Thermodilution injection fluid measurement and control

Abstract

This application relates to thermodilution injection fluid measurement and control. Apparatus and methods for measuring, controlling (or both) the thermodilution injection fluid flow rate used to calculate a thermodilution pulmonary parameter. An injection fluid delivery system includes a syringe for containing injection fluid and a delivery tube configured at one end to connect to a catheter. A flow measurement device is inserted into the delivery tube to generate a signal used to determine the flow rate of fluid from the syringe to the catheter. A processor receives the signal from the flow measurement device and calculates the injection fluid volume to be used as an input for calculating a thermodilution pulmonary parameter such as cardiac output. A GUI is provided to guide the user as to whether the injection rate is too fast or too slow. The system can include a constant flow valve to provide a constant flow rate from the syringe rather than measuring or calculating the flow rate.

Description

[0001] This application is a divisional application. The application date of the original application is October 21, 2015, the application number is 201580084984.9, and the name of the invention is “Measurement and Control of Thermodilution Injection”. Technical Field

[0002] Aspects of the present disclosure generally relate to apparatus and methods for the measurement, control, or both, of fluids expelled from syringes or other containers, and may particularly relate to the accuracy of measured or calculated transpulmonary thermodilution parameters. Background Art

[0003] The most widely used technique for determining cardiac output is thermodilution. Thermodilution uses the principle of indicator dilution—using temperature changes as an indicator.

[0004] A known amount of a solution with a known temperature is rapidly injected into the right atrial cavity of the first catheter. This cooler solution mixes with and cools the surrounding blood, and the temperature of the pulmonary artery downstream is measured by a thermistor bead embedded in the second catheter. The resulting temperature change is then plotted on a time-temperature curve. This curve is similar to the curve produced by the indicator dilution method.

[0005] Since the rapid injection of the injectate, the normal curve characteristically shows a sharp rise. This is followed by a smooth curve and a slightly extended downslope back to the baseline. Since the curve represents a change from a warmer temperature to a cooler temperature and then back to a warmer temperature, the actual curve is in the opposite direction. In many illustrative and display figures, the curve is generated in an upright manner so that the area under the curve is inversely proportional to cardiac output.

[0006] When cardiac output is low, it takes more time for the temperature to return to baseline, resulting in a larger area under the curve. With high cardiac output, the cooler injectate is transported through the heart more quickly, and the temperature returns to baseline more quickly. This results in a smaller area under the curve.

[0007] The key to this technique is the injectate temperature, volume, and flow rate. However, because the injection speed varies between users performing the procedure, the actual volume and solution temperature of the injectate or cold bolus injected may vary greatly, losing the accuracy and precision of cardiac output measurement. Some users apply great force to the syringe to inject the bolus as quickly as possible, while other users inject at a slower rate. Users may make mistakes when injecting the bolus, including injecting a volume that is different from the amount that enters the monitoring device and on which the calculation is based. Summary of the Invention

[0008] According to one embodiment of the concept disclosed herein, an injection delivery system is provided. The system includes a container for accommodating a fluid injection, a delivery tube connected to a catheter configured at one end with the container fluid, and a manually or mechanically driven syringe, another form of injection device, or other devices for manually discharging fluid from the container to the delivery tube. A flow measurement device is inserted into the delivery tube, and the flow measurement device is configured to generate a signal used in determining the flow rate of the fluid from the container to the catheter. The processing unit is suitable for receiving the signal from the flow measurement device and is configured to calculate the injection volume to be used as an input for calculating at least one parameter. In some embodiments, at least one parameter to be calculated is a transpulmonary thermodilution parameter, and in some such embodiments, the transpulmonary thermodilution parameter is at least one of cardiac output, global end diastolic volume, and extravascular lung water.

[0009] In some embodiments and in combination with any of the above embodiments, the container is a syringe and the means for manually expelling the fluid is a plunger of the syringe. In some such embodiments, the system further comprises a catheter in fluid communication with the container, and in some of these embodiments, the catheter is manufactured and sold by Edwards Lifesciences. catheter.

