Median Transit Time Research Articles

P0293 The utility of small bowel capsule endoscopy in Crohn’s Disease – a retrospective cohort study

Abstract Background Small bowel capsule endoscopy (SBCE) has the highest sensitivity and specificity for identifying Crohn’s disease (CD) affecting the small bowel. The recent CURE-CD study demonstrated that proactive treatment optimisation with SBCE monitoring led to improved outcomes. [1] We performed a retrospective cohort study at a tertiary centre in the UK to evaluate the impact of SBCE in the management of Crohn’s disease. Methods We reviewed the capsule database from December 2021 – December 2022. 181 SBCE were performed in this time period. We included patients who were either newly diagnosed with CD following SBCE or patients with known CD undergoing SBCE as part of disease reassessment. All patients included had no/minimal changes on imaging and/or endoscopy to justify treatment initiation/escalation for ongoing symptoms. Data was extracted from their electronic health record. Correlations were analysed using Spearman’s ranked test. Results 96 patients met the inclusion criteria. 67 patients (69.8%) with known CD underwent SBCE as part of disease reassessment and 29 patients (30.2%) were newly diagnosed with CD following SBCE. Their baseline demographics pre-SBCE are illustrated by table 1. Small bowel visualisation was adequate in 93 (96.8%) and the median transit time for a SBCE study was 4hrs and 36 minutes. The median Lewis Score (LS) was 423. 71 (73.9%) patients had active SB Crohn’s disease (defined as a LS >135). Of these, 26 (36.6%) had moderate to severe disease (LS>790). There was a poor correlation between inflammatory biomarkers and symptoms of diarrhoea/abdominal pain with active CD on SBCE with none of these reaching a correlation level greater than 0.3. The impact of SBCE on the management of patients is showed by figure 1. 47 (48.9%) had a repeat SBCE for disease reassessment with a median time of 449 days between the first and second SBCE. The median LS for the repeat SBCE was 112. There was a significant reduction in moderate-to-severe active disease at the follow-up SBCE (baseline 26/96, 27.1% to follow-up 8/47, 17%). Repeat SBCE identified more patients in remission defined as LS <135 (baseline SBCE remission 25/96, 26% vs repeat SBCE remission 27/47, 57.4%, p=0.005). No cases of capsule retention occurred. Conclusion In a large cohort of patients with minimal/no changes on conventional investigative modalities for Crohn’s disease, SBCE led to a change in treatment in 63.5%. Repeat SBCE showed significantly higher proportion of patients in endoscopic remission. Conventional non-invasive markers of inflammation and symptoms correlated poorly with activity on SBCE further highlighting the importance for clinicians to consider SBCE in both the workup and reassessment of disease activity in patients with Crohn’s disease.

The Bering Strait Throughflow Component of the Global Mass, Heat and Freshwater Transport

AbstractAs the only oceanic connection between the Pacific and Arctic‐Atlantic Oceans, Bering Strait throughflow carries a climatological northward transport of about 1 Sv, contributing to the Atlantic Meridional Overturning Circulation (AMOC). Here, Lagrangian analysis quantifies the global distributions of volume transport, transit‐times, thermohaline properties, diapycnal transformation, heat and freshwater transports associated with Bering Strait throughflow. Virtual Lagrangian parcels, released at Bering Strait, are advected by the velocity of Estimating the Circulation and Climate of the Ocean, backward and forward in time. Backward trajectories reveal that Bering Strait throughflow enters the Pacific basin on the southeast side, as part of fresh Antarctic Intermediate Water, then follows the wind‐driven circulation to Bering Strait. Median transit time from S in Indo‐Pacific to Bering Strait is 175 years. Sixty‐four percent of Bering Strait throughflow enters the North Atlantic through the Labrador Sea. The remaining 36% flows through the Greenland Sea, warmed and salinified by the northward flowing Atlantic waters. Deep water formation of water flowing through Bering Strait occurs predominantly in the Labrador Sea. Subsequently, this water joins the lower branch of AMOC, flowing southward in the deep western boundary current as North Atlantic Deep Water. Median transit time from Bering Strait to S in South Atlantic is 160 years. The net heat transport of Bering Strait throughflow is northward everywhere, and net freshwater transport by Bering Strait throughflow is mostly northward. The freshwater transport is largest in the subpolar region of basin sectors: northward in the Pacific and Arctic and southward in the Atlantic.

Geospatial Point-of-Care Testing Strategies for COVID-19 Resilience in Resource-Poor Settings: Rural Cambodia Field Study.

