Correspondence
Cardiopulmonary Resuscitation by Chest Compression Alone
N Engl J Med 2000; 343:815-817September 14, 2000
- Article
To the Editor:
Hallstrom et al. (May 25 issue)1 report that survival among patients with out-of-hospital cardiac arrest was similar whether untrained bystanders performed cardiopulmonary resuscitation (CPR) by chest compression alone or by chest compression and mouth-to-mouth ventilation. We are concerned about whether the results of a trial performed in the unique setting of Seattle can be applied to much of the rest of the world and whether the outcomes elsewhere can be expected to be similar. For example, how would CPR by chest compression alone fare if the mean first-unit response interval was not four minutes, as in the Seattle study, but substantially longer, as is typical in most areas of the United States? The arrival of emergency-medical-services personnel was so prompt in the Seattle study that we also question whether the two groups of patients received the randomly assigned therapy. In a considerable proportion of cases, the instructions for performing CPR were not even completed. The percentage of patients in whom effective CPR was performed by coached bystanders and the duration of the CPR are unclear. An evaluation of the effectiveness of CPR performed by bystanders, as judged by the emergency-medical-services personnel who arrived on the scene, would have been helpful. The overall rate of survival was lower for episodes of ventricular fibrillation that were included in the analysis than for those that were excluded. The authors explain the difference in survival by noting differences in age and location that favored survival in the excluded group.
Clinical data from the Seattle–King County emergency-medical-services system have been a primary factor in advocacy for the use of defibrillation as part of basic life support, the performance of CPR before defibrillation, and the consideration of amiodarone treatment in patients with out-of-hospital cardiac arrest due to refractory ventricular fibrillation.2-4 It is not known whether any of these findings are applicable to the majority of emergency-medical-services systems in the United States.
4 ReferencesWilliam J. Groh, M.D.
Douglas P. Zipes, M.D.
Indiana University, Indianapolis, IN 462021
Hallstrom A ,Cobb L ,Johnson E ,Copass M . Cardiopulmonary resuscitation by chest compression alone or with mouth-to-mouth ventilation. N Engl J Med 2000;342:1546-1553
Full Text | Web of Science | Medline2
Weaver WD ,Hill D ,Fahrenbruch CE , et al. Use of the automatic external defibrillator in the management of out-of-hospital cardiac arrest. N Engl J Med 1988;319:661-666
Full Text | Web of Science | Medline3
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
CrossRef | Web of Science | Medline4
Kudenchuk PJ ,Cobb LA ,Copass MK , et al. Amiodarone for resuscitation after out-of-hospital cardiac arrest due to ventricular fibrillation. N Engl J Med 1999;341:871-878
Full Text | Web of Science | Medline
To the Editor:
Hallstrom et al. excluded from their analysis cases in which a primary respiratory or airway-related cause of an apparent cardiac arrest was subsequently identified (drug overdose, alcohol intoxication, or carbon monoxide poisoning). The lay public cannot be expected to distinguish a true cardiac arrest from cases of apparent cardiac arrest in which respiration and pulse may be either absent or difficult to detect in an unresponsive person because of primary airway-related or respiratory causes rather than cardiac causes. However, it is precisely this group of patients who would be expected to have better prospects for survival if adequate first aid for airway and breathing problems were administered in addition to chest compression. The outcomes in such patients may be adversely affected if chest compression alone becomes accepted practice.
Peter Sprivulis, M.B., B.S.
Fremantle Hospital, Fremantle 6160, WA, AustraliaTo the Editor:
Hallstrom et al. ignored airway patency. Patients with acute coma (irrespective of the cause) have obstruction of upper-airway soft tissue in the absence of a backward tilt of the head, since the pharyngeal air passage is naturally kinked.1,2 Complete obstruction of the airway leads to cardiac arrest in 5 to 10 minutes. Chest compression alone does not produce reliable ventilation.1 Fifteen years ago, we showed that during sudden ventricular fibrillation in dogs, arterial blood remained oxygenated for a long time, but when sternal compression was begun with the airway closed, deoxygenation occurred within 30 to 60 seconds.3
3 ReferencesPeter Safar, M.D.
Patrick Kochanek, M.D.
