Circulation on the Run

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Dec 19, 2016

Dr. Carolyn Lam:               Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr. Carolyn Lam, Associate Editor from The National Heart Center and Duke National University of Singapore. We have such a special issue today. You see, it's entirely focused on resuscitation and I am delighted to have with me today, Associate Editor, Dr. Mark Lane from Puffs Medical Center, who really put this issue together. Welcome, Mark.

Dr. Mark Lane:                  Thank you Carolyn.

Dr. Carolyn Lam:               Mark, maybe you could start by telling us why the focus on resuscitation? I do believe this is the first time we've done this at Circulation.

Dr. Mark Lane:                  Yes, this is the first time we've done this at Circulation. It really was a confluence of a couple things coming together. Once is that over the spring and summer, we had a very high volume of high quality resuscitation papers come to Circ. This was not something that we actually asked for but we noted that there were a number of these. Also, it's an important time in resuscitation because a number of the resuscitation counsels across the world have called for improvements in the survival rate, noting that we already have the tools that we need to increase survival and we have to better apply these tools. The HA has provided a goal of doubling resuscitation and resuscitation counsels in Europe, New Zealand and Australia have also echoed that call.

Dr. Carolyn Lam:               That's great, so this is a really important issue. I just echo your words about their being a remarkable number of original papers. We have seven and they're just such high quality. Let's chat through them, shall we? I'm going to go by pre-hospital setting to the out of hospital setting and finally end up in the in-hospital setting. Shall we do that?

Dr. Mark Lane:                  That sounds great.

Dr. Carolyn Lam:               The first paper is really about identifying patients at risk for pre-hospital sudden cardiac death at the early phase of myocardial infarction. You want to tell us a bit about that one?

Dr. Mark Lane:                  This is a study coming from the emergency medical services in the greater Paris area, where they looked at their cardiac arrest and STEMIs over the last seven or eight years. What they were specifically looking at is, can you identify STEMI patients who are at risk for having a cardiac arrest, because if you could identify those patients, you'd want to get there very quickly because if you know they're going to arrest or they're going to have a cardiac arrest, then having a defibrillator there would be very important.

                                                What they found, is that you can actually identify STEMI patients who are higher likelihood of arrest and those STEMI patients are those with younger age, they're not obese, they don't have diabetes. They have shortness of breath in addition to their chest pain and they have a very short delay from the time of chest pain to their call EMS. That is they're very concerned about their chest pain. You could use these characteristics to predict which STEMI patients, which chest pain patients were at highly likelihood of having a cardiac arrest. There was as much as a 19-fold difference between individuals without any of these factors and individuals with several of these factors.

Dr. Carolyn Lam:               What I like about this, is that simplicity of that score. Age, symptoms and kind of the absence of diabetes, absence of obesity and that short time frame. It's something that could be asked on a routine questionnaire by EMS dispatchers, for example.

Dr. Mark Lane:                  Right. It highlights the importance of the dispatch system. That simple questions, you can really stratify risk and it's not just getting an ambulance out there. Truly stratifying risk in order to get there quicker.

Dr. Carolyn Lam:               There are two papers that deal with out of hospital cardiac arrest. One of them interestingly focusing on the neuro-protective effects of Glucagon-Like Peptide-1 analog Exenatide. Thoughts about that one?

Dr. Mark Lane:                  This is a randomized study from Denmark. Notable that there are very low number of randomized trials in resuscitation so the fact that they did this is remarkable. What they did, is this glucagon-like peptide analog is a type II diabetic medicine and there is some reason to believe that that may protect the brain after resuscitation and ROSP. They had two goals in this trial. One was to see if it was feasible to administer a drug within six hours of a cardiac arrest and the other was to get any sort of outcome measure of whether this could provide some benefit. They randomly assigned 120 comatose patients and half of them got the peptide analog and the other half did not. What they showed, it is feasible to give IV administration of a drug within six hours of a cardiac arrest. Unfortunately, the drug they used did not appear to have any clinical benefit and this was both a composite end-point of death in neurologic function but also an evaluation of a brain neuron specific amylase, which was actually brain damage so they didn't see any biological or clinical neuro-protective effects of this drug.

Dr. Carolyn Lam:               I didn't realize it until you said it, it is very difficult to do a randomized control trial. This is very significant just for that. The next study about the out of hospital arrest, really talks about bystander CPR and I think seeks to answer to what degree bystander CPR remains positively associated with survival with increasing time to potential defibrillation. Important question, what do you think of that?