Point-of-care testing (POCT) generates intrinsically fast, inherently spatial, and immediately actionable results. Lessons learned in rural Cambodia and California create a framework for planning and mobilizing POCT with telehealth interventions. Timely diagnosis can help communities assess the spread of highly infectious diseases, mitigate outbreaks, and manage risks. The aims of this study were to identify the need for POCT in Cambodian border provinces during peak COVID-19 outbreaks and to quantify geospatial gaps in access to diagnostics during community lockdowns. Data sources comprised focus groups, interactive learners, webinar participants, online contacts, academic experts, public health experts, and officials who determined diagnostic needs and priorities in rural Cambodia during peak COVID-19 outbreaks. We analyzed geographic distances and transit times to testing in border provinces and assessed a high-risk province, Banteay Meanchey, where people crossed borders daily leading to disease spread. We strategized access to rapid antigen testing and molecular diagnostics in the aforementioned province and applied mobile-testing experience among the impacted population. COVID-19 outbreaks were difficult to manage in rural and isolated areas where diagnostics were insufficient to meet needs. The median transit time from border provinces (n=17) to testing sites was 73 (range 1-494) minutes, and in the high-risk Banteay Meanchey Province (n=9 districts), this transit time was 90 (range 10-150) minutes. Within border provinces, maximum versus minimum distances and access times for testing differed significantly (P<.001). Pareto plots revealed geospatial gaps in access to testing for people who are not centrally located. At the time of epidemic peaks in Southeast Asia, mathematical analyses showed that only one available rapid antigen test met the World Health Organization requirement of sensitivity >80%. We observed that in rural Solano and Yolo counties, California, vending machines and public libraries dispensing free COVID-19 test kits 24-7 improved public access to diagnostics. Mobile-testing vans equipped with COVID-19 antigen, reverse transcription polymerase chain reaction, and multiplex influenza A/B testing proved useful for differential diagnosis, public awareness, travel certifications, and telehealth treatment. Rural diagnostic portals implemented in California demonstrated a feasible public health strategy for Cambodia. Automated dispensers and mobile POCT can respond to COVID-19 case surges and enhance preparedness. Point-of-need planning can enhance resilience and assure spatial justice. Public health assets should include higher-quality, lower-cost, readily accessible, and user-friendly POCT, such as self-testing for diagnosis, home molecular tests, distributed border detection for surveillance, and mobile diagnostics vans for quick telehealth treatment. High-risk settings will benefit from the synthesis of geospatially optimized POCT, automated 24-7 test access, and timely diagnosis of asymptomatic and symptomatic patients at points of need now, during new outbreaks, and in future pandemics.

Outcomes and risk factors of transported patients with extracorporeal membrane oxygenation: An ECMO center experience

BackgroundExtracorporeal membrane oxygenation (ECMO) has been proven to be a support method and technology for patients with cardiopulmonary failure. However, the transport of patients under ECMO support is challenging given the high-risk technical maneuvers and patient-care concerns involved. Herein, we examined the safety of ECMO during the transport of critically ill patients and its impact on mortality rates, to provide more secure and effective transport strategies in clinical practice. MethodTo assess the safety of ECMO patient transport, this study conducted a retrospective analysis on critically ill adults who required ECMO support and transport at the intensive care unit (ICU) center between 2017 and 2023. The study utilized standard ECMO transport protocols and conducted a comprehensive statistical analysis of the collected clinical data and transport processes. The 28-day survival rate for ECMO patients was determined using Kaplan–Meier analysis, while logistic regression identified prognostic factors. ResultOut of 303 patients supported with ECMO, 111 (36.6%) were transported. 69.4% of the transport group were male, mean age was (42.0±17.0) years, mean body mass index was (24.4±4.6) kg/m2, and veno-arterial-ECMO accounted for 52.5%. The median transportation distance was 190 (interquartile range [IQR]: 70–260) km, and the longest distance was 8100 km. The median transit time was 180 (IQR: 100–260) min, and the maximum duration was 1720 min. No severe adverse events including death or mechanical failure occurred during transportation. The 28-day survival was 64.7% (n=196) and ICU survival was 56.1% (n=170) for the entire cohort; whereas, the 28-day survival was 72.1% (n=80) and ICU survival was 66.7% (n=74) in the transport group. A non-significant difference in survival (P=0.56) was observed between the two groups after propensity score matching. Additionally, we found that acute physiology and chronic health evaluation II score (odds ratio [OR]=1.06, P <0.01), lactate levels (>5 mmol/L, OR=2.80, P=0.01), and renal replacement therapy initiation (OR=3.03, P <0.01) were associated with increased mortality risk. ConclusionTransporting patients on ECMO between medical facilities is a safe procedure that does not increase patient mortality rates, provided it is orchestrated and executed by proficient transport teams. The prognostic outcome for these patients is predominantly influenced by their pre-existing medical conditions or by complications that may develop during the course of ECMO therapy. These results form the basis for the creation of specialized ECMO network hubs within healthcare regions.

