Percolation analysis of the two-dimensional Widom-Rowlinson lattice model

We consider the two-dimensional Widom-Rowlinson lattice model. This discrete spin model describes a surface on Which a one to one mixture of two gases is sprayed. These gases shall be strongly repelling on short distances. We indicate the amount of gas by a positive parameter, the so called activity. The main result of this thesis states that given an activity larger than 2, there are at most two ergodic Widom-Rowlinson measures if the underlying graph is the star lattice. This falls naturally into two parts: The first part is quite general and establishes a new sufficient condition for the existence of at most two ergodic Widom-Rowlinson measures. This condition demands the existence of 1*lassos, i.e., 1*circuits 1*connected to the boundary, with probability bounded away from zero. Our approach is based upon the infinite cluster method. More precisely, we prevent the (co)existence of infinite clusters of certain types. To this end, we first have to improve the existing results in this direction, which will be done in a general setting for two-dimensional dependent percolation. The second part is devoted to verify the sufficient condition of the first part for activities larger than 2. To this end, we have to compare the probabilities of configurations exhibiting 1*lassos to the ones exhibiting 0lassos. This will be done by constructing an injection that fills certain parts of 0circuits with 1spins and, hereby, forms a 1*lasso

Clinical Requirements of Future Patient Monitoring in the Intensive Care Unit: Qualitative Study

BACKGROUND: In the intensive care unit (ICU), continuous patient monitoring is essential to detect critical changes in patients' health statuses and to guide therapy. The implementation of digital health technologies for patient monitoring may further improve patient safety. However, most monitoring devices today are still based on technologies from the 1970s. OBJECTIVE: The aim of this study was to evaluate statements by ICU staff on the current patient monitoring systems and their expectations for future technological developments in order to investigate clinical requirements and barriers to the implementation of future patient monitoring. METHODS: This prospective study was conducted at three intensive care units of a German university hospital. Guideline-based interviews with ICU staff-5 physicians, 6 nurses, and 4 respiratory therapists-were recorded, transcribed, and analyzed using the grounded theory approach. RESULTS: Evaluating the current monitoring system, ICU staff put high emphasis on usability factors such as intuitiveness and visualization. Trend analysis was rarely used; inadequate alarm management as well as the entanglement of monitoring cables were rated as potential patient safety issues. For a future system, the importance of high usability was again emphasized; wireless, noninvasive, and interoperable monitoring sensors were desired; mobile phones for remote patient monitoring and alarm management optimization were needed; and clinical decision support systems based on artificial intelligence were considered useful. Among perceived barriers to implementation of novel technology were lack of trust, fear of losing clinical skills, fear of increasing workload, and lack of awareness of available digital technologies. CONCLUSIONS: This qualitative study on patient monitoring involves core statements from ICU staff. To promote a rapid and sustainable implementation of digital health solutions in the ICU, all health care stakeholders must focus more on user-derived findings. Results on alarm management or mobile devices may be used to prepare ICU staff to use novel technology, to reduce alarm fatigue, to improve medical device usability, and to advance interoperability standards in intensive care medicine. For digital transformation in health care, increasing the trust and awareness of ICU staff in digital health technology may be an essential prerequisite

Non-Coexistence of Infinite Clusters in Two-Dimensional Dependent Site Percolation

This paper presents three results on dependent site percolation on the square lattice. First, there exists no positively associated probability measure on {0,1}^{Z^2} with the following properties: a) a single infinite 0cluster exists almost surely, b) at most one infinite 1*cluster exists almost surely, c) some probabilities regarding 1*clusters are bounded away from zero. Second, we show that coexistence of an infinite 1*cluster and an infinite 0cluster is almost surely impossible when the underlying probability measure is ergodic with respect to translations, positively associated, and satisfies the finite energy condition. The third result analyses the typical structure of infinite clusters of both types in the absence of positive association. Namely, under a slightly sharpened finite energy condition, the existence of infinitely many disjoint infinite self-avoiding 1*paths follows from the existence of an infinite 1*cluster. The same holds with respect to 0paths and 0clusters.Comment: 17 pages, 1 figur