[0010] In some embodiments and in combination with any of the above embodiments, the flow measurement device is configured to generate a signal to the processing device based on the pressure differential. In some embodiments and in combination with any of the above embodiments, the flow measurement device includes a pressure sensor for measuring the pressure drop across the orifice. In some embodiments and in combination with any of the above embodiments, the flow measurement device defines an area of ​​contracting flow and includes a pressure sensor for measuring vortex differential pressure. In some embodiments and in combination with any of the above embodiments, the flow measurement device includes a Venturi tube. In some embodiments and in combination with any of the above embodiments, the flow measurement device includes a pitot tube. In some embodiments and in combination with any of the above embodiments, the flow measurement device includes a hot wire anemometer.

[0011] In some embodiments and in combination with any of the above embodiments, a sensor inserted in the delivery tube is configured to detect changes in pressure or temperature of the injection fluid and signal a timer to start at the beginning of the injection and stop at the end of the injection to measure the elapsed time of the injection.

[0012] According to another embodiment of the concepts disclosed herein, a method for determining the volume of an injectate used in determining a transpulmonary thermodilution parameter is provided. The method includes starting a timer by a processor upon receiving a signal indicating an increase in pressure at a pressure sensor, the signal indicating the start of injection of a fluid injectate from a syringe into a delivery tube. The processor receives a signal from a flow measurement device inserted into the delivery tube. The processor calculates the flow rate of the injectate. The timer is stopped to determine the elapsed time of the injection, and the processor calculates the volume of the injectate injected. The calculated volume is used to calculate at least one transpulmonary thermodilution parameter.

[0013] In some embodiments and in combination with the above embodiments, the transpulmonary thermodilution parameter is at least one of cardiac output, global end-diastolic volume, and extravascular lung water. In some embodiments and in combination with any of the above embodiments, the method further comprises graphically displaying the current flow rate of the infusate. In some such embodiments, the method further comprises graphically displaying a predetermined minimum flow rate and a predetermined maximum flow rate, the predetermined minimum flow rate and the predetermined maximum flow rate defining limits within which the current flow rate is expected to occur.

[0014] According to another embodiment of the concepts disclosed herein, an injection delivery system is provided. The injection delivery system includes a container for holding a fluid injection, a delivery tube in fluid communication with the container and configured at one end to be connected to a catheter, and a syringe, an injection device, or another device for manually expelling the fluid injection from the container into the delivery tube during injection. A constant flow control element is fluidically inserted into the delivery tube, and the constant flow control element is configured to maintain a substantially constant design flow rate during injection as the fluid flows from the container to the catheter. A sensor is inserted into the delivery tube, configured to detect changes in the pressure or temperature of the injection fluid and signal a timer to start at the beginning of the injection and stop at the end of the injection. A processing device is adapted to receive the signal from the sensor, wherein the processing device is configured to calculate the volume of the injection fluid based on the constant flow valve design flow rate and a measured elapsed injection time. The volume is used as input to calculate at least one parameter. In some such embodiments, the at least one parameter to be calculated is a transpulmonary thermodilution parameter including at least one of cardiac output, global end-diastolic volume, and extravascular lung water.

[0015] In some embodiments and in combination with any of the above embodiments, the container comprises a syringe, and the constant flow control element comprises a constant flow valve fluidly inserted into the delivery tube. In other embodiments and in combination with any of the above embodiments, the container comprises a syringe, and the syringe comprises the constant flow control element as an integral component of the syringe.

[0016] According to another embodiment of the concepts disclosed herein, a method for displaying relative flow rates in an infusion delivery system is provided. The method includes calculating, by a processor, the flow rate of a fluid injected into a delivery tube for a thermodilution procedure using parameters measured by a flow measurement device. The processor graphically displays on a display device a predetermined minimum acceptable flow rate, a predetermined maximum acceptable flow rate, and an indication of the current flow rate relative to the minimum and maximum acceptable flow rates.

