Analysis of different model-based approaches for estimating dFRC for real-time application

in BioMedical Engineering OnLine (2013), 12:9

Algorithmic processing of pressure waveforms to facilitate estimation of cardiac elastance

in BioMedical Engineering OnLine (2012)

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

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

Assessment of ventricular contractility and ventricular-arterial coupling with a model-based sensor.

in Computer Methods & Programs in Biomedicine (2012)

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 ▲]

Performance of lung recruitment model in healthy anesthetised pigs

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

Variability of insulin sensitivity during the first 4 days of critical illness

in Critical Care: the Official Journal of the Critical Care Forum (2012), 16 (Suppl 1)

Estimating afterload, systemic vascular resistance and pulmonary vascular resistance in an intensive care setting

in Proceedings of BMS2012 (2012)

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

in Proceedings of BMS 2012 (2012)

Cumulative time in band (cTIB): glycemic level, variability and patient outcome vs mortality

in Proceedings of ANZICS 2012 (2012)

Model-based cardiovascular monitoring of acute pulmonary embolism in porcine trials

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

Porcine trial validation of model-based cardiovascular monitoring of acute pulmonary embolism

in Proceedings of ANZICS 2011 (2011)