References of "Lambermont, Bernard"
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See detailAssessment of ventricular contractility and ventricular-arterial coupling with a model-based sensor.
Desaive, Thomas ULg; LAMBERMONT, Bernard ULg; JANSSEN, Nathalie ULg et al

in Computer Methods & Programs in Biomedicine (2013), 109(2),

Estimation of ventricular contractility and ventricular arterial coupling is clinically important in diagnosing and treating cardiac dysfunction in the critically ill. However, experimental assessment of ... [more ▼]

Estimation of ventricular contractility and ventricular arterial coupling is clinically important in diagnosing and treating cardiac dysfunction in the critically ill. However, experimental assessment of indexes of ventricular contractility, such as the end-systolic pressure-volume relationship, requires a highly invasive maneuver and measurements that are not typical in an intensive care unit (ICU). This research describes the use of a previously validated cardiovascular system model and parameter identification process to evaluate the right ventricular arterial coupling in septic shock. Model-based ventricular arterial coupling is defined by the ratio of the end systolic right ventricular elastance (E(esrvf)) over the pulmonary artery elastance (E(pa)) or the mean pulmonary inflow resistance (R(pulin)). Results are compared to the clinical gold-standard assessment (conductance catheter method). Six anesthetized healthy pigs weighing 20-30kg received a 0.5mgkg(-1) endotoxin infusion over a period of 30min from T0 to T30, to induce septic shock and veno-venous hemofiltration was used from T60 onward. The results show good agreement with the gold-standard experimental assessment. In particular, the model-based right ventricular elastance (E(esrvf)) correlates well with the clinical gold standard (R(2)=0.69) and the model-based non-invasive coupling (E(esrvf)/R(pulin)) follow the same trends and dynamics (R(2)=0.37). The overall results show the potential to develop a model-based sensor to monitor ventricular-arterial coupling in clinical real-time. [less ▲]

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See detailValidation of subject-specific cardiovascular system models from porcine measurements.
Revie, J. A.; Stevenson, D. J.; Chase, J. G. et al

in Computer Methods & Programs in Biomedicine (2013), 109(2),

A previously validated mathematical model of the cardiovascular system (CVS) is made subject-specific using an iterative, proportional gain-based identification method. Prior works utilised a complete set ... [more ▼]

A previously validated mathematical model of the cardiovascular system (CVS) is made subject-specific using an iterative, proportional gain-based identification method. Prior works utilised a complete set of experimentally measured data that is not clinically typical or applicable. In this paper, parameters are identified using proportional gain-based control and a minimal, clinically available set of measurements. The new method makes use of several intermediary steps through identification of smaller compartmental models of CVS to reduce the number of parameters identified simultaneously and increase the convergence stability of the method. This new, clinically relevant, minimal measurement approach is validated using a porcine model of acute pulmonary embolism (APE). Trials were performed on five pigs, each inserted with three autologous blood clots of decreasing size over a period of four to five hours. All experiments were reviewed and approved by the Ethics Committee of the Medical Faculty at the University of Liege, Belgium. Continuous aortic and pulmonary artery pressures (P(ao), P(pa)) were measured along with left and right ventricle pressure and volume waveforms. Subject-specific CVS models were identified from global end diastolic volume (GEDV), stroke volume (SV), P(ao), and P(pa) measurements, with the mean volumes and maximum pressures of the left and right ventricles used to verify the accuracy of the fitted models. The inputs (GEDV, SV, P(ao), P(pa)) used in the identification process were matched by the CVS model to errors <0.5%. Prediction of the mean ventricular volumes and maximum ventricular pressures not used to fit the model compared experimental measurements to median absolute errors of 4.3% and 4.4%, which are equivalent to the measurement errors of currently used monitoring devices in the ICU ( approximately 5-10%). These results validate the potential for implementing this approach in the intensive care unit. [less ▲]

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See detailVisualisation of Time-Variant Respiratory System Elastance in ARDS Models.
Van Drunen, E. J.; Chiew, Y. S.; Zhao, Z. et al

in Biomedizinische Technik. Biomedical engineering (2013), 58(suppl 1)

