Noninvasive Monitoring of Rotary Blood Pumps: Necessity, Possibilities, and Limitations

Schima, Heinrich; Trubel, W.; Moritz, Anton; Wieselthaler, Georg; Stöhr, H; Thoma, H.; Losert, Udo; Wolner, Ernst

doi:10.1111/j.1525-1594.1992.tb00293.x

Cited by 66 publications

(19 citation statements)

References 4 publications

(3 reference statements)

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“…A discussion of venous return and excessive ventricular unloading in implantable rotary blood pumps (7)(8)(9)(10)(11) has continued for many years. The direct way to detect the occurrence of ventricular collapse would be through the use of a reliable pressure measurement; one project was reported (12) in which a strain-gauge-bridge which was built into the concave interior wall of a tubing cannula was used.…”

Section: Discussionmentioning

confidence: 99%

Advanced Suction Detection for an Axial Flow Pump

Vollkron¹,

Schima

Huber³

et al. 2006

Artificial Organs

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An automatic detection system for ventricular collapse was developed and tested in a first clinical trial as part of a physiological speed control concept for axial flow pumps. From this clinical experience, and based on the acquired data during this trial, an optimization of the developed system was performed. An already-existing database of 784 individual cases was extended. For harmonization of this database an additional 412 snap files were extracted from continuous data recordings and classified manually using a standardized procedure. The already-developed and clinically tested algorithms were supplemented by one additional indicator derived from a preexisting criterion. One threshold value was replaced by application of a numerically optimized nonlinear characteristic curve dependent on heart rate. Finally, in a multidimensional optimization process of the entire suction detection system, 7 individual indicators were adjusted by using 17 independent threshold values. The optimization criteria were applied using a three-level hierarchical system. Within the final database consisting of 1196 snap shots the overall amount of maldetections could be reduced to 23 cases including 5 false positive events (0.42%) and 18 false negative decisions (1.5%). By application of the clinical experience from the first clinical trial of a physiologic control system it became possible to optimize the sensitivity and specificity of the suction detection system to unprecedented accuracy.

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Section: Discussionmentioning

confidence: 99%

Advanced Suction Detection for an Axial Flow Pump

Vollkron¹,

Schima

Huber³

et al. 2006

Artificial Organs

Self Cite

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“…The real VAD can be tested with the real inputs and outputs that would be used clinically. For the development of flow or pressure observers [26], cardiac index observers [27], or control strategies [28], the implementation on a real device is a significant step from the purely numerical simulation.…”

Section: Discussionmentioning

confidence: 99%

A Novel Interface for Hybrid Mock Circulations to Evaluate Ventricular Assist Devices

Ochsner

Amacher

Amstutz

et al. 2013

IEEE Trans. Biomed. Eng.

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This paper presents a novel mock circulation for the evaluation of ventricular assist devices (VADs), which is based on a hardware-in-the-loop concept. A numerical model of the human blood circulation runs in real time and computes instantaneous pressure, volume, and flow rate values. The VAD to be tested is connected to a numerical-hydraulic interface, which allows the interaction between the VAD and the numerical model of the circulation. The numerical-hydraulic interface consists of two pressure-controlled reservoirs, which apply the computed pressure values from the model to the VAD, and a flow probe to feed the resulting VAD flow rate back to the model. Experimental results are provided to show the proper interaction between a numerical model of the circulation and a mixed-flow blood pump.

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“…Control of a rotary VAD is usually maintained by setting the pump at a fixed speed such that the pump can provide enough blood flow for the patient's organ perfusion [1]. However, determination of an appropriate pump speed setting to achieve a desired blood flow rate based on the patient's body demand is difficult.…”

Section: Introductionmentioning

confidence: 99%

Mathematical modeling of ventricular suction induced by a rotary ventricular assist device

Porter

2006

2006 American Control Conference

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Ventricular suction (VS) is an event caused by operating a rotary ventricular assist device (VAD) at a high speed in a patient with low blood volume in the left ventricle (LV). VS occurs when the blood flow out of the ventricle exceeds the flow into the ventricle, causing the ventricle to collapse. Because of this, it is risky to use a VAD on a long-term basis without changing the speed as the demand of a human body changes dramatically over time. As a result, a controller that can automatically adjust pump speed based on a patient's physiological needs with the capability of suction detection and avoidance would be important for developing a rotary VAD for long-term use. Computer modeling of the cardiovascular system has been used extensively for controller design and testing. To test the capability of a VAD controller to respond to VS, a mathematical model that can simulate VS must be integrated with a cardiovascular system model. In this paper, a nonlinear resistance as a function of the LV pressure, the absolute value of the LV pressure derivative, and the pump inlet pressure was identified to model VS. This was done by fitting a curve to data sets from animal experiments with the HeartMate II VAD. The model fit the data well with an average root-mean-squared (RMS) error of 10.93%. The model was validated against 23 different animal data sets with a mean RMS error of 29.98%. An existing suction model was tested with the same validation data sets and yielded a mean RMS error of 67.41%. The newly developed model showed a significant improvement from the existing model. It will be integrated with a cardiovascular model for future development of a suction detector and physiologic controller for a VAD.

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Noninvasive Monitoring of Rotary Blood Pumps: Necessity, Possibilities, and Limitations

Cited by 66 publications

References 4 publications

Advanced Suction Detection for an Axial Flow Pump

Advanced Suction Detection for an Axial Flow Pump

A Novel Interface for Hybrid Mock Circulations to Evaluate Ventricular Assist Devices

Mathematical modeling of ventricular suction induced by a rotary ventricular assist device

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