JP6390137B2 - Infusion pump - Google Patents

Description

  The present invention relates to an infusion pump, and more particularly, to an infusion pump that rotates a roller with frictional force with a motor shaft and presses a tube to deliver a medicine or a chemical solution.

  In general, infusion pumps that deliver pharmaceuticals and chemicals are equipped with a drop number detector to monitor the administration status, but portable infusion pumps are not easy to detect due to loss of portability or vibration. It is not possible to equip such a drop detector.

  The portable infusion pump injects the drug solution in the tube into the patient's body by crushing the flexible tube in order from the upstream side to the downstream side with a plurality of rollers that rotate by rubbing against the motor shaft. (See, for example, Patent Document 1).

JP 2012-2158 A

  In a portable infusion pump, if the force of the roller squeezing the tube exceeds the frictional force between the motor shaft and the roller, the motor shaft will slip and the roller will not be able to rotate, and the chemical solution in the tube cannot be delivered. An event occurs. When a motor shaft slip occurs, a load is applied to the motor and the motor current increases. Conventionally, the motor shaft slip is detected by monitoring the upper limit value of the motor current. However, this detection method has a problem that even if slip actually occurs, slip cannot be detected unless the motor current reaches the upper limit value.

  In view of the above problems, the present invention reliably detects that the motor shaft is slipping in an infusion pump that rotates a roller by frictional force with the motor shaft and presses the tube to deliver medicines or chemicals. The challenge is to make it possible.

In an infusion pump according to one aspect of the present invention, a plurality of rollers provided in a cassette are rotated along an inner peripheral surface of an arc-shaped wall of the cassette, and are provided on an inner peripheral surface of the arc-shaped wall. An infusion pump that squeezes the flexible tube with the plurality of rollers and feeds the liquid in the tube, and is driven by a motor and is rotated by the motor. A motor shaft that contacts and rotates the plurality of rollers; a pressure sensor that detects a blockage pressure of the tube; and a control unit that controls driving of the motor, the control unit performing drive control of the motor In addition, when it is detected that the detection signal of the pressure sensor does not change for a predetermined period, it is detected that the motor shaft and the plurality of rollers are slipping without the plurality of rollers rotating.

  According to this, if the roller rotates due to friction with the motor shaft, the detection signal of the pressure sensor fluctuates accordingly, and if the motor shaft slips and the roller does not rotate, the detection signal of the pressure sensor does not fluctuate. Therefore, it is possible to reliably detect the slip of the motor shaft based on the detection signal of the pressure sensor.

  The control unit can calculate an average value of the detection signals of the pressure sensor in a predetermined period and detect that the detection signal of the pressure sensor does not vary based on the average value. Thereby, it can be easily detected that the detection signal of the pressure sensor does not fluctuate.

  Alternatively, the control unit may calculate an appearance interval of a peak value of the detection signal of the pressure sensor in a predetermined period, and detect that the detection signal of the pressure sensor does not vary based on the appearance interval. Thereby, the presence or absence of the fluctuation | variation of the detection signal of the said pressure sensor can be detected reliably.

  As the pressure sensor, an upstream pressure sensor that detects a blocking pressure of the tube on the upstream side of the cassette can be used. The detection signal (voltage change) when the motor shaft slips is the same value on both the upstream and downstream sides, but the detection signal (voltage fluctuation) of the downstream pressure sensor is the same ( Since the voltage is larger than the detection signal of the lower upstream pressure sensor (blocking), the upstream pressure sensor having a small voltage fluctuation during blocking is more advantageous for detection during slipping.

  Or the downstream pressure sensor which detects the obstruction | occlusion pressure of the said tube of the downstream of the said cassette can be used as the said pressure sensor. Some infusion pumps are not equipped with an upstream sensor, and such an infusion pump can detect slippage of a motor shaft based on a detection signal of a downstream pressure sensor.

  According to the present invention, it is possible to reliably detect that the motor shaft is slipping in an infusion pump that rotates a roller by frictional force with the motor shaft and presses the tube to feed a medicine or a drug solution. . Thereby, without adding a new mechanism to the infusion pump, slippage of the motor shaft can be detected by a simple method to notify the patient of the administration abnormality.

