Multi Frequency Isotopes Survey to Improve Transit Time Estimation in a Situation of River-Aquifer Interaction

The Barthelasse alluvial aquifer is used to supply water to 180,000 inhabitants. The pumping field is located less than 200 m from the Rhône and is 100% fed by water from the Rhône, which makes it particularly vulnerable to any pollution from the Rhône. Between the Rhône and the pumping field is a Girardon unit, an arrangement that can be found regularly along the banks of the lower and middle reaches of the Rhône, and whose role is to stabilise the banks (alluvial deposits) and to facilitate river navigation. In order to know the transfer times between the Rhône and the pumping field, fortnightly monitoring was carried out over a hydrological year, as well as hourly monitoring during a flood in the winter of 2019. The Rhône shows a cyclicality in its isotopic signature with enrichment in heavy isotopes during the winter period, particularly during floods, and a depletion during the summer period. This variation is found well within the associated alluvial aquifer. The application of LPMs models showed that the average transfer time between the Rhône and the Girardon unit was 20 days and 50 days between the Rhône and the Barthelasse pumping. This study highlighted the importance of using several sampling frequencies to consider the diversity of hydrological situations. For the Rhône, event-based monitoring (flooding) proved to be relevant to account for isotopic variability throughout the year. This work also highlighted the impact of the disruption of hydraulic exchanges between the river and the water table caused by the presence of the Girardon unit in terms of the propagation of contaminants.

Review of Irish patients meeting ST elevation criteria during the COVID-19 pandemic

IntroductionThe COVID-19 pandemic has seen the introduction of important public health measures to minimise the spread of the virus. We aim to identify the impact government restrictions and hospital-based infection control procedures on ST elevation myocardial infarction (STEMI) care during the COVID-19 pandemic.MethodsPatients meeting ST elevation criteria and undergoing primary percutaneous coronary intervention from 27 March 2020, the day initial national lockdown measures were announced in Ireland, were included in the study. Patients presenting after the lockdown period, from 18 May to 31 June 2020, were also examined. Time from symptom onset to first medical contact (FMC), transfer time and time of wire cross was noted. Additionally, patient characteristics, left ventricular ejection fraction, mortality and biochemical parameters were documented. Outcomes and characteristics were compared against a control group of patients meeting ST elevation criteria during the month of January.ResultsA total of 42 patients presented with STEMI during the lockdown period. A significant increase in total ischaemic time (TIT) was noted versus controls (8.81 hours (±16.4) vs 2.99 hours (±1.39), p=0.03), with increases driven largely by delays in seeking FMC (7.13 hours (±16.4) vs 1.98 hours (±1.46), p=0.049). TIT remained significantly elevated during the postlockdown period (6.1 hours (±5.3), p=0.05), however, an improvement in patient delays was seen versus the control group (3.99 hours (±4.5), p=0.06). There was no difference seen in transfer times and door to wire cross time during lockdown, however, a significant increase in transfer times was seen postlockdown versus controls (1.81 hours (±1.0) vs 1.1 hours (±0.87), p=0.004).ConclusionA significant increase in TIT was seen during the lockdown period driven mainly by patient factors highlighting the significance of public health messages on public perception. Additionally, a significant delay in transfer times to our centre was seen postlockdown.

Perceived Trip Time Reliability and Its Cost in a Rail Transit Network

Time reliability in a Rail Transit Network (RTN) is usually measured according to clock-based trip time, while the travel conditions such as travel comfort and convenience cannot be reflected by clock-based trip time. Here, the crowding level of trains, seat availability, and transfer times are considered to compute passengers’ Perceived Trip Time (PTT). Compared with the average PTT, the extra PTT needed for arriving reliably, which equals the 95th percentile PTT minus the average PTT, is converted into the monetary cost for estimating Perceived Time Reliability Cost (PTRC). The ratio of extra PTT needed for arriving reliably to the average PTT referring to the buffer time index is proposed to measure Perceived Time Reliability (PTR). To overcome the difficulty of obtaining passengers’ PTT who travel among rail transit modes, a Monte Carlo simulation is applied to generated passengers’ PTT for computing PTR and PTRC. A case study of Chengdu’s RTN shows that the proposed metrics and method measure the PTR and PTRC in an RTN effectively. PTTR, PTRC, and influential factors have significant linear relations among them, and the obtained linear regression models among them can guide passengers to travel reliably.

