Strokes Averted by Intravenous Thrombolysis: A Secondary Analysis of a Prospective, Multicenter, Controlled Trial of Mobile Stroke Units

OBJECTIVE

This study was undertaken to examine averted stroke in optimized stroke systems.

METHODS

This secondary analysis of a multicenter trial from 2014 to 2020 compared patients treated by mobile stroke unit (MSU) versus standard management. The analytical cohort consisted of participants with suspected stroke treated with intravenous thrombolysis. The main outcome was a tissue-defined averted stroke, defined as a final diagnosis of stroke with resolution of presenting symptoms/signs by 24 hours attributed to thrombolysis and no acute infarction/hemorrhage on imaging. An additional outcome was stroke with early symptom resolution, defined as a final diagnosis of stroke with resolution of presenting symptoms/signs by 24 hours attributed to thrombolysis.

RESULTS

Among 1,009 patients with a median last known well to thrombolysis time of 87 minutes, 159 (16%) had tissue-defined averted stroke and 276 (27%) had stroke with early symptom resolution. Compared with standard management, MSU care was associated with more tissue-defined averted stroke (18% vs 11%, adjusted odds ratio [aOR] = 1.82, 95% confidence interval [CI] = 1.13-2.98) and stroke with early symptom resolution (31% vs 21%, aOR = 1.74, 95% CI = 1.12-2.61). The relationships between thrombolysis treatment time and averted/early recovered stroke appeared nonlinear. Most models indicated increased odds for stroke with early symptom resolution but not tissue-defined averted stroke with earlier treatment. Additionally, younger age, female gender, hyperlipidemia, lower National Institutes of Health Stroke Scale, lower blood pressure, and no large vessel occlusion were associated with both tissue-defined averted stroke and stroke with early symptom resolution.

INTERPRETATION

In optimized stroke systems, 1 in 4 patients treated with thrombolysis recovered within 24 hours and 1 in 6 had no demonstrable brain injury on imaging. ANN NEUROL 2024;95:347-361.

Outcomes of patients with pre-existing disability managed by mobile stroke units: A sub-analysis of the BEST-MSU study

BACKGROUND

Few data exist on acute stroke treatment in patients with pre-existing disability (PD) since they are usually excluded from clinical trials. A recent trial of mobile stroke units (MSUs) demonstrated faster treatment and improved outcomes, and included PD patients.

AIM

To determine outcomes with tissue plasminogen activator (tPA), and benefit of MSU versus management by emergency medical services (EMS), for PD patients.

METHODS

Primary outcomes were utility-weighted modified Rankin Scale (uw-mRS). Linear and logistic regression models compared outcomes in patients with versus without PD, and PD patients treated by MSU versus standard management by EMS. Time metrics, safety, quality of life, and health-care utilization were compared.

RESULTS

Of the 1047 tPA-eligible ischemic stroke patients, 254 were with PD (baseline mRS 2-5) and 793 were without PD (baseline mRS 0-1). Although PD patients had worse 90-day uw-mRS, higher mortality, more health-care utilization, and worse quality of life than non-disabled patients, 53% returned to at least their baseline mRS, those treated faster had better outcome, and there was no increased bleeding risk. Comparing PD patients treated by MSU versus EMS, 90-day uw-mRS was 0.42 versus 0.36 (p = 0.07) and 57% versus 46% returned to at least their baseline mRS. There was no interaction between disability status and MSU versus EMS group assignment (p = 0.67) for 90-day uw-mRS.

CONCLUSION

PD did not prevent the benefit of faster treatment with tPA in the BEST-MSU study. Our data support inclusion of PD patients in the MSU management paradigm.

Golden Hour Treatment With tPA (Tissue-Type Plasminogen Activator) in the BEST-MSU Study

BACKGROUND

Treatment of patients with acute ischemic stroke on mobile stroke units (MSUs) improves outcomes compared with management by standard emergency medical services ambulances and is associated with more patients treated with intravenous tPA (tissue-type plasminogen activator) in the first golden hour after last known normal. We explored the predictors and outcomes of first-hour treatment (FHT) compared with later treatment in an alternating-week cluster-controlled trial of MSUs.

METHODS

We analyzed all patients treated with intravenous tPA in the BEST-MSU Study (Benefits of Stroke Treatment Delivered by a Mobile Stroke Unit Compared to Standard Management by Emergency Medical Services). After stratifying by treatment timeframe, we identified factors associated with FHT. We performed adjusted analyses of the association between FHT and clinical outcome and modeled the shape of the relationship between last known normal-to-treatment time and excellent outcome.

RESULTS

Among 941 tPA-treated patients, 206 (21.8%) had lytic started within 60 minutes. Treatment on the MSU, older age, male sex, alert by 911, faster arrival on-scene and imaging, more severe stroke, atrial fibrillation, and absence of heart failure and pretreatment antihypertensive treatment were associated with FHT. Compared with later treatment, FHT was associated with higher adjusted odds ratio for 90-day modified Rankin Scale score of 0 to 1 (odds ratio, 1.87 [95% CI, 1.25-2.84]; P=0.003). Among FHT patients, 68% achieved a 90-day modified Rankin Scale of 0 or 1 or returned to their baseline status. FHT was not associated with higher risk of hemorrhage and was associated with reduced risk of treating neurovascular mimics.

CONCLUSIONS

FHT almost doubles the odds of excellent clinical outcome without increased risk compared with later treatment, which supports the use of MSUs.

Abstract WP6: Strokes Averted by Intravenous Thrombolysis: A Secondary Analysis of the BEST-MSU Trial

Introduction: While the goal of IV tissue plasminogen activator (TPA) is to prevent infarction, few data exist on averted stroke.

Methods: Secondary analysis of a multicenter trial from 2014-2020 comparing outcomes between patients treated for stroke by mobile stroke unit (MSU) vs standard care (SC). The analytical cohort were patients with suspected stroke treated with IV TPA. The primary outcome was a time-defined averted stroke diagnosis, defined as a final diagnosis of stroke with resolution of presenting symptoms/signs by 24 hours. The secondary outcome was a tissue-defined averted stroke diagnosis, defined as a final diagnosis of stroke with resolution of presenting symptoms/signs by 24 hours and no acute infarction/hemorrhage on imaging. We used multivariable logistic regression to evaluate associations between study exposures (demographics, comorbidities, stroke characteristics) and outcomes.

Results: Among 1009 patients with a median last known well-to-TPA time of 87 minutes, 276 patients (27%) had a time-defined averted stroke (31% MSU, 21% SC) and 159 patients (16%) had a tissue-defined averted stroke (18% MSU, 11% SC). Factors independently associated with time-defined averted stroke were younger age (OR, 0.98; 95% CI, 0.96-0.99), female sex (0R, 0.51; 95% CI, 0.36-0.74), hyperlipidemia (OR, 1.81, 95% CI, 1.24-2.64), normal premorbid function (0R, 2.22; 95% CI, 1.37-3.67), lower glucose (OR, 0.996; 95% CI, 0.993-0.999), lower MAP (OR, 0.991; 95% CI, 0.983-0.998), MSU care (OR, 1.77; 95% CI, 1.21-2.62), lower NIH stroke scale (OR, 0.89; 95% CI, 0.86-0.93), and no large vessel occlusion (LVO) (OR, 0.52; 95% CI, 0.32-0.83). For tissue-based averted stroke, younger age, female sex, hyperlipidemia, lower MAP, MSU treatment, lower NIH stroke scale, and no LVO were significantly associated.

Conclusion: In a modern acute stroke trial, one-in-four patients treated with TPA for stroke recovered within 24 hours and one-in-six had no demonstrable brain injury on imaging. Younger age, female sex, hyperlipidemia, lower MAP, MSU care, lower stroke severity, and no LVO may increase the odds of averting stroke.

Mobile Stroke Unit Operational Metrics: Institutional Experience, Systematic Review and Meta-Analysis

Background

The available literature on mobile stroke units (MSU) has focused on clinical outcomes, rather than operational performance. Our objective was to establish normalized metrics and to conduct a meta-analysis of the current literature on MSU performance.

