardiac Resuscitation — When Is Enough Enough?
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《新英格兰医药杂志》
Cardiac arrest is a leading cause of death in the United States.1 In spite of periodic updates of the Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care of the American Heart Association (AHA) (hereafter referred to as the AHA guidelines), survival rates are dismal in the absence of early defibrillation and have remained essentially unchanged for decades.1,2 In large cities in the United States, overall survival of out-of-hospital arrest of presumed cardiac cause is about 1 percent — approximately the rate that has been suggested to define medical futility.2,3 The cost of providing emergency medical services (EMS) to persons with out-of-hospital arrest of presumed cardiac cause is considerable. Given these facts, the cost–benefit ratio might be questioned.
At one end of the spectrum of patients with out-of-hospital arrest of presumed cardiac cause are those in whom the arrest was not witnessed, those in whom the arrest was witnessed but no resuscitative efforts were made by a bystander, and those for whom the arrival of EMS personnel was late. This subgroup of patients have little chance of survival. If, in addition, a shock is not delivered or advised and there is no return of spontaneous circulation, almost none survive. Transportation of such patients to the emergency department consumes resources, puts the public (because of road hazards) and the providers at risk, increases costs, and may decrease the availability to other patients of the resources of the EMS system and the emergency department.4
It has therefore been acknowledged by expert groups that for some patients with little or no chance of survival, continued resuscitative efforts in the field are not appropriate. For services delivering advanced cardiac life support in England, the Recognition of Life Extinct (ROLE) guidelines state that "resuscitation attempts should be terminated when the patient remains in asystole despite full advanced life support procedures for more than 20 minutes."5 The 2005 AHA guidelines state that resuscitative efforts should be continued until "reliable criteria indicating irreversible death are present"1 — a recommendation that leaves more latitude than the ROLE guidelines do for the use of judgment by the medical personnel involved but that may be more difficult to apply in practice.
In this issue of the Journal, Morrison and the other investigators of the Termination of Resuscitation (TOR) study6 report on their prospective validation of their previously published "termination of resuscitation prediction rule" for use by EMS personnel equipped with and trained in the use of an automated external defibrillator responding to an out-of-hospital arrest of presumed cardiac cause. The authors found that only 0.5 percent of patients with an arrest survived if there was no return of spontaneous circulation, no shocks were administered, and the arrest was not witnessed by EMS personnel. When a "response interval greater than eight minutes" was retrospectively added to the prediction rule, the survival rate was 0.3 percent, and when "not witnessed by a bystander" was added, no such patients survived. These findings suggest that it is possible to identify a subgroup of patients with out-of-hospital arrest of presumed cardiac cause in whom resuscitative efforts can be discontinued and the patient pronounced dead in the field. This approach would result in the transportation to the emergency department of far fewer patients.
The TOR guidelines of Morrison et al. were recently compared retrospectively with two similar prediction rules for use by emergency medical technicians trained in the use of an automated external defibrillator.4 In an analysis of 13,684 patients with out-of-hospital arrest of presumed cardiac cause, 636 of whom survived to hospital discharge, the TOR guidelines were nearly as sensitive for the identification of survivors as were the other two prediction rules (99.5 percent vs. 99.8 percent) but were much more specific (52.9 percent vs. 9.9 percent and 19.4 percent). Expressed another way, the TOR guidelines would have recommended termination for three surviving patients (as compared with one each according to the other two rules), while also recommending transportation of 6776 patients (as compared with 12,391 and 11,148 according to the algorithms used in the other two rules).
Should the prediction rule of the TOR investigators be considered the definitive approach? Certainly, the survival rate among patients fulfilling their criteria is estimated to be very low, and the benefit in the reduction in the number of patients transported to the emergency department is significant. Two questions arise. First, for how long should resuscitative efforts be attempted and what basic resuscitative techniques should be used before a determination is made that "there is no return of spontaneous circulation"? Second, what other clinical features should be taken into account in efforts to resuscitate the patient (e.g., the very young person with hypothermia)? In resolving these issues, medical judgment is necessary, and therefore the criteria proposed by Morrison et al. should be considered advisory. The authors acknowledge that they consider their prediction rule to be a form of guidance for clinicians, rather than an obligatory policy.