#2292 Incremental peritoneal dialysis: an individualized therapy with better clinical outcomes and reduced environmental and economic impact

Abstract Background and Aims Incremental peritoneal dialysis (IPD) is based on the prescription of a dose lower than the standard “full dose” (SPD). The achievement of individualized clearance goals is based on the combination of peritoneal and renal clearance. IPD as the initial PD strategy seems to be a convenient and resource-sparing technique, but its impact in long term outcomes and in the environment lacks evidence. The aim of this study is to evaluate IPD outcomes and to analyze the potential impact of this initial approach on costs, total and plastic waste, and water consumption. Method Single-center observational retrospective study that included a cohort of 87 prevalent PD adults. Patients were assigned in two groups according to their initial PD prescription—IPD group [continuous ambulatory PD (CAPD): less than 4 dwells daily, less than 2L dwell volume, and/or PD less than 7 days/week; automated PD (APD): without a long dwell, less than 10 L delivered, and/or PD for less than 7 days/week] and SPD group. Primary outcomes were residual kidney function preservation, technique survival and mortality. Secondary outcomes were peritonitis rate and hospitalizations. The reductions related to costs, total and plastic waste, and water usage were also compared between groups. Results In 57 (65%) of the patients IPD was the initial therapy, while 30 (35%) patients were prescribed SPD. The median follow-up was 23 months and the median transition time from 2 to 3 and from 3 to 4 exchanges were 6 and 14 months in CAPD, respectively. APD patients transitioned to SPD after a median of 9 months. Patients in IPD group had a higher glomerular filtration rate (7 vs. 3.7, mL/min/1.73 m2, p &amp;lt; 0.001) in the first 6 months, and after 24 months (4.8 vs. 1.9, mL/min/1.73 m2, p = 0.002. IPD was also associated with a longer technique survival (p = 0.026), lower hospital admissions per year (0.23 vs. 0.5, p = 0.001), and lower mortality (1.8% vs. 13.3%, p = 0.027). Compared to SPD, 2 and 3 exchanges per day led to a reduction in costs of approximately 8500 or 4100 euros/patient-year, total waste of 266 or 143 kg/year/patient, in plastic waste of 159 or 69 kg/year/patient, and water savings of 28,620 or 12,420 L/year/patient, respectively. In APD, IPD led to a reduction of 4400 euros/ patient-year in cost, 211 kg/year/patient in total and of 139 kg/year/patient in plastic waste, and water savings of 25,020 L/year/patient. Conclusion Prescription of initial individualized IPD is associated with better clinical outcomes in patients with substantial RKF. This approach was a significant economic and environmental impact, with a reduction in total and plastic waste, and water consumption.

The value of instream stable water isotope and nitrate concentration data for calibrating a travel time‐based water quality model

AbstractTransit time‐based water quality models using StorAge Selection (SAS) functions are crucial for nitrate (NO3−) management. However, relying solely on instream NO3− concentration for model calibration can result in poor parameter identifiability. This is due to the interaction, or correlation, between transport parameters, such as SAS function parameters, and denitrification rate, which challenges accurate parameters identification and description of catchment‐scale hydrological processes. To tackle this issue, we conducted three Monte‐Carlo experiments for a German mesoscale catchment by calibrating a SAS‐based model with daily instream NO3− concentrations (Experiment 1), monthly instream stable water isotopes (e.g. δ18O) (Experiment 2) and both datasets (Experiment 3). Our findings revealed comparable ranges of SAS transport parameters and median water transit times (TT50) across the experiments. This suggests that, despite their distinct reactive or conservative nature, and sampling strategies, the NO3− and δ18O time series offer similar information for calibration. However, the absolute values of transport parameters and TT50 time series, as well as the degree of parameter interaction differed. Experiment 1 showed greater interaction between certain transport parameters and denitrification rate, leading to greater equifinality. Conversely, Experiment 3 yielded reduced parameters interaction, which enhanced transport parameters identifiability and decreased uncertainty in TT50 time series. Hence, even a modest effort to incorporate only monthly δ18O values in model calibration for highly frequent NO3−, improved the description of hydrological transport. This study showcased the value of combining NO3− and δ18O model results to improve transport parameter identifiability and model robustness, which ultimately enhances NO3− management strategies.