Methods

Our MSU in upstate New York serves 741,000 people. We present prospectively collected, retrospectively analyzed data from the inception of our MSU in October of 2018, through March of 2021. Rates of transportation/dispatch and MSU utilization were reported. We also performed a meta-analysis using MEDLINE, SCOPUS, and Cochrane Library databases, calculating rates of tPA/dispatch, tPA-per-24-operational-hours (“per day”), mechanical thrombectomy (MT)/dispatch and MT/day.

Results

Our MSU was dispatched 1,719 times in 606 days (8.5 dispatches/24-operational-hours) and transported 324 patients (18.8%) to the hospital. Intravenous tPA was administered in 64 patients (3.7% of dispatches) and the rate of tPA/day was 0.317 (95% CI 0.150–0.567). MT was performed in 24 patients (1.4% of dispatches) for a MT/day rate of 0.119 (95% CI 0.074–0.163). The MSU was in use for 38,742 minutes out of 290,760 total available minutes (13.3% utilization rate). Our meta-analysis included 14 articles. Eight studies were included in the analysis of tPA/dispatch (342/5,862) for a rate of 7.2% (95% CI 4.8–9.5%, I² = 92%) and 11 were included in the analysis of tPA/day (1,858/4,961) for a rate of 0.358 (95% CI 0.215–0.502, I² = 99%). Seven studies were included for MT/dispatch (102/5,335) for a rate of 2.0% (95% CI 1.2–2.8%, I² = 67%) and MT/day (103/1,249) for a rate of 0.092 (95% CI 0.046–0.138, I² = 91%).

Conclusions

In this single institution retrospective study and meta-analysis, we outline the following operational metrics: tPA/dispatch, tPA/day, MT/dispatch, MT/day, and utilization rate. These metrics are useful for internal and external comparison for institutions with or considering developing mobile stroke programs.

Hemorrhage Enlargement Is More Frequent in the First 2 Hours: A Prehospital Mobile Stroke Unit Study

Background:

Hematoma enlargement (HE) after intracerebral hemorrhage (ICH) is a therapeutic target for improving outcomes. Hemostatic therapies to prevent HE may be more effective the earlier they are attempted. An understanding of HE in first 1 to 2 hours specifically in the prehospital setting would help guide future treatment interventions in this time frame and setting.

Methods:

Patients with spontaneous ICH within 4 hours of symptom onset were prospectively evaluated between May 2014 and April 2020 as a prespecified substudy within a multicenter trial of prehospital mobile stroke unit versus standard management. Baseline computed tomography scans obtained <1, 1 to 2, and 2 to 4 hours postsymptom onset on the mobile stroke unit in the prehospital setting were compared with computed tomography scans repeated 1 hour later and at 24 hours in the hospital. HE was defined as >6 mL if baseline ICH volume was < 20 mL and 33% increase if baseline volume >20 mL. The association between time from symptom onset to baseline computed tomography (hours) and HE was investigated using Wilcoxon rank-sum test when time was treated as a continuous variable and using Fisher exact test when time was categorized. Kruskal-Wallis and Wilcoxon rank-sum tests evaluated differences in baseline volumes and HE. Univariable and multivariable logistic regression analyses were conducted to identify factors associated with HE and variable selection was performed using cross-validated L1-regularized (Lasso regression). This study adhered to STROBE guidelines (Strengthening the Reporting of Observational Studies in Epidemiology) for cohort studies.

Results:

One hundred thirty-nine patients were included. There was no difference between baseline ICH volumes obtained <1 hour (n=43) versus 1 to 2 hour (n=51) versus >2 hours (n=45) from symptom onset (median [interquartile range], 13 mL [6–24] versus 14 mL [6–30] versus 12 mL [4–19]; P =0.65). However, within the same 3 time epochs, initial hematoma growth (volume/time from onset) was greater with earlier baseline scanning (median [interquartile range], 17 mL/hour [9–35] versus 9 mL/hour [5–23]) versus 4 mL/hour [2–7]; P <0.001). Forty-nine patients had repeat scans 1 hour after baseline imaging (median, 2.3 hours [interquartile range. 1.9–3.1] after symptom onset). Eight patients (16%) had HE during that 1-hour interval; all of these occurred in patients with baseline imaging within 2 hours of onset (5/18=28% with baseline imaging within 1 hour, 3/18=17% within 1–2 hour, 0/13=0% >2 hours; P =0.02). HE did not occur between the scans repeated at 1 hour and 24 hours. No association between baseline variables and HE was detected in multivariable analyses.

Conclusions:

HE in the next hour occurs in 28% of ICH patients with baseline imaging within the first hour after symptom onset, and in 17% of those with baseline imaging between 1 and 2 hours. These patients would be a target for ultraearly hemostatic intervention.

Retrospectively Collected EQ-5D-5L Data as Valid Proxies for Imputing Missing Information in Longitudinal Studies

OBJECTIVES

Studies face challenges with missing 5-level EQ-5D (EQ-5D-5L) data, often because of the need for longitudinal EQ-5D-5L data collection. There is a dearth of validated methodologies for dealing with missing EQ-5D-5L data in the literature. This study, for the first time, examined the possibility of using retrospectively collected EQ-5D-5L data as proxies for the missing data.

METHODS

Participants who had prospectively completed a 3rd month postdischarge EQ-5D-5L instrument (in-the-moment collection) were randomly interviewed to respond to a 2nd "retrospective collection" of their 3rd month EQ-5D-5L at 6th, 9th, or 12th month after hospital discharge. A longitudinal single imputation was also used to assess the relative performance of retrospective collection compared with the longitudinal single imputation. Concordances between the in-the-moment, retrospective, and imputed measures were assessed using intraclass correlation coefficients and weighted kappa statistics.

RESULTS

Considerable agreement was observed on the basis of weighted kappa (range 0.72-0.95) between the mobility, self-care, and usual activities dimensions of EQ-5D-5L collected in-the-moment and retrospectively. Concordance based on intraclass correlation coefficients was good to excellent (range 0.79-0.81) for utility indices computed, and excellent (range 0.93-0.96) for quality-adjusted life-years computed using in-the-moment compared with retrospective EQ-5D-5L. The longitudinal single imputation did not perform as well as the retrospective collection method.

CONCLUSIONS

This study demonstrates that retrospective collection of EQ-5D-5L has high concordance with "in-the-moment" EQ-5D-5L and could be a valid and attractive alternative for data imputation when longitudinally collected EQ-5D-5L data are missing. Future studies examining this method for other disease areas and populations are required to provide more generalizable evidence.

Prospective, Multicenter, Controlled Trial of Mobile Stroke Units

BACKGROUND

Mobile stroke units (MSUs) are ambulances with staff and a computed tomographic scanner that may enable faster treatment with tissue plasminogen activator (t-PA) than standard management by emergency medical services (EMS). Whether and how much MSUs alter outcomes has not been extensively studied.

METHODS

In an observational, prospective, multicenter, alternating-week trial, we assessed outcomes from MSU or EMS management within 4.5 hours after onset of acute stroke symptoms. The primary outcome was the score on the utility-weighted modified Rankin scale (range, 0 to 1, with higher scores indicating better outcomes according to a patient value system, derived from scores on the modified Rankin scale of 0 to 6, with higher scores indicating more disability). The main analysis involved dichotomized scores on the utility-weighted modified Rankin scale (≥0.91 or <0.91, approximating scores on the modified Rankin scale of ≤1 or >1) at 90 days in patients eligible for t-PA. Analyses were also performed in all enrolled patients.