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See detailIs extended or continuous infusion of Carbapenems the obvious solution to improve clinical outcomes and reduce mortality?
FRIPPIAT, Frédéric ULg; VERCHEVAL, Christelle ULg; LAMBERMONT, Bernard ULg et al

in Clinical Infectious Diseases : An Official Publication of the Infectious Diseases Society of America (2013), 57(2), 324-325

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See detailReduction in VAP incidence by subglottic secretion drainage and antibiotic consumption in ICU patients
VAN CAUWENBERGE, Isabelle ULg; ANCION, Arnaud ULg; LAMBERMONT, Bernard ULg et al

in Intensive Care Medicine (2013), 39(Suppl 2), 465-4660898

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See detailEffects of Large-Pore Hemofiltration in a Swine Model of Fulminant Hepatic Failure.
DETRY, Olivier ULg; JANSSEN, Nathalie ULg; CHERAMY-BIEN, Jean-Paul ULg et al

in Artificial Organs (2012), 36(11), 981-987

Among the different potential mechanisms that could lead to brain edema and intracranial hypertension in fulminant hepatic failure (FHF), the inflammatory hypothesis implies that systemic inflammation ... [more ▼]

Among the different potential mechanisms that could lead to brain edema and intracranial hypertension in fulminant hepatic failure (FHF), the inflammatory hypothesis implies that systemic inflammation might be in part responsible for an increase in cerebral blood flow (CBF) and brain water content. In this study, the authors used a validated ischemic FHF swine model to evaluate the effects of 80 kDa large-pore membrane hemofiltration (LPHF) on intracranial pressure (ICP) and CBF, in relation with the clearance of proinflammatory cytokines and blood liver tests, as primary end points. Fifteen pigs were randomized into one of three groups: SHAM, FHF, and FHF + LPHF. All experiments lasted 6 h. In the FHF groups, liver failure was induced by liver ischemia. After 2 h, the FHF + LPHF group underwent 4 h of a zero-balance continuous veno-venous hemofiltration using a 0.7-m(2) , large-pore (78 A) membrane with a cutoff of 80 kDa. ICP, CBF, mean arterial pressure, central venous pressure, and heart rate were continuously monitored and recorded. Arterial aspartate aminotransferase, total bilirubin, creatinine, international normalized ratio, glucose, lactate and serum cytokines interleukin (IL)-6, IL-10, and tumor necrosis factor-alpha were measured at T0, T120, and T360. Over the 6 h following liver ischemia, the FHF group developed a significant increase in ICP. This ICP rise was not observed in the SHAM group and was attenuated in the FHF + LDHF group. However, the ICP levels were not different at T360 in the FHF + LDHF group compared to the FHF group. No significant effect of LPHF on liver tests or levels of proinflammatory cytokines could be demonstrated. In this model, 80 kDa LPHF was not efficient to control FHF intracranial hypertension and to decrease serum cytokine levels. [less ▲]

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See detailNeurally adjusted ventilatory assist (NAVA) improves patient-ventilator interaction during non-invasive ventilation delivered by face mask
Piquilloud, L; Tassaux, D; Bialais, E et al

in Intensive Care Medicine (2012)

PURPOSE: To determine if, compared to pressure support (PS), neurally adjusted ventilatory assist (NAVA) reduces patient-ventilator asynchrony in intensive care patients undergoing noninvasive ventilation ... [more ▼]

