Decision-based interactive model to determine re-opening conditions of a large university campus in Belgium during the first COVID-19 wave.

BACKGROUND: The role played by large-scale repetitive SARS-CoV-2 screening programs within university populations interacting continuously with an urban environment, is unknown. Our objective was to develop a model capable of predicting the dispersion of viral contamination among university populations dividing their time between social and academic environments. METHODS: Data was collected through real, large-scale testing developed at the University of Liège, Belgium, during the period Sept. 28th-Oct. 29th 2020. The screening, offered to students and staff (n = 30,000), began 2 weeks after the re-opening of the campus but had to be halted after 5 weeks due to an imposed general lockdown. The data was then used to feed a two-population model (University + surrounding environment) implementing a generalized susceptible-exposed-infected-removed compartmental modeling framework. RESULTS: The considered two-population model was sufficiently versatile to capture the known dynamics of the pandemic. The reproduction number was estimated to be significantly larger on campus than in the urban population, with a net difference of 0.5 in the most severe conditions. The low adhesion rate for screening (22.6% on average) and the large reproduction number meant the pandemic could not be contained. However, the weekly screening could have prevented 1393 cases (i.e. 4.6% of the university population; 95% CI: 4.4-4.8%) compared to a modeled situation without testing. CONCLUSION: In a real life setting in a University campus, periodic screening could contribute to limiting the SARS-CoV-2 pandemic cycle but is highly dependent on its environment.

Immersion in an emergency department triage center during the Covid-19 outbreak: first report of the Liège University hospital experience.

OBJECTIVES: Since the beginning of the novel coronavirus outbreak, different strategies have been explored to stem the spread of the disease and appropriately manage patient flow. Triage, an effective solution proposed in disaster medicine, also works well to manage Emergency Department (ED) flow. The aim of this study was to describe the role of an ED Triage Center for patients with suspected novel coronavirus disease (Covid-19) and characterize the patient flow. METHODS: In March 2020, we established a Covid-19 triage center close to the Liège University EDs. From March 2 to March 23, we planned to analyze the specific flow of patients admitted to this triage zone and their characteristics in terms of inner specificities, work-up and management. During this period, all patients presented to the ED with symptoms suggestive of Covid-19 were included in the study. RESULTS: A total amount of 1071 patients presented to the triage center during the study period. 41.50% of the patients presented with flu-like symptoms. In 82.00% of the cases, no risk factor of virus transmission was found. The SARS-Cov2 positive patients represented 29.26% of the screened patients. 83.00% of patients were discharged home while 17.00% were admitted to the hospital. CONCLUSION: Our experience suggests that triage centers for the assessment and management of Covid-19 suspected patients is an essential key strategy to prevent the spread of the disease among non-symptomatic patients who present to the EDs for care. This allows for a disease-centered work-up and safer diversion of Covid-19 patients to specific hospital units.

Reliability and validity of an original nurse telephone triage tool for out-of-hours primary care calls: the SALOMON algorithm.

OBJECTIVES: Due to the persistent primary care physicians shortage and the substantial increase in their workload, the organization of primary care calls during out-of-hours periods has become an everyday challenge. The SALOMON algorithm is an original nurse telephone triage tool allowing to dispatch patients to the best level of care according to their conditions. This study evaluated its reliability and criterion validity in rea-life settings. METHODS: In this 5-year study, out-of-hours primary care calls were dispatched into four categories: Emergency Medical Services Intervention (EMSI), Emergency Department referred Consultation (EDRC), Primary Care Physician Home visit (PCPH), and Primary Care Physician Delayed visit (PCPD). We included data of patients' triage category, resources, and destination. Patients included into the primary care cohort were classified undertriaged if they had to be redirected to an emergency department (ED). Patients from the ED cohort were considered overtriaged if they did not require at least three diagnostic resources, one emergency-specific treatment or any hospitalization. In the ED cohort, only patients from the University Hospitals were considered. RESULTS: 10,207 calls were triaged using the SALOMON tool: 19.2% were classified as EMSI, 15.8% as EDRC, 62.8% as PCPH, and 2.2% as PCPD. The triage was appropriate for 85.5% of the calls with a 14.5% overtriage rate. In the PCPD/PCPH cohort, 96.9% of the calls were accurately triaged and 3.1% were undertriaged. SALOMON sensitivity and specificity reached 76.6% and 98.3%, respectively. CONCLUSION: SALOMON algorithm is a valid triage tool that has the potential to improve the organization of out-of-hours primary care work.

