International Stroke Conference (ISC)
February 17-19, 2016
February 17, 2016
This ISC session focused on a hot-topic: pre-hospital stroke triage and care. We learned about optimizing EMS triage protocols by learning from trauma and MI models, improving EMS providers’ clinical recognition of stroke, when to bypass local PSCs in favor of a CSC, and the role of technology in the pre-hospital setting.
Dr. McMullan from Cincinnati began the session discussing his personal experience as a prior EMT, and described the various levels of training that emergency responders may have. While the advanced technology we are coming up with is great, we can’t realistically have that everywhere and so we need to do our best in getting patients to the most appropriate location with the resources we have. We know that there are better outcomes at high volume/specialty centers, and that delays from secondary transfer decrease outcomes. However, we must recognize the limits of comprehensive centers, in terms of number of patients that can be accommodated. In the trauma example given, we learned that up to a 40% “overtriage” rate is acceptable (sending a lower level trauma to a higher level of care based on initial assessment) but that the acceptable rate of “undertriage” is zero. He ended with the recommendation to “put patients first.” While this sounds obvious, I took it to mean that we should create and use algorithms and protocols to improve patient care, but not allow the rules to impede achievement of this goal. Triage algorithms can be complicated and if there is any hesitation on where to send the patient, keeping this mantra at the forefront of our minds will ensure the best care for our patients.
Dr. Katz, also from Cincinnati, followed with a discussion on EMS identification of severe strokes. He acknowledged that there is no consensus on the definition of a large vessel occlusion based on NIHSS, but that certain features are more suggestive. Multiple stroke scales have been created and tested, including the LMAS, 3ISS, C-STAT (previously the CPSS), and RACE scales. We have not yet decided on a universal scale to use, and further testing needs to be done. Ultimately, the scale has to be predictive of a large vessel occlusion in order for EMS to use it to triage patients who should bypass PSCs. The optimal scale will be easy to administer, have good inter-rater reliability, be validated for LVO prediction, and tested in a large real life population of patients by real EMS providers.
Dr. Asimos from Charlotte, NC, continued the discussion with a review of different stroke triage models and the factors which influence our decision to bypass local PSCs for a CSC. Realizing that there is no “easy” tool for in-the-field determination of LVO, and that some patients will arrive at a CSC without an amenable lesion, we need to determine the NNB (number needed to bypass) for taking patients directly to a CSC in lieu of stopping at a local PSC. Based on a trial conducted in Florida, for every 8 patients who bypassed PSCs, 1 received endovascular therapy. Dr. Asimos recommended that we look at the door to needle times of PSCs (often slower than CSCs), and include that in our decision model. There is also variation in the time it takes to image patients at PSCs, and we should consider which imaging is actually necessary prior to transfer. A study at Emory found that doing CTA and CTP prior to transfer added an hour to the time it took the patient to arrive at the CSC. He concluded by stating that we need target metrics, both for pre-hospital and inter-hospital transfers. I think we need to identify each component of the transfer process to determine where there are time delays and whether skipping that component (i.e. CTA CTP which will most likely be repeated at the CSC prior to taking the patient to endovacscular) is possible. If that reduction in time delay is enough to improve outcomes, we can streamline and standardize the expectations we set for transfer protocols.
Dr. Heinrich Audebert concluded the session with a discussion of the role of technology in pre-hospital triage and care. He pointed out that while only 1-5% of stroke patients are eligible for endovascular therapy, and about 20% are eligible for tPA, almost all patients are eligible for specialized stroke ward treatment. He described the results of the PHANTOM-S trial, in which the CT-equipped STEMO ambulance was compared to standard of care. Fewer stroke patients were transported to hospitals without a stroke unit during STEMO weeks (~4%) than during control weeks (~10%). Dr. Audebert recommended a preliminary triage system before deploying STEMO, as well as an on-call telestroke physician to do an evaluation in the ambulance. While it would be ideal to have a CT scanner in each ambulance, or at least have one available for a larger area which can be deployed after some preliminary triage, this may not be possible given the resources required. I think it is much more feasible to employ affordable telemedicine options, which have previously been explored, to better triage patients to the right place and ensure optimal care.
Overall, a great session on a rapidly growing aspect of stroke care. This same session will likely be very different next year – looking forward to it.
– Ilana Spokoyny, MD