Flow monitoring device
First Claim
1. A pulsatile flow monitoring device in combination with an implantagle drug delivery system which includes a solenoid actuated pump and which delivers a drug in quantatized liquid doses at measured intervals, said pulsatile flow monitoring device comprising:
- a liquid conduit for conveying liquid drug doses, said conduit having a wall establishing a lumen in said conduit and an inside wall surface and an outside wall surface, said conduit wall having a portion of normal thickness and a reduced-in-thickness portion which is at least moderately thermally conductive;
temperature sensing means mounted to said liquid conduit on the outside surface of the reduced-in-thickness wall portion for transducing the temperature of the reduced-in-thickness wall portion, the temperature of which varies with the flow of liquid drug doses;
an electrical power supply coupled to said temperature sensing means for providing electrical energy to said temperature sensing means;
regulating means coupled to said power supply for determining a rate at which electrical energy is provided to said temperature sensing means during preselected and discrete power delivery intervals related to said measured intervals; and
measuring means coupled to said power supply and temperature sensing means for measuring the rate parameters at which electrical energy is consumed by said temperature sensing means, the consumption rate being proportional to the reduced-in-thickness wall temperature of said conduit and thus proportional to the flow of liquid drug doses.
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Accused Products
Abstract
The flow monitoring device is used with a pump casing on an outflow tube having a passageway therethrough with a wall thereabout. A solenoid pump communicates with the passageway for providing pulsatile liquid flow therethrough. A reduced-in-thickness area along the wall of the casing or outflow tubing has an outside surface establishing a site to measure pulsatile flow along an adjacent inside surface. A thermistor is mounted on the outside surface of the wall area for sensing the temperature thereof in response to pulsatile flow therebeneath. The thermistor is electrically energized at a predetermined level. A control circuit regulates the input of electrical energy to the thermistor for predetermined time periods. The control circuit includes a sample and hold circuit and a reset switching circuit responsive to the pump activation for supplying thermistor power after pumping begins. An amplifier in the control circuit compares differences in the input power to the thermistor during a selected time interval to measure the pulsatile flow rate through the passageway.
47 Citations
17 Claims
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1. A pulsatile flow monitoring device in combination with an implantagle drug delivery system which includes a solenoid actuated pump and which delivers a drug in quantatized liquid doses at measured intervals, said pulsatile flow monitoring device comprising:
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a liquid conduit for conveying liquid drug doses, said conduit having a wall establishing a lumen in said conduit and an inside wall surface and an outside wall surface, said conduit wall having a portion of normal thickness and a reduced-in-thickness portion which is at least moderately thermally conductive; temperature sensing means mounted to said liquid conduit on the outside surface of the reduced-in-thickness wall portion for transducing the temperature of the reduced-in-thickness wall portion, the temperature of which varies with the flow of liquid drug doses; an electrical power supply coupled to said temperature sensing means for providing electrical energy to said temperature sensing means; regulating means coupled to said power supply for determining a rate at which electrical energy is provided to said temperature sensing means during preselected and discrete power delivery intervals related to said measured intervals; and measuring means coupled to said power supply and temperature sensing means for measuring the rate parameters at which electrical energy is consumed by said temperature sensing means, the consumption rate being proportional to the reduced-in-thickness wall temperature of said conduit and thus proportional to the flow of liquid drug doses. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of monitoring pulsatile flow in an implantable drug delivery system which has a solenoid activated pump and which employs a monitoring device including a liquid conduit having a reduced-in-thickness wall, temperature sensing means for sensing the reduced-in-thickness wall temperature, electrical power supply for providing energy to the temperature sensing means, regulating means coupled to the power supply and the temperature sensing means for determining a rate at which electrical energy is provided to the temperature sensing means during preselected and discrete power delivery intervals, and measuring means coupled to the power supply and the temperature sensing means for measuring the rate parameters of electrical energy consumption of the temperature sensing means, said method comprising the steps of:
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activating the regulating means to provide electrical energy to the temperature sensing means for a power delivery interval which includes a preselected anticipation interval before the solenoid activates a given pump stroke in the delivery system, deactivating the regulating means to end the power delivery interval after a preselected maintenance interval, the preselected maintenance interval terminating after the solenoid activates a given pump stroke in the delivery system but before a successive pump stroke; and measuring the rate parameters of energy consumption by the temperature sensing means with the measuring means during the power delivery interval. - View Dependent Claims (15)
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16. A method of monitoring pulsatile flow in an implantable drug delivery system including a solenoid activated pump, a monitoring device, a liquid conduit having a reduced-in-thickness wall, temperature sensing means for sensing the reduced-in-thickness wall temperature, an electrical power supply for providing energy to the sensing means, regulating means for determining a rate at which electrical energy is provided to the temperature sensing means during preselected and discrete power delivery intervals, and resetable measuring means for measuring the rate parameters of electrical energy consumption of the temperature sensing means relative to an electrical parameter reference, said method comprising the steps of:
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activating the regulating means to provide electrical energy to the temperature sensing means for a power delivery interval which includes a preselected anticipation interval before the solenoid activates a given pump stroke in the delivery system; deactivating the regulating means to end the power delivery interval after a preselected maintenance interval, the preselected maintenance interval terminating after the solenoid activates a given pump stroke in the delivery system but before a successive pump stroke; reseting the resetable measuring means for providing a stable electrical parameter reference during the preselected anticipation interval; and measuring the rate parameters of energy consumption by the temperature sensing means with the resetable measuring means during the power delivery interval after reseting the resetable measuring means. - View Dependent Claims (17)
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Specification