Improved pressure contour analysis for estimating cardiac stroke volume using pulse wave velocity measurement (2017)
Background: Pressure contour analysis is commonly used to estimate cardiac performance for patients suffering from cardiovascular dysfunction in the intensive care unit. However, the existing techniques for continuous estimation of stroke volume (SV) from pressure measurement can be unreliable during hemodynamic instability, which is inevitable for patients requiring significant treatment. For this reason, pressure contour methods must be improved to capture changes in vascular properties and thus provide accurate conversion from pressure to flow. Methods: This paper presents a novel pressure contour method utilizing pulse wave velocity (PWV) measurement to capture vascular properties. A three-element Windkessel model combined with the reservoir-wave concept are used to decompose the pressure contour into components related to storage and flow. The model parameters are identified beat-to-beat from the water-hammer equation using measured PWV, wave component of the pressure, and an estimate of subject-specific aortic dimension. SV is then calculated by converting pressure to flow using identified model parameters. The accuracy of this novel method is investigated using data from porcine experiments (N = 4 Pietrain pigs, 20-24.5 kg), where hemodynamic properties were significantly altered using dobutamine, fluid administration, and mechanical ventilation. In the experiment, left ventricular volume was measured using admittance catheter, and aortic pressure waveforms were measured at two locations, the aortic arch and abdominal aorta. Results: Bland-Altman analysis comparing gold-standard SV measured by the admittance catheter and estimated SV from the novel method showed average limits of agreement of ±26% across significant hemodynamic alterations. This result shows the method is capable of estimating clinically acceptable absolute SV values according to Critchely and Critchely. Conclusion: The novel pressure contour method presented can accurately estimate and track SV even when hemodynamic properties are significantly altered. Integrating PWV measurements into pressure contour analysis improves identification of beat-to-beat changes in Windkessel model parameters, and thus, provides accurate estimate of blood flow from measured pressure contour. The method has great potential for overcoming weaknesses associated with current pressure contour methods for estimating SV.
CitationKamoi S, Pretty C, Balmer J, Davidson S, Pironet A, Desaive T, Shaw GM, Chase JG (2017). Improved pressure contour analysis for estimating cardiac stroke volume using pulse wave velocity measurement. BioMedical Engineering Online. 16(1). 51-.
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KeywordsCardiovascular system; Hemodynamic monitor; Intensive care; Physiological modelling; Pressure contour analysis; Pulse wave velocity; Reservoir–wave pressure; Stroke volume; Water hammer; Windkessel model
ANZSRC Fields of Research32 - Biomedical and clinical sciences::3201 - Cardiovascular medicine and haematology::320101 - Cardiology (incl. cardiovascular diseases)
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Incorporating pulse wave velocity into model-based pulse contour analysis method for estimation of cardiac stroke volume Smith, Rachel; Balmer, Joel; Pretty, C.G.; Mehta-Wilson, T.; Desaive, T.; Shaw, Geoff; Chase, Geoff (Elsevier BV, 2019)Background and Objectives: Stroke volume (SV) and cardiac output (CO) are important metrics for hemodynamic management of critically ill patients. Clinically available devices to continuously monitor these metrics are ...
Smith R; Balmer J; Shaw, Geoff; Chase, Geoff; Pretty, Christopher (Elsevier BV, 2020)Abstract: A system is needed for monitoring stroke volume (SV) and cardiac output (CO) in unstable patients which is non-additionally invasive, reproducible and reliable in a variety of physiological states. This study ...
Balmer J; Pretty CG; Kamoi S; Davidson S; Pironet A; Desaive T; Shaw, Geoff; Chase, Geoff (2017)Pulse wave velocity (PWV) measurements are commonly used to evaluate a patient’s arterial stiffness, an indicator of cardiovascular dysfunction. PWV is usually calculated by measuring the pulse transit time (PTT) over a ...