Advanced triage to redirect non-urgent Emergency Department visits to alternative care centers: the PERSEE algorithm.

OBJECTIVES: Primary care treatable visits in the Emergency Department (ED) are part of the different factors leading to the overcrowding. Their triage and diversion to alternative care centers could potentially help manage the increasing inflow provided the establishment of an advanced triage to ensure patients' safety. We aim to suggest a new triage tool, PERSEE, and prove its feasibility, safety and performance. METHODS: All self-referrals presented to the ED were triaged with the PERSEE algorithm: first, patients were classified with a five-level ED acuity scale and then evaluated by algorithms to determine their appropriate category (ED or Primary Care). Patients were eligible for a redirection if they were triaged by the acuity scale as level 3 or lower, considered as ambulatory patients and finally categorized as primary care patients. We defined appropriate redirections as patients requiring less than three emergency resources, no emergency-specific treatment and no hospitalization. RESULTS: During the study, 1999 patients were admitted to the ED. Among those, 1333 patients were self-referred (66.9%) of whom 1167 patients were triaged as level 3 or below (58.6%) and 775 patients triaged as ambulatory (39.0%). Among the 775 patients, 200 patients were categorized as primary care treatable (10.0%) and thereby, as potentially eligible for a redirection. We noticed an error rate of 7%, sensitivity of 24.06% and specificity of 97.6%. The redirection rate reached 15% of the self-referrals. CONCLUSION: These results indicate that PERSEE triage could lead to a safe redirection and could be an efficient tool to reduce ED crowding provided several adjustments.

Development and validation of a predictive model to determine the level of care in patients confirmed with COVID-19.

BACKGROUND: The COVID-19 pandemic has imposed significant challenges on hospital capacity. While mitigating unnecessary crowding in hospitals is favourable to reduce viral transmission, it is more important to prevent readmissions with impaired clinical status due to initially inappropriate level of care. A validated predictive tool to assist clinical decisions for patient triage and facilitate remote stratification is of critical importance. METHODS: We conducted a retrospective study in patients with confirmed COVID-19 stratified into two levels of care, namely ambulatory care and hospitalization. Data on socio-demographics, clinical symptoms, and comorbidities were collected during the first (N = 571) and second waves (N = 174) of the pandemic in Belgium (2 March to 6 December 2020). Univariate and multivariate logistic regressions were performed to build and validate the prediction model. RESULTS: Significant predictors of hospitalization were old age (OR = 1.08, 95%CI:1.06-1.10), male gender (OR = 4.41, 95%CI: 2.58-7.52), dyspnoea (OR 6.11, 95%CI: 3.58-10.45), dry cough (OR 2.89, 95%CI: 1.54-5.41), wet cough (OR 4.62, 95%CI: 1.93-11.06), hypertension (OR 2.20, 95%CI: 1.17-4.16) and renal failure (OR 5.39, 95%CI: 1.00-29.00). Rhinorrhea (OR 0.43, 95%CI: 0.24-0.79) and headache (OR 0.36, 95%CI: 0.20-0.65) were negatively associated with hospitalization. A receiver operating characteristic (ROC) curve was constructed and the area under the ROC curve was 0.931 (95% CI: 0.910-0.953) for the prediction model (first wave) and 0.895 (95% CI: 0.833-0.957) for the validated dataset (second wave). CONCLUSION: With a good discriminating power, the prediction model might identify patients who require ambulatory care or hospitalization and support clinical decisions by Emergency Department staff and general practitioners.

Clinical decision support tool for diagnosis of COVID-19 in hospitals.

