Emergency Medicine

(2001)

13

, 145–146

Blackwell Science Asia

Commentary

Asystolic cardiac arrest: Poor outcome or terminal event?

Ian JacobsDepartment of Emergency Medicine, University of Western Australia, and Western Australian

Pre-Hospital Care Research Unit, Western Australia, Australia

The quest to reverse sudden cardiac death continues tobe one of the most dramatic interventions in currentmedical practice. Over the past 40 years resuscitativemeasures have restored the lives of many people whowould have died in the absence of such techniques.However, despite considerable advances in the scienceof resuscitation during this period, the overall chanceof survival remains at best mediocre and at worstdismal. Published studies have consistently identifiedcardiac rhythm, the initiation of bystander cardiopul-monary resuscitation (CPR) and time to defibrillationas key determinants of survival.

1,2

Where the under-lying cardiac arrest rhythm is ventricular fibrillation(VF) or ventricular tachycardia (VT), bystander CPRis initiated and defibrillation is achieved withinminutes, survival rates of in excess of 70% have beenreported.

3

Such survival is not achieved in those victims

whose underlying arrest rhythm is asystole. In thisissue, Meyer and colleagues review the outcome ofpatients suffering cardiac arrest in Melbourne, Aus-tralia, whose initial cardiac rhythm was asystole onarrival of ambulance personnel.

4

Their findings areconsistent with other published studies with reportedsurvival rates less than 1%.

5–7

The dismal outcomeof patients suffering asystolic cardiac arrest raisesa number of important issues for those managingout-of-hospital cardiac arrests.

First, is asystole a terminal event? From the avail-able data it is clear that very few patients ever surviveasystolic arrest. The presence of asystole more oftenconfirms death, rather than being an indicator for

maximal resuscitation efforts. This is evident in Meyer

et al.

’s study where resuscitation was attempted byambulance personnel in only 37% of asystolic cases.While the outcome of these patients is poor, it couldbe argued that these cases represent a failure of theemergency medical services to provide care in a timelyfashion. Larsen and Valenzuela have demonstrated anaverage decline of 10% in survival with each increas-ing minute in ambulance response time intervals.

8,9

The average response time intervals in Meyer

et al.

’sstudy was just under 10 min. Asystolic patients mayrepresent a cohort of cardiac arrest victims whoseinitial cardiac rhythm has degraded from being treatable(i.e. VF or VT) to becoming unresponsive (asystole).Earlier intervention may prevent a number of thesepatients moving down this final pathway to theirdemise. Notwithstanding the importance of enhancingearly intervention strategies, I believe it is reasonableto consider asystole as a terminal event in the absenceof any treatable causes.

Second, should asystolic cardiac arrest victimsreceive maximal resuscitation efforts in the field? Mostambulance service clinical guidelines call for resuscita-tion to be commenced on all cardiac arrest patientsexcept in cases where there is clear evidence that deathhas occurred. The recently published internationalguidelines for CPR and emergency cardiac care (ECC)state that asystolic patients should receive an adequatetrial of basic and advanced life support.

10

While initialresuscitation efforts are warranted, the salient questionis whether or not these patients should be transportedto hospital. Consistent with other published reports,

Ian Jacobs, BAppSci, DipEd, PhD, RN, FRCNA, Senior Lecturer, University of Western Australia and Director, Western Australian Pre-Hospital Care Research Unit.

EMM202.fm Page 145 Tuesday, May 8, 2001 1:59 PM

I Jacobs

146

this study supports the overall futility of continuingmaximal resuscitation in asystolic cardiac arrest.

In view of the minimal likelihood of survival andincreased risks associated with emergency trans-portation, it would be reasonable to terminate resu-scitation at the scene following adequate resuscitationefforts and subsequent failure to achieve a return ofspontaneous circulation. This is somewhat divergentfrom Meyer

et al.’

s recommendation that ‘all patientsin asystolic cardiac arrest should receive no treat-ment’. We should be in no hurry to terminate resus-citation, nor even to withhold such measures, in thefield. However, there needs to be clear criteria thatallow terminating resuscitation where ongoing effortsare likely to be futile.

Asystolic cardiac arrest with no obvious treatablecause and unresponsive to resuscitation meets suchcriteria. Clearly, as the resources required to get anambulance to the cardiac arrest victim have already beenutilized, there is little to be gained by not initiatingadequate resuscitation measures.

Asystolic cardiac arrest is clearly associated witha dismal outcome. Nevertheless it should not be seenas totally untreatable or even unpreventable. While wehave little understanding of the natural history ofasystole it is unclear whether it is associated withduration of cardiac arrest or, indeed, a primary event.There are opportunities for prehospital care providersto identify innovative strategies to reduce the timeto care following cardiac arrest, thus reducing theincidence of asystole as the initial cardiac rhythmupon arrival of ambulance.

Finally, while the chance of survival for asystoliccardiac arrest is less than one in a hundred, it is not

zero; if you are the survivor, the rest is meaningless!

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