PURPOSE: To determine if, compared to pressure support (PS), neurally adjusted ventilatory assist (NAVA) reduces patient-ventilator asynchrony in intensive care patients undergoing noninvasive ventilation with an oronasal face mask. METHODS: In this prospective interventional study we compared patient-ventilator synchrony between PS (with ventilator settings determined by the clinician) and NAVA (with the level set so as to obtain the same maximal airway pressure as in PS). Two 20-min recordings of airway pressure, flow and electrical activity of the diaphragm during PS and NAVA were acquired in a randomized order. Trigger delay (T(d)), the patient's neural inspiratory time (T(in)), ventilator pressurization duration (T(iv)), inspiratory time in excess (T(iex)), number of asynchrony events per minute and asynchrony index (AI) were determined. RESULTS: The study included 13 patients, six with COPD, and two with mixed pulmonary disease. T(d) was reduced with NAVA: median 35 ms (IQR 31-53 ms) versus 181 ms (122-208 ms); p = 0.0002. NAVA reduced both premature and delayed cyclings in the majority of patients, but not the median T(iex) value. The total number of asynchrony events tended to be reduced with NAVA: 1.0 events/min (0.5-3.1 events/min) versus 4.4 events/min (0.9-12.1 events/min); p = 0.08. AI was lower with NAVA: 4.9 % (2.5-10.5 %) versus 15.8 % (5.5-49.6 %); p = 0.03. During NAVA, there were no ineffective efforts, or late or premature cyclings. PaO(2) and PaCO(2) were not different between ventilatory modes. CONCLUSION: Compared to PS, NAVA improved patient ventilator synchrony during noninvasive ventilation by reducing T(d) and AI. Moreover, with NAVA, ineffective efforts, and late and premature cyclings were absent. [less ▲]

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See detailStructural model of the mitral valve included in a cardiovascular closed loop model. Static and dynamic validation
Paeme, Sabine ULg; Pironet, Antoine ULg; Chase, J. Geoffrey et al

in proceedings of 8th IFAC Symposium on Biological and Medical Systems, Budapest 29-31 août 2012 (2012, August 31)

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See detailBeat-to-beat estimation of the continuous left and right cardiac elastance from metrics commonly available in clinical settings.
Stevenson, David; Revie, James; Chase, J. Geoffrey et al

in BioMedical Engineering OnLine (2012), 11(1), 73

ABSTRACT: INTRODUCTION: : Functional time-varying cardiac elastances (FTVE) contain a rich amount of information about the specific cardiac state of a patient. However, a FTVE waveform is very invasive to ... [more ▼]

ABSTRACT: INTRODUCTION: : Functional time-varying cardiac elastances (FTVE) contain a rich amount of information about the specific cardiac state of a patient. However, a FTVE waveform is very invasive to directly measure, and is thus currently not used in clinical practice. This paper presents a method for the estimation of a patient specific FTVE, using only metrics that are currently available in a clinical setting. METHOD: : Correlations are defined between invasively measured FTVE waveforms and the aortic and pulmonary artery pressures from 2 cohorts of porcine subjects, 1 induced with pulmonary embolism, the other with septic shock. These correlations are then used to estimate the FTVE waveform based on the individual aortic and pulmonary artery pressure waveforms, using the "other" dysfunction's correlations as a cross validation. RESULTS: : The cross validation resulted in 1.26% and 2.51% median errors for the left and right FTVE respectively on pulmonary embolism, while the septic shock cohort had 2.54% and 2.90% median errors. CONCLUSIONS: : The presented method accurately and reliably estimated a patient specific FTVE, with no added risk to the patient. The cross validation shows that the method is not dependent on dysfunction and thus has the potential for generalisation beyond pulmonary embolism and septic shock. [less ▲]

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See detailAlgorithmic Processing of Pressure Waveforms to FacilitateEstimation of Cardiac Elastance
Stevenson, D.; Revie, J.; Chase, J. G. et al

in BioMedical Engineering OnLine (2012), 11

Introduction: Cardiac elastances are highly invasive to measure directly, but are clinically useful due tothe amount of information embedded in them. Information about the cardiac elastance, which can be ... [more ▼]

Introduction: Cardiac elastances are highly invasive to measure directly, but are clinically useful due tothe amount of information embedded in them. Information about the cardiac elastance, which can be used toestimate it, can be found in the downstream pressure waveforms of aortic pressure (Pao) and the pulmonaryartery (Ppa). However these pressure waveforms are typically noisy and biased, and require processing in orderto locate the specific information required for the cardiac elastance estimation. This paper presents the methodto algorithmically process the pressure waveforms. Methods: A shear transform is developed in order to helplocate information in the pressure waveforms. This transform turns difficult to locate corners into easy to locatemaximum or minimum points as well as providing error correction. Results: The method located all points 87out of 88 waveforms for Ppa to within the sampling frequency. For Pao, out of 616 total points, 605 were foundwithin 1%, 5 within 5%, 4 within 10% and 2 within 20%. Conclusions: The presented method provides arobust, accurate and dysfunction independent way to locate points on the aortic and pulmonary artery pressurewaveforms, allowing the non-invasive estimation of the left and right cardiac elastance. [less ▲]