A multi-objective multi-agent optimization algorithm for the multi-skill resource-constrained project scheduling problem with transfer times

This paper addresses the Multi-Skill Resource-Constrained Project Scheduling Problem with Transfer Times (MSRCPSP-TT). A new model has been developed that incorporates the presence of transfer times within the multi-skill RCPSP. The proposed model aims to minimize project’s duration and cost, concurrently. The MSRCPSP-TT is an NP-hard problem; therefore, a Multi-Objective Multi-Agent Optimization Algorithm (MOMAOA) is proposed to acquire feasible schedules. In the proposed algorithm, each agent represents a feasible solution that works with other agents in a grouped environment. The agents evolve due to their social, autonomous, and self-learning behaviors. Moreover, the adjustment of environment helps the evolution of agents as well. Since the MSRCPSP-TT is a multi-objective optimization problem, the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) is used in different procedures of the MOMAOA. Another novelty of this paper is the application of TOPSIS in different procedures of the MOMAOA. These procedures are utilized for: (1) detecting the leader agent in each group, (2) detecting the global best leader agent, and (3) the global social behavior of the MOMAOA. The performance of the MOMAOA has been analyzed by solving several benchmark problems. The results of the MOMAOA have been validated through comparisons with three other meta-heuristics. The parameters of algorithms are determined by the Response Surface Methodology (RSM). The Kruskal-Wallis test is implemented to statistically analyze the efficiency of methods. Computational results reveal that the MOMAOA can beat the other three methods according to several testing metrics. Furthermore, the impact of transfer times on project’s duration and cost has been assessed. The investigations indicate that resource transfer times have significant impact on both objectives of the proposed model

Abstract P149: Regional Transfer Protocols Can Improve Transfer Times and Reduce Length of Stay for Thrombectomy Candidates Seen on Telestroke

Introduction: Our telestroke (TS) network instituted a regional transfer protocol (RTP) that allows for stroke patients in need of higher level of care to be pre-accepted and transferred to the nearest appropriate comprehensive stroke center (CSC). We studied the impact of the RTP on resource utilization and time metrics in patients transferred for evaluation of intra-arterial thrombectomy (IAT). Before the RTP, all potential IAT patients were transferred to one central CSC. After the RTP was initiated, the network had the capability to transfer to two additional CSCs within the same health system that are strategically located in the Houston area. Methods: We identified patients evaluated via TS in spoke emergency rooms that were subsequently transferred for IAT evaluation from 1/1/2016 to 12/31/2017 - one year prior and one year after the RTP. Baseline demographic characteristics, transfer and IAT metrics, and outcomes were compared for the two time periods. Results: Of 220 patients, 102 patients were transferred pre-RTP, and 120 were transferred to the three CSCs post-RTP. There were no significant differences in baseline characteristics, except fewer patients received tPA post-RTP (Table 1). In total, 30 patients (29%) pre-RTP and 42 patients (35%) post-RTP underwent IAT (p=0.38). Post-RTP, there was a trend toward faster travel times (median 40 vs 32 minutes, p=.07) and transfer initiation times to hub arrival times (median 109 vs 100.5 minutes, p=0.09). Door to groin puncture times were not statistically different between the two time periods. Post-RTP patients had a significantly shorter length of stay (median 6 vs 5 days, p=0.03). Conclusions: Regional transfer protocols can potentially help reduce transfer times and length of stay for stroke patients at CSCs that were initially seen by TS at community hospitals; however, larger sample size is needed to study its impact on other IAT-related metrics and clinical outcomes.

