A CLINICAL MONITORING-SYSTEM FOR CENTRIFUGAL BLOOD PUMPS

In clinical application of rotary blood pumps, flow obstruction as a r esult of suction of the inflow cannula, kinking of tubing, or thrombus formation occurs quite frequently. Early detection of such problems i s essential to avoid hemolysis, tissue degradation, or release of thro mbi to the patient. A program was developed for automatic observation of pump performance, tubing resistance, and suction effects, which req uires 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 th e mean graft flow are observed to detect suction in the left atrium. F urthermore, 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 b etween 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 reliabl y in more than 90% of events. This system improves and standardizes mo nitoring of pump performance; it should therefore lead to greater safe ty during application of such devices.