RESULTS

We enrolled 1515 patients, of whom 1047 were eligible to receive t-PA; 617 received care by MSU and 430 by EMS. The median time from onset of stroke to administration of t-PA was 72 minutes in the MSU group and 108 minutes in the EMS group. Of patients eligible for t-PA, 97.1% in the MSU group received t-PA, as compared with 79.5% in the EMS group. The mean score on the utility-weighted modified Rankin scale at 90 days in patients eligible for t-PA was 0.72 in the MSU group and 0.66 in the EMS group (adjusted odds ratio for a score of ≥0.91, 2.43; 95% confidence interval [CI], 1.75 to 3.36; P<0.001). Among the patients eligible for t-PA, 55.0% in the MSU group and 44.4% in the EMS group had a score of 0 or 1 on the modified Rankin scale at 90 days. Among all enrolled patients, the mean score on the utility-weighted modified Rankin scale at discharge was 0.57 in the MSU group and 0.51 in the EMS group (adjusted odds ratio for a score of ≥0.91, 1.82; 95% CI, 1.39 to 2.37; P<0.001). Secondary clinical outcomes generally favored MSUs. Mortality at 90 days was 8.9% in the MSU group and 11.9% in the EMS group.

CONCLUSIONS

In patients with acute stroke who were eligible for t-PA, utility-weighted disability outcomes at 90 days were better with MSUs than with EMS. (Funded by the Patient-Centered Outcomes Research Institute; BEST-MSU ClinicalTrials.gov number, NCT02190500.).

Dosing Tissue Plasminogen Activator on a Mobile Stroke Unit: Comparison Between Estimated and Hospital-Measured Weights

ABSTRACT

BACKGROUND: Prehospital tissue plasminogen activator dosing in a mobile stroke unit (MSU) is estimated by the paramedic and nurse. We aimed to determine the accuracy of the estimated weight method compared with the actual weight of patients treated with tissue plasminogen activator on the MSU. METHODS: We prospectively collected the estimated weight used on the MSU for treatment and the first-documented hospital-measured weight (bed scale) within 24 hours of hospital arrival. Median absolute and percent difference in weights were calculated; less than 10% of difference in weights was considered acceptable. To compare the estimated and measured weights, we conducted a Wilcoxon signed rank test and Fisher exact test to explore the association between weight difference of greater than 10% and patient outcomes. RESULTS: Among 337 patients, median estimated and hospital-measured weights were 79.0 kg (interquartile range [IQR], 66.0-94.5) and 78.5 kg (IQR, 65.0-91.7), respectively. The median of the absolute value of the difference in estimated versus measured weight was 2.7 kg (IQR, 0.6-7.6; P < .0001). The median percent difference in weight was 3.6% (IQR, 0.8%-9.4%). The median difference between the tissue plasminogen activator dosage administered on the MSU and the recommended dose based on the actual weight was 1.3 mg (IQR, 0.06-4.8) in absolute value. In 56 patients (16.6% of the entire sample) with overestimation of weight by greater than 10%, there were no symptomatic intracerebral hemorrhages. There was no association between weight difference and discharge modified Rankin score (P = .59). CONCLUSION: Weight estimation on an MSU can lead to similar tissue plasminogen activator dosing for 83.4% of subjects compared with if dosing were determined based on actual weight. Weight overestimation or underestimation had no detected impact on tissue plasminogen activator outcomes.

Successful conduct of an acute stroke clinical trial during COVID

Most clinical research stopped during COVID due to possible impact on data quality and personnel safety. We aimed to assess the impact of COVID on acute stroke clinical trial conduct at sites that continued to enroll patients during the pandemic. BEST-MSU is an ongoing study of Mobile Stroke Units (MSU) vs standard management of tPA-eligible acute stroke patients in the pre-hospital setting. MSU personnel include a vascular neurologist via telemedicine, and a nurse, CT technologist, paramedics and emergency medicine technicians on-board. During COVID, consent, 90-day modified Rankin Scale (mRS) and EQ5D were obtained by phone instead of in-person, but other aspects of management were similar to the pre-COVID period. We compared patient demographics, study metrics, and infection of study personnel during intra- vs pre-COVID eras. Five of 6 BEST-MSU sites continued to enroll during COVID. There were no differences in intra- (n = 57) vs pre- (n = 869) COVID enrolled tPA eligible patients’ age, sex, race (38.6% vs 38.0% Black), ethnicity (15.8% vs 18.6% Hispanic), or NIHSS (median 11 vs 9). The percent of screened patients enrolled and adjudicated tPA eligible declined from 13.6% to 6.6% (p < .001); study enrollment correlated with local stay-at-home and reopening orders. There were no differences in alert to MSU arrival or arrival to tPA times, but MSU on-scene time was 5 min longer (p = .01). There were no differences in ED door to CT, tPA treatment or thrombectomy puncture times, hospital length of stay, discharge disposition, or remote vs in-person 90-day mRS or EQ5D. One MSU nurse tested positive but did not require hospitalization. Clinical research in the pre-hospital setting can be carried out accurately and safely during a pandemic. tPA eligibility rates declined, but otherwise there were no differences in patient demographics, deterioration of study processes, or serious infection of study staff.

Trial registration:NCT02190500

Retrospective collection of 90-day modified Rankin Scale is accurate

BACKGROUND

The 90-day modified Rankin Scale is a widely used outcome after stroke but is sometimes hard to ascertain due to loss to follow-up. Missing outcomes can result in biased and/or inefficient estimates in clinical trials. The aim of this study is to assess the validity of acquiring the 90-day modified Rankin Scale at a later point of time when the patient has been lost at 90 days to impute the missing value.

METHODS

Participants who had prospectively completed a 90-day modified Rankin Scale questionnaire on their own in the Benefits of Stroke Treatment Using a Mobile Stroke Unit study were randomly interviewed to recall the 90-day modified Rankin Scale at 6, 9, or 12 months after hospital discharge over the phone. Concordance between the two scores was assessed using kappa and weighted kappa statistics. Logistic regression was used to identify factors associated with inconsistent reporting of the 90-day modified Rankin Scale.

RESULTS

Substantial agreement was observed between in-the-moment and retrospective 90-day modified Rankin Scale recalled at 6, 9, or 12 months (weighted kappa = 0.93, 95% confidence interval: 0.89-0.98; weighted kappa = 0.93, 95% confidence interval: 0.85-1.00 and weighted kappa = 0.89, 95% confidence interval: 0.82-0.95, respectively).

CONCLUSION

Retrospective recall of 90-day modified Rankin Scale at a later time point is a valid means to impute missing data in stroke clinical trials.

Enhanced dispatch and rendezvous doubles the catchment area and number of patients treated on a mobile stroke unit

INTRODUCTION

Mobile Stroke Units (MSUs) deliver acute stroke treatment on-scene in coordination with Emergency Medical Services (EMS). One criticism of the MSU approach is the limited range of a single MSU. The Houston MSU is evaluating MSU implementation, and we developed a rendezvous approach as an innovative solution to expand the range and number of patients treated.

METHODS

In addition to direct 911 dispatch of our MSU to the scene within our 7-mile catchment area, we empowered more distant EMS units to activate the MSU. We also monitored EMS radio communications to identify possible patients. For these distant patients, the MSU met the EMS unit en route to the stroke center and treated the patient at that intermediate location. The distribution of the distance from MSU base station to site of stroke and time from 911 alert to tissue plasminogen activator (tPA) bolus were compared between patients treated on-scene and by rendezvous using Wilcoxon rank sum test.

RESULTS

Over 4 years, 338 acute ischemic stroke patients were treated with tPA on our MSU. Of these, 169 (50%) were treated on-scene after MSU dispatch at a median of 6.4 miles (IQR 6.4 miles) from MSU base station. 169 (50%) were treated by 'rendezvous' pathway with assessment and treatment of stroke a median of 12.4 miles from base (IQR 5.5 miles) (p< 0.0001). Time (min) from MSU alert to tPA bolus did not differ: 36.0 ± 10.0 for on-scene vs 37.0 ± 10.0 with rendezvous (p=0.65). 13% of patients alerted via direct 911 dispatch were treated vs 44% of rendezvous patients.

CONCLUSION

Adding a rendezvous approach to an MSU dispatch pathway doubles the range of operations and the number of patients treated by an MSU in an urban area, without incurring delay.