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See detailComputer-based monitoring of global cardiovascular dynamics during acute pulmonary embolism and septic shock in swine
Revie, JA; Stevenson, D; Chase, JG et al

in Critical Care (2012), 16 (Suppl 1)

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See detailProcalcitonin usefulness for the initiation of antibiotic treatment in intensive care unit patients.
LAYIOS, Nathalie ULg; LAMBERMONT, Bernard ULg; CANIVET, Jean-Luc ULg et al

in Critical Care Medicine (2012), 40(8), 2304-9

OBJECTIVES: : To test the usefulness of procalcitonin serum level for the reduction of antibiotic consumption in intensive care unit patients. DESIGN: : Single-center, prospective, randomized controlled ... [more ▼]

OBJECTIVES: : To test the usefulness of procalcitonin serum level for the reduction of antibiotic consumption in intensive care unit patients. DESIGN: : Single-center, prospective, randomized controlled study. SETTING: : Five intensive care units from a tertiary teaching hospital. PATIENTS: : All consecutive adult patients hospitalized for > 48 hrs in the intensive care unit during a 9-month period. INTERVENTIONS: : Procalcitonin serum level was obtained for all consecutive patients suspected of developing infection either on admission or during intensive care unit stay. The use of antibiotics was more or less strongly discouraged or recommended according to the Muller classification. Patients were randomized into two groups: one using the procalcitonin results (procalcitonin group) and one being blinded to the procalcitonin results (control group). The primary end point was the reduction of antibiotic use expressed as a proportion of treatment days and of daily defined dose per 100 intensive care unit days using a procalcitonin-guided approach. Secondary end points included: a posteriori assessment of the accuracy of the infectious diagnosis when using procalcitonin in the intensive care unit and of the diagnostic concordance between the intensive care unit physician and the infectious-disease specialist. MEASUREMENTS AND MAIN RESULTS: : There were 258 patients in the procalcitonin group and 251 patients in the control group. A significantly higher amount of withheld treatment was observed in the procalcitonin group of patients classified by the intensive care unit clinicians as having possible infection. This, however, did not result in a reduction of antibiotic consumption. The treatment days represented 62.6 +/- 34.4% and 57.7 +/- 34.4% of the intensive care unit stays in the procalcitonin and control groups, respectively (p = .11). According to the infectious-disease specialist, 33.8% of the cases in which no infection was confirmed, had a procalcitonin value >1microg/L and 14.9% of the cases with confirmed infection had procalcitonin levels <0.25 microg/L. The ability of procalcitonin to differentiate between certain or probable infection and possible or no infection, upon initiation of antibiotic treatment was low, as confirmed by the receiving operating curve analysis (area under the curve = 0.69). Finally, procalcitonin did not help improve concordance between the diagnostic confidence of the infectious-disease specialist and the ICU physician. CONCLUSIONS: : Procalcitonin measuring for the initiation of antimicrobials did not appear to be helpful in a strategy aiming at decreasing the antibiotic consumption in intensive care unit patients. [less ▲]

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See detailArterial dP/dtmax accurately reflects left ventricular contractility during shock when adequate vascular filling is achieved
MORIMONT, Philippe ULg; LAMBERMONT, Bernard ULg; Desaive, Thomas ULg et al

in BMC Cardiovascular Disorders (2012), 12:13

Background: Peak first derivative of femoral artery pressure (arterial dP/dt max) derived from fluid-filled catheter remains questionable to assess left ventricular (LV) contractility during shock. The ... [more ▼]

Background: Peak first derivative of femoral artery pressure (arterial dP/dt max) 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/dt maxis 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/dt maxwas 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/dt maxand Ees were significantly correlated during various hemodynamic conditions, arterial dP/dt maxwas more accurate for assessing LV contractility when adequate vascular filling, defined as PPV ≤ 11%, was achieved. © 2012 Morimont et al; licensee BioMed Central Ltd. [less ▲]