[0017] According to another embodiment of the concepts disclosed herein, a system for displaying relative flow rates in an infusion delivery system is provided. The system includes a display device, a processor operably connected to the display device, and a memory. The memory is operably connected to the processor to store a predetermined minimum acceptable flow rate and a predetermined maximum acceptable flow rate, and is further operably connected to store computer program code that, when executed, causes the processor to calculate the flow rate of a fluid injected into a delivery tube for a thermodilution procedure using parameters measured by a flow measurement device, and to graphically present on the display device the predetermined minimum acceptable flow rate, the predetermined maximum acceptable flow rate, and an indication of the current flow rate relative to the minimum and maximum acceptable flow rates.

[0018] According to another embodiment of the concepts disclosed herein, an apparatus for displaying relative flow rates of an infusion fluid delivery system is provided. The apparatus includes means for storing a predetermined minimum acceptable flow rate and a predetermined maximum acceptable flow rate, means for calculating the flow rate of a fluid injected into a delivery tube for a thermodilution procedure using parameters measured by a flow measurement device, and means for graphically displaying the predetermined minimum acceptable flow rate, the predetermined maximum acceptable flow rate, and an indication of the current flow rate relative to the minimum and maximum acceptable flow rates. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] For a more complete understanding, reference should now be made to the embodiments illustrated in the accompanying drawings and described below. In the drawings;

[0020] Figure 1 is a perspective view of a prior art injection delivery system.

[0021] Figure 2 is a schematic diagram of an injection delivery system according to an example embodiment of the present invention.

[0022] Figure 3 is a flow chart illustrating a process that may be performed by an example embodiment of the present invention.

[0023] Figure 4 It is for Figure 2 Screen shot of a screen of a display device of a portion of the system. Such a screen may be produced by an embodiment of the present invention.

[0024] Figure 5 is a block diagram of a system according to an example embodiment of the present invention.

[0025] Figure 6 is a schematic diagram of another injection delivery system according to an example embodiment of the present invention.

[0026] Figure 7-9 is a graph representing the effect of incorrect injectate volume being injected or recorded on transpulmonary thermodilution parameters. DETAILED DESCRIPTION

[0027] The following detailed description of the embodiments refers to the accompanying drawings, which illustrate specific embodiments. Other embodiments having different structures and operations do not depart from the scope of the present disclosure.

[0028] Embodiments of the concepts disclosed herein relate to apparatus and methods for measuring, controlling, or both, characteristics of an injected bolus. Characteristics may include, for example, pressure, temperature, and flow rate, and although the disclosed apparatus and methods may be applied to automated devices such as syringe pumps, they are discussed herein with respect to manually operated syringes and containers. Additionally, real-time feedback may be provided to the user to help reduce variability in injection technique and reduce the likelihood of user error when entering data into a monitoring device.

[0029] As will be appreciated by those skilled in the art, the present invention may be embodied as a method, apparatus, article of manufacture, system, computer program product, or any combination thereof. Any suitable computer-usable or computer-readable medium may be used in a computer program product including non-transitory computer program code to implement all or part of the embodiments of the present invention. The computer-usable or computer-readable medium may be, for example, but not limited to, a tangible electronic, magnetic, optical, electromagnetic, or semiconductor system, apparatus, or device.

[0030] There are two main injection delivery systems for thermodilution procedures. One is an open system, which utilizes a syringe pre-filled with ice-cold or room temperature injection. The other is a closed system, also used for ice-cold or room temperature injection, which is maintained in a closed loop to reduce multiple entries into the sterile system. Available data show that if ice-cold solutions are used, the variability of cardiac output determination will be reduced. Optionally, an injection temperature warmer than body temperature can be used. The computer records the temperature change of the patient's baseline (which can be through the signal), which may be noise. In some cases, a temperature change of 0.05°C may occur with breathing. This reduces the "signal-to-noise" ratio and may produce abnormally low cardiac output values. Other situations where an increased signal-to-noise ratio may be beneficial include patients with fever, low cardiac output states, and patients with wide respiratory variation.

