A cannula is described for insertion within the nose of a patient to provide drainage or to allow for postoperative suction of the sinus after surgery. The second assembly is fastened to the outer perimeter of the tube such that the second assembly is disposed on a second side of the wall. The cir-clip is provided at one end thereof with an inwardly bent curved portion and a linear portion linearly extending inwardly from the tip of the curved portion and having a tip which always comes in contact with the bottom of an annular groove of the end cap. The derived inverse transfer function is used to generate a coefficient map which a compensation filter responsively compensates for from variations in the output load of the amplifier system. The system includes combiners and distributors which can interface with the SCS cable through standard modular, multi-pin plug and jack connectors. The outflow from the nozzle then creates a low pressure condition within a mixing chamber.