Medical infusion pump with closed loop stroke feedback system and method
First Claim
1. A medical pump for use with a pumping chamber, comprising:
- a plunger, disposed between a passive inlet valve and a passive outlet valve of the pumping chamber, adapted to intermittently pressurize the pumping chamber during a pumping cycle, the pumping cycle defining an attempted fluid delivery stroke of the pump;
a pressure sensor directly connected to the plunger and adapted to detect the pressure, between the passive inlet valve and the passive outlet valve, exerted by the plunger on the pumping chamber;
a position sensor operatively associated with the plunger to detect the position of the plunger;
a processing unit in electronic communication with the pressure sensor and position sensor; and
a memory coupled to the processing unit, wherein the memory contains programming code executed by the processing unit to process pressure data from the pressure sensor and position data from the position sensor to determine a calculated actual stroke volume of the pump for the pumping cycle from a beginning of a compression stroke of the pumping cycle to a point when the passive outlet valve opens, and to modify stroke frequency to compensate for variation between the calculated stroke volume and a desired dosage rate; and
wherein the passive outlet valve is operated by the pressure exerted by the plunger on the pumping chamber, and the programming code executed by the processing unit processes pressure data from the pressure sensor to identify when the passive outlet valve has opened.
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Accused Products
Abstract
A medical pump with a closed loop stroke feedback system and method, for use with a pumping chamber, for example in a cassette, is disclosed. The pump includes a pumping element that intermittently pressurizes a pumping chamber during a pumping cycle. A pressure sensor detects the pressure exerted by the pumping element on the pumping chamber. A position sensor detects the position of the pumping element. A processing unit processes pressure data from the pressure sensor and position data from the position sensor to determine a calculated stroke volume of the pump for a pump cycle, and to adjust a stroke frequency of the pump to compensate for variation in the stroke volume.
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Citations
37 Claims
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1. A medical pump for use with a pumping chamber, comprising:
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a plunger, disposed between a passive inlet valve and a passive outlet valve of the pumping chamber, adapted to intermittently pressurize the pumping chamber during a pumping cycle, the pumping cycle defining an attempted fluid delivery stroke of the pump; a pressure sensor directly connected to the plunger and adapted to detect the pressure, between the passive inlet valve and the passive outlet valve, exerted by the plunger on the pumping chamber; a position sensor operatively associated with the plunger to detect the position of the plunger; a processing unit in electronic communication with the pressure sensor and position sensor; and a memory coupled to the processing unit, wherein the memory contains programming code executed by the processing unit to process pressure data from the pressure sensor and position data from the position sensor to determine a calculated actual stroke volume of the pump for the pumping cycle from a beginning of a compression stroke of the pumping cycle to a point when the passive outlet valve opens, and to modify stroke frequency to compensate for variation between the calculated stroke volume and a desired dosage rate; and wherein the passive outlet valve is operated by the pressure exerted by the plunger on the pumping chamber, and the programming code executed by the processing unit processes pressure data from the pressure sensor to identify when the passive outlet valve has opened. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A medical pump for use with a pumping chamber, comprising:
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a plunger, disposed between a passive inlet valve and a passive outlet valve of the pumping chamber, adapted to intermittently pressurize the pumping chamber during a pumping cycle, the pumping cycle defining an attempted fluid delivery stroke of the pump; a pressure sensor directly connected to the plunger and adapted to detect the pressure, between the passive inlet valve and the passive outlet valve, exerted by the plunger on the pumping chamber; a position sensor operatively associated with the plunger to detect the position of the plunger; a processing unit in electronic communication with the pressure sensor and position sensor; and a memory coupled to the processing unit, wherein the memory contains programming code executed by the processing unit to establish an expected nominal stroke volume associated with the attempted fluid delivery stroke of the pump, set a first stroke frequency based upon a desired dosage rate and the expected nominal stroke volume, thence, during pressurization of the pumping chamber for at least one attempted fluid delivery stroke, process pressure data from the pressure sensor and position data from the position sensor to; identify by a slope change in the pressure data when the passive outlet valve of the pumping chamber has opened, determine a calculated pressurization volume from a beginning of the pumping cycle to the point when the passive outlet valve opens, determine a change in pressurization volume by subtracting the calculated pressurization volume from a nominal pressurization volume, determine a change in stroke volume by multiplying the change in pressurization volume by a ratio of pumping chamber expansion under pressure at the end of the compression stroke of the pumping cycle to pumping chamber expansion under pressure at the beginning of a compression stroke of the pumping cycle, determine a calculated actual stroke volume based on the change in stroke volume, and, if the calculated actual stroke volume is greater than a given threshold value, modify the stroke frequency to a second stroke frequency that is different than the first stroke frequency in order to compensate for variation between the calculated actual stroke volume and the expected nominal stroke volume; and wherein the passive outlet valve is operated by the pressure, between the passive inlet valve and the passive outlet valve, exerted by the plunger on the pumping chamber. - View Dependent Claims (23, 24, 25, 26, 27)