It is a perspective view which shows the external appearance of the infusion pump which concerns on one Embodiment of this invention. It is a top view which shows the cassette with which an infusion pump is mounted | worn. It is front sectional drawing which shows the internal structure of the sensor block of an infusion pump. It is a block diagram which shows an example of the electric control system of an infusion pump. It is a graph which shows the example of a change of the detection signal of the pressure sensor before and behind slip generation. (A) is a measured waveform diagram of the detection signal of the upstream pressure sensor during normal operation, and (B) is a measured waveform diagram of the detection signal of the upstream pressure sensor when slip occurs. It is a flowchart which shows an example of operation | movement of an infusion pump. It is a flowchart which shows another example of operation | movement of an infusion pump.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In addition, this invention is not limited to the following embodiment.

  FIG. 1 is a perspective view showing an appearance of an infusion pump according to an embodiment of the present invention. The infusion pump 10 according to the present embodiment is used for administering a medical solution in an infusion set (not shown) to a patient. The infusion pump 10 is a small portable device that incorporates a battery (not shown) and can operate without an external power source.

  A display device 1 is arranged at the center of the upper surface of the main body of the infusion pump 10, and various operation buttons 2 are arranged around it. The operation buttons 2 include a power button, a start / stop button, a selection button, and the like. The display device 1 displays the operating state of the infusion pump 10 and the drug solution administration conditions. The display device 1 is composed of, for example, a color liquid crystal device.

  An operation indicator lamp 3 is disposed in the back of the infusion pump 10. During the operation of the infusion pump 10, the operation indicator lamp 3 is lit or blinked in green, for example, to inform the patient that the drug solution is being introduced. Further, when an abnormality occurs during the operation of the infusion pump 10, the operation indicator lamp 3 is lit or blinked in red, for example, to notify the patient of the abnormality.

  On the right side of the main body of the infusion pump 10, a cassette base 4 on which a cassette described later is mounted is disposed. A motor shaft 5 of a motor (not shown) built in the infusion pump 10 protrudes at the center position of the cassette base 4. Around the motor shaft 5, a circular plate 41 in which the motor shaft 5 portion is perforated is disposed. The plate 41 is slidable in the vertical direction along the motor shaft 5 in a state where the motor shaft 5 is inserted, and is urged upward by a spring (not shown).

  An eject button 6 and a lock lever 7 are disposed in the back of the cassette base 4. The eject button 6 is a button to be pushed when removing the cassette mounted on the cassette base 4. However, for example, in order to prevent the eject button 6 from being unintentionally operated during the operation of the infusion pump 10 to remove the cassette from the cassette base 4, the pushing operation of the eject button 6 is locked by the lock lever 7. Yes.

  A sensor block 8 in which various sensors described later are embedded is disposed in front of the cassette table 4. The sensor block 8 is formed with two grooves on the left and right sides, and the upstream side of the tube passed through the cassette is inserted into the left side groove and the downstream side is inserted into the right side groove.

  A stopper 9 is disposed in front of the sensor block 8. The stopper 9 has an interlock mechanism, and holds the lower end of the cassette in a state where the cassette is mounted on the cassette base 4 and the tube is correctly inserted into each groove of the sensor block 8.

  FIG. 2 is a plan view showing a cassette mounted on the infusion pump 10. The cassette 100 is one of the components of the infusion set described above. The cassette 100 includes a circular bottom plate 101 at the bottom. A hole 102 through which the motor shaft 5 can be inserted is formed in the center of the bottom plate 101.

  An arc-shaped wall 103 is provided along the outer periphery of the bottom plate 101, and a flexible tube 200 is provided on the inner peripheral surface of the arc-shaped wall 103. Further, three rollers 104 are provided in the cassette 100 so as to crush the tube 200. These three rollers 104 are arranged such that when the motor shaft 5 is inserted from the back surface of the bottom plate 101, the outer peripheral surface contacts the motor shaft 5 with a certain degree of frictional force.

  When the cassette 100 is attached to the infusion pump 10, the hook-shaped protrusion formed on the bottom surface of the cassette 100 is inserted into the groove formed on the plate 41 of the cassette base 4, and the cassette 100 is pushed downward. When the cassette 100 is pushed to a predetermined position, the cassette 100 is held on the cassette base 4 by a latch mechanism (not shown). In a state where the cassette 100 is mounted on the infusion pump 10, the motor shaft 5 contacts the outer peripheral surface of the three rollers 104, and the upstream and downstream sides of the tube 200 are correctly inserted into the left and right grooves of the sensor block 8. .