Creation of an Evidence-Based Implementation Framework for Digital Health Technology in the Intensive Care Unit: Qualitative Study

Background: Digital health technologies such as continuous remote monitoring and artificial intelligence–driven clinical decision support systems could improve clinical outcomes in intensive care medicine. However, comprehensive evidence and guidelines for the successful implementation of digital health technologies into specific clinical settings such as the intensive care unit (ICU) are scarce. We evaluated the implementation of a remote patient monitoring platform and derived a framework proposal for the implementation of digital health technology in an ICU. Objective: This study aims to investigate barriers and facilitators to the implementation of a remote patient monitoring technology and to develop a proposal for an implementation framework for digital health technology in the ICU. Methods: This study was conducted from May 2018 to March 2020 during the implementation of a tablet computer–based remote patient monitoring system. The system was installed in the ICU of a large German university hospital as a supplementary monitoring device. Following a hybrid qualitative approach with inductive and deductive elements, we used the Consolidated Framework for Implementation Research and the Expert Recommendations for Implementing Change to analyze the transcripts of 7 semistructured interviews with clinical ICU stakeholders and descriptive questionnaire data. The results of the qualitative analysis, together with the findings from informal meetings, field observations, and previous explorations, provided the basis for the derivation of the proposed framework. Results: This study revealed an insufficient implementation process due to lack of staff engagement and few perceived benefits from the novel solution. Further implementation barriers were the high staff presence and monitoring coverage in the ICU. The implementation framework includes strategies to be applied before and during implementation, targeting the implementation setting by involving all ICU stakeholders, assessing the intervention’s adaptability, facilitating the implementation process, and maintaining a vital feedback culture. Setting up a unit responsible for implementation, considering the guidance of an implementation advisor, and building on existing institutional capacities could improve the institutional context of implementation projects in the ICU. Conclusions: Implementation of digital health in the ICU should involve a thorough preimplementation assessment of the ICU’s need for innovation and its readiness to change, as well as an ongoing evaluation of the implementation conditions. Involvement of all stakeholders, transparent communication, and continuous feedback in an equal atmosphere are essential, but leadership roles must be clearly defined and competently filled. Our proposed framework may guide health care providers with concrete, evidence-based, and step-by-step recommendations for implementation practice, facilitating the introduction of digital health in intensive care. Trial Registration: ClinicalTrials.gov NCT03514173; https://clinicaltrials.gov/ct2/show/NCT0351417

A Remote Patient-Monitoring System for Intensive Care Medicine: Mixed Methods Human-Centered Design and Usability Evaluation

Background: Continuous monitoring of vital signs is critical for ensuring patient safety in intensive care units (ICUs) and is becoming increasingly relevant in general wards. The effectiveness of health information technologies such as patient-monitoring systems is highly determined by usability, the lack of which can ultimately compromise patient safety. Usability problems can be identified and prevented by involving users (ie, clinicians). Objective: In this study, we aim to apply a human-centered design approach to evaluate the usability of a remote patient-monitoring system user interface (UI) in the ICU context and conceptualize and evaluate design changes. Methods: Following institutional review board approval (EA1/031/18), a formative evaluation of the monitoring UI was performed. Simulated use tests with think-aloud protocols were conducted with ICU staff (n=5), and the resulting qualitative data were analyzed using a deductive analytic approach. On the basis of the identified usability problems, we conceptualized informed design changes and applied them to develop an improved prototype of the monitoring UI. Comparing the UIs, we evaluated perceived usability using the System Usability Scale, performance efficiency with the normative path deviation, and effectiveness by measuring the task completion rate (n=5). Measures were tested for statistical significance using a 2-sample t test, Poisson regression with a generalized linear mixed-effects model, and the N-1 chi-square test. P<.05 were considered significant. Results: We found 37 individual usability problems specific to monitoring UI, which could be assigned to six subcodes: usefulness of the system, response time, responsiveness, meaning of labels, function of UI elements, and navigation. Among user ideas and requirements for the UI were high usability, customizability, and the provision of audible alarm notifications. Changes in graphics and design were proposed to allow for better navigation, information retrieval, and spatial orientation. The UI was revised by creating a prototype with a more responsive design and changes regarding labeling and UI elements. Statistical analysis showed that perceived usability improved significantly (System Usability Scale design A: mean 68.5, SD 11.26, n=5; design B: mean 89, SD 4.87, n=5; P=.003), as did performance efficiency (normative path deviation design A: mean 8.8, SD 5.26, n=5; design B: mean 3.2, SD 3.03, n=5; P=.001), and effectiveness (design A: 18 trials, failed 7, 39% times, passed 11, 61% times; design B: 20 trials, failed 0 times, passed 20 times; P=.002). Conclusions: Usability testing with think-aloud protocols led to a patient-monitoring UI with significantly improved usability, performance, and effectiveness. In the ICU work environment, difficult-to-use technology may result in detrimental outcomes for staff and patients. Technical devices should be designed to support efficient and effective work processes. Our results suggest that this can be achieved by applying basic human-centered design methods and principles. Trial Registration: ClinicalTrials.gov NCT03514173; https://clinicaltrials.gov/ct2/show/NCT0351417