Mobile Stroke Unit Computed Tomography Angiography Substantially Shortens Door-to-Puncture Time

Background and Purpose- Endovascular thrombectomy (ET) door-to-puncture time (DTPT) is a modifiable metric. One of the most important, yet time-consuming steps, is documentation of large vessel occlusion by computed tomography angiography (CTA). We hypothesized that obtaining CTA on board a Mobile Stroke Unit and direct alert of the ET team shortens DTPT by over 30 minutes. Methods- We compared DTPT between patients having CTA onboard the Mobile Stroke Unit then subsequent ET from September 2018 to November 2019 and patients in Mobile Stroke Unit from August 2014 to August 2018, when onboard CTA was not yet being used. We also correlated DTPT with change in National Institutes of Health Stroke Scale between baseline and 24 hours. Results- Median DTPT was 53.5 (95% CI, 35-67) minutes shorter with onboard CTA and direct ET team notification: 41 minutes (interquartile range, 30.0-63.5) versus 94.5 minutes (interquartile range, 69.8-117.3; P<0.001). Median on-scene time was 31.5 minutes (interquartile range, 28.8-35.5) versus 27.0 minutes (interquartile range, 23.0-31.0) (P<0.001). Shorter DTPT correlated with greater improvement of National Institutes of Health Stroke Scale (correlation=-0.2, P=0.07). Conclusions- Prehospital Mobile Stroke Unit management including on-board CTA and ET team alert substantially shortens DTPT. Registration- URL: https://clinicaltrials.gov; Unique identifier: NCT02190500.

Abstract 99: Mobile Stroke Unit CTA and Direct Notification of Interventional Team Shortens Door-to-Puncture Time by One Hour

Introduction: Endovascular thrombectomy (ET) is an effective but time sensitive treatment of acute ischemic stroke. Time from Emergency Department (ED) arrival to start of ET (door-to-puncture time, DTPT) is a modifiable metric. One of the most time consuming steps in prolonging DTPT is identification of large vessel occlusion (LVO) by CT angiography (CTA). BEST-MSU is a prospective multicenter comparative effectiveness study of tPA-eligible patients managed on a mobile stroke unit (MSU) vs Emergency Medical Services (Standard Management, SM). After discovering that DTPT was greater than 60 minutes in both groups at three BEST-MSU centers in 2018, we began to routinely obtain CTA on the MSU and directly alert the ET team at receiving hospitals if a LVO was identified. We hypothesized this would shorten DTPT by over 30 minutes.

Methods: In this single center experience, we compared the median (interquartile range, IQR) DTPT and MSU on-scene time for MSU patients having on-board CTA and then ET from 9/2018 to 7/2019 to corresponding MSU ET patients (excluding any that had on-board CTA) from 8/2014 to 8/2018. All CTAs were completed after tPA bolus and during tPA infusion on a Ceretom 8 slice scanner with OptiStat hand injector. All imaging occurred on-scene with the MSU stationary. Consent was obtained for all patients and strict radiation safety guidelines followed.

Results: 13 consecutive patients having CTA on-board the MSU and then ET were compared to 84 patients in the pre-on-board CTA group. Baseline characteristics including median NIHSS score (20 in both groups) and frequency of tPA (85% on-board CTA vs 89% pre-on-board CTA) were comparable. Median DTPT was 60 minutes shorter with on-board CTA and direct notification of the interventional team from the MSU; 34 minutes (IQR 30-57) vs 94.5 minutes (IQR 69.75-117.25) (p < 0.001). Despite the additional time to obtain the CTA on the MSU, on-scene time was only slightly prolonged and did not offset the reduction in DTPT (on-board CTA 30 minutes (IQR 28-33) vs pre-on-board CTA 27 minutes (IQR 23-31) (p = 0.01).

Conclusion: Pre-hospital identification and notification of LVO by a MSU allows a one hour reduction of DTPT, and can be utilized to establish a direct to angiosuite protocol.

Emergency Department Door-to-Puncture Time Since 2014

Background and Purpose- The impact of a mobile stroke unit (MSU) on access to intraarterial thrombectomy (IAT) is a prespecified BEST-MSU substudy (Benefits of Stroke Treatment Delivered Using a Mobile Stroke Unit Compared to Standard Management by Emergency Medical Services). On the MSU, IAT decision-making steps, such as computed tomography, neurological exam, and tPA (tissue-type plasminogen activator) treatment are completed before emergency department arrival. We hypothesized that such pre-ED assessment of potential IAT patients on an MSU improves the time from ED arrival to skin puncture time (door-to-puncture-time, DTPT). Methods- BEST-MSU is a prospective comparative effectiveness study of MSU versus standard management by emergency medical services (EMS). We compared ED DTPT among the following groups of MSU and EMS patients: all IAT patients, IAT patients post-tPA, and IAT patients post-tPA meeting thrombolytic adjudication criteria over the first 4 years of the study. Results- From August 2014 to July 2018, a total of 161 patients underwent IAT. Ninety-four patients presented to the ED via the MSU and 67 by EMS. One hundred forty patients received tPA before IAT, 85 in the MSU arm, and 55 in the EMS arm. One hundred twenty-six patients received tPA within thrombolytic adjudication criteria: 76 MSU and 50 EMS. DTPT in minutes was shorter for MSU patients (all IAT MSU versus EMS 89 versus 99, P=0.01; IAT post-tPA MSU versus EMS 93 versus 100, P=0.03; and IAT post-tPA within adjudicated criteria MSU versus EMS 93 versus 99.5, P=0.03). From 2014 to 2018, DTPT decreased at a faster rate for EMS compared with MSU-managed patients, improving by about an hour. Conclusions- Pre-ED IAT evaluation on an MSU results in faster DTPT compared with arrival by EMS. Since 2014, dramatic improvement in ED IAT metrics has attenuated this difference. However, DTPT in all groups indicates substantial room for improvement.

Abstract TMP11: Emergency Room Door-to-Puncture Time Since 2015: Observations From the BEST-MSU Study

Introduction: The impact of a Mobile stroke unit (MSU) on access to Endovascular Thrombectomy (ET) is a pre-specified BEST-MSU sub-study. On the MSU, ET decision-making steps such as CT, neurologic exam, and tPA treatment are completed prior to Emergency Room (ER) arrival. We hypothesized that such pre-ER assessment of potential ET patients on a MSU improves metrics.

Methods: BEST-MSU is a prospective comparative effectiveness study of MSU vs Standard Management by Emergency Medical Services (SM). We compared ER door-to-puncture-time (mins, DTPT) among the following groups of MSU and SM patients: all ET patients (ETP), ET patients post-tPA (ETT), and ET patients post-tPA meeting thrombolytic adjudication criteria (ETTA) over the first four years of the study.

Results: There were 161 ETP (67 SM, 94 MSU), 140 ETT (55 SM, 85 MSU), and 126 ETTA (50 SM, 76 MSU) patients. DTPT was shorter for MSU patients (ETP 89 vs 99, p=0.01; ETT 93 vs 100, p=0.03; ETTA 93 vs 99.5, p=0.03). From 2015 to 2018, DTPT decreased at a faster rate for SM compared with MSU-managed patients, improving by about an hour (Figure).

Conclusion: Pre-ER ET evaluation on a MSU results in faster DTPT. Since 2015, dramatic improvement in ER ET metrics has attenuated this difference. However, DTPT of 90-100 mins in all groups indicates substantial room for improvement.

Time to Decision and Treatment With tPA (Tissue-Type Plasminogen Activator) Using Telemedicine Versus an Onboard Neurologist on a Mobile Stroke Unit

BACKGROUND AND PURPOSE

Mobile stroke units (MSUs) can speed treatment with intravenous tPA (tissue-type plasminogen activator). We previously showed substantial agreement between a telemedicine-based vascular neurologist (TM-VN) and an onboard vascular neurologist (OB-VN) for the evaluation of patients with stroke for tPA eligibility on an MSU. However, the time efficiency of the telemedicine-based evaluation remained uncertain. In this study, we examined the speed of decision and treatment from MSU arrival for the TM-VN compared with an OB-VN.

METHODS

In 50 consecutive situations, the TM-VN served as the primary decision maker. Times from MSU arrival to tPA decision and tPA bolus were compared with the same metrics for when the OB-VN served as the primary decision maker.