  When the motor is rotated while the cassette 100 is mounted on the infusion pump 10, the motor shaft 5 rotates clockwise as viewed from the upper surface of the infusion pump 10. As the motor shaft 5 rotates, the three rollers 104 that come into contact with the motor shaft 5 rotate counterclockwise (arrow 110 in FIG. 2) counterclockwise to the motor shaft 5 due to frictional force. It revolves in the clockwise direction (arrow 120 in FIG. 2), that is, rotates along the inner peripheral surface of the arc-shaped wall 103. As a result, the tube 200 provided around the inner peripheral surface of the arc-shaped wall 103 is crushed by the three rollers 104, and the chemical solution in the tube 200 is fed from the upstream side toward the downstream side. .

  When removing the cassette 100 from the infusion pump 10, the interlock of the stopper 9 is released, the lock lever 7 is slid to release the lock of the eject button 6, and the eject button 6 is pushed in. Thereby, the cassette stand 4 pushes the cassette 100 upward, and the cassette 100 can be detached from the cassette stand 4.

  Next, the configuration of the sensor block 8 will be described. FIG. 3 is a front sectional view showing the internal structure of the sensor block 8. The sensor block 8 includes an upstream pressure sensor 81, a downstream pressure sensor 82, and a bubble sensor 83.

  The upstream pressure sensor 81 is disposed in the left groove of the sensor block 8. When the cassette 100 is mounted on the infusion pump 10, the tube 200 inserted through the left groove of the sensor block 8, that is, the cassette 100. The occlusion pressure of the tube 200 on the upstream side is detected. Specifically, the upstream pressure sensor 81 includes a plate-shaped load sensor 811 and a contact portion 812. The base end of the load sensor 811 is inserted into the slide base 84a. The slide base 84a is fixed to the frame 85. The contact portion 812 is attached to the tip of the load sensor 811 and is disposed so as to protrude from the left side opening of the left groove of the sensor block 8 and to contact the tube 200. When the blockage pressure of the tube 200 is changed and the diameter of the tube 200 is changed, the contact portion 812 is displaced, and the load sensor 811 is distorted. The load sensor 811 detects the strain and outputs a detection signal.

  When there is no longer any chemical solution to be delivered during the operation of the infusion pump 10 or when the tube 200 is broken and the chemical solution cannot be delivered, the tube 200 on the upstream side of the cassette 100 is in a decompressed state, and the diameter of the tube 200 is reduced. Shrinks. The upstream pressure sensor 81 detects such a reduction in the diameter of the tube 200. Note that when the detection signal of the upstream pressure sensor 81 changes in the negative direction (the direction in which the diameter of the tube 200 decreases) and falls below the threshold value, the end of the drug solution administration is determined.

  The downstream pressure sensor 82 is disposed in the groove on the right side of the sensor block 8. When the cassette 100 is attached to the infusion pump 10, the tube 200 inserted into the groove on the right side of the sensor block 8, that is, the cassette 100. The occlusion pressure of the tube 200 on the downstream side is detected. Specifically, the downstream pressure sensor 82 includes a plate-shaped load sensor 821 and a contact portion 822. The base end of the load sensor 821 is inserted into the slide base 84b. The slide base 84b is fixed to the frame 85. The contact portion 822 is attached to the tip of the load sensor 821 and is disposed so as to protrude from the right side opening of the right groove of the sensor block 8 and contact the tube 200. When the occlusion pressure of the tube 200 changes and the diameter of the tube 200 changes, the contact portion 822 is displaced and strain is generated in the load sensor 821. The load sensor 821 detects the strain and outputs a detection signal.

  When a blockage occurs downstream of the cassette 100 during the operation of the infusion pump 10, the tube 200 on the downstream side of the cassette 100 is in a pressure increasing state, and the diameter of the tube 200 is expanded. The downstream pressure sensor 82 detects such an expansion of the diameter of the tube 200. In addition, when the detection signal of the downstream pressure sensor 82 changes in the positive direction (the direction in which the diameter of the tube 200 expands) and exceeds the threshold value, the occurrence of blockage is determined.