BACKGROUND: The coronavirus infectious disease 19 (COVID-19) pandemic has resulted in significant morbidities, severe acute respiratory failures and subsequently emergency departments' (EDs) overcrowding in a context of insufficient laboratory testing capacities. The development of decision support tools for real-time clinical diagnosis of COVID-19 is of prime importance to assist patients' triage and allocate resources for patients at risk. METHODS AND PRINCIPAL FINDINGS: From March 2 to June 15, 2020, clinical patterns of COVID-19 suspected patients at admission to the EDs of Liège University Hospital, consisting in the recording of eleven symptoms (i.e. dyspnoea, chest pain, rhinorrhoea, sore throat, dry cough, wet cough, diarrhoea, headache, myalgia, fever and anosmia) plus age and gender, were investigated during the first COVID-19 pandemic wave. Indeed, 573 SARS-CoV-2 cases confirmed by qRT-PCR before mid-June 2020, and 1579 suspected cases that were subsequently determined to be qRT-PCR negative for the detection of SARS-CoV-2 were enrolled in this study. Using multivariate binary logistic regression, two most relevant symptoms of COVID-19 were identified in addition of the age of the patient, i.e. fever (odds ratio [OR] = 3.66; 95% CI: 2.97-4.50), dry cough (OR = 1.71; 95% CI: 1.39-2.12), and patients older than 56.5 y (OR = 2.07; 95% CI: 1.67-2.58). Two additional symptoms (chest pain and sore throat) appeared significantly less associated to the confirmed COVID-19 cases with the same OR = 0.73 (95% CI: 0.56-0.94). An overall pondered (by OR) score (OPS) was calculated using all significant predictors. A receiver operating characteristic (ROC) curve was generated and the area under the ROC curve was 0.71 (95% CI: 0.68-0.73) rendering the use of the OPS to discriminate COVID-19 confirmed and unconfirmed patients. The main predictors were confirmed using both sensitivity analysis and classification tree analysis. Interestingly, a significant negative correlation was observed between the OPS and the cycle threshold (Ct values) of the qRT-PCR. CONCLUSION AND MAIN SIGNIFICANCE: The proposed approach allows for the use of an interactive and adaptive clinical decision support tool. Using the clinical algorithm developed, a web-based user-interface was created to help nurses and clinicians from EDs with the triage of patients during the second COVID-19 wave.

Emergency department crowding: why do patients walk-in?

Objectives: For years, general practitioners (GP) shortage and patients' increasing demand for acute care have been associated with Emergency Department (ED) crowding. Indeed, EDs admissions for non-emergency care seem to constantly increase. Surprisingly, the rationale for patients own decision to directly reach EDs over primary care have been poorly investigated to date.Methods: We conducted a study on patients admitted in two University EDs during nine consecutive days. Patients were asked to answer a survey about their frames for coming and if they were self-referred, referred by a GP, a specialist or after calling the Emergency Number.Results: During the study period, 68.0% of patients were self-referred, 17.0% referred by their GP, 8.5% by a specialist and 7% after an emergency call. 51.0% of the self-referrals thought EDs were the appropriate location to deal with their health problem and 24.0% because of a better accessibility. We noticed that 15.0% of the incomings looked for specialized care and 4.22% reported that the stress had motivated them. Of note, 4.6% of the patients were attracted by the hospital reputation. Financial concerns represented less than 1.0% of the motives invocated.Conclusion: We found that patients' self-perceived severity of illness is the predominant frame to each the ED when they face needs for acute care. EDs' accessibility as compared with other facilities also seems to encourage patients to come to the ED. Other factors such as the hospital reputation or patients' stress tend to influence ED attendance but to a much lesser extent.

Parsonage-Turner Syndrome as a Rare Extrahepatic Complication of Hepatitis E Infection.

Parsonage-Turner syndrome, also known as neuralgic amyotrophy, is a rare disorder characterized by painful clinical manifestations mainly involving the upper limbs. This syndrome seems to be triggered, among other factors, by some viral infections, although its pathophysiology remains unclear. Moreover, it has rarely been related to hepatitis E virus infection. We report the case of a 33-year-old man who was diagnosed with Parsonage-Turner syndrome following acute hepatitis E infection. LEARNING POINTS: Parsonage-Turner syndrome is a painful and disabling condition.Hepatitis E infection can lead to extra-hepatic manifestations such as neurological complications.The association of Parsonage-Turner syndrome with hepatitis E infection is rare but some cases have been reported previously in the literature.

Triage for out-of-hours primary care calls: a reliability study of a new French-language algorithm, the SALOMON rule.

