A Clinical Monitoring System for Centrifugal Blood Pumps

Abstract

In clinical application of rotary blood pumps, flow obstruction as a result of suction of the inflow cannula, kinking of tubing, or thrombus formation occurs quite frequently. Early detection of such problems is essential to avoid hemolysis, tissue degradation, or release of thrombi to the patient. A program was developed for automatic observation of pump performance, tubing resistance, and suction effects, which requires only the measurement of already available parameters (i.e., pump speed, pump flow, aortic pressure). The software is based on Visual-C and provides a user surface formatted in Windows. Pump flow, its time derivate, and the relationship between the pulsatile component and the mean graft flow are observed to detect suction in the left atrium. Furthermore, the generated pressure head is predicted from pump speed, graft flow, and the resistance of tubing/cannula and compared with the actually measured aortic pressure. An alarm sounds if a given limit between prediction and measurement is exceeded. In a mock circulation, suction events were detected in more than 95% with a mean deviation of actual aortic pressure from its predicted value of less than 5%. For in vivo application, even incomplete suction could be detected reliably in more than 90% of events. This system improves and standardizes monitoring of pump performance; it should therefore lead to greater safety during application of such devices.

Suction Due to Left Ventricular Assist: Implications for Device Control and Management

“…6). In clinical practice, suction is more likely to occur during full bypass than with partial support (12,14,20,25). Although the results of the present study confirm this, they also show that under pathophysiological conditions even partial LV bypass may lead to suction problems, when pulmonary venous return is disturbed (Figs.…”

“…The presented results demonstrate that the use of pump speed manipulation may serve two purposes, namely reversal of suction‐induced inlet collapse and monitoring pulmonary hemodynamics. Assessment of circulatory hemodynamic status during LVAD support is of crucial importance for device control and management (4,14–16).…”

First Clinical Experience With the DeBakey VAD Continuous-Axial-Flow Pump for Bridge to Transplantation

“…Some of them are general concerns applicable to all kinds of rotary blood pumps, such as the absence of an inherent FrankStarling mechanism and its consequences during exercise, as well as the definition of control parameters to optimize pump-speed adjustments and avoid excess suction. 8,9 Such questions as noninvasive measurement of nonpulsatile or low-pulsatile blood pressures of fully mobilized and exercising patients will have to be addressed in the future. Furthermore, episodes of stalling and consecutive pump stops and restarts have not yet been sufficiently explained.…”

Flow Measurement at the Pump Head of Centrifugal Pumps: Comparison of Ultrasonic Transit Time and Ultrasonic Doppler Systems

“…Unrecognized flow stagnation or reversal can lead to the increase of blood trauma and thromboembolism. The shape of the flow pattern can be used for indirect determination of filling pressures and venous return (11).…”