Dr. Mark Lane:                  It's an important question that surprisingly has not been evaluated that closely. Most either studies either look at bystander CPR or EMS arrival times but don't look at the interaction between the two. This study looks at the interaction between bystander CPR and EMS response time and that's the critical thing in this paper that's very interesting.

                                                What they did is, they split bystander CPR with or without and then EMS response times five minutes, 10 minutes and longer. If EMS responds within five minutes and you had bystander CPR, the survival rates with good neurological outcome were 14.5%, which is really a remarkable number. If there was no bystander CPR and the EMS arrived within five minutes, it dropped to 6.3%. There was 2.3-fold higher likelihood of good neurologic survival with bystander CPR with EMS within five minutes.

                                                They also looked at the 10 minute response time of EMS and if you had bystander CPR and EMS arrived within 10 minutes, the survival rate was 6.7% and without bystander CPR, it was 2.2%. With bystander CPR and EMS arrival within 10 minutes, there was a three-fold higher likelihood of survival with bystander CPR. It's interesting that by 13 minutes, there really was essentially no difference in those individuals who had bystander CPR or not, suggesting that at that point it's taken so long for EMS to arrive, it really doesn't make really much difference between whether you have bystander CPR.

                                                A really important paper showing that bystander CPR is critical, but so is EMS arrival within five minutes especially, but even 10 minutes.

Dr. Carolyn Lam:               I like that paper and I really like the way you crystallized the findings so clearly like that. What I'm also liking is the way, even though these papers weren't invited or anything, there is this nice flow because from bystander CPR we now talk about duration of resuscitation. There's one regarding adults and followed by one in pediatric population so very nice set of papers. Could we start by maybe talking about the adult one? The one looking at the association between duration of resuscitation and favorable outcomes after out of hospital cardiac arrest from North America.

Dr. Mark Lane:                  The reason that these two papers are important is really the futility issue. When is it futile to continue a CPR and that's a very important question. This adult paper is from the ROC Consortium. The ROC is a North American Seer NIH Sponsored consortium that's been going on over the last 10 or so years. What they looked at was outpatients and they had a very large number of greater than 11,000 subjects and of those 8% survived with a good outcome. That's 8% of those 11,000. If you looked at those 8% that survived, 90% of those had return of spontaneous circulation with 20 minutes. You really wanted to get their blood pressure back within 20 minutes.

                                                If you went beyond 20 minutes to the return of spontaneous circulation, you still could get good outcome. It was less likely but it was more likely if you had initial shockable rhythm, you had a witnessed cardiac arrest or you had bystander CPR. If you had some of those features, then you would argue to continue CPR for a longer time period. Actually a very nice important paper that if you had those other three features, you could still get good neurologic functioning, even with resuscitation attempts up to 40 minutes.

Dr. Carolyn Lam:               Exactly. I thought I saw 47 minutes somewhere, but it gives us a bit of a guidance when we're making these really tough decisions and talking about tough decisions and futility, I think it's even more amplified in the pediatric population, isn't it? This next paper from Japan talks about the duration of pre-hospital CPR in the pediatric population. What are your thoughts on that one?

Dr. Mark Lane:                  This was a study from Japan, using their nation-wide Japanese data base. Actually, in many ways mirrored the adult experience. The number of patients analyzed with roughly the same. This was nearly 13,000. They looked at 30 day survival both overall and 30 day survival with good neurologic function and 30 day survival overall were 9% so similar to the 8% in adults and good neurologic function were 2.5%, which wasn't quite as good as in the adults and that the duration of CPR also was very important. Once CPR went out to 42 minutes there was less than 1% chance that that individual was going to survive with any significant neurologic outcome. If you had bystander CPR you could increase that time by four to five minutes but again showing very similar numbers to the adult population that once you start hitting that 40 to 45 minute time frame, if there's no return of spontaneous circulation then the odds of survival are really quite low.

                                                The time frame may be extended a bit by CPR, maybe be extended by a bit if you had a shockable rhythm. Again, very similar features to what were found in the adult study.

Dr. Carolyn Lam:               What a nice pair of papers. You know, the pediatric paper was paired by yet another, wasn't it? This one now addresses very importantly conventional versus compression only CPR in the pediatric population. Again, from Japan. I know both the pediatric papers were of great interest because you invited an editorial on this as well. You want to comment on those?