Introduction: Triage systems for out-of-hours primary care physician (PCP) calls have been implemented empirically but no triage algorithm has been validated to date. A triage algorithm named SALOMON (Système Algorithmique Liégeois d'Orientation pour la Médecine Omnipraticienne Nocturne) was developed to guide triage nurses. This study assessed the performance of the algorithm using simulated PCP calls. Methods: Ten nurses were involved in 130 simulated PCP call scenarios, allowing the determination of SALOMON's inter-rater agreement by comparing the actual choices of a specific triage flowchart and the level of care selected as compared with reference assignments. Intra-rater agreement was estimated by comparing triage after training (T1) and 3 to 6 months after SALOMON use in clinical practice (T2). Results: Overall selection of flowcharts was accurate for 94 .1% of scenarios at T1 and 98.7% at T2. Level of triage was adequate for 93.4% of scenarios at T1 and 98.5% at T2. Both flowchart and triage level accuracy improved significantly from T1 to T2 (p < 0.0001). SALOMON algorithm use is associated with a 0.97/0.99 sensitivity and 0.97/0.99 specificity, at T1/T2 respectively. Conclusions: Results revealed that using the SALOMON algorithm is valid for out-of-hours PCP calls triage by nurses. The criterion validity of this algorithm should be further evaluated through its implementation in a real life setting.

Interactive videoconferencing versus audio telephone calls for dispatcher-assisted cardiopulmonary resuscitation using the ALERT algorithm: a randomized trial.

OBJECTIVES: The ALERT algorithm, a telephone cardiopulmonary resuscitation (CPR) protocol, has been shown to help bystanders initiate CPR. Mobile phone communications may play a role in emergency calls and improve dispatchers' understanding of the rescuer's situation. However, there is currently no validated protocol for videoconference-assisted CPR (v-CPR). We initiated this study to validate an original protocol of v-CPR and to evaluate the potential benefit in comparison with classical telephone-CPR (t-CPR). MATERIALS AND METHODS: We developed an algorithm for v-CPR, adapted from the ALERT t-CPR protocol. A total of 180 students were recruited from secondary school and assigned randomly either to t-CPR or to v-CPR. A manikin was used to evaluate CPR performance. RESULTS: The mean chest compression rate was higher in the v-CPR group (v-CPR: 110±16 vs. t-CPR: 86±28; P<0.0001), whereas depth was comparable between both groups (v-CPR: 48±13 vs. t-CPR: 47±16 mm; P=0.64). Hand positioning was correct in 91.7% with v-CPR, but only 68% with t-CPR (P=0.001). There was almost no 'hands-off' period in the v-CPR group [v-CPR: 0 (0-0.4) vs. t-CPR: 7 (0-25.5) s; P<0.0001], but the median no-flow time was increased in the v-CPR group [v-CPR: 146 (128-173.5) vs. t-CPR: 122 (105-143.5) s, P<0.0001]. The overall score of CPR performance was improved in the v-CPR group (P<0.001). CONCLUSION: The v-CPR protocol allows bystanders to reach compression rates and depths close to guidelines and to reduce 'hands-off' events during CPR.

Prevention of ventilator-associated pneumonia and ventilator-associated conditions: a randomized controlled trial with subglottic secretion suctioning.

OBJECTIVES: Ventilator-associated pneumonia diagnosis remains a debatable topic. New definitions of ventilator-associated conditions involving worsening oxygenation have been recently proposed to make surveillance of events possibly linked to ventilator-associated pneumonia as objective as possible. The objective of the study was to confirm the effect of subglottic secretion suctioning on ventilator-associated pneumonia prevalence and to assess its concomitant impact on ventilator-associated conditions and antibiotic use. DESIGN: Randomized controlled clinical trial conducted in five ICUs of the same hospital. PATIENTS: Three hundred fifty-two adult patients intubated with a tracheal tube allowing subglottic secretion suctioning were randomly assigned to undergo suctioning (n = 170, group 1) or not (n = 182, group 2). MAIN RESULTS: During ventilation, microbiologically confirmed ventilator-associated pneumonia occurred in 15 patients (8.8%) of group 1 and 32 patients (17.6%) of group 2 (p = 0.018). In terms of ventilatory days, ventilator-associated pneumonia rates were 9.6 of 1,000 ventilatory days and 19.8 of 1,000 ventilatory days, respectively (p = 0.0076). Ventilator-associated condition prevalence was 21.8% in group 1 and 22.5% in group 2 (p = 0.84). Among the 47 patients with ventilator-associated pneumonia, 25 (58.2%) experienced a ventilator-associated condition. Neither length of ICU stay nor mortality differed between groups; only ventilator-associated condition was associated with increased mortality. The total number of antibiotic days was 1,696 in group 1, representing 61.6% of the 2,754 ICU days, and 1,965 in group 2, representing 68.5% of the 2,868 ICU days (p < 0.0001). CONCLUSIONS: Subglottic secretion suctioning resulted in a significant reduction of ventilator-associated pneumonia prevalence associated with a significant decrease in antibiotic use. By contrast, ventilator-associated condition occurrence did not differ between groups and appeared more related to other medical features than ventilator-associated pneumonia.

