JP2013514839A - Circulating pressure monitoring using infusion pump - Google Patents

Abstract

A low cost mobile system is provided for monitoring central venous pressure of a patient receiving an infusion. The pressure monitoring system of the present invention utilizes a pump and a flow meter to deliver infusion fluid to the patient. Relative changes in the patient's venous pressure and / or quantitative pressure data are obtained based on control factors communicated to the pump by the controller and changes thereof to achieve and maintain the desired infusion fluid flow rate. . The pressure monitoring system of the present invention preferably utilizes a piezoelectric micropump and a flow meter for the inflow of fluid into the patient.

Description

(Cross-reference of related applications)
The present application is based on US provisional patent application 61 / 287,881 (named “MEMS Pump for Medical Infusion Pump”, filed December 18, 2009), US provisional patent application 61 / 287,903 (named “Pump Stay”). ", Filed December 18, 2009), US provisional patent application 61 / 287,912 (named" Micro Infusion Pump System Software ", filed December 18, 2009), and US provisional patent application 61/287. , 991 (named “Central Venous Pressure Monitoring Using Micro Infusion Pump”, filed December 18, 2009), the contents of each of which are hereby incorporated by reference in their entirety.

(Field of Invention)
The present invention relates to a circulating pressure monitoring system and related methods, and more particularly to a central venous pressure monitoring system that utilizes a piezoelectrically driven infusion pump.

  Information obtained from the patient's body during medical treatment is an important tool in assessing the patient's health. In particular, biological information from a patient can be used as an indicator of a disease or medical treatment status. Such information can generally only be obtained through the use of special medical equipment. However, such specialized medical devices are often costly and / or impractical for movement and use outside a hospital, clinic, or other medical location. Therefore, it is very difficult to obtain real-time biological information for patients receiving home care or care at another remote location. Inability to obtain real-time patient information in light of the trend toward increased use of home and other remote patient care models is a serious problem, and in some cases, the patient's It has been shown that it can contribute to the development of health conditions.

  Real-time central venous pressure is an example of biological information that can be critical to patient care. For example, central parenteral nutrition, which is a high-calorie infusion method, is widely practiced as a nutritional support method during postoperative recovery. In particular, in the case of surgery involving the circulatory system, more than 2000 cc of fluid is infused into the patient's body per day, so central venous pressure is generally monitored during the infusion. The patient's central venous pressure value serves, among other things, to indicate whether the patient's heart is under stress by relatively high volume injections. When high calorie infusion is performed, a double catheter (double lumen) or triple catheter (triple lumen) is often used. One of the lumens is used to introduce infusion fluid and the second lumen is used to measure central venous pressure. A pressure gauge operable to measure central venous pressure is very expensive. Therefore, such an instrument is not available for patients undergoing central parenteral nutrition as part of a home care model.

  What is needed in this field is a low-cost movable means for determining patient circulation pressure.

  The present invention provides a low-cost movable means for monitoring the central venous pressure of a patient receiving an infusion. The pressure monitoring system of the present invention preferably utilizes a piezoelectric micropump and a flow meter for the inflow of fluid into the patient. Relative changes in the patient's venous pressure and / or quantitative pressure data are obtained based on the control factors communicated to the micropump and changes to achieve and maintain the desired infusion fluid flow rate.

  These and other aspects, features, and advantages of which embodiments of the present invention are possible will become apparent and elucidated from the following description of embodiments of the invention with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of a pressure monitoring system according to an embodiment of the present invention. FIG. 2 is a schematic diagram of a pressure monitoring system according to an embodiment of the present invention.

  Next, specific embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are disclosed in this disclosure. Are provided so as to be detailed and complete and to fully convey the scope of the invention to those skilled in the art. The terms used in the detailed description of the embodiments illustrated in the accompanying drawings are not intended to be limiting of the invention. In the drawings, the same number indicates the same element.

  The present invention provides a low-cost, movable and highly accurate circulating pressure monitoring system that can be used in a hospital or clinic, but is also suitable for use during patient home care. In general, the present invention achieves these goals by utilizing an infusion pump to provide infusion fluid to a patient and closely monitoring infusion pump control factors to derive patient circulation pressure data.

  As shown in FIG. 1, the pressure monitoring system 10 according to one embodiment of the present invention includes an infusion pump 20, a flow meter 30, a controller 40, and a patient fluid line 50. Patient line 50 is in fluid communication with a patient vein 60 downstream of pump 20 and a fluid reservoir (not shown) upstream of pump 20.