There is a caveat to this study. At the time that the study was being conducted, EMS personnel followed the 2000 AHA guidelines, which are no longer considered to be optimal.7 For example, there is good evidence that when following the 2000 guidelines, paramedics and other EMS personnel compressed the patient's chest only half the time during which the resuscitative efforts were performed, thus perfusing the heart and brain only half that time.8,9 When the study by Morrison et al. was being conducted, bystanders initiating cardiopulmonary resuscitation used a ventilation:compression ratio that is so ineffective that it is no longer recommended.1 Since the completion of this study, the 2005 AHA guidelines, which differ in a number of ways from the 2000 AHA guidelines, have been published.1 Furthermore, new approaches to resuscitative efforts in out-of-hospital arrest of presumed cardiac cause, such as cardiocerebral resuscitation,10,11,12,13 may result in a shift in the entire approach to out-of-hospital cardiac arrest. As noted by the authors, it is plausible that their guidelines for the termination of resuscitative efforts, with some minor modifications, may still be applicable. However, proof of continued validity may require additional testing.
This is an exciting era in cardiopulmonary resuscitation. Decades ago, the approach to cardiopulmonary resuscitation was thought to be so well understood that we had "standards," then "standards and guidelines," and now "guidelines."1,7,14,15,16 As our knowledge evolves, it may be necessary to develop clinical protocols that move beyond the present rules and guidelines. The TOR investigators' clinical prediction rule may be one such protocol. Even then, medical judgment will still be required to determine when enough is enough.
No potential conflict of interest relevant to this article was reported.
Source Information
From the University of Arizona Sarver Heart Center, University of Arizona Health Sciences Center, Tucson.
References
2005 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation 2005;112:Suppl IV:IV-1.
Eckstein M, Stratton SJ, Chan LS. Cardiac Arrest Resuscitation Evaluation in Los Angeles: CARE-LA. Ann Emerg Med 2005;45:504-509.
Schneiderman LJ, Jecker NS, Jonsen AR. Medical futility: its meaning and ethical implications. Ann Intern Med 1990;112:949-951.
Ong MEH, Jaffey J, Stiell I, Nesbitt L. Comparison of termination-of-resuscitation guidelines for basic life support: defibrillator providers in out-of-hospital cardiac arrest. Ann Emerg Med 2006;47:337-343.
Recognition of Life Extinct (ROLE) by ambulance staff. London: The Joint Royal Colleges Ambulance Liaison Committee, March 2003. (Accessed July 13, 2006, at http://www.asancep.org.uk/JRCALC/publications/docs/ROLE_Most_FINAL_March2003.pdf.)
Morrison LJ, Visentin LM, Kiss A, et al. Validation of rule for termination of resuscitation in out-of-hospital cardiac arrest. N Engl J Med 2006;355:478-487.
Guidelines 2000 for cardiopulmonary resuscitation and emergency cardiovascular care: International Consensus on Science. Circulation 2000;102:Suppl:I-1.
Wik L, Kramer-Johansen J, Myklebust H, et al. Quality of cardiopulmonary resuscitation during out-of-hospital cardiac arrest. JAMA 2005;293:299-304.
Valenzuela TD, Kern KB, Clark LL, et al. Interruptions of chest compressions during emergency medical systems resuscitation. Circulation 2005;112:1259-1265.
Ewy GA. A new approach for out-of-hospital CPR: a bold step forward. Resuscitation 2003;58:271-272.
Kern KB, Valenzuela TD, Clark LL, et al. An alternative approach to advancing resuscitation science. Resuscitation 2005;64:261-268.
Ewy GA. Cardiocerebral resuscitation: the new cardiopulmonary resuscitation. Circulation 2005;111:2134-2142.
Kellum MJ, Kennedy KW, Ewy GA. Cardiocerebral resuscitation improves survival of patients with out-of-hospital cardiac arrest. Am J Med 2006;119:335-340.
Standards for cardiopulmonary resuscitation (CPR) and emergency cardiac care (ECC). JAMA 1974;227:Suppl 7:833-868.