CFP/Yit: An Inbred Mouse Strain with Slow Gastrointestinal Transit

BackgroundGastrointestinal transit (GIT) is influenced by factors including diet, medications, genetics, and gut microbiota, with slow GIT potentially indicating a functional disorder linked to conditions, such as constipation. Although GIT studies have utilized various animal models, few effectively model spontaneous slow GIT.AimsWe aimed to characterize the GIT phenotype of CFP/Yit (CFP), an inbred mouse strain with suggested slow GIT.MethodsFemale and male CFP mice were compared to Crl:CD1 (ICR) mice in GIT and assessed based on oral gavage of fluorescent-labeled 70-kDa dextran, feed intake, fecal amount, and fecal water content. Histopathological analysis of the colon and analysis of gut microbiota were conducted.ResultsCFP mice exhibited a shorter small intestine and a 1.4-fold longer colon compared to ICR mice. The median whole-GIT time was 6.0-fold longer in CFP mice than in ICR mice. CFP mice demonstrated slower gastric and cecal transits than ICR mice, with a median colonic transit time of 4.1 h (2.9-fold longer). CFP mice exhibited lower daily feed intakes and fecal amounts. Fecal water content was lower in CFP mice, apparently attributed to the longer colon. Histopathological analysis showed no changes in CFP mice, including tumors or inflammation. Moreover, CFP mice had a higher Firmicutes/Bacteroidota ratio and a relative abundance of Erysipelotrichaceae in cecal and fecal contents.ConclusionsThis study indicates that CFP mice exhibit slow transit in the stomach, cecum, and colon. As a novel mouse model, CFP mice can contribute to the study of gastrointestinal physiology and disease.

Altered Weddell Sea warm- and dense-water pathways in response to 21st-century climate change

Abstract. The transport of water masses with ocean circulation is a key component of the global climate system. In this context, the Filchner Trough in the southern Weddell Sea is critical, as it is a hotspot for the cross-shelf-break exchange of Dense Shelf Water and Warm Deep Water. We present results from Lagrangian particle tracking experiments in a global-ocean–sea-ice model (FESOM-1.4) which includes ice-shelf cavities and has eddy-permitting resolution on the southern Weddell Sea continental shelf. With backward and forward experiments, we assess changes between a present-day and a future (SSP5-8.5) time slice in the origin of waters reaching the Filchner Ice Shelf front and the fate of waters leaving it. We show that particles reaching the ice-shelf front from the open ocean originate from 173 % greater depths by 2100 (median; 776 m as compared to 284 m for the present day), while waters leaving the cavity towards the open ocean end up at 35 % shallower depths (550 m as compared to 850 m for the present day). Pathways of water leaving the continental shelf increasingly occur in the upper ocean, while the on-shelf flow of waters that might reach the ice-shelf cavity, i.e., at deeper layers, becomes more important by 2100. Simultaneously, median transit times between the Filchner Ice Shelf front and the continental shelf break decrease (increase) by 6 (9.5) months in the backward (forward) experiments. In conclusion, our study demonstrates the sensitivity of regional circulation patterns in the southern Weddell Sea to ongoing climate change, with direct implications for ice-shelf basal melt rates and local ecosystems.

Noninvasive sampling of the small intestinal chyme for microbiome, metabolome and antimicrobial resistance genes in dogs, a proof of concept

BackgroundThe gastrointestinal microbiome and metabolome vary greatly throughout the different segments of the gastrointestinal tract, however current knowledge of gastrointestinal microbiome and metabolome in health and disease is limited to fecal samples due to ease of sampling. The engineered Small Intestinal MicroBiome Aspiration (SIMBA™) capsule allows specific sampling of the small intestine in humans. We aimed to determine whether administration of SIMBA™ capsules to healthy beagle dogs could reliably and safely sample the small intestinal microbiome and metabolome when compared to their fecal microbiome and metabolome.ResultsEleven beagle dogs were used for the study. Median transit time of capsules was 29.93 h (range: 23.83–77.88). Alpha diversity, as measured by the Simpson diversity, was significantly different (P = 0.048). Shannon diversity was not different (P = 0.114). Beta diversity results showed a significant difference between capsule and fecal samples regarding Bray–Curtis, weighted and unweighted unifrac (P = 0.002) and ANOSIM distance metric s (R = 0.59, P = 0.002). In addition to observing a statistically significant difference in the microbial composition of capsules and feces, distinct variation in the metabolite profiles was seen between the sample types. Heat map analysis showed 16 compounds that were significantly different between the 2 sampling modes (adj-P value ranged between 0.004 and 0.036) with 10 metabolites more abundant in the capsule than in the feces and 6 metabolites more abundant in the feces compared to the capsules.ConclusionsThe engineered Small Intestinal MicroBiome Aspiration (SIMBA™) capsule was easy and safe to administer to dogs. Microbiome and metabolome analysis from the capsule samples were significantly different than that of the fecal samples and were like previously published small intestinal microbiome and metabolome composition.Graphical abstract