  With respect to pump 20, it is contemplated that various types of infusion pumps can be utilized as pump 20, including peristaltic pumps, syringe pumps, and elastomeric pumps. In order to achieve maximum accuracy and convenience, the pump 20 is preferably a micro-electromechanical machine driven by the piezoelectric effect, ie a MEMS micro-pump. In short, such micropumps can be processed using well-known integrated circuit processing methods and techniques. For example, small channels can be formed on the surface of a silicon wafer using integrated circuit manufacturing processing techniques. By attaching a thin piece of material, such as glass, onto the surface of a treated silicon wafer, flow paths and fluid chambers can be formed from the channels and chambers. A layer of piezoelectric material, ie a piezoelectric material such as quartz, is then attached to the glass on the opposite side of the silicon wafer. When a voltage is applied to the piezoelectric body, an inverse piezoelectric effect, ie vibration, is generated by the piezoelectric body and transmitted through the glass and into the fluid in the chamber. A resonance is then generated in the fluid in the chamber of the silicon wafer. Through the inclusion of valves and other design features in the fluid flow path, a net directional flow of fluid through the chamber formed by the silicon wafer and the glass coating can be achieved. Examples of such pumps and associated control systems are described in more detail in assignee's co-pending US patent application (currently pending) “Infusion Pump” and (currently pending) “Patient Fluid Management System”. The contents of which are incorporated herein by reference in their entirety.

  The flow meter 30 may include various flow meters well known in the art. For example, the flow meter 30 may be configured to determine the fluid flow rate by utilizing a heater that heats the monitored fluid and senses the flow of the heated fluid downstream of the heater. Such flow meters are commercially available from Sensirion AG (Switzerland) and Siargo Incorporated (USA) and are more detailed at least by Mayer et al. US Pat. No. 6,813,944 and US Patent Application Publication No. 2009/0164163. And are incorporated herein by reference. Alternatively, the flow meter 34 may be configured to utilize two pressure sensors located on either side of the stenosis in the fluid flow path. The fluid flow rate is determined by the relative difference between the pressure sensors and its change.

  Although the flow meter 30 is shown in FIGS. 1 and 2 as being separate from the pump 20 and the controller 40, the flow meter 30 is physically incorporated into either the pump 20 or the controller 40, or both. It will be appreciated that The controller 40 is in electrical communication with the pump 20 and the flow meter 30 and provides power to each of these components, and any control or data feedback, eg, fluid flow generated by the pump 20 and flow meter 30. It fulfills the function of receiving data. Patient line 50 may comprise a variety of different tubing and catheter systems well known in the art.

  In operation, the pump 20 generates the infusion pressure shown in FIG. 1 by arrow P1, thereby overcoming the patient central venous pressure shown in FIG. A net fluid flow is generated inside. If the throughput of the pump 20 is kept constant and the patient venous pressure P2 remains constant, the infusion pressure P1 minus the patient venous pressure P2, ie, (P1-P2) also remains constant. Will. However, if the patient venous pressure P2 changes, the throughput of the pump 20, and thus the infusion pressure P1 generated by the pump 20, must be changed to maintain a constant fluid flow to the patient. In order to achieve the necessary changes in the throughput of the pump 20, the control factors for the pump 20 are changed. For example, such control factors include, but are not limited to, the voltage and / or frequency at which the voltage is provided to the pump 20 and the rate at which the voltage is increased and decreased. As a result, changes in patient venous pressure P2 are directly reflected in the control factors provided to pump 20 in order for pump 20 to generate or maintain the desired fluid flow to the patient. In other words, by monitoring changes in control factors for the pump 20, it is possible to monitor and determine information regarding the patient's central venous pressure.

  It will be appreciated that, according to the foregoing description, only the relative change in patient venous pressure P2 is determined. In order to determine the quantitative change in patient venous pressure P2, the change in control factor for pump 20 must be calibrated and correlated with the measured pressure value. However, once the control factor for the pump 20 is calibrated by the measured data, it is possible to derive the patient's venous pressure P2 based solely on the readily available control factor for the pump 20, ie, The patient venous pressure P2 can be determined without using expensive non-movable medical equipment such as a sphygmomanometer.

  Quantitative venous pressure data is derived by experimentally correlating specific control factors for the pump 20 with specific pressures such as central venous pressure over a functional range of control factors and pressures. The pressure monitoring system 10 of the present invention independently measures the central venous pressure of the patient and directly inputs the central venous pressure of the patient into the user interface 70 shown in FIG. It can be initially calibrated against the data.

  Alternatively, more accurate initial calibration can be achieved at least temporarily by combining a sphygmomanometer with the pressure monitoring system 10. For example, referring to FIG. 2, before the patient line 50 is connected to the patient, the system 10 removes the pump 20, flow meter 30 from the fluid reservoir 90 while the patient line 50 is in an open or unconstrained configuration. , And through the patient line 50, for example, by pumping infusion fluid such as total parenteral nutrition. When the infusion fluid is pumped through the pump 20, flow meter 30, and patient line 50, the user is present in the controller 40 via the user interface 70 that this unconstrained flow is in the zero back pressure state of the system 10. It represents representing a first calibration point. The patient line 50 is then placed in fluid communication with the patient vein 60. Simultaneously or substantially simultaneously, the sphygmomanometer 80 is placed in fluid communication with the patient line 50 downstream of the pump 20 and the flow meter 30. Infusion fluid pumping is initiated at the desired throughput, and the user indicates via the user interface 70 to the controller 40 that a second calibration point has been achieved. The control factors and pressures corresponding to the first and second calibration points are then correlated with the previously obtained experimentally acquired control factor / pressure data for a patient receiving infusion fluid from the pressure monitoring system 10 Deriving real-time pressure data.

