How medical technology devices operate to determine compliance of external cavities.

Abstract

The present invention relates to a method for determining cavity compliance in minimally invasive surgery and a device for carrying out said method.

Description

Technical Field

[0001] The present invention relates to a method for determining the compliance of a cavity in minimally invasive surgery and a device for carrying out the method.

Background Art

[0002] In minimally invasive surgery, it is necessary to expand a cavity or surgical area within the human body. This example is the abdominal cavity or a sac. To enable sufficient vision for surgical inventions, in order to expand this cavity, depending on the size of the cavity, the required flow rate (e.g., CO2, physiological saline) changes.

[0003] In the case of a gaseous fluid (e.g., CO2, etc.), a device is used that regulates the volumetric flow rate required to next supply the cavity by using a pressure reducing valve.

[0004] When using a liquid fluid (e.g., physiological saline, etc.), the situation is different. Here, for example, a peristaltic pump is used that can vary the volumetric flow rate by controlling the pump rotation.

[0005] By introducing the volumetric flow rate into the cavity, the cavity is filled with fluid and the pressure of this cavity increases. At the same time, thus, the cavity expands to a certain extent so that the field of vision widens.

[0006] The so-called equation C c , c = V c / p c is used to determine the compliance (stretchability) C of the cavity as a static characteristic by using the relationship between the volume V c and the resulting pressure p c (see Figure 1a). c (see Figure 1a).

[0007] The compliance C c The reciprocal of the compliance C is regarded as the elasticity E c = 1 / C c and is regarded as such.

[0008] Here, the basic condition is that the specific pressure in this cavity should not cause any adverse effects on the patient. For this reason, a pressure sensor is usually used to determine the cavity pressure. With proper adjustment, the required volumetric flow rate can be calculated so that no cavity pressure harmful to the patient occurs. Therefore, the required volumetric flow rate is achieved by adjusting the pressure reducing valve or peristaltic pump. However, it is necessary to consider that the pressure should not be measured during ventilation. Pressure equilibrium is achieved by briefly shutting off ventilation for pressure measurement. The value at pressure equilibrium represents the actual pressure in the body cavity. After measurement, ventilation is resumed.

[0009] Depending on the surgical and physical characteristics of the patient (e.g., child or adult), a significant change in volume is required to inflate the body cavity to the desired pressure (see Figure 1b).

[0010] Therefore, in practice, the device user needs to perform many necessary settings to communicate information about the intended indicators and cavity sizes to the device.

[0011] From this information, specific parameters and limits for controlling / adjusting the device can be derived. For example, a dataset is then loaded that quantifies the maximum allowable fluid flow rate.

[0012] When the body cavity is larger than initially estimated, the expansion of the body cavity takes a considerably long time, resulting in undesirable surgical delays. However, when the body cavity is smaller than initially estimated, pressure may be achieved quite quickly in some cases, which can lead to tissue damage.

[0013] Another problem can arise if the attending physician accidentally hits a body cavity with the gas-insufflation needle. In this case, emphysema, which can be quite painful, may form.

[0014] Therefore, if a user sets the device with incorrect metrics and / or an incorrectly estimated cavity size (e.g., by preselecting adult or child), it may result in the malfunction behavior of the device. In this specification, for example, an inappropriate maximum flow rate limit may result in an undesirable surgical time delay or otherwise a high-pressure load.

[0015] So far, it has been impossible to solve the described problems with prior art devices and methods. Documents included in the relevant prior art are U.S. Patent Application Publication No. 2007 / 0083126, U.S. Patent Application Publication No. 2010 / 0236555, German Patent Application Publication No. 4309380, German Patent Invention No. 19809867, Tautorat, C. et al., 「Balloon-based measuring systems for compliance investigations」 Current Directions in Biomedical Engineering 4(1), 2018.

Prior Art Documents

Patent Documents

[0016]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document **4**

Non-Patent Documents

[0017]

Non-Patent Document 1

[0018] There is a need for a calibration system for medical technology devices that automatically determines extremely important cavity characteristics. [Means for solving the problem]

[0019] This invention discloses a medical technology device for introducing fluid into a body cavity, the device determining the characteristics of the cavity and, consequently, automatically identifying the necessary operating parameters.

[0020] A fluid reservoir (1) from which fluid is taken and supplied to a supply unit (4) using a connecting element (2). The fluid may be a gas (e.g., CO2 or N2) or a liquid (e.g., saline solution).

[0021] A regulating pump (actuator or supply unit (4)) for supplying fluid in a controlled manner.

[0022] A device for measuring the volumetric flow rate of a fluid (5).

[0023] A pressure sensor (6) for determining the dynamic and static pressure of a fluid.

[0024] A connecting element (7) (e.g., a tube) for supplying fluid from the device to the body cavity (8).

