Evaluation of clearance kinetics of a portal vascular access system

A portal vascular access system is a totally implantable system composed of a fluid reservoir with an attached catheter. The system provides easy access for the patient who needs a continuous supply of medication or repeated blood sampling. To ensure no obstruction of flow, the system must be flushed to clear the port and catheter, making it important to establish the clearance parameters. These parameters can be obtained by use of a tetrapolar impedance cell to monitor the relative impedance change using two solutions of different impedances to fill and flush the system. The resulting impedance dilution curve allows calculation of time delay, dilution time, clearance time, and clearance volume. This method and resulting data may be used to characterize a portal vascular access system and provide a basis for comparative analysis of newly introduced systems.