Liquid infusion apparatus

• US 9,878,089 B2
• Filed: 06/20/2013
• Issued: 01/30/2018
• Est. Priority Date: 11/10/2005
• Status: Active Grant

• Current Assignee: Iradimed Corporation
• Original Assignee: Iradimed Corporation
• Inventors: Susi, Roger E.
• Primary Examiner(s): Mehta, Bhisma
• Assistant Examiner(s): FREHE, WILLIAM R
• Application Number:
  US13/923,082
• Publication Number:
  US 20130281966A1
• Time in Patent Office: 1,685 Days
• CPC Class Codes: A61M 2205/14 Detection of the presence or absence of a tube, a connector or a container in an apparatus
• CPC Class Codes: A61M 39/26 Valves closing automatically on disconnecting the line and opening on reconnection thereof check valves A61M39/24
• CPC Class Codes: A61M 5/1413 Modular systems comprising interconnecting elements
• CPC Class Codes: A61M 5/142 Pressure infusion, e.g. using pumps
• CPC Class Codes: A61M 5/14228 with linear peristaltic action, i.e. comprising at least three pressurising members or a helical member
• CPC Class Codes: A61M 5/172 electrical or electronic A61M5/16804, A61M5/16831 take precedence
• CPC Class Codes: F04B 43/082 the tubular flexible member being pressed against a wall by a number of elements, each having an alternating movement in a direction perpendicular to the axes of the tubular member and each having its own driving mechanism

Abstract

An apparatus and method are disclosed for controlling infusion of liquid into a patient using a peristaltic pump. The liquid infusion apparatus includes a liquid conduit having a proximal segment, a distal segment and an intermediate segment. The liquid infusion apparatus also includes a flow valve in fluid communication with the intermediate and distal segments. The flow valve includes a shuttle member slidably disposed within a housing about the distal segment, the shuttle member being configured for lateral movement relative to an elongated axis of the distal segment. The shuttle member is configured to operate in a first configuration to impede fluid flow through the liquid conduit and in a second configuration for which fluid flow through the liquid conduit is unimpeded. The shuttle member includes a resilient grasper for selectively engaging and disengaging a mating actuator resiliently received by the grasper.

Claims

1. A liquid pumping apparatus configured for use in a magnetic resonance imaging (MRI) scan room, comprising:

a linear peristaltic pump operated by an ultrasonic motor coupled thereto;

an encoder installed along a main shaft of the linear peristaltic pump, the encoder being configured to output signals indicative of positions of a plurality of pumping elements of the linear peristaltic pump, wherein the encoder comprises an optical encoder disk and an optical sensor,

wherein the optical encoder disk comprises an index mark detectable by the optical sensor to identify an exact angular position of the main shaft of the linear peristaltic pump and a plurality of graticule marks about a periphery of the optical encoder disk detectable by the optical sensor to provide fine indication of angular positioning of the main shaft relative to the index mark; and

a controller configured to apply drive signals to the ultrasonic motor to modulate speed of motion of the plurality of pumping elements at specific positions during a pumping cycle in response to the output signals received from the encoder to substantially linearize volumetric flow of liquid through the pump per revolution of the pumping cycle,

wherein the controller comprises a pair of coreless transformers configured to produce the drive signals, wherein the drive signals comprise substantially sinusoidal, high-voltage drive signals of low harmonic content in a range of 8 MHz to 130 MHz within which magnetic resonance scanners are sensitive to radiofrequency signals,

wherein the controller is configured to determine a mechanical offset indicative of a starting position of a dead band interval and to control timing and application of speed modulation during the pumping cycle based on the output signals indicative of positions of the plurality of pumping elements of the linear peristaltic pump received from the encoder, and

wherein the speed modulation comprises use of multiple different speeds during a region of non-linear flow of the pumping cycle.

2. The apparatus of claim 1, wherein the ultrasonic motor is adapted to start and stop within a time range of 3 to 10 milliseconds.

3. The apparatus of claim 1, wherein the ultrasonic motor is adapted to start and stop within an angular displacement range of 0.3 to about 0.9 degrees of arc.

