Review of: Morrison LJ, Visentin LM, Kiss A, et al: Validation of a rule for termination of resuscitation in out-of-hospital cardiac arrest. New England Journal of Medicine. 2006. 355:510–512.
This study from Canada explores the application of a decision rule that could be used to determine which cardiac arrest patients are least likely to survive. The authors created this rule by examining retrospective data, then applied it prospectively to determine its impact on the number of patients transported who did not survive. They transported 100% of cardiac arrest patients while they applied the rule prospectively.
The rule recommended termination of cardiac arrest resuscitation in the field if all three of the following conditions applied: 1) the arrest was not witnessed by the EMT; 2) the AED never delivered a shock; and 3) there was no return of spontaneous circulation (ROSC) at any time.
By applying this rule to their 1,240 cardiac arrest patients, 776 would have met the criteria and termination in the field would have occurred. Four of these patients survived (0.5). The authors positively predicted who would not survive 99.5% of the time. Implementation of the rule would have resulted in only 37.4% of the patients being transported.
If the researchers had added the additional criteria of response time greater than 8 minutes or the arrest not witnessed by a bystander, the rule would have predicted non-survival 100% of the time, but would have resulted in a greater number of patient transports.
The basic principle at the core of this issue is what constitutes medical futility. We all understand that we can't save everyone. We understand that we don't have unlimited resources. However, we also recognize the level of critical review our failure to "save" someone can bring. Medical literature generally defines medical futility as any therapy or procedure with less than 1% probability of success. This definition is felt by some not to apply to cardiac arrest, for which the survival rate is already so low that a 1% survival rate may be more significant than it appears.
With that said, we need objective criteria to apply to out-of-hospital cardiac arrest so that we can more effectively use our resources. The transportation of cardiac arrest patients with continued resuscitation efforts underway in the back of the ambulance are of questionable value to the patient and pose significant potential for harm to the rescuers.
As one who feels that medical futility in cardiac arrest may be closer to 0.5% than 1%, I was intrigued by the data regarding the effect of not terminating resuscitation for patients whose arrest was witnessed by bystanders intriguing. Response intervals are simply too vague to use in the field, although it's very clear whether the arrest was witnessed or not.
The addition to the rule of "working" the patients whose arrest was witnessed would have included all four survivors, who would been terminated by the original rule. This addition would have required the transport of 75 additional non-survivors for each additional survivor. This number seems like a reasonable one to me, and the addition of this rule would more comfortably address the issue of dealing with family and bystanders who witnessed the arrest and have greater expectations regarding our efforts than the data would otherwise indicate.