Standards and guidelines for cardiopulmonary resuscitation (CPR) and emergency cardiac care (ECC). JAMA 1980;244:453-509.
Standards and guidelines for cardiopulmonary resuscitation (CPR) and emergency cardiac care (ECC). JAMA 1986;255:2905-2989.(Gordon A. Ewy, M.D.)
At one end of the spectrum of patients with out-of-hospital arrest of presumed cardiac cause are those in whom the arrest was not witnessed, those in whom the arrest was witnessed but no resuscitative efforts were made by a bystander, and those for whom the arrival of EMS personnel was late. This subgroup of patients have little chance of survival. If, in addition, a shock is not delivered or advised and there is no return of spontaneous circulation, almost none survive. Transportation of such patients to the emergency department consumes resources, puts the public (because of road hazards) and the providers at risk, increases costs, and may decrease the availability to other patients of the resources of the EMS system and the emergency department.4
It has therefore been acknowledged by expert groups that for some patients with little or no chance of survival, continued resuscitative efforts in the field are not appropriate. For services delivering advanced cardiac life support in England, the Recognition of Life Extinct (ROLE) guidelines state that "resuscitation attempts should be terminated when the patient remains in asystole despite full advanced life support procedures for more than 20 minutes."5 The 2005 AHA guidelines state that resuscitative efforts should be continued until "reliable criteria indicating irreversible death are present"1 — a recommendation that leaves more latitude than the ROLE guidelines do for the use of judgment by the medical personnel involved but that may be more difficult to apply in practice.
In this issue of the Journal, Morrison and the other investigators of the Termination of Resuscitation (TOR) study6 report on their prospective validation of their previously published "termination of resuscitation prediction rule" for use by EMS personnel equipped with and trained in the use of an automated external defibrillator responding to an out-of-hospital arrest of presumed cardiac cause. The authors found that only 0.5 percent of patients with an arrest survived if there was no return of spontaneous circulation, no shocks were administered, and the arrest was not witnessed by EMS personnel. When a "response interval greater than eight minutes" was retrospectively added to the prediction rule, the survival rate was 0.3 percent, and when "not witnessed by a bystander" was added, no such patients survived. These findings suggest that it is possible to identify a subgroup of patients with out-of-hospital arrest of presumed cardiac cause in whom resuscitative efforts can be discontinued and the patient pronounced dead in the field. This approach would result in the transportation to the emergency department of far fewer patients.
The TOR guidelines of Morrison et al. were recently compared retrospectively with two similar prediction rules for use by emergency medical technicians trained in the use of an automated external defibrillator.4 In an analysis of 13,684 patients with out-of-hospital arrest of presumed cardiac cause, 636 of whom survived to hospital discharge, the TOR guidelines were nearly as sensitive for the identification of survivors as were the other two prediction rules (99.5 percent vs. 99.8 percent) but were much more specific (52.9 percent vs. 9.9 percent and 19.4 percent). Expressed another way, the TOR guidelines would have recommended termination for three surviving patients (as compared with one each according to the other two rules), while also recommending transportation of 6776 patients (as compared with 12,391 and 11,148 according to the algorithms used in the other two rules).
Should the prediction rule of the TOR investigators be considered the definitive approach? Certainly, the survival rate among patients fulfilling their criteria is estimated to be very low, and the benefit in the reduction in the number of patients transported to the emergency department is significant. Two questions arise. First, for how long should resuscitative efforts be attempted and what basic resuscitative techniques should be used before a determination is made that "there is no return of spontaneous circulation"? Second, what other clinical features should be taken into account in efforts to resuscitate the patient (e.g., the very young person with hypothermia)? In resolving these issues, medical judgment is necessary, and therefore the criteria proposed by Morrison et al. should be considered advisory. The authors acknowledge that they consider their prediction rule to be a form of guidance for clinicians, rather than an obligatory policy.