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See detailInterventricular septal rupture caused by vehicular trauma
ROBINET, Sébastien ULg; MORIMONT, Philippe ULg; LAMBERMONT, Bernard ULg et al

in Heart & Lung (2012), 41(2), 200-202

We report the case of a patient admitted at the emergency unit after a severe car accident. As ECG showed a ST segment elevation in all leads, the working diagnosis was coronary dissection. Coronary ... [more ▼]

We report the case of a patient admitted at the emergency unit after a severe car accident. As ECG showed a ST segment elevation in all leads, the working diagnosis was coronary dissection. Coronary angiography revealed a large interventricular septal rupture, confirmed by echocardiography. After discussion and as haemodynamics permitted, 6 weeks of medical observation were decided. A surgical repair was then performed, and provided a perfect repair of the shunt. We discuss about the prevalence and management of this rare traumatic complication. [less ▲]

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See detailPhysiological relevance and performance of a minimal lung model -- an experimental study in healthy and acute respiratory distress syndrome model piglets
Chiew, Y. S.; Chase, J. G.; LAMBERMONT, Bernard ULg et al

in BMC Pulmonary Medicine (2012), 12:59

Background: Mechanical ventilation (MV) is the primary form of support for acute respiratory distress syndrome (ARDS) patients. However, intra- and inter- patient-variability reduce the efficacy of ... [more ▼]

Background: Mechanical ventilation (MV) is the primary form of support for acute respiratory distress syndrome (ARDS) patients. However, intra- and inter- patient-variability reduce the efficacy of general protocols. Model-based approaches to guide MV can be patient-specific. A physiological relevant minimal model and its patient-specific performance are tested to see if it meets this objective above. Methods: Healthy anesthetized piglets weighing 24.0 kg [IQR: 21.0-29.6] underwent a step-wise PEEP increase manoeuvre from 5cmH2O to 20cmH2O. They were ventilated under volume control using Engstrom Care Station (Datex, General Electric, Finland), with pressure, flow and volume profiles recorded. ARDS was then induced using oleic acid. The data were analyzed with a Minimal Model that identifies patient-specific mean threshold opening and closing pressure (TOP and TCP), and standard deviation (SD) of these TOP and TCP distributions. The trial and use of data were approved by the Ethics Committee of the Medical Faculty of the University of Liege, Belgium.Results and discussions3 of the 9 healthy piglets developed ARDS, and these data sets were included in this study. Model fitting error during inflation and deflation, in healthy or ARDS state is less than 5.0% across all subjects, indicating that the model captures the fundamental lung mechanics during PEEP increase. Mean TOP was 42.4cmH2O [IQR: 38.2-44.6] at PEEP = 5cmH2O and decreased with PEEP to 25.0cmH2O [IQR: 21.5-27.1] at PEEP = 20cmH2O. In contrast, TCP sees a reverse trend, increasing from 10.2cmH2O [IQR: 9.0-10.4] to 19.5cmH2O [IQR: 19.0-19.7]. Mean TOP increased from average 21.2-37.4cmH2O to 30.4-55.2cmH2O between healthy and ARDS subjects, reflecting the higher pressure required to recruit collapsed alveoli. Mean TCP was effectively unchanged. Conclusion: The minimal model is capable of capturing physiologically relevant TOP, TCP and SD of both healthy and ARDS lungs. The model is able to track disease progression and the response to treatment. [less ▲]

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See detailLe débit de filtration glomérulaire est-il un déterminant de la concentration plasmatique du NGAL aux soins intensifs ?
DELANAYE, Pierre ULg; Claisse, Guillaume; Mehdi, Manoli et al

Poster (2012)

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See detailPhysiological Relevance of a Minimal Model in Healthy Pigs Lungs
Chiew, YS; Desaive, Thomas ULg; LAMBERMONT, Bernard ULg et al

in Proceedings of BMS 2012 (2012)

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See detailPerformance of lung recruitment model in healthy anesthetised pigs
Chiew, YS; LAMBERMONT, Bernard ULg; JANSSEN, Nathalie ULg et al

in Proceedings of the World Congress on Medical Physics and Biomedical Engineering 2012 (2012)

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