RESULTS

Time to tPA decision for the TM-VN was 21 minutes (interquartile range, 16.25-26) versus 18 minutes (interquartile range, 14-22) for the OB-VN (P=0.01). Initiation of tPA bolus was 24 minutes (interquartile range, 19.75-30) for the TM-VN versus 24 minutes (interquartile range, 19-27.75) for the OB-VN (P=0.5).

CONCLUSIONS

Assessment by a TM-VN is comparable with an OB-VN in making decisions about tPA administration on an MSU and does not lead to treatment delays.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique identifier: NCT02190500.

Abstract WP223: Accelerating Growth in Medicare Beneficiary US Population Served by Mobile Stroke Units During Early Pilot Years (2014-2017)

Background: Mobile Stroke Units (MSUs, mobile CT ambulances) are a new platform for accelerated delivery of proven, time-dependent therapies for acute ischemic and hemorrhagic stroke, undergoing systematic evaluation to determine cost-effectiveness. Formal analysis of the reach of MSU programs in the US during the early pilot period has not previously been undertaken.

Methods: We identified all US MSU programs, active or expected to be active by the end of 2017, via the PRESTO consortium, program leader referrals, vehicle and scanner manufacturer informants, and press release search. MSU access was calculated using geospatial mapping of each vehicle and its surrounding 10 mile radius catchment area, for: 1) population aged ≥ 65, using US Census Bureau county-level values for land area, population density, and proportion of population ≥ 65; and 2) strokes in CMS beneficiaries, using CDC/CMS county-level values for annual stroke hospitalizations.

Results: During the 4 year study period, the number of active MSUs grew from 1 in 2014, 2 in 2015, 6 in 2016, to 13 in 2017, all operating in distinct counties, including 7 (54%) in Census-defined large central metros with high population density, 3 (23%) in large fringe metros with moderately high population density, 3 (23%) in medium/small metros with moderate population density, and 0 (0%) in rural areas. The population over age 65 with MSU access increased from 153,860 in 2014, 315,884 in 2015, 671,960 in 2016, to 1,495,896 in 2017. The number of annual CMS stroke hospitalizations in MSU-covered regions increased from 1,831 in 2014, 3,775 in 2015, 7,031 in 2016, to 15,566 in 2017. By the end of 2017, MSUs were positioned to provide service to 2.9% of all Medicare beneficiaries experiencing stroke hospitalization in the US.

Conclusions: In the short span of the first 4 years of MSU pilot programs in the United States, with only 13 vehicles in service, expanding MSU programs provide access to accelerated treatment for 3 of every 100 US Medicare beneficiaries. This early geomapping analysis indicates that, if demonstration projects confirm cost-effectiveness, supporting wider dissemination, MSU care could provide rapid therapy to a substantial proportion of older Americans with acute ischemic and hemorrhagic stroke.

Benefits of stroke treatment delivered using a mobile stroke unit trial

Rationale

Mobile stroke units speed treatment for acute ischemic stroke, thereby possibly improving outcomes.

Aim

To compare mobile stroke unit and standard management clinical outcomes, healthcare utilization, and cost-effectiveness in tissue plasminogen activator-eligible acute ischemic stroke patients calling 911.

Sample size

693. Eighty percent power with 0.05 type I error rate to detect a difference of 0.09 in mean utility-weighted modified Rankin scale between groups.

Design

Phase III, multicenter, prospective cluster-randomized (mobile stroke unit versus standard management weeks) comparative effectiveness study in tissue plasminogen activator-eligible patients.

Outcomes

Primary: Ninety-day mean utility-weighted modified Rankin scale. Coprimary: cost-effectiveness based on EQ5D quality of life and one year poststroke costs.

Analysis

Two-sample t-test and linear regression adjusting for covariates; incremental cost-effectiveness ratio and net benefit regression.

Results

As of March 2017, 288 tissue plasminogen activator-eligible patients have been enrolled (173 in the mobile stroke unit arm and 115 in the standard management arm). Two new centers start in early 2017 with target end of recruitment September 2019.

Conclusion

This is the first randomized study to test for disability, healthcare utilization, and cost-effectiveness of a mobile stroke unit. The progress of the study suggests that it is feasible. Management of tissue plasminogen activator eligible acute ischemic stroke patients by a mobile stroke unit could potentially result in less disability and healthcare utilization, and be cost effective. Mobile stroke units are very costly. This trial may determine if the fixed cost can be justified by a reduction in disability and healthcare utilization.

Clinical Trial Registration

NCT02190500.

Abstract 21: Can Telemedicine Replace an On-board Vascular Neurologist in Deciding about Tissue Plasminogen Activator Treatment? A Pre-Specified Substudy of the BEST-MSU Study

Background: Faster treatment with tPA may be achieved by optimizing prehospital triage with mobile stroke units (MSUs). The Benefits of Stroke Treatment Delivered Using a Mobile Stroke Unit (BEST-MSU) study is a prospective comparative effectiveness trial of outcomes in patients randomized to MSU or standard management (SM).

Purpose: To evaluate the inter-rater agreement for tPA eligibility between a telemedicine vascular neurologist (TM-VN) and the onboard vascular neurologist (OB-VN) in acute stroke patients seen on the MSU.

Methods: Cluster randomization of MSU and SM weeks started on August 18, 2014. On scene, both the TM-VN and OB-VN evaluated the patient and independently documented their tPA treatment decision, NIHSS and CT interpretation. Agreement was determined using Cohen’s kappa (K) statistic. TM related technical failures that impeded remote assessment were recorded.

Results: The remote TM-VN evaluated 173 patients. In 4 (2%) cases the TM-VN was not able to make a decision about tPA because of technical difficulties ( 1 case due to TM camera failure and 3 cases due to poor connectivity). The TM-VN agreed with the OB-VN on 88% of evaluations, with a K of 0.73 representing substantial agreement. Baseline NIHSS correlation between the TM-VN and OB-VN was 0.88. Agreement about ICH on CTH was a near-perfect K of 0.97.

Conclusions: We conclude from these results that remote VN assessment of stroke patients in the MSU via TM is clinically and technologically feasible, reliable and accurate. TM assessment of CTH and NIHSS was also comparable to the OB evaluation. These findings will allow either OB-VN or TM-VN assessment for the remainder of the study.

Telemedicine Can Replace the Neurologist on a Mobile Stroke Unit

BACKGROUND AND PURPOSE

The BEST-MSU study (Benefits of Stroke Treatment Delivered Using a Mobile Stroke Unit) is a comparative effectiveness trial in patients randomized to mobile stroke unit or standard management. A substudy tested interrater agreement for tissue-type plasminogen activator eligibility between a telemedicine vascular neurologist and onboard vascular neurologist.

METHODS

On scene, both the telemedicine vascular neurologist and onboard vascular neurologist independently evaluated the patient, documenting their tissue-type plasminogen activator treatment decision, National Institutes of Health Stroke Scale score, and computed tomographic interpretation. Agreement was determined using Cohen κ statistic. Telemedicine-related technical failures that impeded remote assessment were recorded.

RESULTS

Simultaneous and independent telemedicine vascular neurologist and onboard vascular neurologist assessment was attempted in 174 patients. In 4 patients (2%), the telemedicine vascular neurologist could not make a decision because of technical problems. The telemedicine vascular neurologist agreed with the onboard vascular neurologist on 88% of evaluations (κ=0.73).

CONCLUSIONS

Remote telemedicine vascular neurologist assessment is reliable and accurate, supporting either telemedicine vascular neurologist or onboard vascular neurologist assessment on our mobile stroke unit.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT02190500.

Promoting Inclusion Through Instructional Leadership: The Roles Of the Secondary School Principal

Learning is the core purpose, the quintessential mission of schools and schooling. Learning and its sundry issues also present problems and questions for school leaders: Who can learn? What can they learn? How should opportunities for learning be structured? To whom should such opportunities be directed? These questions are fundamental to the issue of inclusion in schools.