[0025] An electronic memory element (not explicitly shown) that works to detect measurement data. Furthermore, an electronic computing unit (e.g., a microcontroller) that sends necessary control commands to the actuator, evaluates the data, and loads / writes parameter datasets from the memory element. [Effects of the Invention]

[0026] Using medical technology devices containing the components mentioned, lumen compliance can be automatically determined using volumetric flow rate and pressure values ​​to avoid operational errors by medical staff. To achieve this objective, different determination methods described below can be applied. [Brief explanation of the drawing]

[0027] [Figure 1a] Figure 1a shows the relationship between the volume Vc of the body cavity and the resulting pressure pc. [Figure 1b] Figure 1b shows the relationship between the volume Vc of large and small body cavities and the resulting pressure pc. [Figure 2] Figure 2 shows a medical technology device (3) for supplying a fluid, which includes the following components, according to the present invention. [Figure 3] Figure 3 shows the relationship between the volumetric flow rate q and time t, and the relationship between the partial pressure p and time t. [Figure 4] Figure 4 shows a pV diagram illustrating the relationship between partial pressure pc and volume Vc. [Figure 5] Figure 5 shows the relationship between the volumetric flow rate q and time t, and the relationship between the partial pressure p and time t. [Figure 6] Figure 6 shows the relationship between the volumetric flow rate q and time t, and the relationship between the partial pressure p and time t. [Figure 7] Figure 7 shows the relationship between the volumetric flow rate q and time t, and the relationship between the partial pressure p and time t. [Figure 8] Figure 8 shows the Vc / pc relationship in the pV diagram. [Figure 9] Figure 9 shows the relationship between the actual cavity pressure p and time t, and the relationship between n and time t. [Figure 10] Figure 10 shows the relationship between the volumetric flow rate q and time t, and the relationship between the partial pressure p and time t. [Figure 11] Figure 11 shows the Vc / pc relationship in the pV diagram. [Modes for carrying out the invention]

[0028] Method Ia First, the device is connected to the body cavity via a connecting element. Next, the device is turned on. Before first utilizing the volumetric flow rate, the device determines the pressure in the cavity. Then, an actuator is used to generate a predetermined temporal volumetric flow rate q (e.g., a pulsed volumetric flow rate of a defined time length). The volumetric flow rate increases the pressure q in the cavity. c This will occur.

[0029] The measurement unit can determine the volume V by integrating the volumetric flow rate. After defining the volumetric flow rate, the device stops supplying and determines the static pressure of the cavity. Thus, the partial pressure increase (dp c / dV c The elasticity can be determined using the following. This procedure can be repeated until the desired reference pressure in the lumen is achieved. Next, a so-called pV diagram can be derived from the partial pressure increase. Thus, this diagram provides information about the size of the lumen or the position of the indicator. Next, by comparing the system parameters, the optimal system parameters (e.g., maximum flow parameter, control parameter, and adjustment parameter) can be parameterized and selected. Automatic lumen detection can be confirmed by user confirmation of options.

[0030] Figure 4 shows an example of this method. Two volumes V1 and V2 are supplied into the cavity with a time offset. Next, the pressure p in the cavity is... c The pressure sensor p increases, and d The pressure in the cavity can be determined using this. This allows the operating point V c1 =V1, p c1 =p d1 , and V c2 =V2+V1, p c2 =pd2 This is obtained. Next, for example, the approximate values ​​of the pV diagram can be calculated by linear approximation (see Figure 4). The "transient response" of the pressure measurement signal at the start and stop points of the volumetric flow rate can be clearly seen in the measurement diagram (the lower diagram in Figures 5 to 7).

[0031] Method Ib In practice, minimally invasive interventions often result in leakage into the lumen. Due to this unknown amount of fluid outflow, such leakage demonstrates that the procedure of Method Ia is flawed. To compensate for the impact of leakage on the measurement data, Method Ia is extended as follows:

[0032] Pressure is generated in the chamber by a pressure regulating device. In this case, the volumetric flow rate required to achieve the desired pressure is predefined. In a closed chamber without leaks, the pressure regulating device adjusts the volumetric flow rate to zero when the desired pressure is achieved (see Figure 6).

[0033] If there is an existing leak in the body cavity, the pressure regulating system permanently adjusts the volumetric flow rate to compensate for the leak. This volumetric flow rate required to maintain the pressure is the leak volumetric flow rate q of the existing cavity pressure. l This is illustrated in Figure 7. Leakage volume flow rate q l Therefore, the volumes V2 and V3 leaving the body cavity can be determined from the leakage rate. Next, the volume introduced can be determined from the leakage rate.

[0034] The cavity p at the point when the volumetric flow rate stops c1 The pressure is the pressure drop across the connecting element and the measured pressure p d1 This can be determined or approximated by prior knowledge. At this point, p d ≒p c1 That is the case.

[0035] In this specification, the evaluation can be applied as in Method Ia. The reference pressure can be (temporarily) increased to allow for several operating points for the calculation of the pV diagram.

[0036] By repeatedly verifying other reference pressure values, it is possible to determine different operating points in the pV diagram, and consequently, the size of the cavity.