[0031] Taking temperature changes into account as an indicator, a modified Stewart-Hamilton equation is used to calculate cardiac output. The correction includes the measured temperature of the injected solution and the patient's blood temperature, as well as the specific gravity of the injected solution. The Stewart-Hamilton equation is as follows:

[0032] CO=(V x(T B –T I ) / A)x(S I x C I ) / (S B x C B )x(60x C x K)

[0033] in:

[0034] CO = cardiac output

[0035] V = volume of injection (mL)

[0036] A = area of ​​the thermal dilution curve (square millimeters) divided by paper speed (mm / sec)

[0037] T B 、T I = Temperature of blood (B) and injection solution (I)

[0038] S B 、S I =Specific gravity of blood and injection solution

[0039] C B 、C I =Specific heat of blood and injection solution

[0040] (S I x C I ) / (S B x C B ) = 1.08, when 5% dextrose is used

[0041] 60=60sec / min

[0042] C T = Correction factor for warming of injection solution

[0043] Dilution apparatus, methods, and computer programs applicable to thermodilution are disclosed in U.S. Patent No. 8,343,058, issued to Pfeiffer et al. on January 1, 2013, and assigned to Edwards Lifesciences IPRM AG, the contents of which are incorporated herein by reference in their entirety. At least three key transpulmonary thermodilution parameters can be affected by the volume of the injected fluid, namely, cardiac output, global end-diastolic volume, and extravascular lung water.

[0044] Referring to the drawings, wherein like reference numerals designate like or similar parts, Figure 1 A prior art injection delivery system 20 is shown, which in this embodiment is an open system. The system 20 includes a sterile injection solution container 22 connected to the outlet of a syringe 26 or a tube connected thereto via an injection delivery tube 24. A non-venting IV spike 28 and a device to prevent flow from the tube, such as a snap clamp 30, can be provided along the injection delivery tube 24. A check valve 34 can be provided near the connection of the tube 24 to the syringe outlet to allow flow from the container 22 to the syringe 26, but not back to the container 22.

[0045] Downstream of the connection between the check valve 34 and the syringe outlet, a flow-through housing 36 can be provided to receive a temperature probe 40. The temperature probe 40 is one of several components electrically connected to a computer 42, which can include a processor or processing device, a CPU, a monitor, and a control unit associated with a cable 44 and a catheter connector 46. A three-way stopcock and a continuous flush device 48 can be connected downstream of the flow-through housing 36 from the temperature probe 40. The most downstream component can be a catheter 50, which can be, for example, a Swan-Ganz catheter. The catheter 50 can include a proximal injection hub 52. At the distal end of the catheter 50, there can be a balloon 54 and a distal lumen 56, with a thermistor 58 proximal to the balloon 54 and spaced apart from a proximal injection port 60. At the proximal end of the catheter 50, in addition to the proximal injection hub 52, there can also be a balloon inflation valve 62, an IV / pressure monitoring line 64, and a thermistor connector 66—connected to the computer 42 via the catheter connector 46.

[0046] The injection delivery system 70 according to an exemplary embodiment of the present invention is Figure 2 Schematically shown in . In this embodiment, a flow measurement device can be provided. In the flow measurement device, the pressure difference can be measured through a decompression component such as an orifice, a contraction flow area that causes a vortex pressure difference, a pressure differential transducer (transducer), or a venturi tube to calculate the flow rate of the injection. The flow measurement device can optionally include a pitot tube or a hot wire anemometer type device. Taking into account the time of measurement, the flow rate can be used to calculate the volume of the injection, and the volume of the injection can in turn be used for the Stewart-Hamilton equation and the equation of incorporated U.S. Patent No. 8,343,058, and can provide more accurate results than otherwise achievable.

[0047] Figure 2The infusion delivery system 70 may include a container, such as a syringe 26, which can be drawn from the infusion container 22, with a check valve 34 allowing flow from the container 22 but preventing flow back into the container 22. Alternatively, the container 22, tubing 24, and check valve 34 may be omitted, resulting in a closed system with only the syringe 26 serving as the source of infusion; the syringe 26 may be prefilled and self-cooled. Another check valve 72 may be provided, allowing flow of infusion discharged from the syringe 26 but preventing backflow from the tubing 24 into the syringe 26 when the syringe 26 is aspirated to withdraw infusion from the container 22. As described above, a flow measurement device 74 may be inserted linearly with the tubing 24. Pressure sensors 78 and 80 may be provided upstream and downstream of the flow measurement device 74, and a temperature sensor 82, which may be a thermistor, may also be provided, preferably downstream of the flow measurement device 74. The pressure sensors 78 and 80 and the temperature sensor 82 may be connected to the computer 42 via a cable 44. A stopcock 84 or other valve may be provided and may be connected to a proximal injection hub (not shown). Figure 2 It is represented by a single pipeline, but it should be understood that there can be multiple connecting pipelines (lines) incorporated into the catheter for various functions, such as Figure 1 The example given.