Abstract P818: Increased Eligibility for Endovascular Therapy Following Intensive Door-To-Transfer Improvement Project

Background and Purpose: Early EVT for large vessel acute ischemic stroke is associated with reduced disability and mortality. Longer transfer times from the sending facility contribute to poorer EVT outcomes, and in some circumstances, patient ineligibility for EVT due to a completed stroke on arrival to the endovascular site. Reducing avoidable delays will result in overall improved EVT outcomes and reduce the frequency of completed stroke upon arrival. Methods: A multidisciplinary group utilized the Lean A3 process and PDCA improvement cycle to reduce transfer times. Avoidable delays and resources to expedite the transfers were identified. A standardized plan with defined roles and responsibilities, communication pathways, early transport team activation, and robust staff education were implemented. The PI team met weekly for 3 months to review each individual transfer, determine what went well and what did not, and to identify additional improvement opportunities. A weekly summary with feedback was provided to front line staff and managers. Staff involved in patient transfers that had a DIDO of 90 min or less were recognized with a “Brain Pin” and staff recognition certificate. Results: Since its implementation, 23 patients were transferred for potential EVT. Compared with 12 months prior to implementation, the DIDO median time was reduced from 119 minutes to 80.5 minutes, transfers were achieved in 90 min or less 61% (n=15) of the time vs. 27.2%, and percentage of EVT eligible patients increased from 58.3 to 78.3%. Conclusion: In conclusion, rapid reduction of DIDO times and increased patient eligibility for thrombectomy is attainable through an intensive multidisciplinary process improvement project. Implementing a standardized workflow that includes rapid identification of potential EVT transfers, early activation of the transport team, development of clear pathways of communication, defined roles and responsibilities within the team, and regular staff feedback are essential.

Abstract P463: Direct to Angio in Transferred Patients is Associated With Faster Reperfusion and Higher Functional Independence Rates Both During Regular and On-Call Hours: A Multi Center Cohort

Background: Direct To Angio (DTA) for transferred large vessel occlusions (LVO) lowers time to endovascular thrombectomy (EVT), reperfusion and potentially improves outcomes. Safety and efficacy of DTA in late time window and on-call hours is unknown. Methods: Pooled cohort from 6 centers (EU, US) from 1/14-5/20 (ICA, M1, M2) LVO pts transferred for EVT≤24 hrs from LKW. Pts stratified into with repeat imaging (RI) (CT+/- CTA/CTP) and without RI (DTA). We compared time metrics, good outcome (90 day mRS 0-2), safety (sICH, mortality) and assessed the impact of arrival for EVT; regular (M-F, 8am-5pm) vs on-call hrs. Propensity matched analysis was done. Results: Of 1178 EVT transfers, 334 (28%) were DTA. DTA pts had more tPA (61% vs 51%, p=0.002), trended to lower NIHSS 17 (12, 20) vs 17 (13, 21), p=0.07 and lower LKW to arrival 268 (190, 430) min vs 280 (190, 518), p=0.097. Groin puncture (GP) was faster with DTA (p<0.001) Fig 1. Good outcomes were higher with DTA overall (53% vs 38%, aOR 1.7, 95%CI 1.3-2.4, p=0.001), regular (54% vs 41%, p=0.07) and on-call hrs (52% vs 36%, p=0.008), mortality was lower overall (17% vs 24%, p=0.04) and all hrs Fig 2 A-C. sICH rates were similar. A 10 min increase arrival to GP with RI correlated to 5% reduction in good outcome odds (aOR 0.95, 95%CI 0.91-0.99, p=0.01). The results did not vary by time window (0-6 hrs vs >6-24, p=0.88 for interaction). In propensity matched 75 pairs, DTA had shorter time to EVT (19 min vs 52, p<0.001) and higher mRS 0-2 (55% vs 32%, aOR 4.8 (1.9-12.4), p=0.001) fig 2D. However, the probability of mRS 0-2 decreased with increasing transfer times in DTA pts (< 3 hrs 59% vs 36% ≥ 3 hrs, p<0.001) but not in RI (36% vs 37%, p=0.88) fig 3. Conclusion: In pooled, non-randomized data DTA may result in faster treatment, safe and better functional outcomes, during all hours and treatment windows. Repeat imaging may be reasonable with prolonged transfer times. Optimal EVT workflow in transfers may result in faster, safe reperfusion with higher good outcomes.