Delayed Defibrillation: Research and Results / Interview with Paul S. Chan, MD

What made you look into the topic of delayed defibrillation? What interested you about this topic? There has been a trend over the past decade in examining processes of care, and probably the most prominent one in the hospital setting is door-to-balloon time for ST elevation myocardial infarction (STEMI). Much research has also been done on out-of-hospital resuscitation, in terms of how quickly EMS could provide services to cardiac arrest victims in the field. However, very little is known about cardiac arrest inside the hospital. We knew there was a recommendation from the American Heart Association (AHA) to achieve prompt defibrillation within two minutes of cardiac arrest; we wanted to find out how reasonable that was, how achievable that was and what the impact of delays beyond two minutes would be for survival. Describe your patient selection. What patients from what hospital units were studied? Who was excluded, and why? We studied patient data from the National Registry of Cardiopulmonary Resuscitation (NRCPR). Specifically, we examined in-hospital cardiac arrests that were caused by ventricular fibrillation or pulseless ventricular tachycardia. We excluded patients who had cardiac arrest due to asystole or pulseless mechanical activity, which do not respond to defibrillation. It is important to note that we also only included those patients whose first identified rhythm was ventricular fibrillation or pulseless ventricular tachycardia; sometimes patients are in cardiac arrest from ventricular tachycardia or ventricular fibrillation, but their first rhythm might have been asystole or some other rhythm, so those patients were not considered. Only the patients whose first identified rhythm was ventricular fibrillation or pulseless ventricular tachycardia were included in this study. The hospital units we looked at included the intensive care units, the telemetry-monitored hospital units where patients were monitored 24 hours a day, and the unmonitored floors, primarily general medical or surgical floors. We did not include cardiac arrest patients who had their cardiac arrest during procedures (e.g., during surgery, right after surgery or in the recovery area) or during cardiac procedures like catheterizations or ablation therapy. We also excluded patients who already had an implantable cardioverter-defibrillator (ICD) implanted, and those patients who were receiving medications for cardiac arrhythmias. These medications included continuous infusions of epinephrine, amiodarone, lidocaine, or procainamide. Explain your findings. What were the most common characteristics that determined delayed defibrillation? Were you surprised by the data? There were two main findings. The first was seeing who was more likely to have delays in defibrillation and what the impact of delay was on patient survival. The patients who experienced delayed defibrillation tended to cluster into two types of characteristics: being of black race and being admitted with a noncardiac admitting diagnosis (e.g., pneumonia). There were other hospital level characteristics that were associated with delays, including being admitted at a small hospital (i.e., under 250 beds), having a cardiac arrest in the middle of the night (i.e., after 5 p.m. and before 8 a.m.) or on the weekends, and being in an unmonitored hospital unit. The other primary finding was looking at the impact of delayed defibrillation. We found that 30 percent of the study population had delays in their defibrillation time (i.e., beyond two minutes). That is not surprising in the sense that we expected a certain number of patients to have delays, but we didn t know what the actual number would be. In addition, the hospitals that participate in the NRCPR are involved in an active ongoing quality assessment, so in effect, the actual rates of delays may be much higher than 30 percent, because these hospitals are likely among the higher performing hospitals. We also found that patients who had delays in defibrillation time were half as likely to survive to discharge from the hospital than patients who had prompt defibrillation within two minutes. In addition, of those patients who had delays in defibrillation who survived to being discharged, their chances of surviving without major neurologic or functional damage were significantly less. Another interesting thing we found when analyzing this from a minute-to-minute aspect was that it really didn t matter whether or not there was a cutoff of two minutes or three minutes ultimately it was a matter of time. So the faster patients were defibrillated, the better their outcomes, regardless of which comparisons of minutes we were studying. What do hospitals need to do to improve defibrillation times include more AEDs, more staff, etc.? I believe this article has done a good job of describing the epidemiology of this problem how extensive it is, how pervasive it is, and what its impact on survival is. However, as you ve pointed out, it is important to not only discuss what the epidemiology is, but what the potential solutions are. In effect, we really do not know what the real solutions are, but we can speculate as to what may make a huge difference in survival. I tend to think of it as both a logistics and a technology issue. As Dr. Leslie Saxon pointed out, we have the technology available in the form of automated external defibrillators (AEDs). These defibrillators can read and shock patients in a very efficient manner. We also have this technology in existing defibrillator systems in the hospital, so