[0048] The flow measurement device 74 can have known flow characteristics and flow area that provide a relationship between pressure loss and injection velocity, so that when the pressure loss is known, the velocity can be determined. In addition, when the bolus discharge from the syringe 26 begins, the initial change in pressure—or, if desired, temperature—can trigger a timer to be started in the computer 42. Knowing the injection velocity and fluid characteristics, and measuring the elapsed time, the volume of the injection can be calculated.

[0049] An embodiment of a method 88 for determining an injectate volume for use in determining transpulmonary thermodilution parameters is described in Figure 3 . First, the injection is discharged from the syringe 90. A timer is started upon receiving a signal of an increase in pressure at a pressure sensor (e.g., a pressure sensor in the line from the syringe) 92; which pressure sensor (or both) to use can be selected as needed to suit the application and the equipment. A signal is received 94 from a flow measuring device in the line from the syringe, which can be located on both sides of the pressure reducing device (upstream and downstream), or alternatively from a flow cooled hot wire anemometer to generate the signal. The flow rate can then be calculated 96 from, for example, the pressure differential across the pressure reducing device, a pitot tube, or from a hot wire anemometer.

[0050] Optionally, a graphical user interface (GUI) can be provided that graphically displays the real-time flow rate of the infusate 98. The display can include limits within which the flow rate should appear. Upon receiving a signal indicating a drop in pressure at one or both of the selected pressure sensors, a timer can be stopped 100. The volume is calculated using the flow rate and the measured elapsed time 102. A signal is received from a temperature sensor indicating the temperature of the infusate 104, and the volume and temperature are used to calculate at least one transpulmonary thermodilution parameter 106.

[0051] Figure 4 Shown is a diagram of a computer 42 ( Figure 1 and 2 ) is associated with a monitor 120. The monitor 120 can display a GUI of the flow rate of the injectate from the syringe 26 into the catheter 50. The flow rate can be displayed in real time, as represented by the bubble 122a in this embodiment. Figure 3 The flow rate increases from left to right. A minimum limit 124 and a maximum limit 126 for the flow rate can be displayed on the monitor 120. The target 130 can be located in the center, and various example positions of the bubbles are shown in dashed lines. The second bubble 122b indicates that the flow rate is too slow because it is outside the acceptable range and below the minimum limit 124. The third bubble 122c indicates that the flow rate is acceptable but should be increased because it is just within the acceptable range and above the minimum limit 124. The fourth bubble 122d indicates that the flow rate is too fast because it is outside the acceptable range and above the maximum limit 126. The fifth bubble 122e indicates that the flow rate is acceptable but should be reduced because it is just within the acceptable range and below the maximum limit 124. The user applying force to the syringe 26 can observe the monitor 120 for guidance as to how fast the plunger of the syringe 26 should be depressed, and accordingly, what force should be applied to induce an acceptable flow rate.

[0052] Figure 5 Schematically illustrates Figure 1 Detail of the computer 42 and associated CPU, monitor, and control unit are shown, along with other components of the selected infusion delivery system and patient 200. The system includes an I / O interface 202, which in turn may include appropriate connectors and circuitry for monitoring signals from the sensor system. The circuitry may include analog-to-digital converters, encoders, decoders, etc. The I / O interface 202 is coupled to a central processing unit (CPU) 204 that controls the operation of the entire system.