  The bubble sensor 83 is disposed in the right groove of the sensor block 8, and in a state where the cassette 100 is attached to the infusion pump 10, the tube 200 inserted through the right groove of the sensor block 8, that is, downstream of the cassette 100. Air bubbles in the side tube 200 are detected. Specifically, the bubble sensor 83 includes a transmission unit 831 and a reception unit 832. The transmitter 831 is disposed in the right side opening of the right groove of the sensor block 8. The receiving unit 832 is supported by the subframe 86 fixed to the frame 85 and is disposed in the left side opening of the right groove of the sensor block 8. That is, the transmission unit 831 and the reception unit 832 are disposed on both sides of the tube 200 inserted through the right groove of the sensor block 8. The transmission unit 831 outputs sound waves. The receiving unit 832 receives a sound wave transmitted through the tube 200 and detects bubbles in the tube 200 according to the strength of the received sound wave.

  Next, the electric control system of the infusion pump 10 will be described. FIG. 4 is a block diagram illustrating an example of an electric control system of the infusion pump 10.

  The infusion pump 10 includes a control unit 50. The control unit 50 includes a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and the like (not shown). Detection signals from various sensors such as an upstream pressure sensor 81, a downstream pressure sensor 82, a bubble sensor 83, a lock detection sensor 51, and a motor rotation detection sensor 52 are input to the control unit 50. The lock detection sensor 51 is a sensor that detects that the eject button 6 is locked by the lock lever 7. The motor rotation detection sensor 52 is a sensor that detects the number of rotations and the direction of rotation of the motor 53 that rotationally drives the motor shaft 5. Specifically, a rotation detection plate (not shown) is attached to the motor shaft 5, and the rotation detection plate rotates with the rotation of the motor shaft 5. The motor rotation detection sensor 52 detects the rotation speed and rotation direction of the motor 53 by detecting the rotation of the rotation detection plate.

  The control unit 50 also receives signals from various operation buttons 2 such as a power button, a start / stop button, and a selection button. The control unit 50 receives the signals from these sensors and operation buttons, controls the drive of the motor 53, displays various types on the display device 1, and controls the operation indicator lamp 3 to turn on or blink. Further, the control unit 50 displays various indications on the display device 1 and the operation indicator lamp 3 and emits an alarm sound from the speaker 54 when the end of drug administration, occurrence of blockage, generation of bubbles, or the like is detected.

  One important function of the control unit 50 is a slip detection function of the motor shaft 5. The slip of the motor shaft 5 occurs when the force that the roller 104 of the cassette 100 tries to rotate by squeezing the tube 200 exceeds the frictional force between the motor shaft 5 and the outer peripheral surface of the roller 104. When slip of the motor shaft 5 occurs, the roller 104 does not rotate even though the motor shaft 5 rotates, and the chemical solution in the tube 200 cannot be fed. Therefore, when slip occurs in the motor shaft 5, a characteristic change is seen in the detection signal of the pressure sensor (the upstream pressure sensor 81 or the downstream pressure sensor 82).

  FIG. 5 is a graph showing an example of change in the detection signal of the pressure sensor before and after the occurrence of slip. The pressure sensor is the upstream pressure sensor 81 or the downstream pressure sensor 82. As shown in FIG. 5, when the motor shaft 5 is not slipping, the three rollers 104 rotate and the crushing portion of the tube 200 moves. Therefore, the detection signal of the pressure sensor corresponds to the rotation of the roller 104. It fluctuates periodically. In addition, the broken line in a figure has shown the fluctuation period of the detection signal. On the other hand, when the motor shaft 5 is slipping, the three rollers 104 are stopped and cannot move while the same portion of the tube 200 is crushed, so that the detection signal of the pressure sensor does not change.