There is a caveat to this study. At the time that the study was being conducted, EMS personnel followed the 2000 AHA guidelines, which are no longer considered to be optimal.7 For example, there is good evidence that when following the 2000 guidelines, paramedics and other EMS personnel compressed the patient's chest only half the time during which the resuscitative efforts were performed, thus perfusing the heart and brain only half that time.8,9 When the study by Morrison et al. was being conducted, bystanders initiating cardiopulmonary resuscitation used a ventilation:compression ratio that is so ineffective that it is no longer recommended.1 Since the completion of this study, the 2005 AHA guidelines, which differ in a number of ways from the 2000 AHA guidelines, have been published.1 Furthermore, new approaches to resuscitative efforts in out-of-hospital arrest of presumed cardiac cause, such as cardiocerebral resuscitation,10,11,12,13 may result in a shift in the entire approach to out-of-hospital cardiac arrest. As noted by the authors, it is plausible that their guidelines for the termination of resuscitative efforts, with some minor modifications, may still be applicable. However, proof of continued validity may require additional testing.
This is an exciting era in cardiopulmonary resuscitation. Decades ago, the approach to cardiopulmonary resuscitation was thought to be so well understood that we had "standards," then "standards and guidelines," and now "guidelines."1,7,14,15,16 As our knowledge evolves, it may be necessary to develop clinical protocols that move beyond the present rules and guidelines. The TOR investigators' clinical prediction rule may be one such protocol. Even then, medical judgment will still be required to determine when enough is enough.
No potential conflict of interest relevant to this article was reported.
Source Information
From the University of Arizona Sarver Heart Center, University of Arizona Health Sciences Center, Tucson.
References
2005 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation 2005;112:Suppl IV:IV-1.
Eckstein M, Stratton SJ, Chan LS. Cardiac Arrest Resuscitation Evaluation in Los Angeles: CARE-LA. Ann Emerg Med 2005;45:504-509.
Schneiderman LJ, Jecker NS, Jonsen AR. Medical futility: its meaning and ethical implications. Ann Intern Med 1990;112:949-951.
Ong MEH, Jaffey J, Stiell I, Nesbitt L. Comparison of termination-of-resuscitation guidelines for basic life support: defibrillator providers in out-of-hospital cardiac arrest. Ann Emerg Med 2006;47:337-343.
Recognition of Life Extinct (ROLE) by ambulance staff. London: The Joint Royal Colleges Ambulance Liaison Committee, March 2003. (Accessed July 13, 2006, at http://www.asancep.org.uk/JRCALC/publications/docs/ROLE_Most_FINAL_March2003.pdf.)
Morrison LJ, Visentin LM, Kiss A, et al. Validation of rule for termination of resuscitation in out-of-hospital cardiac arrest. N Engl J Med 2006;355:478-487.
Guidelines 2000 for cardiopulmonary resuscitation and emergency cardiovascular care: International Consensus on Science. Circulation 2000;102:Suppl:I-1.
Wik L, Kramer-Johansen J, Myklebust H, et al. Quality of cardiopulmonary resuscitation during out-of-hospital cardiac arrest. JAMA 2005;293:299-304.
Valenzuela TD, Kern KB, Clark LL, et al. Interruptions of chest compressions during emergency medical systems resuscitation. Circulation 2005;112:1259-1265.
Ewy GA. A new approach for out-of-hospital CPR: a bold step forward. Resuscitation 2003;58:271-272.
Kern KB, Valenzuela TD, Clark LL, et al. An alternative approach to advancing resuscitation science. Resuscitation 2005;64:261-268.
Ewy GA. Cardiocerebral resuscitation: the new cardiopulmonary resuscitation. Circulation 2005;111:2134-2142.
Kellum MJ, Kennedy KW, Ewy GA. Cardiocerebral resuscitation improves survival of patients with out-of-hospital cardiac arrest. Am J Med 2006;119:335-340.
Standards for cardiopulmonary resuscitation (CPR) and emergency cardiac care (ECC). JAMA 1974;227:Suppl 7:833-868.
Standards and guidelines for cardiopulmonary resuscitation (CPR) and emergency cardiac care (ECC). JAMA 1980;244:453-509.
Standards and guidelines for cardiopulmonary resuscitation (CPR) and emergency cardiac care (ECC). JAMA 1986;255:2905-2989.(Gordon A. Ewy, M.D.)