Model-based Monitoring of Septic Shock Treated with Large-Pore Hemofiltration Therapy

in Proceedings of BMS 2012 (2012)

Procalcitonin usefulness for the initiation of antibiotic treatment in intensive care unit patients*.

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 ▲]

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

in BioMedical Engineering OnLine (2011), 10(1), 86

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 ... [more ▼]

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. 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. 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. 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. [less ▲]

Interventricular septal rupture caused by vehicular trauma.

in Heart & Lung (2011)

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 ▲]

Do dead from cardiovascular death donors experience end-of-life shortening?

Conference (2011, March 24)

Patient specific identification of the cardiac driver function in a cardiovascular system model.

in Computer Methods & Programs in Biomedicine (2011)

The cardiac muscle activation or driver function, is a major determinant of cardiovascular dynamics, and is often approximated by the ratio of the left ventricle pressure to the left ventricle volume. In ... [more ▼]

The cardiac muscle activation or driver function, is a major determinant of cardiovascular dynamics, and is often approximated by the ratio of the left ventricle pressure to the left ventricle volume. In an intensive care unit, the left ventricle pressure is usually never measured, and the left ventricle volume is only measured occasionally by echocardiography, so is not available real-time. This paper develops a method for identifying the driver function based on correlates with geometrical features in the aortic pressure waveform. The method is included in an overall cardiovascular modelling approach, and is clinically validated on a porcine model of pulmonary embolism. For validation a comparison is done between the optimized parameters for a baseline model, which uses the direct measurements of the left ventricle pressure and volume, and the optimized parameters from the approximated driver function. The parameters do not significantly change between the two approaches thus showing that the patient specific approach to identifying the driver function is valid, and has potential clinically. [less ▲]

Pulmonary embolism diagnostics from the driver function

in Critical Care: the Official Journal of the Critical Care Forum (2011), 15 (Suppl 1)

Model-based cardiovascular monitoring of large pore hemofiltration during endotoxic shock in pigs

in Critical Care: the Official Journal of the Critical Care Forum (2011), 15 (Suppl 1)

Diagnosing pulmonary embolism from a model-based cardiac driver function

in Proceedings of ANZICS 2011 (2011)

Neurally Adjusted Ventilatory Assist (NAVA) improves the matching of diaphragmatic electrical activity and tidal volume in comparison to pressure support (PS)

in Intensive Care Medicine (2011), 37 (Suppl 1)