Nicholas Bircher, M.D.
University of Pittsburgh, Pittsburgh, PA 152601
Safar P ,Brown TC ,Holtey WJ ,Wilder RJ . Ventilation and circulation with closed-chest cardiac massage in man. JAMA 1961;176:574-576
Web of Science | Medline2
Safar P ,Escarraga LA ,Chang F . Upper airway obstruction in the unconscious patient. J Appl Physiol 1959;14:760-764
Web of Science | Medline3
Lesser R ,Bircher N ,Safar P ,Stezoski W . Sternal compression before ventilation in cardiopulmonary resuscitation (CPR). Prehospital Disaster Med 1985;1:Suppl 1:239-241
Author/Editor Response
Dr. Hallstrom replies:
To the Editor: Drs. Groh and Zipes pose two important questions, which can be summarized as follows: Is the result real, and if so, can it be extrapolated to other communities? The possibility that neither form of dispatcher-instructed CPR is effective cannot be refuted, but two facts are noteworthy. First, the observed difference in survival associated with the two forms of CPR reached a marginal level of significance of 0.09 (the study was designed as a one-sided test, but two-sided P values were reported as required by the Journal ). This provides a reasonable level of evidence that something is happening. Second, the outcome for the randomized patients was equivalent to the outcome for the nonrandomized patients (the main reason for nonrandomization being that a trained bystander was performing CPR) after adjustment for known factors that predict the outcome, such as age and the location of the cardiac arrest. This finding suggests that CPR performed according to instructions provided by telephone was as effective as bystander-initiated CPR. The emergency-medical-services personnel who first arrived on the scene did not assess the quality of the ongoing CPR because CPR is usually discontinued in order to let emergency-medical-services personnel into the home. In some of the recorded dispatch calls, however, one can clearly hear what seem to be rigorous attempts at compression and ventilation.
The sample was too small for us to perform a meaningful analysis of a treatment effect or lack of effect according to the response time of the emergency-medical-services system. However, the point estimate of the relative benefit was not affected when the analysis was restricted to episodes in which the response time was four or more minutes. Fortunately, there are too few cases in Seattle in which the response time is longer than six minutes to attempt such an analysis. Thus, we cannot answer the question of whether this strategy would be effective in systems that have substantially longer response times than those in Seattle.
I agree with Dr. Sprivulis that patients who have primary respiratory arrest would presumably benefit from airway management and ventilation. We are currently reviewing the dispatch recordings to determine whether the dispatcher should have been able, if required, to make a judgment about whether the arrest was primarily respiratory. Anecdotally, it appears that such a judgment would have been very easy to make in almost all instances of recreational-drug overdose, which account for most respiratory arrests treated in Seattle. As we noted in our article, among the patients with respiratory arrest, the survival rate was only slightly higher for those randomly assigned to treatment with ventilation and chest compression than for those randomly assigned to treatment with chest compression alone.
I agree with Safar et al. that airway patency may be very important. Unfortunately, I also know, from pilot work for this study, that providing instruction in airway-patency management over the telephone is very difficult. If this study leads to a reconsideration of the protocol for CPR performed by bystanders, the issue of airway patency should not be ignored, but I believe the method of obtaining airway patency needs to be investigated. I suspect that a typical bystander, trained in CPR three or four years ago, would probably not manage the airway very well.
Alfred P. Hallstrom, Ph.D.
University of Washington, Seattle, WA 98105-4689- Citing Articles (1)
Citing Articles
1
Subha Varahan, Ruchir Sehra, Sanjiv M. Narayan. (2010) Improved survival in the real world with revised cardiopulmonary resuscitation guidelines: Doing better out of hospital but not out of the woods yet. Heart Rhythm 7:10, 1363-1364
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