References of "Desaive, Thomas"
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See detailDevelopment and Identification of a Closed-Loop Model of the Cardiovascular System Including the Atria
Pironet, Antoine ULg; Revie, James A.; Paeme, Sabine ULg et al

Conference (2012, August 31)

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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 detailAutonomous electrical activity induced by cardiac tissue deformation in a thermo-electro-mechanical background
Collet, Arnaud ULg; Desaive, Thomas ULg; Dauby, Pierre ULg

in 8th IFAC Symposium on Biological and Medical Systems (2012, August)

In a healthy heart, the mechano-electric feedback (MEF) process acts as an intrinsic regulatory mechanism of the myocardium which allows the normal cardiac contraction by damping mechanical perturbations ... [more ▼]

In a healthy heart, the mechano-electric feedback (MEF) process acts as an intrinsic regulatory mechanism of the myocardium which allows the normal cardiac contraction by damping mechanical perturbations in order to generate a new healthy electromechanical situation. However, under certain conditions, the MEF can be a generator of dramatic arrhythmias by inducing local electrical depolarizations as a result of abnormal cardiac tissue deformations, via stretch-activated channels (SACs). Then, these perturbations can propagate in the whole heart and lead to global cardiac dysfunctions. In the present study, we examine the spatio-temporal behavior of the autonomous electrical activity induced by the MEF when the heart is subject to temperature variations. For instance, such a situation can occur during a therapeutic hypothermia. This technique is usually used to prevent neuronal injuries after a cardiac resuscitation. From this perspective, we introduce a one-dimensional time-dependent model containing all the key ingredients that allow accounting for excitation-contraction coupling, MEF and thermoelectric coupling. Our simulations show that an autonomous electrical activity can be induced by cardiac deformations, but only inside a certain temperature interval. In addition, in some cases, the autonomous electrical activity takes place in a periodic way like a pacemaker. We also highlight that some properties of the action potentials that are generated by the MEF, are significantly influenced by temperature. Moreover, in the situation where a pacemaker activity occurs, we also show that the period is heavily temperature-dependent. [less ▲]

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See detailDevelopment and Identification of a Closed-Loop Model of the Cardiovascular System Including the Atria
Pironet, Antoine ULg; Revie, James A.; Paeme, Sabine ULg et al

in Proceedings of the 8th IFAC Symposium on Biological and Medical Systems (2012, August)

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See detailInsulin Kinetics during Hyper-Insulinemia Euglycemia Therapy (HIET)
Penning, Sophie ULg; MASSION, Paul ULg; Le Compte, Aaron J. et al

in Proceedings of the 8th IFAC Symposium on Biological and Medical Systems (2012, August)

Hyper-insulinemia euglycemia therapy (HIET) is a supra-physiological insulin dosing protocol used in acute cardiac failure to reduce dependency on inotropes to augment or generate cardiac output, and is ... [more ▼]

Hyper-insulinemia euglycemia therapy (HIET) is a supra-physiological insulin dosing protocol used in acute cardiac failure to reduce dependency on inotropes to augment or generate cardiac output, and is based on the inotropic effects of insulin at high doses up to 45-250x normal daily dose. Such high insulin doses are managed using intravenous glucose infusion to control glycemia and prevent hypoglycemia. However, both insulin dosing and glycemic control in these patients is managed ad-hoc. This research examines a selection of clinical data to determine the effect of high insulin dosing on renal clearance and insulin sensitivity, to assess the feasibility of using model-based methods to control and guide these protocols. The results show that the model and, in particular, the modeled renal clearance constant are adequate and capture measured data well, although not perfectly. Equally, insulin sensitivity over time is similar to broader critical care cohorts in level and variability, and these results are the first time they have been presented for this cohort. While more data is needed to confirm and further specify these results, it is clear that the model used is adequate for controlling HIET in a model-based framework. [less ▲]

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See detailInsulin Kinetics during Hyper-Insulinemia Euglycemia Therapy (HIET)
Penning, Sophie ULg; MASSION, Paul ULg; Le Compte, Aaron J. et al

Conference (2012, August)