  FIG. 6A is an actually measured waveform diagram of the detection signal of the upstream pressure sensor 81 during normal operation. FIG. 6B is an actually measured waveform diagram of the detection signal of the upstream pressure sensor 81 when a slip occurs. In both waveform diagrams, the upper graph represents the detection signal of the upstream pressure sensor 81, and the lower graph represents the drive signal of the motor 53. As shown in FIG. 6A, when the motor 53 rotates and the roller 104 also rotates, the detection signal of the upstream pressure sensor 81 varies. On the other hand, since the roller 104 also stops when the motor 53 stops, the detection signal of the upstream pressure sensor 81 does not fluctuate. On the other hand, as shown in FIG. 6B, when the motor shaft 5 is slipping, the roller 104 is stopped both when the motor 53 is rotating and when it is stopped. The detection signal of the pressure sensor 81 does not fluctuate.

  From the characteristics of the detection signal of the pressure sensor as described above, the control unit 50 detects the slip of the motor shaft 5 based on the detection signal of the upstream pressure sensor 81 or the downstream pressure sensor 82. Therefore, the slip that could not be detected by the conventional detection method based on the motor current can be detected by the detection method based on the detection signal of the pressure sensor as in this embodiment.

  Next, the operation of the infusion pump 10 will be described. FIG. 7 is a flowchart showing an example of the operation of the infusion pump 10.

  When the power of the infusion pump 10 is turned on, the control unit 50 determines whether or not the cassette 100 is attached to the infusion pump 10 (S1). Whether or not the cassette 100 is mounted can be determined from, for example, a voltage change in a detection signal of the downstream pressure sensor 82.

  If it determines with the cassette 100 having been mounted | worn with the infusion pump 10 (it is YES at S1), the control part 50 will calibrate (calibrate) various sensors (S2). Various sensors have manufacturing variations, mounting variations, temperature variations, and the like, and there is an offset in the detection signal, but the offset is canceled by performing a calibration process.

  When the patient (user) attaches the cassette 100 to the infusion pump 10, after setting the administration speed, administration time, etc., the patient (user) operates the start button (operation button 2).

  The control unit 50 receives the signal from the start button (operation button 2), starts to rotate the motor 53, and starts to administer the drug solution to the patient (YES in S3).

  During the rotation drive of the motor 53, the control unit 50 calculates the average value of the detection signal of the pressure sensor (upstream pressure sensor 81 or downstream pressure sensor 82) in a predetermined period (S4a).

  And the control part 50 compares the calculated average value with a threshold value, and if an average value is larger than a threshold value (it is NO at S5a), it will calculate the average value of the detection signal of a pressure sensor continuously. The average value of the detection signals of the pressure sensor is larger than the threshold value because the detection signal of the pressure sensor is considered to fluctuate as shown in FIG. On the other hand, if the average value is smaller than the threshold value (YES in S5a), the control unit 50 detects the slip of the motor shaft 5 and issues a warning of administration abnormality to the display device 1, the operation indicator lamp 3, and the speaker 54 ( S6). The reason that the average value of the detection signals of the pressure sensor is smaller than the threshold value is that the detection signal of the pressure sensor is considered to be almost zero without fluctuation as shown in FIG.

  The predetermined period for calculating the average value may be changed according to the rotation speed of the motor 53. For example, when the rotation speed of the motor 53 is fast, the predetermined period may be set short.

  FIG. 8 is a flowchart showing another example of the operation of the infusion pump 10.

  When the power of the infusion pump 10 is turned on, the control unit 50 determines whether or not the cassette 100 is attached to the infusion pump 10 (S1). Whether or not the cassette 100 is mounted can be determined from, for example, a voltage change in a detection signal of the downstream pressure sensor 82.

  If it determines with the cassette 100 having been mounted | worn with the infusion pump 10 (it is YES at S1), the control part 50 will calibrate (calibrate) various sensors (S2). Various sensors have manufacturing variations, mounting variations, temperature variations, and the like, and there is an offset in the detection signal, but the offset is canceled by performing a calibration process.

  When the patient (user) attaches the cassette 100 to the infusion pump 10, after setting the administration speed, administration time, etc., the patient (user) operates the start button (operation button 2).

  The control unit 50 receives the signal from the start button (operation button 2), starts to rotate the motor 53, and starts to administer the drug solution to the patient (YES in S3).

  During the rotation drive of the motor 53, the control unit 50 calculates the interval of the peak value of the detection signal of the pressure sensor (upstream pressure sensor 81 or downstream pressure sensor 82) in a predetermined period (S4b).

