Effect of Tubing Length Pump on Flow Derived Index During Rotary Blood Pump Support

Thananya Khienwad, Ronnachit Deepankaew, Praemai Wannawat, and Phornphop Naiyanetr


Rotary blood pump, Mock circulatory loop, Pump flow


The variable of connecting tube length (CTL) in rotary blood pumps (RBPs) is normally existed for the external circulatory support and thus eventually incurs the different outcome as compared to the internal circulatory support. This study aims to determine the effect of the various CTL on the measured parameters from RBP. To serve this purpose, a derived indexes from RBP under mock circulatory loop (MCL) were examined. I_Q which is a slope of the linear regression between the maximal time derivative of pump flow, dQ/dt_max, and its peak to peak, Q_P2P, was determined to evaluate the effect of 3 different CTLs; 130, 50 and 10 cm (length of inlet tube), and 130, 50 and 50 cm (length of outlet tube). Moreover, the parameters dH/dt_max, which are the maximal time derivative of pressure head (H); AOP-LVP, and its peak to peak were derived. The slope of a linear regression between dQ/dt_max and dH/dt_max decreased during reduce CTL in contrast to I_Q index. Thus, this study proved that I_Q index was not significant influenced by a hydraulic resistance (including CTL) and therefore can be used to monitor the cardiac function in case of both external and internal RBPs support.

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