  Once the pressure monitoring system 10 is calibrated as described above, the sphygmomanometer 80 can be removed from the system 10 and the healthcare provider relies on the pressure monitoring system 10 to determine the patient venous pressure P2. Can be provided. Thus, the patient can be transferred without sacrificing important patient information or without having to transfer the costly sphygmomanometer 80.

  The controller 40 is operable to analyze the measured flow data and compare it with the desired flow entered by the user. If desired, the controller 40 may determine the compensated or revised control factor and communicate to the pump 20 according to the changing condition, eg, the change in patient venous pressure P2 encountered during infusion. The controller 40 is also operable to communicate any of the aforementioned data to a remote location.

  For example, if a high calorie infusion is received by the patient at the patient's home, the controller communicates the flow rate and determined patient venous pressure data to the patient's health care provider's hospital or clinic for monitoring. Can be operated. If the controller 40 indicates to the health care provider that the patient's health is at risk and needs attention to the components of the infusion system, the health care provider will assess the situation quickly and if necessary It is possible to send assistance to patients. Thus, the present invention is operable to reduce or prevent serious patient illness.

  Although the present invention has been described in terms of particular embodiments and applications, those skilled in the art will recognize additional teachings in light of this teaching without departing from or exceeding the spirit of the claimed invention. Various embodiments and modifications can be provided. Therefore, it should be understood that the drawings and descriptions herein are proposed as examples for facilitating the understanding of the present invention and should not be construed as limiting the scope thereof.

Claims (19)

A method for monitoring patient circulation pressure, comprising:
The method
Generating a first infusion fluid pressure for delivery of the infusion fluid to the patient;
Generating a second infusion fluid pressure in response to the patient circulation pressure;
Determining patient circulation pressure data based on differences in control factors utilized to generate the first infusion fluid pressure and the second infusion fluid pressure.   The method of claim 1, wherein generating a first infusion fluid pressure for delivery of the infusion fluid to the patient comprises pumping the infusion fluid via a piezoelectrically driven pump.   The method of claim 1, wherein generating a first infusion fluid pressure for delivery of infusion fluid to a patient comprises determining an infusion fluid flow rate with a flow meter.   The method of claim 1, wherein generating a first infusion fluid pressure for delivery of an infusion fluid to a patient comprises generating a first infusion fluid pressure that exceeds the patient circulation pressure.   The method of claim 1, wherein generating the second infusion fluid pressure in response to the patient circulation pressure comprises determining the infusion fluid flow rate with a flow meter.   The method of claim 1, wherein generating a second infusion fluid pressure in response to the patient circulation pressure includes generating a second infusion fluid pressure that is greater than the patient circulation pressure.   The method of claim 1, wherein generating the second infusion fluid pressure in response to the patient circulation pressure comprises providing a control factor to the infusion pump.   The method of claim 7, wherein providing the control factor to the infusion pump comprises determining the control factor based on infusion fluid flow data received from the flow meter.   Determining patient circulation pressure data based on the difference in control factors utilized to generate the first infusion fluid pressure and the second infusion fluid pressure is to direct operation of the infusion pump. The method of claim 1, comprising analyzing the control factors utilized.   The method of claim 1, further comprising correlating specific control factors to different pressure ranges.   The method of claim 1, further comprising: specifying a control factor for the injection pressure to be equal to zero. A patient circulation pressure monitoring system,
The system
An infusion pump;
A flow meter in fluid communication with the infusion pump;
A controller in electrical communication with the infusion pump and the flow meter, the controller further comprising a data correlation between the infusion pump control factor and the circulation pressure.   The system of claim 13, wherein the infusion pump is a piezoelectric driven infusion pump.   The system of claim 13, wherein the control factor comprises a voltage.   The system of claim 13, wherein the control factor comprises a frequency. A method for monitoring patient circulation pressure, comprising:
The method
Providing a first control factor to the infusion pump;
Providing a second control factor to the infusion pump in response to patient circulation pressure;
Determining patient circulation pressure data based on the difference between the first and second control factors.   The method of claim 17, wherein providing the first control factor to the infusion pump comprises providing the first control factor to a piezoelectric driven infusion pump.   18. The method of claim 17, wherein providing a first control factor to an infusion pump includes instructing the infusion pump to generate an infusion fluid pressure that is greater than the patient circulation pressure.   18. In response to patient circulation pressure, providing the second control factor to the infusion pump includes directing the infusion pump to produce an infusion fluid pressure that is greater than the patient circulation pressure. The method described.

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