  Then, the control unit 50 compares the calculated peak value interval with the threshold value, and if the peak value interval is smaller than the threshold value (NO in S5b), the control unit 50 continues to calculate the average value of the detection signals of the pressure sensor. The reason why the interval between the peak values of the detection signals of the pressure sensor is smaller than the threshold value is that the detection signal of the pressure sensor is considered to fluctuate as shown in FIG. On the other hand, if the interval between the peak values is larger than the threshold value (YES in S5b), the control unit 50 detects the slip of the motor shaft 5, and gives an alarm of administration abnormality to the display device 1, the operation indicator lamp 3, and the speaker 54. (S6). The reason why the interval between the peak values of the detection signals of the pressure sensor is larger than the threshold value is that the detection signal of the pressure sensor is considered not to fluctuate periodically as shown in FIG.

  The predetermined period for calculating the peak value interval may be changed according to the rotational speed of the motor 53. For example, when the rotation speed of the motor 53 is fast, the predetermined period may be set short.

  As described above, according to the present embodiment, the slip detection of the motor shaft 5 is performed based on the detection signal of the pressure sensor (the upstream pressure sensor 81 or the downstream sensor 82). Can be detected. Thereby, without adding a new mechanism to the infusion pump 10, it is possible to detect a slip of the motor shaft 5 by a simple method and notify the patient of the administration abnormality.

  Since the detection signal of the upstream pressure sensor 81 is easier to detect periodic fluctuations accompanying the rotation of the roller 104 than the detection signal of the downstream pressure sensor 82, as in the infusion pump 10 according to the present embodiment. When pressure sensors are mounted on both the upstream side and the downstream side of the cassette 100, it is preferable to detect slip of the motor shaft 5 based on the detection signal of the upstream pressure sensor 81. On the other hand, in an infusion pump in which a pressure sensor that detects the blockage pressure of the tube 200 is mounted only on the downstream side of the cassette 100, the slip detection of the motor shaft may be performed based on the detection signal of the downstream pressure sensor. Is possible.

  Although the embodiment of the present invention has been described above, the present invention is not limited to the configuration of the above embodiment, and various modifications can be made. The configuration and processing shown in the above embodiment with reference to FIGS. 1 to 8 are only one embodiment of the present invention, and are not intended to limit the present invention to the configuration and processing.

  The infusion pump according to the present invention is particularly effective for a portable infusion pump because it can reliably detect a slip between a roller for squeezing a tube and a motor shaft.

10 Infusion pump 50 Control unit 53 Motor 5 Motor shaft 81 Upstream pressure sensor (pressure sensor)
82 Downstream pressure sensor (pressure sensor)
100 cassette 104 roller 103 arcuate wall 200 tube

Claims (5)

A plurality of rollers provided in the cassette are rotated along an inner peripheral surface of the arc-shaped wall of the cassette, and a flexible tube provided on the inner peripheral surface of the arc-shaped wall is moved to the plurality of rollers. An infusion pump for squeezing with a roller to deliver the liquid in the tube;
A motor,
A motor shaft that is rotationally driven by the motor and rotates the plurality of rollers in contact with the outer peripheral surfaces of the plurality of rollers;
A pressure sensor for detecting the blocking pressure of the tube;
A control unit for driving and controlling the motor,
When the control unit detects that the detection signal of the pressure sensor does not change for a predetermined period during the drive control of the motor, the motor shaft and the plurality of rollers slip without the plurality of rollers rotating. An infusion pump characterized by detecting that   2. The infusion pump according to claim 1, wherein the control unit calculates an average value of the detection signals of the pressure sensor in a predetermined period and detects that the detection signal of the pressure sensor does not vary based on the average value. .   The said control part calculates the appearance interval of the peak value of the detection signal of the said pressure sensor in a predetermined period, and detects that the detection signal of the said pressure sensor does not change based on the said appearance interval. Infusion pump.   The infusion pump according to any one of claims 1 to 3, wherein the pressure sensor is an upstream pressure sensor that detects a blocking pressure of the tube on the upstream side of the cassette.   The infusion pump according to any one of claims 1 to 3, wherein the pressure sensor is a downstream pressure sensor that detects a blocking pressure of the tube on the downstream side of the cassette.