Radiation Monitoring Results from the First Year of Operation of a Unique Ambulance-based Computed Tomography Unit for the Improved Diagnosis and Treatment of Stroke Patients

When a blood clot blocks the blood supply to the brain or when a blood vessel bursts, resulting in brain cell death, the medical condition is referred to as a "stroke." Stroke is a main cause of death worldwide and is a common cause of disability. A common form of stroke, called ischemic stroke, is when blood flow to the brain is decreased. Clinical research has revealed that treatment within the very first hours of symptom onset is key for ischemic stroke with recanalization of occluded arteries by thrombolysis with alteplase. Computed tomography (CT) is one of the diagnostic tools used to determine if this treatment path is appropriate. To determine if health outcomes of possible stroke patients can be improved by decreasing the time from symptom presentation to treatment, the first mobile stroke ambulance unit in the United States was deployed by The University of Texas Health Science Center at Houston (UTHealth) in 2014, equipped with a computed tomography imaging system. The mobile stroke unit shortens the time to treatment for stroke patients by allowing pre-hospital treatment. Having completed its first year of operation, radiation-monitoring data describing the doses delivered to various entities have been characterized. The CT operator's cumulative deep dose equivalent for 1 y of operation was 1.14 mSv resulting from the care of 106 patients. Area monitors were deployed and measurements performed demonstrating that general public doses did not exceed 0.02 mSv h⁻¹ or 1.0 mSv year.

Establishing the First Mobile Stroke Unit in the United States

Background and Purpose—

Recently, the Mobile Stroke Unit (MSU) concept was introduced in Germany demonstrating prehospital treatment of more patients within the first hour of symptom onset. However, the details and complexities of establishing such a program in the United States are unknown. We describe the steps involved in setting up the first MSU in the United States.

Methods—

Implementation included establishing leadership, fund-raising, purchase and build-out, knitting a collaborative consortium of community stakeholders, writing protocols to ensure accountability, radiation safety, purchasing supplies, licensing, insurance, establishing a base station, developing a communication plan with city Emergency Medical Services, Emergency Medical Service training, staffing, and designing a research protocol.

Results—

The MSU was introduced after ≈1 year of preparation. Major obstacles to establishing the MSU were primarily obtaining funding, licensure, documenting radiation safety protocols, and establishing a smooth communication system with Emergency Medical Services. During an 8 week run-in phase, ≈2 patients were treated with recombinant tissue-type plasminogen activator per week, one-third within 60 minutes of symptom onset, with no complications. A randomized study to determine clinical outcomes, telemedicine reliability and accuracy, and cost effectiveness was formulated and has begun.

Conclusion—

The first MSU in the United States has been introduced in Houston, TX. The steps needed to accomplish this are described.

Secreted production of assembled Norovirus virus-like particles from Pichia pastoris

BACKGROUND

Norovirus virus-like particles (NoV VLPs) have recently been explored as potential vaccine platforms due to their ability to produce an effective immune response. Expression of the main structural protein, VP1, leads to formation of self-assembled particles with similar characteristics to the original virus. These NoV VLPs have been expressed in Escherichia coli, yeast and insect cells. Expression in E. coli and insect cells share downstream processing issues due to the presence of inclusion bodies or the need for numerous purification steps. NoV VLPs have also been produced in the yeast P. pastoris; however the protein was only expressed intracellularly.

RESULTS

We have successfully expressed and secreted the VP1 protein in the novel P. pastoris strain, Bg11, using the methanol inducible pJ912 expression vector, containing the cDNA of NoV VP1. Expression of the VP1 protein in Bg11 was carried out in a 1.5 L bioreactor resulting in a total yield of NoV VLPs greater than 0.6 g/L. NoV VLPs obtained from the culture supernatant were purified via ion-exchange chromatography, resulting in particles with a purity over 90%. The average size of the particles after purification was 40 nm. Transmission electron microscopy was used to visualize the morphology of the particles and saliva-binding assay confirmed that the NoV VLPs bind to Histo-Blood Group Antigens (HBGA).

CONCLUSIONS

In this study we describe the expression and characterization of fully assembled Norovirus virus-like particles obtained from P. pastoris. The particles are similar in size, morphology and binding capacity, as previously described, for the original NoV. Our results detail the successful expression and secretion of VLPs in P. pastoris, improving their candidacy as a vaccine platform.

Thrombelastography detects possible coagulation disturbance in patients with intracerebral hemorrhage with hematoma enlargement

BACKGROUND AND PURPOSE

Intracerebral hemorrhage (ICH) has high morbidity, and hematoma enlargement (HE) causes worse outcome. Thrombelastography (TEG) measures the dynamics of clot formation and dissolution, and might be useful for assessing bleeding risk. We used TEG to detect changes in clotting in patients with and without HE after ICH.

METHODS

This prospective study included 64 patients with spontaneous ICH admitted from 2009 to 2013. TEG was performed within 6 hours of symptom onset and after 36 hours. Brain imaging was obtained at baseline and at 36±12 hours, and HE was defined as total volume increase>6 cc or >33%. TEG was also obtained from 57 controls.

RESULTS

Compared with controls, patients with ICH demonstrated faster and stronger clot formation; shorter R and delta (P<0.0001) at baseline; and higher MA and G (P<0.0001) at 36 hours; 11 patients had HE. After controlling for potential confounders, baseline K and delta were longer in HE+ compared with HE- patients, indicating that HE+ patients had slower clot formation (P<0.05). TEG was not different between HE+ and HE- patients at 36 hours.

CONCLUSIONS

TEG may detect important coagulation changes in patients with ICH. Clotting may be faster and stronger in immediate response to ICH, and a less robust response may be associated with HE. These findings deserve further investigation.

Abstract 34: Hypercoagulable Response After Intracerebral Hemorrhage Does Not Occur in Patients With Hematoma Enlargement

Background: Intracerebral hemorrhage (ICH) has high morbidity, and hematoma enlargement (HE) causes worse outcome. Thromboelastography (TEG) measures the dynamics of clot formation and dissolution, and might be useful for assessing bleeding risk. Speed of clot formation in minutes is measured by parameters R, K, and delta, and clot strength in dynes of resistance by MA and G. We used TEG to detect changes in clotting in patients with and without HE after ICH.

Methods: This prospective study included 64 patients with spontaneous ICH admitted from 2009 to 2013. TEG was performed within 6 hours of symptom onset and after 36 hours. Brain imaging was obtained at baseline and 36 ±12 hours, and HE defined as total volume increase > 6cc or >33%.TEG was also obtained from 57 healthy controls. Comparisons between groups were assessed by t-test or Wilcoxon rank sum tests. Multivariable regression was performed after controlling for potential confounders.

Results: Age and gender were not different between ICH patients and controls. Compared to controls, ICH patients demonstrated faster and stronger clot formation; shorter R and delta (p<0.0001) at baseline; and higher MA and G (p < 0.0001) at 36 hours. 11/64 (17%) patients had HE. Male sex and prior clopidrogel use were more frequent in the HE + group (p<0.05) compared to HE -. After controlling for potential confounders (age, clopidrogel, INR, platelet count), baseline K and delta were longer in HE + vs. HE - patients, indicating that HE+ patients had slower clot formation (p<0.05). TEG was not different between HE + and HE - patients at 36 hours.

Discussion: TEG may detect important coagulation changes in patients with ICH; clotting may become faster and stronger in immediate response to ICH; a less robust response may be associated with HE. These findings may have relevance to patient management and deserve further investigation.

Delta values at baseline for controls, all hemorrhage patients, hemorrhage enlargement (HE) + and (HE) - patients.

Abstract W P366: Hypothermia Does Not Affect Tissue Plasminogen Activator Activity in Acute Ischemic Stroke Patients as Measured by Thromboelastography

Background: Currently, t-PA is the only FDA approved treatment for acute ischemic stroke (AIS). Supplementing t-PA with therapeutic hypothermia is being evaluated, but cooler temperatures may affect the enzymatic activity of t-PA. Thromboelastography (TEG) determines coagulation status in whole blood, and has detected hypercoagulability in AIS patients compared to healthy controls. Using TEG, we evaluated the effect of variable degrees of hypothermia on clot formation and lysis in AIS patients receiving t-PA.