Central retinal artery occlusion without cherry-red spots

BackgroundCherry-red spots are a very important sign for the clinical diagnosis of central retinal artery occlusion (CRAO). We retrospectively summarized the clinical manifestations of CRAO and analysed the causes and characteristics of CRAO without cherry-red spots. In this study, we explored a diagnostic method for CRAO without cherry red spots.MethodsSeventy patients (70 eyes) with CRAO were examined retrospectively. Corrected distance visual acuity, fundus photos, FA and OCT images were collected at the first outpatient visit. The causes of CRAO without cherry-red spots were analysed through fundus photos. The incidence of increased hyperreflectivity of the inner retina, central macular thickness (CMT) and arteriovenous transit time in patients with and without cherry-red spots were compared.ResultsFundus examination showed posterior retinal whitening in 57 cases (81.43%) and cherry-red spots in 39 cases (55.71%). Thirty-one patients presented at the first outpatient visit without cherry-red spots. The reasons for the absence of cherry-red spots included leopard fundus (32.26%), retinal vein occlusion (25.81%), no obvious inner retinal coagulative necrosis (19.35%), ciliary retinal artery sparing (12.90%), high macular oedema (9.68%) and cherry-red spot enlargement (3.23%). OCT revealed increased hyperreflectivity of the inner retina in 67 CRAO patients (95.71%). All 3 patients without increased hyperreflectivity of the inner retina did not present with cherry-red spots at the first visit. The median CMT in patients without cherry-red spots was 166.00 μm, while the median MCT in patients with cherry-red spots was 180.00 μm; there was no significant difference between these two groups (P = 0.467). FA showed delayed arteriovenous transit time > 23 s in 20 patients (28.57%), > 15 s in 43 patients (61.43%) and no delay in 27 patients (30.77%). The median arteriovenous transit time in patients without cherry-red spots was 19.00 s, while it was 18.00 s in patients with cherry-red spots; there was no significant difference between these two groups (P = 0.727).ConclusionsThere are multiple factors that could cause the absence of cherry-red spots in CRAO. The use of OCT to observe increased hyperreflectivity of the inner retina is the most effective imaging method for the early diagnosis of CRAO without cherry-red spots.

Uncertainty in water transit time estimation with StorAge Selection functions and tracer data interpolation

Abstract. Transit time distributions (TTDs) of streamflow are useful descriptors for understanding flow and solute transport in catchments. Catchment-scale TTDs can be modeled using tracer data (e.g. oxygen isotopes, such as δ18O) in inflow and outflows by employing StorAge Selection (SAS) functions. However, tracer data are often sparse in space and time, so they need to be interpolated to increase their spatiotemporal resolution. Moreover, SAS functions can be parameterized with different forms, but there is no general agreement on which one should be used. Both of these aspects induce uncertainty in the simulated TTDs, and the individual uncertainty sources as well as their combined effect have not been fully investigated. This study provides a comprehensive analysis of the TTD uncertainty resulting from 12 model setups obtained by combining different interpolation schemes for δ18O in precipitation and distinct SAS functions. For each model setup, we found behavioral solutions with satisfactory model performance for in-stream δ18O (KGE &gt; 0.55, where KGE refers to the Kling–Gupta efficiency). Differences in KGE values were statistically significant, thereby showing the relevance of the chosen setup for simulating TTDs. We found a large uncertainty in the simulated TTDs, represented by a large range of variability in the 95 % confidence interval of the median transit time, varying at the most by between 259 and 1009 d across all tested setups. Uncertainty in TTDs was mainly associated with the temporal interpolation of δ18O in precipitation, the choice between time-variant and time-invariant SAS functions, flow conditions, and the use of nonspatially interpolated δ18O in precipitation. We discuss the implications of these results for the SAS framework, uncertainty characterization in TTD-based models, and the influence of the uncertainty for water quality and quantity studies.

