Effect of tubing length pump on flow derived index during rotary blood pump support

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. IQ which is a slope of the linear regression between the maximal time derivative of pump flow, dQ/dtmax, and its peak to peak, QP2P, 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/dtmax, 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/dtmax and dH/dtmax decreased during reduce CTL in contrast to IQ index. Thus, this study proved that IQ 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 RBP support.