Cognitive support for a better handoff: does it improve the quality of medical communication at shift change in an emergency department?

AIM: To improve the communication during shift handover in an emergency department. METHODS: We observed the handover process and analysed the discourse between physicians at shift change first, and then we created two cognitive tools and tested their clinical impact on the field. We used different measures to evaluate this impact on the health care process including the frequency and type of information content communicated between physicians, duration of the handoff, physician self-evaluation of the quality of the handoff and a posthandover study of patient handling. RESULTS: Our results showed that the patient's medical history, significant test results, recommendations (treatment plan) and patient follow-up were communicated to a greater extent when the tools are used. We also found that physicians spent more time at the bedside and less time consulting medical records using these tools. CONCLUSION: The present study showed how in-depth observations and analyses of real work processes can be used to better support the quality of patient care.

Air versus ground transport of patients with acute myocardial infarction: experience in a rural-based helicopter medical service.

AIMS: Primary prehospital Helicopter Emergency Medical Service (HEMS) interventions may play a role in timely reperfusion therapy for patients with ST-segment elevation myocardial infarction (STEMI). We designed a prospective study involving patients with acute myocardial infarction aimed at the evaluation of the potential benefit of such primary HEMS interventions as compared with classical Emergency Medical Services ground transport. METHODS AND RESULTS: This prospective study was conducted from 1 July 2007 to 15 June 2012. Successive patients with STEMI eligible for percutaneous coronary intervention were included. Simulated ground-based access times were computed using a digital cartographic program, allowing the estimation of healthcare system delay from call to admission to the catheterization laboratory.During the study period, 4485 patients benefited from HEMS activations. Of these patients, 342 (8%) suffering from STEMI were transferred for primary percutaneous coronary intervention. The median primary response time was 11 min (interquartile range: 8-14 min) using the helicopter and 32 min (25-44 min) using road transport. The median transport time was 12 min (9-15 min) using HEMS and 50 min (36-56 min) by road. The median system delay using HEMS was 52 min (45-60 min), whereas this time was 110 min (95-126 min) by road. Finally, the system delay median gain was 60 min (47-72 min). CONCLUSION: Using HEMS in a rural region allows STEMI patients to benefit from appropriate rescue care with delays similar to those seen in urban settings.

Reliability and validity of a new French-language triage algorithm: the ELISA scale.

OBJECTIVE: Overcrowding in emergency departments (ED) leads to reductions in quality of care. Consequently, several different triage tools have been developed to prioritise patient intake. Differences in emergency medical services in different countries have limited the generalisation of pre-existing triage systems; for this reason, specific algorithms corresponding to local characteristics are needed. Accordingly, we developed a specific French-language triage system named Echelle Liégeoise d'Index de Sévérité à l'Admission (ELISA). This study tested its validity and efficiency. METHODS: ELISA is a five-category nursing triage algorithm. Intrarater agreement was tested by comparing triage levels attributed to the same clinical scenarios at two different times. Interrater agreement was investigated by comparing triage categories attributed to clinical cases by different triage nurses. Finally, validity was estimated by studying the correlations between the triage ranking assigned by the nurse and actual resource consumption and patient outcome. RESULTS: The distribution of the difference between nurse classification at the two times was statistically unrelated to which nurse carried out the evaluation. Regarding interrater agreement, assigned classifications were compared to the reference assignment. Cohen's κ coefficient revealed an almost perfect agreement between classification by nurses and the reference. Finally, statistical analysis revealed a strong relation between ELISA and the overall need for supplementary clinical testing. Outcomes were also significantly correlated with ELISA. CONCLUSIONS: The need for a specific, French-language triage tool in our ED led us to develop a new triage scale. This study demonstrates that the scale is a valid triage tool with high interrater and intrarater agreement and considerable efficiency.

Implementation of the ALERT algorithm, a new dispatcher-assisted telephone cardiopulmonary resuscitation protocol, in non-Advanced Medical Priority Dispatch System (AMPDS) Emergency Medical Services centres.