[0053] The I / O interface receives sensor signals from pressure sensors, temperature sensors, and / or flow rate detectors 205, etc. The CPU 204 is further operably connected to a memory 206. The memory 206 stores all information required for the operation of the system. Such information can be stored in a temporary manner, or it can be stored more permanently. The memory can include a single or multiple types of memory. For example, the portion of the memory connected to the CPU 204 can be a "flash" memory ("flash" memory), which semi-permanently stores information for use by the system. In either case, the memory in this example embodiment Figure 5 The memory 206 includes computer program code 208 that, when executed by the CPU 204, causes the system to perform various processes to graphically display information according to example embodiments disclosed herein. The memory 206 also stores data 210, which in example embodiments includes historical values ​​of pressure, temperature, time, flow rate, and injection volume.

[0054] Still refer to Figure 5 The monitoring and control unit 12 may also include a network interface 213. This network interface may allow the system to connect to a wired or wireless network to allow monitoring on a remote display (not shown). For example, the remote display may replicate or be used in place of the local display panel. Figure 5 In the embodiment of the present invention, the local display device 217 (which can be Figure 4 The local display device 217 (similar to the monitor 120) is connected to the CPU 204 via a graphics engine 224. The local display device can be an LCD panel, a plasma panel, or any other type of display component and accompanying circuitry that interfaces the display device to the graphics engine 224. The graphics engine 224 can be located on its own chip, or in some embodiments it can be located on the same chip as the CPU 204. Note that the display device 217 can include user input capabilities, such as an optical or capacitive touch screen on the display screen. In this case, the monitoring control unit 42 may include additional circuitry to process such input. Alternatively, such circuitry may be included in the display device itself, the graphics engine, or the CPU 204.

[0055] Figure 6 Another exemplary embodiment of an injection delivery system 300 according to the present invention is schematically shown. Figure 2 Injection delivery system 70, Figure 6The inoculum delivery system 300 may include a container, such as a syringe 26, which can be drawn from an inoculum container 22, with a check valve 34 allowing flow from the container 22 but preventing flow back into the container 22. Alternatively, the container 22, tubing 24, and check valve 34 may be omitted, rendering the system closed, with only the syringe 26 serving as the source of inoculum; the syringe 26 may be prefilled and self-cooled. Another check valve 72 may be provided, allowing flow of inoculum discharged from the syringe 26 but preventing backflow from the tubing 24 into the syringe 26 when the syringe 26 is aspirated to withdraw inoculum from the container 22. However, in this embodiment, a constant flow valve 302 may be inserted linearly with the tubing 24. The constant flow valve 302 will remain closed until a "cracking pressure" is reached by actuating the plunger of the syringe 26, at which point the seal will open and flow will begin, maintained at a constant flow rate based on the valve design. The pressure required to break the seal may be, for example, approximately one pound. Alternatively, a constant flow syringe may be provided, combining a syringe and a constant flow valve.

[0056] A pressure sensor 306 and a temperature sensor 308 (which may be a thermistor) may be provided in line with the constant flow valve 302, and preferably provided downstream of the constant flow valve 302. The pressure sensor 306 and the temperature sensor 308 may be connected to the computer 42 via a cable 44. The pressure sensor 306 may be used to start and stop a timer to allow volume calculations based on the flow rate of the valve multiplied by the elapsed time, while the temperature sensor 308 is required for thermodilution calculations. A stopcock 84 or other valve may be provided and connected to a proximal injection hub (not shown). The catheter 50 is located at Figure 6 It is represented by a single line, but it should be understood that there may be multiple connecting lines incorporated into the catheter for various functions, such as Figure 1 The example given.

[0057] Materials for components of the devices disclosed herein can be selected by one of ordinary skill in the art of medical device design.

[0058] As discussed above, the thermodilution algorithm is sensitive to the volume of injectate applied to the patient. If the injectate volume is incorrectly entered into the system, or the volume applied to the patient is different, the calculated values ​​will be inaccurate. To demonstrate the effect of injectate volume on the results of key transpulmonary thermodilution parameters, an analysis was performed. Using thermodilution boluses from clinical studies, the output parameters were recalculated using a range of injectate volumes between 10 mL and 20 mL to allow for examination of the range and error in parameter values ​​caused by incorrect injectate volumes. The effect of injectate volume on the three key transpulmonary thermodilution parameters of cardiac output, global end-diastolic volume, and extravascular lung water was considered.