A Lagrangian Estimate of the Mediterranean Outflow's Origin

AbstractThe origin of the Mediterranean Outflow is investigated by deploying six millions virtual Lagrangian parcels at the Strait of Gibraltar, and tracing them backward in time using velocity estimates from an eddy‐permitting reanalysis. The Lagrangian parcels are followed until they intercept one of three sections. The hypothesis is that each section is associated with distinct water masses: the Gulf of Lions, related to Western Mediterranean Deep Water and Western Intermediate Water, carries 86% of the Outflow's transport; the Northern Tyrrhenian, related to Tyrrhenian Deep and Intermediate Waters, carries 1% of the transport; the Strait of Sicily, related to Levantine Intermediate Waters, carries 13% of the transport. The median transit times from the sections to the Strait of Gibraltar range from 5 years (Gulf of Lions) to 8 years (Strait of Sicily).

Dynamic contrast-enhanced computed tomography in dogs with nasal tumors.

Treatment of nasal tumors in dogs is associated with high morbidity and reliable prognostic factors are lacking. Dynamic contrast-enhanced computed tomography (DCECT) can be used to assess tumor perfusion. To assess perfusion parameters of nasal tumors (correlating with tumor type) before and during radiotherapy (RT) and find potential correlation with survival. Twenty-four client-owned dogs with nasal tumors, including 16 epithelial tumors and 8 sarcomas. Prospective cross-sectional study. All dogs had baseline DCECT to assess fractional vascular volume (BV), blood flow (BF), and transit time (TT). Thirteen dogs had repeat DCECT after 12 Gy of megavoltage RT. Survival times were calculated. Median BV was 17.83 mL/100 g (range, 3.63-66.02), median BF was 122.63 mL/100 g/minute (range, 23.65-279.99), and median TT was 8.91 seconds (range, 4.57-14.23). Sarcomas had a significantly lower BF than adenocarcinomas (P = .002), carcinomas (P = .01), and other carcinomas (P = .001), and significantly lower BV than adenocarcinomas (P = .03) and other carcinomas (P = .004). Significant associations were found between epithelial tumors and sarcoma for change in tumor volume (P = .01), width (P = .004), and length (P = .02) in that epithelial tumors decreased in volume whereas sarcomas increased in volume. Perfusion parameters were not correlated with survival. Nasal sarcomas have lower BV and BF than nasal carcinomas, and sarcomas have a lower size reduction than carcinomas early on during RT. Baseline results and changes in perfusion parameters may not be correlated with survival.

Incremental peritoneal dialysis allows to reduce the time spent for dialysis, glucose exposure, economic cost, plastic waste and water consumption.

Incremental peritoneal dialysis (incPD) as the initial PD strategy represents a convenient and resource-sparing approach, but its impact on patient, healthcare and environment has not been thoroughly evaluated. This study includes 147 patients who started incPD at our institution between 1st January, 2009 and 31st December, 2021. Adequacy measures, peritoneal permeability parameters, peritonitis episodes, hospitalizations and increase in CAPD dose prescriptions were recorded. The savings related to cost, patient glucose exposure, time needed to perform dialysis, plastic waste, and water usage were compared to full-dose PD treatment. During the study follow-up 11.9% of the patients transitioned from incremental to full dose PD. Patient cumulative probability of remaining on PD at 12, 24, 36, 48 and 60months was 87.6, 65.4, 46.1, 30.1 and 17.5%, respectively. The median transition time from 1 to 2 exchanges, from 2 to 3 and 3 to 4 exchanges were 5, 9 and 11.8months, respectively. Compared to full dose PD, 1, 2, and 3 exchanges per day led to reduction in glucose exposure of 20.4, 14.8 or 8.3kg/patient-year, free lifetime gain of 18.1, 13.1 or 7.4day/patient-year, a decrease in cost of 8700, 6300 or 3540 €/patient-year, a reduction in plastic waste of 139.2, 100.8 or 56.6kg/patient-year, and a decline in water use of 25,056, 18,144 or 10,196 L/patient-year. In comparison with full-dose PD, incPD allows to reduce the time spent for managingdialysis, glucose exposure, economic cost, plastic waste, and water consumption.

Comparison of gastrointestinal landmarks using the gas-sensing capsule and wireless motility capsule.