[0037] Method II The actual operating point of the pV diagram of the body cavity during device operation can be determined. Low partial volume value (ΔC) c =ΔV c / Δp c A large value suggests a large body cavity, or a large value suggests a small body cavity. To obtain this information, a pause in measurement occurs during device operation. In this specification, the volumetric flow rate is briefly interrupted, and the resting chamber pressure p c1 The volume is identified. Next, an actuator is used to generate a predetermined temporal volumetric flow rate (e.g., a pulsed volumetric flow rate of a defined time length). The volumetric flow rate causes an increase in the pressure in the chamber. The measuring unit can determine the volume V2 supplied during this period by integrating the volumetric flow rates. After defining the volumetric flow rate, the device stops supplying and the static pressure p in the chamber is determined. c2 Identify the issue. Next, the device resumes normal functioning (see Figure 7). From the measurement results, ΔC c =V2 / (p c2 -p c1 Unlike Method I, complete information regarding the size of the cavity or the pV diagram is unknown. Therefore, only this information is applied to the actual operating point of the volumetric flow rate required to maintain the cavity pressure. However, at this operating point, the user can adjust the settings to a reasonable value relative to the default settings selected by the user and the actually determined characteristic values ​​(see Figure 8). Therefore, if there are discrepancies, the device can automatically adjust its parameter set to allow the user to perform the intervention and enable the optimal system setup.

[0038] Method III During device operation, the pressure temporarily increases. To achieve this objective, active pressure control / regulation is used. The additional volume required to obtain the desired lumen pressure is determined during the pressure increase phase. From these values, the partial volume value (ΔC = ΔV / Δp) can be determined. This is identical to the procedure in Method II. However, Method III can also be used during the initial lumen filling phase. To achieve this objective, the desired reference pressure for pressure regulation is increased (over a very slow period of time, or in stages) in a quasi-steady state. Pausing the measurement does not require current system parameters regarding the device and the connection unit between the device and the body lumen. Therefore, the volume and generated pressure data can be transferred to a pV diagram. This provides a reference for deriving the lumen size or index, similar to Method I. This thus allows for the parameterization and selection of optimal system parameters (e.g., maximum flow parameter, control parameter, and adjustment parameter). User confirmation of options confirms automatic lumen detection.

[0039] Method IV In Method II, the actual chamber pressure p c1 After the determination, the volumetric flow rate increases. The rising pressure at the sensor correlates with the rise in pressure in the chamber (see Figure 9). Therefore, as a result, the chamber pressure p c2 The measurement of is no longer necessary (unlike Method II). Instead, the increase Δp relative to volume V2 is used. c Identify the value (see Figure 10). After determining the value, the device resumes its previous operation.

[0040] Therefore, in contrast to Method II, in Method IV, the chamber pressure p c2 Although precise knowledge of the values ​​is lacking, the same partial increase occurs, and therefore, to ensure optimal parameterization of the device, the user can use the values ​​to compare the device's parameter set with the determined lumen values ​​(Figure 11) and modify the values ​​as needed. [Explanation of Symbols]

[0041] (1) Fluid reservoir (2) Fluid connection section (fluid supply tube between the reservoir and the medical technology device (3) for supplying fluid) (3) Medical technology devices for supplying fluids (4) Supply device (5) Measuring device for the volumetric flow rate of a fluid (6) Pressure sensor (7) Fluid connection (8) Body cavity

Claims

1. At least one regulating pump for supplying fluid in a regulating manner, A measuring device (5) for measuring the volumetric flow rate of the fluid, At least one pressure sensor (6) for determining the dynamic and static pressure of the fluid, At least one connecting element (7) for supplying the fluid to the external cavity, At least one electronic computing unit for transmitting necessary control commands to the adjustment pump and evaluating the data, Includes external cavity compliance C ｃ A method for operating a medical technology device that determines, a) The pressure sensor (6) determines the static pressure p inside the cavity when no fluid is supplied to the cavity. ｃ1 The process of measuring, b) The electronic computing unit transmits a control command to the adjustment pump to supply a predetermined volumetric flow rate into the cavity for a predetermined period of time, c) The volume V of the fluid supplied by the measuring device (5) during the predetermined time. ２ The process of measuring, d) The pressure sensor (6) determines the static pressure p in the cavity after the supply of the predetermined volumetric flow rate has been stopped. ｃ２ The process of measuring, e) the electronic computing unit calculates the compliance C ｃ = V ２ / (p ｃ２ - p ｃ１ ) and a method of operating a medical technology device comprising the step of calculating the compliance C ｃ .

2. The method for operating a medical technology device according to claim 1, wherein the volumetric flow rate during the predetermined time is a pulsed volumetric flow rate having a predetermined time length.

3. A method for operating a medical technology device according to claim 1 or 2, further comprising at least one fluid reservoir (1) from which a fluid is taken and supplied to a supply unit (4) through a connecting element (2).

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