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28. A medical pump for use with a cassette having a pumping chamber, comprising:
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a plunger, disposed between a passive inlet valve and a passive outlet valve of the pumping chamber, operatively associated with a shaft and adapted to intermittently pressurize the pumping chamber during a pumping cycle, the pumping cycle defining an attempted fluid delivery stroke of the pump; a pressure sensor positioned outside of the pumping chamber in-line with and directly connected to the plunger between the pumping chamber and the shaft connected to a motor, wherein the shaft is configured to move the plunger against a flexible membrane of the pumping chamber to displace the flexible membrane and intermittently pressurize the pumping chamber during the pumping cycle, the pressure sensor being adapted to detect the pressure, between the passive inlet valve and the passive outlet valve, exerted by the plunger on the pumping chamber; a position sensor operatively associated with the plunger to detect the position of the plunger; a processing unit in electronic communication with the pressure sensor and position sensor; and a memory coupled to the processing unit, wherein the memory contains programming code executed by the processing unit to establish an expected nominal stroke volume associated with the attempted fluid delivery stroke of the pump, set a first stroke frequency based upon a desired pump flow rate and the expected nominal stroke volume, thence, during pressurization of the pumping chamber for at least one attempted fluid delivery stroke, to process pressure data from the pressure sensor and position data from the position sensor to determine a calculated actual stroke volume of the pump for the pumping cycle, and to modify the first stroke frequency to a second stroke frequency different than the first stroke frequency in order to compensate for variation between the calculated actual stroke volume and the expected nominal stroke volume so as to more closely approach the desired pump flow rate for a subsequent pumping cycle; and wherein the passive outlet valve is operated by the pressure, between the passive inlet valve and the passive outlet valve, exerted by the plunger on the pumping chamber, and the programming code executed by the processing unit processes pressure data from the pressure sensor to identify when the passive outlet valve has opened. - View Dependent Claims (29, 30, 31)
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32. A medical pump for use with a pumping chamber, comprising:
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a plunger, disposed between a passive inlet valve and a passive outlet valve of the pumping chamber, adapted to intermittently pressurize the pumping chamber during a pumping cycle, the pumping cycle defining an attempted fluid delivery stroke of the pump; a pressure sensor positioned outside of the pumping chamber in-line with and directly connected to the plunger between the pumping chamber and a shaft connected to a motor, wherein the shaft is configured to move the plunger against a flexible membrane of the pumping chamber to displace the flexible membrane and intermittently pressurize the pumping chamber during the pumping cycle, and the pressure sensor is adapted to detect the pressure exerted by the plunger on the pumping chamber; a position sensor operatively associated with the plunger to detect the position of the plunger; a processing unit in electronic communication with the pressure sensor and position sensor; and a memory coupled to the processing unit, wherein the memory contains programming code executed by the processing unit to process pressure data from the pressure sensor and position data from the position sensor to determine a calculated actual stroke volume of the pump for the pumping cycle, and to modify stroke frequency to compensate for variation between the calculated stroke volume and a desired dosage rate; and wherein the passive outlet valve is operated by the pressure exerted by the plunger on the pumping chamber, and the programming code executed by the processing unit processes pressure data from the pressure sensor to identify when the passive outlet valve has opened. - View Dependent Claims (33, 34)
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35. A medical pump for use with a pumping chamber, comprising:
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a plunger, disposed between a passive inlet valve and a passive outlet valve of the pumping chamber, adapted to intermittently pressurize the pumping chamber during a pumping cycle, the pumping cycle defining an attempted fluid delivery stroke of the pump; a pressure sensor directly connected to the plunger and adapted to detect the pressure, between the passive inlet valve and the passive outlet valve, exerted by the plunger on the pumping chamber; a position sensor operatively associated with the plunger to detect the position of the plunger; a processing unit in electronic communication with the pressure sensor and position sensor; and a memory coupled to the processing unit, wherein the memory contains programming code executed by the processing unit to process pressure data from the pressure sensor and position data from the position sensor to determine a calculated stroke volume of the pump for the pumping cycle, and, if the calculated stroke volume is greater than a given threshold value, to modify a stroke frequency in order to compensate for variation between the calculated stroke volume and a desired dosage rate and, if the calculated stroke volume is not greater than the given threshold value, does not modify the stroke frequency until the calculated stroke volume exceeds the given threshold value; and wherein the passive outlet valve is operated by the pressure exerted by the plunger on the pumping chamber, and the programming code executed by the processing unit processes pressure data from the pressure sensor to identify when the passive outlet valve has opened. - View Dependent Claims (36, 37)
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Specification