Accurate definition of the gastroduodenal and ileocaecal junctions (GDJ, ICJ) is essential for the measurement of regional transit times. To compare the assessment of these landmarks using the novel gas-sensing capsule and validated wireless motility capsule (WMC), and to evaluate intra-subject variance in transit times METHODS: Healthy subjects ingested the gas-sensing capsule and WMC tandemly in random order. Inter-observer agreement was evaluated by intra-class correlation coefficient (ICC). Agreement between the paired devices' transit times was assessed using Bland-Altman analysis; coefficient of variation was performed to express intra-individual variance in transit times. Similar analyses were completed with tandemly ingested gas-sensing capsules. The inter-observer agreement for landmarks for both capsules was excellent (mean ICC ≥0.97) in 50 studies. The GDJ was identifiable in 92% of the gas-sensing capsule studies versus 82% of the WMC studies (p= 0.27); the ICJ in 96% versus 84%, respectively (p= 0.11). In the primary cohort (n= 26), median regional transit times differed by less than 6min between paired capsules. Bland-Altman revealed a bias of -0.12 (95% limits of agreement, -0.94 to 0.70) hours for GDJ and -0.446 (-2.86 to 2.0) hours for ICJ. Similar results were found in a demographically distinct validation cohort (n= 24). For tandemly ingested gas-sensing capsules, coefficients of variation of transit times were 11%-35%, which were similar to variance between the paired gas-sensing capsule and WMC, as were the biases. The capsules were well tolerated. Key anatomical landmarks are accurately identified with the gas-sensing capsule in healthy individuals. Intra-individual differences in transit times between capsules are probablydue to physiological factors. Studies in populations with gastrointestinal diseases are now required.

Brown Trout Upstream Passage Performance for a Fishway with Water Drops between Pools beyond Fish Passage Design Recommendations

This work aims to assess brown trout (Salmo trutta) passage through a free-flow pool-weir-type fishway with hydrodynamic notches and extreme water drops between pools. It consists of an old-school fishway design, commonly constructed in salmon rivers of Spain during the period of 1950–1980. To assess their performance, a field test was designed with confined trial conditions during the spawning migratory season. The mean water drop between pools was 0.65 m and the total water height considered for the trial was 11.8 m. The monitoring was carried out using PIT telemetry. The initial hypothesis, considering the fishway design and assessment guidelines, classified this structure as hardly insurmountable. Results showed an ascent success of 19% with a median transit time of 29.1 min/m of ascended height. Larger fish and fishway sections with lower values of volumetric power dissipation were related to a better performance in the passage. The results suggest that in certain circumstances, such as limited construction areas where other design or management options are difficult to implement (e.g., canyons), this type of fishway may be an alternative for the upstream passage of at least a small proportion of the brown trout population, although a selection effect is expected.

Efficacy and safety of capsule endoscopy in octogenarian patients: a retrospective study.

Life expectancy and the number of ultra-octogenarians increased significantly, thus making crucial the appropriateness of several endoscopic procedures in elderly patients. The aim of our study was to provide a retrospective analysis of the efficacy and safety of capsule endoscopy (CE) in patients aged over 80 years. In this single-centre study, 900 patients underwent capsule endoscopy between 2002 and 2015 for different indications; of these 106 patients aged ≥80 years (group A) and 99 patients aged 40-60 years (control group B) were retrospectively selected. Occult gastrointestinal bleeding accounted for 62.1% of all indications for capsule endoscopy in group B, compared to 95.2% in group A (P<0.001). Although not statistically significant, the diagnostic yield was higher in group A (71%) vs. group B (62%). The percentages of reaching the cecum and the median gastric transit time were uniform within the two groups. In contrast, small bowel transit time was longer in group A vs. B. Small bowel preparation was similar in the two groups. The exam was generally well tolerated in both groups, with capsule aspiration being one of the main adverse events, which occurred in two elderly patients. Our data expand previous findings confirming that capsule endoscopy can be performed safely even in very old patients and show that the diagnostic yield is similar to that of younger patients.

Evaluation of gastrointestinal transit times and pH in healthy cats using a continuous pH monitoring system.