protocol for a prospective, observational, multi-centre patient cohort study (DACAPO)

Background Health-related quality of life (HRQoL) and return to work are important outcomes in critical care medicine, reaching beyond mortality. Little is known on factors predictive of HRQoL and return to work in critical illness, including the acute respiratory distress syndrome (ARDS), and no evidence exists on the role of quality of care (QoC) for outcomes in survivors of ARDS. It is the aim of the DACAPO study (“Surviving ARDS: the influence of QoC and individual patient characteristics on quality of life”) to investigate the role of QoC and individual patient characteristics on quality of life and return to work. Methods/Design A prospective, observational, multi-centre patient cohort study will be performed in Germany, using hospitals from the “ARDS Network Germany” as the main recruiting centres. It is envisaged to recruit 2400 patients into the DACAPO study and to analyse a study population of 1500 survivors. They will be followed up until 12 months after discharge from hospital. QoC will be assessed as process quality, structural quality and volume at the institutional level. The main outcomes (HRQoL and return to work) will be assessed by self-report questionnaires. Further data collection includes general medical and ARDS-related characteristics of patients as well as sociodemographic and psycho-social parameters. Multilevel hierarchical modelling will be performed to analyse the effects of QoC and individual patient characteristics on outcomes, taking the cluster structure of the data into account. Discussion By obtaining comprehensive data at patient and hospital level using a prospective multi-centre design, the DACAPO-study is the first study investigating the influence of QoC on individual outcomes of ARDS survivors

Influence of quality of intensive care on quality of life/return to work in survivors of the acute respiratory distress syndrome: prospective observational patient cohort study (DACAPO)

BackgroundSignificant long-term reduction in health-related quality of life (HRQoL) is often observed in survivors of the acute respiratory distress syndrome (ARDS), and return to work (RtW) is limited. There is a paucity of data regarding the relationship between the quality of care (QoC) in the intensive care unit (ICU) and both HRQoL and RtW in ARDS survivors. Therefore, the aim of our study was to investigate associations between indicators of QoC and HRQoL and RtW in a cohort of survivors of ARDS.MethodsTo determine the influence of QoC on HRQoL and RtW 1 year after ICU-discharge, ARDS patients were recruited into a prospective multi-centre patient cohort study and followed up regularly after discharge. Patients were asked to complete self-report questionnaires on HRQoL (Short Form 12 physical component scale (PCS) and mental component scale (MCS)) and RtW. Indicators of QoC pertaining to volume, structural and process quality, and general characteristics were recorded on ICU level. Associations between QoC indicators and HrQoL and RtW were investigated by multivariable linear and Cox regression modelling, respectively. B values and hazard ratios (HRs) are reported with corresponding 95% confidence intervals (CIs).Results877 (of initially 1225 enrolled) people with ARDS formed the DACAPO survivor cohort, 396 were finally followed up to 1 year after discharge. The twelve-month survivors were characterized by a reduced HRQoL with a greater impairment in the physical component (Md 41.2 IQR [34-52]) compared to the mental component (Md 47.3 IQR [33-57]). Overall, 50% of the patients returned to work. The proportion of ventilated ICU patients showed significant negative associations with both 12months PCS (B=-11.22, CI -20.71; -1,74) and RtW (HR=0,18, CI 0,04;0,80). All other QoC indicators were not significantly related to outcome.ConclusionsAssociations between ICU QoC and long-term HrQoL and RtW were weak and largely non-significant. Residual confounding by case mix, treatment variables before or during ICU stay and variables pertaining to the post intensive care period (e.g. rehabilitation) cannot be ruled out.Trial registrationClinicaltrials.govNCT02637011.(December 22, 2015, retrospectively registered