Dr. Mark Lane:                  This issue of compression only CPR versus standard CPR, which includes compression and ventilation is a very hot one because we know that if you can do compression only CPR, the individuals willing to do that type of CPR are much greater than the individuals willing to do mouth to mouth. In the adult population, there's been a number of very good retrospective registries and also randomized trials that showed that compression only CPR may be very similar ... In fact some studies better, some studies a little worse than compression-ventilation CPR.

                                                Whether this applies to the pediatric population is not clear. There is more asphyxial arrest in the pediatric population whereas in the adult it's more cardiac so there is concern that compression only CPR will not be as good in children. This group of investigators used the same registry. A little shorter time-frame. They looked at it for two years and thus only had 2,000 patients in this registry. Of these 2,000 patients 400 received conventional CPR, 700 received compression only CPR and 1,000 did not receive any CPR. The important findings in this study was that any CPR increases survival so if you did not get any CPR, your survival was 3.7%. If you got conventional CPR your survival was 25.9% and if you got compression only CPR your survival was 9.3%.

                                                When you compared unadjusted survival with compression only versus the standard CPR, the odds ratio were 3.42 that standard CPR was better than compression only CPR. However when you did multi-variable adjustment, that big difference decreased and was no longer statistically significant between conventional CPR and compression only CPR. The same was true when you did propensity score matching which is an attempt to randomize to match groups. There was really no difference between conventional CPR and and compression only CPR.

                                                From this study, it's clear that any CPR is better than no CPR. There was a hint here that standard CPR was better than compression only CPR but because that improvement disappeared with multi-variable adjustment and propensity score matching both the authors and the editorialists have called that it's time for a randomized trial of compression CPR in kids.

Dr. Carolyn Lam:               Very nice. That brings us already, to the last original paper. Into the in-hospital setting and it talks about time to epinephrine. That's nice. We've got time to balloon and time to door and and now we've got time to epinephrine. Tell us about this one.

Dr. Mark Lane:                  This was a very nice study from the guidelines database. This is a data base that the HA is using to evaluate resuscitation in hospitals. In this database, the investigators looked at times to the epinephrine administration and then overall patient survival for the hospitals. What they found is that there was wide variability in the time to first epinephrine dose. The HA and other counsels have recommended that it be given as soon as possible or early-on in resuscitation and in this database 12.7% of patients had delays greater than five minutes to epinephrine.

                                                What importantly they showed, when you looked at the hospital's overall time to epinephrine administration and the hospital's overall resuscitation survival rates, they were inversely proportional. That is, the longer that hospitals took to give the first dose of epinephrine, the lower their survival rate. This really leads to a very important question, is it the delay in epinephrine administration that makes the difference between these good functioning hospitals and poor functioning hospitals, or is it that the delay to epinephrine administration is really a surrogate for poor CPR performance. I suspect that both of them could be true, although I suspect the second one is probably a higher likelihood.

Dr. Carolyn Lam:               Congratulations again on this amazing issue with extremely important take-home messages just from the original papers. Were there other papers you wanted to highlight in this issue?

Dr. Mark Lane:                  Yeah, there were three research letters and this is a newer type thing for SERP. These are original manuscripts but in a very succinct fashion in that they're making a single point. I actually thought these three research papers were very interesting also. One was on the mechanical CPR in the cares database and in this paper they actually showed that mechanical CPR was associated with poor outcomes in resuscitation so a paper well worth reading. In another paper from France looked at pulmonary embolism related to sudden cardiac death and what they found is that PEs were present in a significant percentage of people who had sudden cardiac arrest and again if you had a non-shockable rhythm, female, prior thromboembolism or absence of heart disease you were more likely to have a pulmonary embolism.

                                                The final research letter looked at ticagrelor versus clopidogrel in comatose patients undergoing PCI, a randomized study. Succinct paper well worth reading. In addition to those three research letters, there were four frames of reference. These are more a personal perspective on resuscitation and resuscitation signs over time and interesting reading, all four of them.

Dr. Carolyn Lam:               Mark, that was a beautiful summary and I am sure you've whet the appetites of all the listeners to just grab hold of this issue. Thank you so much for joining me today. Thank you listeners for tuning in and don't forget to tune in next week.