Methods: Between June 2012 -July 2013, venous blood from 18 AIS patients receiving t-PA within 4.5 hours of symptom onset was collected prior to and 10 minutes after t-PA bolus. Blood samples were analyzed by TEG at 30°C, 33°C, and 37°C. The variables of interest were R (initiation of clot formation), K (speed of clot strengthening), Angle α (rate of clot formation), and LY30 (percentage of clot lysis over 30 minutes) (see figure). All statistical analyses were performed using SAS 9.3.

Results: Baseline R averaged 6.0, 5.6, and 4.6 minutes at 30°C, 33°C, and 37°C (p=0.02),K averaged 2.5, 2.3, and 1.4 (p=0.01),and Angle averaged 59.1, 62.4, and 69.3(p=0.01), indicating slower clotting at lower temperatures. Post t-PA LY30 averaged 93.9, 93.9, 89.8 (p= 0.61, N=18) indicating no effect on t-PA lytic activity at lower temperatures.

Conclusions: Our data suggest that hypothermia progressively slows clot formation in AIS patients but has no effect on the lytic effect of t-PA as measured by TEG.

Abstract W P58: Thromboelastography Can Detect the Anticoagulant Effect of Factor Xa Inhibitors in Patients Who Might Be Eligible for Tissue Plasminogen Activator Treatment for Acute Ischemic Stroke

Background: Factor Xa inhibitors are approved for stroke prevention in patients with atrial fibrillation. The management of such patients is challenging if they are candidates for intravenous tPA since there is no rapidly available test to detect their anticoagulant effect. Thromboelastography (TEG) analyzes the dynamics of coagulation (Figure 1) and has previously demonstrated a hypercoagulable state in acute stroke patients. We sought to determine whether TEG can detect the anticoagulation effect of Factor Xa inhibitors in stroke patients.

Methods: Venous blood from seven subacute cardioembolic stroke patients prescribed Rivaroxaban was analyzed before (baseline) and 2, 4, 6 hours after drug administration with four patients also analyzed at 18 hours. Comparison of TEG parameters at various time intervals were assessed by repeated measures analysis of variance. Generalized Estimating Equations with an autoregressive correlation matrix was applied to account for the correlation within patients.

Results: Baseline TEG results required approximately 11 minutes to obtain. Higher R values were seen from baseline upto 18 hours, along with increased K values lasting upto 6 hours. Lower G, MA, and alpha-angle values were seen from baseline till 4 hours (Table 2). Together these results indicate slower and less strong clotting, and that the anti-coagulation effects of the drug peak at about 4-6 hours, with a trend towards normalization by 18 hours.

Conclusion: TEG can detect the anticoagulant effect of Factor Xa inhibitors in stroke patients, and might be useful for guiding emergency management of those eligible for tPA.

Thrombelastography detects the anticoagulant effect of rivaroxaban in patients with stroke

BACKGROUND AND PURPOSE

Factor Xa inhibitors are prescribed for stroke prevention in atrial fibrillation. Managing such patients is challenging especially if they are eligible for thrombolysis because there is no rapidly available test to detect the effect of such medications. Thrombelastography analyzes the dynamics of coagulation and can be rapidly performed. We sought to determine whether thrombelastography can detect the anticoagulation effect of factor Xa inhibitors in patients with stroke.

METHODS

Blood from 10 patients with stroke was analyzed by thrombelastography at baseline and 2 to 18 hours after rivaroxaban administration.

RESULTS

Increased R, K, and δ were seen at 2, 4, and 6 hours, while G, maximum amplitude, α-angle, and LY30 were decreased. Baseline R was 5.8±0.5 when compared with 11.4±1.0 at 2 hours. R remained prolonged at 18 hours. Other thrombelastography parameters were normal by 18 hours.

CONCLUSIONS

Thrombelastography can detect the anticoagulant effect of factor Xa inhibitors in patients with stroke and might be useful in the emergency management of those eligible for thrombolysis.

A multi-functional polyhydroxybutyrate nanoparticle for theranostic applications

One-step enzymatic synthesis of theranostic PHB nanoparticles using PHA synthase fused with A33scFv and GFP.

Iodinated contrast does not alter clotting dynamics in acute ischemic stroke as measured by thromboelastography

BACKGROUND AND PURPOSE

Iodinated contrast agents used for computed tomography angiography (CTA) may alter fibrin fiber characteristics and decrease fibrinolysis by tissue plasminogen activator (tPA). Thromboelastography (TEG) measures the dynamics of coagulation and correlates with thrombolysis in acute ischemic stroke patients. We hypothesized that receiving CTA before tPA will not impair thrombolysis as measured by TEG.

METHODS

Acute ischemic stroke patients receiving 0.9 mg/kg tPA <4.5 hours of symptom onset were prospectively enrolled. For CTA, 350 mg/dL of iohexol or 320 mg/dL of iodixanol at a dose of 2.2 mL/kg was administered. TEG was measured before tPA and 10 minutes after tPA bolus. CTA timing was left to the discretion of the treating physician.

RESULTS

Of 136 acute ischemic stroke patients who received tPA, 47 had CTA before tPA bolus, and 42 had either CTA after tPA and post-tPA TEG draw or no CTA (noncontrast group). Median change in clot lysis (LY30) after tPA was 95.3% in the contrast group versus 95.0% in the noncontrast group (P=0.74). Thus, tPA-induced thrombolysis did not differ between contrast and noncontrast groups. Additionally, there was no effect of contrast on any pre-tPA TEG value.

CONCLUSIONS

Our data do not support an effect of iodinated contrast agents on clot formation or tPA activity.

Abstract 105: Iodinated Contrast Does Not Alter Clotting Dynamics in Acute Ischemic Stroke as Measured by Thromboelastography

Introduction: Modern treatment of acute ischemic stroke (AIS) has increasingly incorporated multimodal CT imaging. Data illustrating that radiographic contrast agents alter fibrin fiber characteristics and decrease fibrinolysis by thrombolytic agents are potentially concerning. Thromboelastography (TEG) provides an integrated, dynamic view of coagulation and has recently been correlated with thrombolysis in AIS patients. This is the first study to examine the effects of contrast agents on tPA-induced clot lysis using TEG. We hypothesized that receiving computed tomography angiography (CTA) prior to tPA will impair thrombolysis as measured by TEG.

Methods: AIS patients receiving 0.9 mg/kg tPA within 4.5 hours of symptom onset were enrolled. For CTA, iohexol dose was calculated using Medrad’s P3T software. Blood was drawn for TEG prior to CTA or tPA treatment and again 10-minutes after tPA bolus. TEG values, time of TEG draw and tPA administration, and CTA times were recorded. TEG values in patients having CTA prior to tPA were compared with patients in whom a CTA was performed either after tPA or not at all. Results were analyzed using Mann-Whitney U Test.

Results: 100 AIS patients received tPA. Of these, 17 patients had CTA prior to TEG blood draws and tPA bolus. 57 patients had either CTA following tPA or no CTA. The median change in clot lysis (LY30) following tPA was 94.8% in the contrast group vs. 94.5% in controls (p = 0.84). The median reduction in clot strength (G) was -8.8 dyn/cm 2 in the contrast group vs. -8.6 dyn/cm 2 in controls (p = 0.51). Pre-tPA G appeared to be attenuated by contrast (7.7 vs. 5.9 dyn/cm 2 ) when corrected for platelet activity; however, this difference was not significant (p = 0.14). There was no effect of contrast on any other pre-tPA TEG value.

Conclusion: The current data do not support any impairment of tPA-induced clot lysis by contrast agents. Baseline TEG also appears to be unaffected by contrast, but more patients are needed to better examine a possible interaction between clot strength and contrast agents.