4. The apparatus of claim 1, wherein an output shaft of the ultrasonic motor is coupled to the main shaft of the linear peristaltic pump.

5. The apparatus of claim 1, further comprising an RF-shielded, non-magnetic housing configured to facilitate use of the apparatus within the magnetic resonance imaging scan room.

6. The apparatus of claim 1, wherein the linear peristaltic pump is formed of non-magnetic material.

7. The apparatus of claim 1, wherein the multiple different speeds comprise eight discrete speeds.

8. The apparatus of claim 1, wherein the volumetric flow is configured to be about 1 mL/hour.

9. A method of altering liquid flow characteristics of a linear peristaltic pumping apparatus to overcome inherent non-linearities in a rate of fluid flow over a pumping cycle thereof, the method comprising:

receiving signal information from an optical encoder comprising an optical encoder disk and an optical sensor, wherein the optical encoder disk comprises an index mark detectable by the optical sensor to identify an exact angular position of a main shaft of a linear peristaltic pumping apparatus and a plurality of graticule marks about a periphery of the optical encoder disk detectable by the optical sensor to provide fine indication of angular positioning of the main shaft relative to the index mark,

wherein the signal information is indicative of exact locations of a plurality of pump elements during a dead band interval of a pumping cycle so as to determine a mechanical offset indicative of a starting position of the dead band interval;

determining an amount of speed modulation and when to apply the speed modulation during the dead band interval of the pumping cycle based on the received signal information indicative of exact locations of the plurality of pump elements;

altering an operating speed of an ultrasonic motor of the linear peristaltic pumping apparatus during the dead band interval to modulate the speed of motion of the plurality of pump elements at multiple different speeds during the dead band interval, thereby substantially linearizing volumetric flow of liquid through the linear peristaltic pumping apparatus per unit increment of the pumping cycle based on said determining, wherein altering the operating speed of the ultrasonic motor comprises using a pair of coreless transformers to produce sinusoidal drive signals of low harmonic content in a range of 8 MHz to 130 MHZ within which magnetic resonance scanners are sensitive to radiofrequency signals to start and stop the ultrasonic motor.

10. The method of claim 9, further comprising causing the ultrasonic motor to start and stop within a time range of 3 to 10 milliseconds.

11. The method of claim 9, further comprising causing the ultrasonic motor to start and stop within an angular displacement range of 0.3 to about 0.9 degrees of arc.

12. The method of claim 9, wherein the plurality of different speeds comprises eight discrete speeds.

13. A liquid pumping apparatus configured for use in a magnetic resonance imaging (MRI) scan room, comprising:

a linear peristaltic pump operated by a motor coupled thereto;

an encoder installed along a main shaft of the linear peristaltic pump, the encoder being configured to output signals indicative of positions of a plurality of pumping elements of the linear peristaltic pump,

wherein the encoder comprises an optical encoder disk and an optical sensor,

wherein the optical encoder disk comprises an index mark detectable by the optical sensor to identify an exact angular position of the main shaft of the linear peristaltic pump and a plurality of graticule marks about a periphery of the optical encoder disk detectable by the optical sensor to provide fine indication of angular positioning of the main shaft relative to the index mark; and

a controller configured to apply drive signals to the motor to modulate speed of motion of the plurality of pumping elements at specific positions during a pumping cycle in response to the output signals received from the encoder to substantially linearize volumetric flow of liquid through the pump per revolution of the pumping cycle,

wherein the controller comprises a pair of coreless transformers configured to produce the drive signals, wherein the drive signals comprise substantially sinusoidal, high voltage drive signals of low harmonic content in a range of 8 MHz to 130 MHz within which magnetic resonance scanners are sensitive to radiofrequency signals,

wherein the controller is configured to determine a mechanical offset indicative of a starting position of a dead band interval and to control timing and application of speed modulation during the pumping cycle based on the output signals indicative of positions of the plurality of pumping elements of the linear peristaltic pump received from the encoder, and

wherein the speed modulation comprises use of multiple different speeds during the dead band interval of the pumping cycle.

14. The liquid pumping apparatus of claim 13, further comprising an RF-shielded, non-magnetic housing configured to facilitate use of the apparatus within the MRI scan room.