Expert Conversations: The Future of the Mobile Stroke Unit

In part three of this series, Section Editor Amrou Sarraj, MD, discusses future possibilities for the Mobile Stroke Unit, including upcoming integrations with clinical practices, the application of telemedicine, and how future research could be applied with James Grotta, MD, Director of Stroke Research, Clinical Institute for Research and Innovation, Memorial Hermann Hospital– TMC; Director, Mobile Stroke Unit Consortium as well as Geoffrey Donnan AO, and Stephen Davis AM, Professors of Neurology and Translational Neuroscience at the University of Melbourne and Co-Chairs of the Australian Stroke Alliance.

Listen to part one and part two. 

Read the Transcript:

Dr. Sarraj:  With that, this is a very important point. One would say, "Well, you all are dedicated. You are in major medical centers where you have other physicians and fellows that can cover the mobile stroke unit," but there are areas where you do not have stroke specialists.

I want to go to Dr. Grotta with this because I know the innovation with using the telemedicine, the physician does not have to be on the mobile stroke unit 24/7 but we can utilize the concept of telemedicine.

Dr. Grotta:  I was in clinic today. I did my mobile stroke in a call from clinic today. I had a clinic full of patients and I still treated two to three patients on the mobile stroke unit.

One physician could cover easily a whole region of five or six mobile stroke units. But I agree, we have to make them more nimble in the future, but it's not like we can't get started now.

Dr. Sarraj:  Definitely. The thrombolysis is you go, and you deliver it to the patients, but we have another problem. Those are the major strokes where decreasing with the disability with large vessel occlusion, decreasing the disability would translate to better clinical outcomes and more cost-effectiveness because this is where probably the money is.

We have done a paper, you and I, Jim, a year ago, that showed only one-third of the United States population is within 60 minutes from a thrombectomy center. That leaves a large number of population without that.

With that, that would be a good leeway to how the mobile stroke units are being utilized into screening, identifying these patients, and instead of taking them to non-thrombectomy center, triaging them to thrombectomy center.

Dr. Grotta:  Mobile stroke unit is a stroke center. It's basically a stroke-ready hospital.

Dr. Sarraj:  Right. So, triage in the patients, saving time instead of the patient going to the non-thrombectomy center rather to the thrombectomy center, pre-notifying the endovascular team to be ready and receive the patient probably going directly to the angio and saving time on the images. I'm sure the same model is being utilized in Australia as well.

Dr. Davis:  It's interesting that cost-effectiveness study, which we published in Stroke. The main driver for cost-effectiveness is exactly as you are describing, the mobile stroke unit allowing more efficient triage of patients for thrombectomy to directly to a thrombectomy-capable center.

As you know, the recovery from a thrombectomy is quite spectacular. This is a pretty strong driver economically.

Dr. Sarraj:  That is great. We have to touch, for the future, we talked a lot about the future with the lightweight imaging devices and the telemedicine. We have to touch on some of the work done, not only for ischemic stroke, but for hemorrhagic stroke.

Dr. Grotta, you're leading a clinical trial for acutely treating intracerebral hemorrhage in the prehospital setting. Do you want to tell us a little about that?

Dr. Grotta:  We were preempted by my colleagues in Australia who did a job before we did in hemorrhage. Everyone is interested in treating hemorrhage. I don't think we're going to have quite as big an impact on intracerebral hemorrhage as we do on ischemic stroke because we can't put the blood back and take it out of the brain with our treatment.

We can only limit further growth. It stands to reason the sooner we intercede in the first few minutes in limiting hemorrhage growth, the bigger impact we're going to have. Right now, we don't have any option. Looking back at the data from factor VIIA studies suggest that very early treatment in moderate-sized hemorrhages is where the money is. That's the trial we're about to start.

Dr. Donnan:  In Australia, we're doing the STOP-MSU trial, which is the same principle, which hemorrhages are dynamic that grow early, particularly in the first three hours. It's a little analogous to the ischemic penumbra story of early intervention and salvage, but a completely different concept where they continue to ooze.

We're using tranexamic acid within the first two hours. In Jim's trial, we use factor VIIA. These are hemostatic drugs. We hope that they will be a hyperacute treatment that we can give to many patients.

Dr. Sarraj:  It might not improve the functional outcome but might reduce the growth of the hemorrhages as mentioned. It might decrease the herniation rate and decrease the need for hemicraniectomy and decrease the length of stay and hopefully the mortality and disability. We definitely suffer for treating intracerebral hemorrhage for the longest time.

Hopefully, something can help. I have to mention our colleague cardiologists. They have the EKG in the field to diagnose with MI, and triage the patients, and call to get the cath lab ready, and all of that.

The mobile stroke unit is part of the solution for the prehospital care and was the dominant part of our discussion, but there are other things with that [such as] screening in the field with the ultrasound and biomarkers. Let's quickly touch on that. Where do we see this falling in the whole prehospital care concept, in the mobile stroke unit if there's any component of that.

Dr. Davis:  I think it’s a long way off. What we need is brain imaging to determine if there's bleeding in the brain because we can't see CPA if there is any blood. I'm fairly pessimistic that in the short to medium term, ultrasound can achieve that aim or biomarkers. It's brain imaging. Currently, CT is the gold standard. MRI is logistically more difficult, at least is heavy. So, I think lightweight imaging is going to be the way forward.