technology is not the issue. It seems that this is more an issue of logistics, but what type of logistics are we talking about? In most hospitals across this country, outside of the intensive care unit, when nurses come across a patient in cardiac arrest they are not empowered to defibrillate them out of their life-threatening arrhythmia. They can start CPR, call a code, and bring other staff to the patient s bedside, but in most hospitals the only ones who are allowed to shock patients are physicians or members of the code team. Unfortunately, even though a nurse is able to administer CPR, this may not be adequate. So the question is: why can we empower laypeople to use AEDs in public places but not empower nurses to defibrillate? If you think about it, not having an AED in a patient s room is not the issue, although it may play a role in fact, the longest delay in time is between when a person encounters a patient in cardiac arrest to the time it takes to find an appropriate hospital staff member who can perform the defibrillation. Therefore, that is the most important question: does this makes a huge difference in time? We believe that it probably will, although we don t know for sure at this time. There has also been a discussion on AED use. There are hospitals that have implemented a more generous availability of AEDs maybe not in every room, but certainly in hospital units that don t have monitored patients. The AEDs are located along the hallway corridors of the hospital, making the transition of calling a code and bringing a defibrillator that is not as hefty into the patient s room much easier. Of course, even if AEDs are more available, you also need to make sure that staff are familiar with their use. Administering treatment with an AED is not simply just having an AED and hoping for the best; people have to know how to use them and how to apply them to a patient s chest, so there is going to be an educational component involved in their use. In addition, some people have speculated that practicing more mock code drills in hospitals might be helpful. This would be similar to how fire drills are practiced in schools, and knowing that when a real fire drill is called, people would know what to do. It is the same thing in a code setting; going through the motions on a regular routine basis whether it is on a monthly or quarterly basis and assessing what the problems or obstacles are will help to enhance efficiency and also defibrillation time. Therefore, I believe Dr. Saxon highlights one potential solution. We really do not yet know which one or combination of these solutions will ultimately make a difference in defibrillation times for patients. I think we need to take a step back before we consider suggesting that all hospitals should: 1) monitor all patients for cardiac arrest, which can be expensive, or 2) put AEDs in without knowing how cost effective and how frequently these codes occur on unmonitored unit settings. The reality is the majority of the arrests (about 80 to 85 percent) in our study occurred in settings such as the intensive care unit or the telemetry floor, so these patients were already being monitored. Therefore, it wasn t a question of discovering that the patients were in cardiac arrest, it was getting the logistics of a defibrillator shock to them. Thus, it may be much more complex than one solution. Do you know if there were any hospitals that had significantly more problems than others? Or were there worse defibrillation times in particular areas of the U.S.? At the time of the analysis we had only very crude geographic markers, including four geographic regions (northeast, midwest, south, and west). We are obtaining more hospital information as we speak that is much more refined and will provide data on the economic status of the hospitals, the nurse-to-patient ratio, academic status, and whether or not the hospitals had AEDs available. We are looking at about 50 variables at each of the hospitals that we hope will ultimately identify which of these hospitals perform better and what the unique qualities were at these hospitals. We are particularly interested in knowing which hospitals with greater resources and academic affiliations perform better. Do you know if the hospitals included in this study will be making changes to improve patient survival? Yes, the NRCPR hospitals have been doing an ongoing quality improvement. They receive quarterly feedback reports, and a number of them have also implemented rapid response teams that typically intervene before a patient suffers from cardiac arrest. In a rapid response team, a nurse or staff person calls this team because the patient is looking poorly and going for the worse. The members of this team come and evaluate the patient, and determine whether or not the patient needs intervention. The hope is that they can prevent a cardiac arrest from ever occurring, let alone improving their outcomes. A number of the NRCPR hospitals have implemented rapid response teams; we will be getting the information soon to look at whether or not they ve had an impact. Will you be doing further research on this topic? Yes, I will be involved in the statistical analyses of the rapid response teams; one of the other task force members is heading that study. I will also be looking at hospital level differences in defibrillation times. Ultimately we are considering how best to do interventions to see which of the things we discussed may potentially modify the times for defibrillation and hopefully affect overall survival rates. More information can be found at: N Engl J Med 2008;358:9-17.