[0059] The program used thermodilution boluses from clinical studies to recalculate output parameters using a range of injection volumes between 10 mL and 20 mL, and then investigated the range and error in parameter values ​​caused by incorrect injection volumes. The results are as follows:

[0060] Injection volume (mL) CO(L / min) GEDV (mL) EVLW (mL) 10 3.28 1005.7 304.2 11 3.64 1105.6 332.7 12 4 1205.4 316.3 13 4.35 1305.2 389.8 14 4.71 1405.1 418.4 15 5.07 1504.9 447 16 5.43 1604.7 475.5 17 5.79 1704.6 504.1 18 6.15 1804.4 532.6 19 6.51 1904.3 561.2 20 7.01 2004.1 589.7

[0061] Figure 7-9 The results are shown with the parameters plotted, each as a function of the volume of the injected fluid. The above graph and table show that, assuming the original 10 mL value is correct, in this particular example, if 20 mL is incorrectly injected instead of the intended 10 mL, there can be an error of up to 114% with respect to CO ( Figure 7 ), about 99% error of GEDV ( Figure 8 ), and up to 94% error on EVLW ( Figure 9 ).

[0062] Although specific embodiments have been illustrated and described herein, it will be understood by those skilled in the art that any arrangement calculated to achieve the same purpose may be substituted for the specific embodiments shown, and that the embodiments herein have other applications in other contexts. This application is intended to cover any adaptation or variation of the present disclosure. The following claims are in no way intended to limit the scope of the present disclosure to the specific embodiments described herein. Although the foregoing relates to embodiments of thermodilution injection measurement and control, other and further embodiments may be devised without departing from the basic scope of the invention, and the scope of the same is determined by the claims that follow.

Claims

1. An injection delivery system comprising: Containers for holding fluid injections; a delivery tube in fluid communication with the container and configured at one end to be connected to a catheter; an injection device configured to expel the fluid from the container into the delivery tube; wherein the container is a syringe container comprising a manually operable plunger as the injection device; a flow measurement device inserted into the delivery tube and configured to generate a signal for use in determining a flow rate of the fluid from the container to the conduit based on a pressure differential within the delivery tube; and processing means adapted to receive said signal from said flow measurement means and configured to calculate an infusate volume to be used as input for calculating at least one parameter, wherein the injection delivery system is configured to calculate the injection volume from the flow rate of the injection, wherein the injection delivery system is configured to: expelling the injection liquid from the syringe; upon receiving a signal of a pressure increase at a pressure sensor in the line from the syringe, starting a timer; receiving a signal from the flow measurement device in a line from the injector; calculating the flow rate of the injection liquid from a signal received from the flow measurement device, wherein the flow measurement device has known flow characteristics and a flow area, which provides a relationship between pressure loss and the flow rate of the injection liquid, thereby determining the flow rate of the injection liquid from the pressure loss; When a pressure drop signal is received at the pressure sensor, the timer is stopped; and the volume of the injection liquid is calculated using the flow rate of the injection liquid and the measured elapsed time. 2 . The system according to claim 1 , wherein the at least one parameter to be calculated is a transpulmonary thermodilution parameter.

3. The system of claim 2, wherein the transpulmonary thermodilution parameter is at least one of cardiac output, global end-diastolic volume, and extravascular lung water.

4. The system of claim 1, further comprising a conduit in fluid communication with the container.

5. The system of claim 1, wherein the flow measurement device comprises a pressure sensor for measuring a pressure drop across an orifice.

6. The system of claim 1, wherein the flow measurement device defines an area of ​​contracting flow and includes a pressure sensor for measuring vortex pressure differential.

7. The system of claim 1, wherein the flow measurement device comprises a venturi tube.

8. The system of claim 1, wherein the flow measurement device comprises a Pitot tube.

9. The system of claim 1, wherein a sensor inserted in the delivery tube is configured to detect a change in temperature of the injection fluid.

10. The system of claim 1, wherein the pressure sensor is configured to signal the timer to start at the beginning of an injection and to stop at the end of an injection to measure the elapsed time of an injection.

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