Dr. Donnan:  I agree, Steve. There's fascinating research going on with biomarkers trying to distinguish hemorrhaging brain from infarcting brain. Frankly, this has been going on now for more than a decade. It's very hard to get a definitive distinction based on blood biomarkers, at least.

It doesn't mean you shouldn't keep trying. Also, ultrasound is too crude compared to the sharp-imagining devices that we have at our fingertips, ultra lightweight CT promises to give a very, very sharp distinction between blood and no blood.

Ultrasound is never going to quite cut it to the same extent. Nor can you get a nice complete picture of the brain, which you need with these imaging devices.

Dr. Sarraj:  We also have seen recently the small magnet MRIs that's pretty much portable that can be used in the ICUs, so maybe this can be done in the mobile stroke units.

Dr. Davis:  It's possible that MRI may be later deployed. The challenges with MRI are much greater than with CT. While they have these portable ones, they're still pretty heavy. They're about 600 kilograms or more, 700. To get them down to 200, 100, and less is pretty difficult but not impossible. I wouldn't discount it.

Dr. Grotta:  I do think that one of the big problems we have on the mobile stroke unit is identifying stroke mimics and a large...We get called for 10 stroke calls for every one that we treat. Probably some of those nine that we exclude, may be having a stroke, because we won't treat the patient unless we're pretty sure.

Among the ones we do treat, nine percent of them are mimics. Among the ones we don't treat, there's probably some that are real strokes. There, MRI eventually may be helpful. Right now, we're not there.

Technology moves fast. We built the vaccine in a year. We probably can develop MRI scanners that are fast enough and small enough that eventually that would be able to help us with a mimic problem. I do agree with you, imaging is critical. The mobile stroke unit is a great platform for all sorts of research.

One of the big reasons we can't treat patients now is because they are on DOACs. How do you do the test to identify whether patients are anticoagulated or not? We use tag now on the mobile stroke unit to try to determine this. There are other ways that this may be done, other tests. Bottom line is, there’s all sorts of new technology that can be tested on the mobile stroke unit.

Dr. Donnan:  We certainly have to publish our experience, we give idarucizumab before giving dabigatran, in patients on dabigatran, and then follow it immediately with TPA. It's not feasible with andexanet which we don't have any way yet. In Australia, you can't reverse it quickly enough to get thrombolysis.

Dr. Grotta:  How do you know if someone's took a 10-day inhibitor? First of all, you don't know whether they did or not. And, how many hours ago? Are they still anticoagulated or not? A lot of these patients, they've had a stroke just like with warfarin, they're probably not effectively anticoagulated.

Dr. Donnan:  One of the big problems we have are just moving away from the reversal issue is the stroke mimic issue which you've touched on. We usually quite at a ratio of about 1:4 actually had a stroke. More than half of the stroke…at 60 percent. Of the ones we attend, only about half have a stroke. Of course, only a proportion of those are eligible for acute stroke treatment. Improvements in triaging is from call centers is another major challenge.

Dr. Grotta:  The other thing is that none of us have touched on is that if people don't call 911, then we can't even get started. When you realize we're only treating 10 or 20 percent at the most of stroke patients, even in the best circumstances, if we could double the likelihood of someone calling 911 when they have a stroke, and that requires removing the impediments to doing it.

If people don't call 911. Why don't they call 911? Well, one reason is they don't recognize it's a stroke. A lot of the reason is they don't want to engender the cost. They don't want to bother coming to the hospital. Inconvenience and all the rest of stuff. We need to get rid of that we need to make it more attractive for someone who may be having stroke symptoms to call 911 and call for help.

That would work to reducing morbidity from stroke than any new drug.

Dr. Donnan:  Jim, that's a very interesting point you make about awareness in the community. We've found, and you may have done the same and others that having a mobile stroke unit in your city raises the awareness of stroke enormously. It's like having a giant flagship wandering around saying…It’s one of the best advertisements for community education we've come across. Would you agree, Steve?

Dr. Davis:  Absolutely, the first message rolling around Melbourne, virtually everyone's seen the mobile stroke unit and are aware that stroke is an emergency, and that treatment is possible if you get there fast.

Dr. Sarraj:  That is a wonderful way also to come to the end of this. We covered a lot of ground. We covered from the core concept, the history, integrating the high level of evidence, all the way to how this can be affecting the upcoming changes with the guidelines and integrating into our clinical practices, how this could be cost-effective in saving disability and saving dollars and giving more quality of life years, to talking about the future and the lightweight images, the application of telemedicine, the research with the biomarkers and tag, and talked about the challenges in treating intracerebral hemorrhage on the mobile stroke unit, we even covered drones.

Hopefully, some legislators can hear this and help with funding those units to deliver the much-needed acute care to the stroke patients to improve their clinical outcomes.

I want to thank you all for joining us as I said at the beginning of this, a wealth of experience of clinical trials that has done this for the longest time. This definitely was not planned to advertise for the Mass General Fellowship program, but it's great that we could bring you all together after all of this. Hopefully, in two or three years we'll talk about the air ambulance unit.

We'll talk about the results of the intracerebral hemorrhage with Dr. Grotta, and all of the great and innovative things that you all are doing.