The aim of this study was to characterize gastrointestinal (GI) transit times and pH in healthy cats. GI transit times and pH were measured in six healthy, colony-housed, purpose-bred spayed female cats using a continuous, non-invasive pH monitoring system in a sequential order design. For the first period ('pre-feeding'), food was withheld for 20 h, followed by oral administration of a pH capsule. Five hours post-capsule administration, cats were meal-fed by offering them their daily allowance of food for 1 h. For the second period ('post-feeding'), food was withheld for 24 h and cats were fed for 1 h, after which a pH capsule was orally administered. Studies in both periods were repeated three times. GI transit times and pH were compared between the two periods. The median transit times for the pre- and post-feeding periods, respectively, were: gastric - 94 mins (range 1-4101) and 1068 mins (range 484-5521); intestinal - 1350 mins (range 929-2961) and 1534 mins (range 442-2538); and GI - 1732 mins (range 1105-5451) and 2795 mins (range 926-6563). The median GI pH values for the first and second periods, respectively, were: esophageal - 7.0 (range 3.5-7.8) and 4.5 (range 2.9-6.4); gastric - 2.7 (range 1.7-6.2) and 2.0 (range 1.1-3.3); intestinal - 8.2 (range 7.6-8.7) and 7.8 (range 6.7-8.5); first-hour small intestinal - 8.2 (range 7.4-8.7) and 8.3 (range 7.9-8.6); and last-hour large intestinal - 8.5 (range 7.0-8.9) and 7.8 (range 6.3-8.7). Gastric (P <0.0020) and intestinal pH (P <0.0059) were significantly increased in the pre-feeding period compared with the post-feeding period. Gastric and intestinal pH differed significantly when the capsule was administered 5 h prior to feeding compared with 1 h after feeding. Transit times for both periods showed high degrees of intra- and inter-individual variability.

Applicability of colon capsule endoscopy as pan-endoscopy: From bowel preparation, transit, and rating times to completion rate and patient acceptance.

Background and study aims Colon capsule endoscopy (CCE) has the potential to explore the entire gastrointestinal tract. The aim of this study was to assess the applicability of CCE as pan-endoscopy. Patients and methods Healthy participants received CCE with bowel preparation (bisacodyl, polyethylene electrolyte glycol (PEG) + ascorbic acid) and booster regimen (metoclopramide, oral sulfate solution (OSS)). For each segment of the gastrointestinal tract, the following quality parameters were assessed: cleanliness, transit times, reading times, patient acceptance and safety of the procedure. When all gastrointestinal segments had cleansing score good or excellent, cleanliness of the whole gastrointestinal tract was assessed as good. Participants’ expected and perceived burden was assessed by questionnaires and participants were asked to grade the procedure (scale 0–10). All serious adverse events (SAEs) were documented. Results A total of 451 CCE procedures were analyzed. A good cleansing score was achieved in the stomach in 69.6%, in the SB in 99.1 % and in the colon in 76.6 %. Cleanliness of the whole gastrointestinal tract was good in 52.8 % of the participants. CCE median transit time of the whole gastrointestinal tract was 583 minutes IQR 303–659). The capsule reached the descending colon in 94.7 %. Median reading time per procedure was 70 minutes (IQR 57–83). Participants graded the procedure with a 7.8. There were no procedure-related SAEs. Conclusions CCE as pan-endoscopy has shown to be a safe procedure with good patient acceptance. When cleanliness of all gastrointestinal segments per patient, completion rate and reading time will be improved, CCE can be applied as a good non-invasive alternative to evaluate the gastrointestinal tract.

112 A Geographical Analysis of Access to Trauma Care From US National Parks in 2018

Each year there are millions of visits to US national parks, which result in the need for emergency medical services. Our objective was to determine the transit time from each US national park to the nearest emergency department (ED), adult advanced trauma center (ATC), and ED that receives telehealth services (TH), and the percentage of national parks by US region that had timely access (<60 minutes) to each type of ED. The address of the main visitor center at 61 US national parks open in 2018 was identified using information publicly available on nps.gov. ED-specific information was obtained using the 2018 National ED Inventory-USA database. Driving distance and time (on a typical Saturday at noon), and approximate air transport time from each national park to the nearest ED, ATC, and ED that receives TH was determined using ArcMap 10.3 and Google Maps. In the West, 5 national parks not accessible by road were excluded from drive time calculations. We determined the median and interquartile range (IQR) of travel time and percentage of national parks in each US region that had a transit time of <60 minutes by ground or air to each type of ED. Overall, 79% of US national parks had timely access (<60 minutes) by ground transit to an ED, 24% had access to an ATC, and 59% had access to an ED that receives TH. By air, 97% of national parks had timely access to an ED, 85% had access to an ATC, and 52% had access to an ED that receives TH. National parks are unequally distributed in the US, with only 1 in the East, versus 42 in the West. The median transit time to each type of ED varied regionally, with the longest ground and air transit times in the West for all types of EDs. Of the 61 US national parks analyzed, most had access to an ED in <60 min by ground or air. Regional differences were observed, with greater access in the Northeast, Midwest, and South regions compared to the West region for all types of EDs. To address regional disparities in timely access to trauma care, we encourage increased adoption of ED telehealth with an emphasis on advanced trauma care.