OBJECTIVES: Early bystander cardiopulmonary resuscitation (CPR) is a key factor in improving survival from out-of-hospital cardiac arrest (OHCA). The ALERT (Algorithme Liégeois d'Encadrement à la Réanimation par Téléphone) algorithm has the potential to help bystanders initiate CPR. This study evaluates the effectiveness of the implementation of this protocol in a non-Advanced Medical Priority Dispatch System area. METHODS: We designed a before and after study based on a 3-month retrospective assessment of victims of OHCA in 2009, before the implementation of the ALERT protocol in Liege emergency medical communication centre (EMCC), and the prospective evaluation of the same 3 months in 2011, immediately after the implementation. RESULTS: At the moment of the call, dispatchers were able to identify 233 OHCA in the first period and 235 in the second. Victims were predominantly male (59%, both periods), with mean ages of 64.1 and 63.9 years, respectively. In 2009, only 9.9% victims benefited from bystander CPR, this increased to 22.5% in 2011 (p<0.0002). The main reasons for protocol under-utilisation were: assistance not offered by the dispatcher (42.3%), caller physically remote from the victim (20.6%). Median time from call to first compression, defined here as no flow time, was 253s in 2009 and 168s in 2011 (NS). Ten victims were admitted to hospital after ROSC in 2009 and 13 in 2011 (p=0.09). CONCLUSION: From the beginning and despite its under-utilisation, the ALERT protocol significantly improved the number of patients in whom bystander CPR was attempted.

A fatal case of Perthes syndrome.

Perthes syndrome, or traumatic asphyxia, is a clinical syndrome associating cervicofacial cyanosis with cutaneous petechial haemorrhages and subconjonctival bleeding resulting from severe sudden compressive chest trauma. Deep inspiration and a Valsalva maneuver just prior to rapid and severe chest compression, are responsible for the development of this syndrome. Current treatment is symptomatic: urgent relief of chest compression and cardiopulmonary resuscitation if needed. Outcome may be satisfactory depending on the duration and severity of compression. Prolonged thoracic compression may sometimes lead to cerebral anoxia, irreversible neurologic damage and death. We report a fatal case of Perthes syndrome resulting from an industrial accident.

Arterial dP/dtmax accurately reflects left ventricular contractility during shock when adequate vascular filling is achieved.

BACKGROUND: Peak first derivative of femoral artery pressure (arterial dP/dtmax) derived from fluid-filled catheter remains questionable to assess left ventricular (LV) contractility during shock. The aim of this study was to test if arterial dP/dtmax is reliable for assessing LV contractility during various hemodynamic conditions such as endotoxin-induced shock and catecholamine infusion. METHODS: Ventricular pressure-volume data obtained with a conductance catheter and invasive arterial pressure obtained with a fluid-filled catheter were continuously recorded in 6 anaesthetized and mechanically ventilated pigs. After a stabilization period, endotoxin was infused to induce shock. Catecholamines were transiently administrated during shock. Arterial dP/dtmax was compared to end-systolic elastance (Ees), the gold standard method for assessing LV contractility. RESULTS: Endotoxin-induced shock and catecholamine infusion lead to significant variations in LV contractility. Overall, significant correlation (r=0.51; p<0.001) but low agreement between the two methods were observed. However, a far better correlation with a good agreement were observed when positive-pressure ventilation induced an arterial pulse pressure variation (PPV)≤11% (r=0.77; p<0.001). CONCLUSION: While arterial dP/dtmax and Ees were significantly correlated during various hemodynamic conditions, arterial dP/dtmax was more accurate for assessing LV contractility when adequate vascular filling, defined as PPV≤11%, was achieved.

Mathematical multi-scale model of the cardiovascular system including mitral valve dynamics. Application to ischemic mitral insufficiency.