Characteristics and provision of care of patients with the acute respiratory distress syndrome: descriptive findings from the DACAPO cohort baseline and comparison with international findings: a cross-sectional study

Background: Little is known about the characteristics and real world life circumstances of ARDS (acute respiratory distress syndrome) patient populations. This knowledge is essential for transferring evidence-based therapy into routine healthcare. The aim of this study was to report socio-demographic and clinical characteristics in an unselected population of ARDS patients and to compare these results to findings from other large ARDS cohorts. Methods: A German based cross-sectional observational study was carried out. A total of 700 ARDS patients were recruited in 59 study sites between September 2014 and January 2016. Socio-demographic, disease and care related variables were recorded. Additionally, characteristics of other large ARDS cohorts identified by a systematic literature search were extracted into evidence tables. Results: Median age of ARDS patients was 58 years, 69% were male. Sixty percent had no employment, predominantly due to retirement. Seventy-one percent lived with a partner. The main cause of ARDS was a pulmonary 'direct' origin (79%). The distribution of severity was as follows: mild (14%), moderate (48%), severe (38%). Overall ICU mortality was calculated to be 34%. The observed prevalence of critical events (hypoxemia, hypoglycemia, re-intubation) was 47%. Supportive measures during ICU-treatment were applied to 60% of the patients. Other ARDS cohorts revealed a high heterogeneity in reported concomitant diseases, but sepsis and pneumonia were most frequently reported. Mean age ranged from 54 to 71 years and most patients were male. Other socio-demographic factors have been almost neglected. Conclusions: The proportion of patients suffering of mild ARDS was lower compared to the only study identified, which also applied the Berlin definition. The frequency of critical events during ICU treatment was high and the implementation of evidence-based therapy (prone positioning, neuro-muscular blockers) was limited. More evidence on socio-demographic characteristics and further studies applying the current diagnostic criteria are desirable

German-wide prospective DACAPO cohort of survivors of the acute respiratory distress syndrome (ARDS): a cohort profile

Purpose While most research focuses on the association between medical characteristics and residual morbidity of survivors of the acute respiratory distress syndrome (ARDS), little is known about the relation between potentially modifiable intensive care unit (ICU) features and the course of health-related quality of life (HRQoL). Accordingly, the DACAPO study was set up to elucidate the influence of quality of intensive care on HRQoL and return to work (RtW) in survivors of ARDS. The continued follow-up of these former ICU patients leads to the establishment of the DACAPO (survivor) cohort. Participants Sixty-one ICUs all over Germany recruited patients with ARDS between September 2014 and April 2016. Inclusion criteria were: (1) age older than 18 years and (2) ARDS diagnosis according to the 'Berlin definition'. No further inclusion or exclusion criteria were applied. 1225 patients with ARDS could be included in the DACAPO ICU sample. Subsequently, the 876 survivors at ICU discharge form the actual DACAPO cohort. Findings to date The recruitment of the participants of the DACAPO cohort and the baseline data collection has been completed. The care-related data of the DACAPO cohort reveal a high proportion of adverse events (in particular, hypoglycaemia and reintubation). However, evidence-based supportive measures were applied frequently. Future plans Three months, 6 months and 1 year after ICU admission a follow-up assessment is conducted. The instruments of the follow-up questionnaires comprise the domains: (A) HRQoL, (B) RtW, (C) general disability, (D) psychiatric symptoms and (E) social support. Additionally, an annual follow-up of the DACAPO cohort focusing on HRQoL, psychiatric symptoms and healthcare utilisation will be conducted. Furthermore, several add-on projects affecting medical issues are envisaged