Dosimetric characteristics with spatial fractionation using electron grid therapy

Recently, promising clinical results have been shown in the delivery of palliative treatments using megavoltage photon grid therapy. However, the use of megavoltage photon grid therapy is limited in the treatment of bulky superficial lesions where critical radiosensitive anatomical structures are present beyond tumor volumes. As a result, spatially fractionated electron grid therapy was investigated in this project. Dose distributions of 1.4-cm-thick cerrobend grid blocks were experimentally determined for electron beams ranging from 6 to 20 MeV. These blocks were designed and fabricated at out institution to fit into a 20 x 20-cm(2) electron cone of a commercially available linear accelerator. Beam profiles and percentage depth dose (PDD) curves were measured in Solid Water phantom material using radiographic film, LiF TLD, and ionometric techniques. Open-field PDD curves were compared with those of single holes grid with diameters of 1.5, 2.0, 2.5, 3.0, and 3.5 cm to find the optimum diameter. A 2.5-cm hole diameter was found to be the optimal size for all electron energies between 6 and 20 MeV. The results indicate peak-to-valley ratios decrease with depth and the largest ratio is found at Dmax. Also, the TLD measurements show that the dose under the blocked regions of the grid ranged from 9.7% to 39% of the dose beneath the grid holes, depending on the measurement location and beam energy.

A comparison of different intensity modulation treatment techniques for tangential breast irradiation

PURPOSE

Several intensity modulation (IM) treatment techniques for tangential breast irradiation were evaluated in terms of dose uniformity in the treated breast volume, contralateral breast dose, and treatment irradiation time.

METHODS AND MATERIALS

Contralateral breast dose was measured via TLD chips, and the dose uniformity was calculated on two anthropomorphic phantoms. IM was applied to all beams or to the lateral-medial (LM) beam only. The techniques evaluated include (a) IM via "step & shoot" multileaf collimator (MLC), (b) IM via intensity modulator (compensator), (c) virtual wedge, and (d) physical wedge. A dose optimization algorithm was used for the first two techniques.

RESULTS

Collimator-generated IM techniques (MLC-IM and the virtual wedge) produced 50% (average) less contralateral breast dose than the conventional two-wedge technique. When the compensator or the physical wedge was used, contralateral breast dose was reduced 30% (average) by leaving the ML beam open.

CONCLUSION

The treatments generated by dose optimization algorithm and delivered via the compensator and MLC techniques offered superior dose uniformity. Single-beam IM techniques in general use less irradiation time without significant degradation of dose uniformity. The MLC-IM technique in this study required the longest treatment irradiation time, while the virtual wedge and compensator IM techniques required the least.

Solution structure of a duplex DNA with an abasic site in a dA tract

The presence of dA tracts in DNA can lead to stable curvature of the DNA, and this curvature can be important in gene regulation, DNA packaging, and other processes. Since damage to DNA may eliminate this stable curvature, the solution state structure of the duplex of d(CGCAAAAATGCG) paired with d(CGCATTDTTCCG), with D indicating an abasic site, has been determined. The undamaged DNA bends into the major groove both in solution and in the crystal state. The presence of the abasic site in the dA tract region induces changes in the DNA structure up to four base pairs away from the damaged site. The structure of the DNA is dependent on whether the abasic site is in the alpha or beta hemiacetal form. These consequences are quite different from the more localized effects that have been observed for "normal" DNAs containing abasic sites. Thus, there appears to be a strong sequence dependence of the structural effects of abasic sites just as there is for undamaged DNA. Furthermore, these results indicate that the presence of an abasic site can alter DNA bending and hence is likely to have significant long range effects on gene regulation and other properties that are dependent on the stable curvature of DNA.

Measurement of 6-MV X-ray surface dose when topical agents are applied prior to external beam irradiation

PURPOSE

Radiation therapy patients are typically warned not to apply lotions, deodorants, or powders to the skin within the treatment area because of the possible increase in surface dose due primarily to a bolus effect. This study investigates the effect of 15 products, with and without high atomic number components, on surface dose.

METHODS AND MATERIALS

A Markus-type parallel plate ionization chamber in a polystyrene phantom was used to measure surface doses for normal applications of the products for a small (5 x 5-cm2) and a large (25 x 25-cm2) field size.

RESULTS

The greatest surface dose increase for any product was 5.4% (21.8-27.2%) of the d(max) dose for the small field and 1.0% (43.6-44.6%) for the large field. Products with high-atomic-number components did not increase the surface dose relative to radiation therapy specialty products.

CONCLUSION

No large increase in surface dose was detected with a normal application of the products. However, the possibility exists that an increase in skin reaction may occur owing to chemical irritants in the applied product.

Effect of breakfast cereals on short-term food intake

We evaluated the effect of high-fiber cereals on short-term food intake. At 0730, 14 subjects ingested one of five cereals, plus milk and orange juice. At 1100 they were presented with a buffet lunch. There was a significant inverse correlation between fiber content of the cereals and energy intake at lunch. In a second study subjects ingested a very-high-fiber (VHF) cereal or a very-low-fiber (VLF) cereal. Fewer kcalories were ingested at lunch after ingestion of the VHF cereal than after ingestion of the VLF cereal. The degree of colonic microbial fermentation of the various cereals was evaluated by breath-hydrogen analysis. The higher-fiber cereals resulted in greater hydrogen production; however, this may not influence energy intake. The results of questionnaires that asked about hunger indicated that food intake can be reduced without the perception of feeling less hungry. Thus, we found that cereals containing relatively large quantities of dietary fiber may decrease short-term food intake.

Ultrasound in the perinatal necropsy

Although plain and contrast radiology have become a well established part of the perinatal and fetal necropsy, the role of ultrasound has been less comprehensively explored. We have found a variety of ultrasonographic approaches to be of value in diagnosis, quality control, and teaching. Ultrasound is of particular help where consent for formal necropsy has been declined.

The bleaching of the bacteriorhodopsin chromophore by ionizing radiation

The visible chromophore of bacteriorhodopsin, BR(570), undergoes progressive bleaching when subjected to 60CO gamma-irradiation. The low G-value for bleaching confirms that the site of the chromophore is highly protected. Positive and negative circular dichroic (CD) bands associated with the chromosphone undergo concomitant decrease in a manner which is consistent with two independent chromophores rather than exciton coupling between neighbouring chromophoric site.

The blink reflex in coma and after recovery from coma

Comparative studies of the blink reflex in a series of head injuries through the stages of coma and recovery from coma in a series of miscellaneous hemispheral lesions, and in a normal series, reveals that, although the principal centre for the R1 component of the blink reflex seems to be localised in the upper pons, the seat of the R2 late component is in the reticular system. The reappearance of this late component of the blink reflex in our cases of coma although seeming to depend on the integrity of the mesencephalic formation, correlates with the recovery of the patient's alertness. On the other hand, habituation of this reflex depends on the integrity of global cognitive function, rather than on any localised centre. The roles of the cortex, selective attention, and emotional factors, are discussed. The recovery of the normal habituation of the blink reflex obtained by glabellar tapping was found to be a useful sign in the follow up of patients recovering from concussion and other lesions, such as subdural haematomas and brain tumours, with global mental impairment.

Memory recovery after traumatic coma

Serial memory testings of 108 head injury cases were studied over a two year follow up period. The length of the post-traumatic disorientation period (PTD) was found to be an important factor in the rate of memory recovery. In the first year after injury marked differences were seen in the recovery rates of all four PTD groups, the three short PTD groups (less than one month) finally yielding from 74% to 92% cases (according to the group) with normal memory function, while the long PTD group (more than one month) only produced 45% cases (statistical significance 0.05). During the second year and up to the end of this survey relatively little change in memory status occurred in any of the cases, regardless of their PTD. Any improvement that did occur was at an extremely slow rate. Brain damage was the main cause of memory defect in the long PTD group, while anxiety symptoms had a more important role in the short PTD cases. The shapes of memory recall curves were analysed in recovering patients. Three types of curve were found. The incidence of the shape of the curve also varied according to the PTD time (statistical significance 0.05) between long and short PTD groups. Curve shapes are discussed in terms of memory mechanisms, and a possible prognostic value is suggested. Analysis of test errors indicated not only a defective transfer of material from short term long term memory storage but also in some cases, a more complex mechanism involving inappropriate fixation of attention. Reverberation of memory traces is suggested as being a possible cause of interference in both short and long term memory mechanisms. A marked difference in recall performance between auditory and visual presentation of word lists was found to be a useful lateralising sign.

The arteriographic pattern of the insula: its normal appearance and variations in cases of tumour of the cerebral hemispheres

Images