BACKGROUND: Valve dysfunction is a common cardiovascular pathology. Despite significant clinical research, there is little formal study of how valve dysfunction affects overall circulatory dynamics. Validated models would offer the ability to better understand these dynamics and thus optimize diagnosis, as well as surgical and other interventions. METHODS: A cardiovascular and circulatory system (CVS) model has already been validated in silico, and in several animal model studies. It accounts for valve dynamics using Heaviside functions to simulate a physiologically accurate "open on pressure, close on flow" law. However, it does not consider real-time valve opening dynamics and therefore does not fully capture valve dysfunction, particularly where the dysfunction involves partial closure. This research describes an updated version of this previous closed-loop CVS model that includes the progressive opening of the mitral valve, and is defined over the full cardiac cycle. RESULTS: Simulations of the cardiovascular system with healthy mitral valve are performed, and, the global hemodynamic behaviour is studied compared with previously validated results. The error between resulting pressure-volume (PV) loops of already validated CVS model and the new CVS model that includes the progressive opening of the mitral valve is assessed and remains within typical measurement error and variability. Simulations of ischemic mitral insufficiency are also performed. Pressure-Volume loops, transmitral flow evolution and mitral valve aperture area evolution follow reported measurements in shape, amplitude and trends. CONCLUSIONS: The resulting cardiovascular system model including mitral valve dynamics provides a foundation for clinical validation and the study of valvular dysfunction in vivo. The overall models and results could readily be generalised to other cardiac valves.

Dispatcher-assisted telephone cardiopulmonary resuscitation using a French-language compression-only protocol in volunteers with or without prior life support training: A randomized trial.

OBJECTIVES: Due to the recent interest in hands-only protocols for dispatcher-assisted cardiopulmonary resuscitation (CPR) and the lack of any validated algorithms in French, our primary objective was to evaluate a new French-language protocol in terms of its efficacy to help previously untrained volunteers in performing basic life support efforts of appropriate quality, and secondarily to investigate its potential utility in subjects with previous training. METHODS: Untrained volunteers were recruited among adults in a public movie centre and previously trained volunteers among undergraduate nursing students. Participants were randomly assigned to 'phone CPR' versus 'no phone CPR' by drawing sets of envelopes. Primary outcome measures were the results of the Cardiff evaluation test; the secondary measures were global scoring of a complete 5min period of CPR, in a manikin model of cardiac arrest. RESULTS: Out of 146 volunteers assessed for eligibility, 36 previously untrained candidates declined participation. 110 participants, distributed into four groups, completed the study: the previously untrained non-guided group (group A, n=30), the previously untrained guided group (group B, n=30), the previously trained non-guided group (group C, n=25) and the previously trained guided group (group D, n=25). Results of the Cardiff test and global evaluation of CPR performance revealed a significant improvement in group B as compared with group A, approaching the level of the group C. Previously trained guided bystanders had the best CPR scores, notably because of an improvement in the quality of airway management. CONCLUSION: When used by dispatchers, this new French-language algorithm offers the opportunity to help previously untrained bystanders initiate CPR. The same protocol may serve to guide volunteers with prior basic life support training to reach their best CPR performance.

Comparison of functional residual capacity and static compliance of the respiratory system during a positive end-expiratory pressure (PEEP) ramp procedure in an experimental model of acute respiratory distress syndrome.

INTRODUCTION: Functional residual capacity (FRC) measurement is now available on new ventilators as an automated procedure. We compared FRC, static thoracopulmonary compliance (Crs) and PaO2 evolution in an experimental model of acute respiratory distress syndrome (ARDS) during a reversed, sequential ramp procedure of positive end-expiratory pressure (PEEP) changes to investigate the potential interest of combined FRC and Crs measurement in such a pathologic state. METHODS: ARDS was induced by oleic acid injection in six anesthetised pigs. FRC and Crs were measured, and arterial blood samples were taken after induction of ARDS during a sequential ramp change of PEEP from 20 cm H2O to 0 cm H2O by steps of 5 cm H2O. RESULTS: ARDS was responsible for significant decreases in FRC, Crs and PaO2 values. During ARDS, 20 cm H2O of PEEP was associated with FRC values that increased from 6.2 +/- 1.3 to 19.7 +/- 2.9 ml/kg and a significant improvement in PaO2. The maximal value of Crs was reached at a PEEP of 15 cm H2O, and the maximal value of FRC at a PEEP of 20 cm H2O. From a PEEP value of 15 to 0 cm H2O, FRC and Crs decreased progressively. CONCLUSION: Our results indicate that combined FRC and Crs measurements may help to identify the optimal level of PEEP. Indeed, by taking into account the value of both parameters during a sequential ramp change of PEEP from 20 cm H2O to 0 cm H2O by steps of 5 cm H2O, the end of overdistension may be identified by an increase in Crs and the start of derecruitment by an abrupt decrease in FRC.