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See detailDevelopment and Pilot Trial Results of Stochastic Targeted (STAR) Glycemic Control in a Medical ICU
Fisk, Liam M.; Le Compte, Aaron J.; Shaw, Geoffrey M. et al

in Proceedings of the 8th IFAC Symposium on Biological and Medical Systems (2012, August)

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See detailVariability of insulin sensitivity during the first 4 days of critical illness: implications for tight glycemic control
Pretty, Christopher ULg; Le Compte, Aaron J.; Chase, J. Geoffrey et al

in Annals of Intensive Care (2012)

Introduction: Effective tight glycaemic control (TGC) can improve outcomes in critical care patients, but is difficult to achieve consistently. Insulin sensitivity defines the metabolic balance between ... [more ▼]

Introduction: Effective tight glycaemic control (TGC) can improve outcomes in critical care patients, but is difficult to achieve consistently. Insulin sensitivity defines the metabolic balance between insulin concentration and insulin mediated glucose disposal. Hence, variability of insulin sensitivity can cause variable glycaemia. This study quantifies and compares the daily evolution of insulin sensitivity level and variability for critical care patients receiving TGC. <br /> <br />Methods: A retrospective analysis of data from the SPRINT TGC study involving patients admitted to a mixed medical-surgical ICU between August 2005 and May 2007. Only patients who commenced TGC within 12 hours of ICU admission and spent at least 24 hours on the SPRINT protocol were included (N=164). Model-based insulin sensitivity (SI) was identified each hour. Absolute level and hour-to-hour percent changes in SI were assessed on cohort and per-patient bases. Levels and variability of SI were compared over time on 24-hour and 6-hour timescales for the first 4 days of ICU stay. <br /> <br />Results: Cohort and per-patient median SI levels increased by 34% and 33% (p<0.001) between days 1 and 2 of ICU stay. Concomitantly, cohort and per-patient SI variability decreased by 32% and 36% (p<0.001). For 72% of the cohort, median SI on day 2 was higher than on day 1. The day 1-2 results are the only clear, statistically significant trends across both analyses. <br /> <br />Analysis of the first 24 hours using 6-hour blocks of SI data showed that most of the improvement in insulin sensitivity level and variability seen between days 1 and 2 occurred during the first 12-18 hours of day 1. <br /> <br />Conclusions: Critically ill patients have significantly lower and more variable insulin sensitivity on day 1 than later in their ICU stay and particularly during the first 12 hours. This rapid improvement is likely due to the decline of counter-regulatory hormones as the acute phase of critical illness progresses. Clinically, these results suggest that while using TGC protocols with patients during their first few days of ICU stay, extra care should be afforded. Increased measurement frequency, higher target glycaemic bands, conservative insulin dosing and modulation of carbohydrate nutrition should be considered to safely minimize outcome glycaemic variability and reduce the risk of hypoglycaemia. [less ▲]

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See detailDoes Tight Glycemic Control positively impact on patient mortality?
Penning, Sophie ULg; Le Compte, Aaron J.; Signal, Matthew et al

Poster (2012, March 20)

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See detailDoes Tight Glycemic Control positively impact on patient mortality?
Penning, Sophie ULg; Le Compte, Aaron J.; Signal, Matthew et al

in Critical Care (2012, March 20)

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See detailPilot Trial of STAR in Medical ICU
Fisk, Liam M.; Le Compte, Aaron J.; Shaw, Geoffrey M. et al

Poster (2012, March)

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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 detailVariability of insulin sensitivity during the first 4 days of critical illness
Pretty, Christopher ULg; Le Compte, A; Chase, JG et al

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

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See detailCumulative time in band (cTIB): glycemic level, variability and patient outcome vs mortality
Penning, Sophie ULg; Signal, M; Preiser, JC et al

in Proceedings of ANZICS 2012 (2012)

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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 detailRespiratory system elastance monitoring during PEEP titration
Chiew, YS; Chase, JG; Shaw, GM et al

in Critical Care (2012), 34 (Suppl 1)

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See detailPilot Trial of STAR in Medical ICU
Fisk, LM; Le Compte, A; Shaw, GM et al

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

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