Insufflation device with novel pressure measurement

Abstract

The present invention relates to an insufflator with a novel pressure measuring device for minimally invasive surgery. This novel device allows for the reliable measurement of pressure within the body cavity while simultaneously ensuring that the gas supply lines remain unobstructed.

Description

[0001] The present invention relates to an insufflator with a novel pressure measuring device. The new device makes it possible to reliably measure the pressure in the body cavity and simultaneously ensure that the gas supply lines are unobstructed. Background and state of the art

[0002] Insufflators are known in various designs from the prior art. Insufflators typically have a tube through which a medical gas is introduced into a body cavity (e.g., the abdomen). The gas creates overpressure, which expands the body cavity to provide sufficient space for visual inspection or therapeutic intervention. Optional embodiments allow the gas to be aspirated from the abdominal cavity via a second tube. Such embodiments are used particularly in therapeutic procedures using electrosurgery or lasers to remove and filter harmful gases.

[0003] In practice, accurately determining the pressure within a body cavity has proven difficult. Various designs of measuring devices are known for this purpose. Measuring the pressure directly within the body cavity using a pressure sensor has the disadvantage that, in addition to the necessary medical instruments, the pressure sensor itself must also be positioned within the cavity. This means, on the one hand, an additional element within the body cavity, with its associated connections, which takes up space and simultaneously poses a risk of infection. On the other hand, this results in higher costs for the pressure sensor, as it must either be extensively cleaned and sterilized or designed as a disposable item.

[0004] Therefore, designs have become established in which the pressure sensor is not located in the body cavity itself, but rather in one of the tubes, at a greater or lesser distance from the body cavity. The inherent disadvantage of this sensor arrangement is that there is a pressure difference between the body cavity and the measuring position (e.g., in the tube), caused by the tube, the trocar, and possibly other devices. Determining this pressure loss is not straightforward and is the subject of much research. The further the pressure sensor is from the body cavity, the greater the deviations between the measured pressure and the pressure in the body cavity. The closer the pressure sensor is to the gas supply device (e.g., a valve-controlled pump) or a suction pump, the greater the deviations due to the activity of the pumps (e.g., pressure pulses) or the valves.Furthermore, these effects are compounded by errors caused by blocked tubes that prevent fluid flow to or from the body cavity. Such a blockage can occur due to a kinked tube or because the patient-side opening is obstructed by body tissue. In such a case of tube occlusion, the pressure sensor only measures the pressure within the tube, not the pressure in the body cavity, leading to significant safety concerns.

[0005] From DE 202004 021703 U1, a device for delivering substances (e.g. chemotherapeutic agents) into an insufflated body cavity is also known, which, however, does not allow for the avoidance of the measurement errors mentioned at the beginning, in particular the detection of a tube occlusion.

[0006] US 5,908,402A describes a method and device for detecting pipe blockages in an electrosurgical argon system.

[0007] In order to overcome the aforementioned disadvantages of previous pressure measurement systems, the task was set to provide an insufflator that ensures precise pressure measurement and reliably detects any hose occlusion that may occur.

[0008] The present invention therefore relates to an insufflator for minimally invasive surgery, comprising a) Gas connection for a gas cylinder or domestic gas (1) b) First pressure and flow control unit (2) equipped with a proportional valve, c) Supply line (3) with a cross-section of 5.5 to 15 mm, designed for a gas flow of 0-50 L / min at 2-3 bar, with first controllable valve (4), first gas pressure sensor (5), first gas flow sensor (6) and connection to a first trocar (7) into a cavity (8), d) Sensor line (9) with a cross-section of 2 to 5 mm with an optional throttle (10), designed for a gas flow of less than 1 L / min at 2-3 bar, with a second controllable valve (11) and a second gas pressure sensor (12) and connection to a second trocar (13) into the cavity (8), e) Control unit (14) for controlling the insufflation and evaluating the measurement data from the first gas pressure sensor (5) and the second gas pressure sensor (12) wherein the sensor line (9) is connected to the first pressure and flow control unit (2) and wherein the second controllable valve (11) enables a pulsatile gas flow into the cavity (8) controlled by the computing unit (14).

[0009] Further embodiments of the invention, including the associated operating methods, are described below and are partly the subject of dependent and sub-claims. Basic features of the invention: simple embodiments

[0010] The invention is generally in Figure 1The diagram shows a gas connection for a gas cylinder or domestic gas supply, leading to a first pressure and flow control unit with a proportional valve. The line then continues to a controllable valve. The first pressure and flow control unit can deliver a gas flow of up to 50 liters / minute at a pressure of 2 to 3 bar. Also visible are a gas flow sensor for measuring the gas flow and a first gas pressure sensor. The supply line leads into the body cavity via the hose and trocar.

[0011] It can also be seen that a sensor line branches off between the first pressure and flow control unit and the first controllable valve. This sensor line has a significantly smaller cross-section (3 to 5 mm) and is designed for a gas flow of less than 1 liter / min at the aforementioned pressure of 2 to 3 bar. Preferably, the gas flow through the sensor line is less than 0.5 liters / min, and particularly preferably less than 0.1 liters / min. The sensor line can contain a restrictor to limit the gas flow; optionally, the restrictor can be adjustable. The sensor line leads first to a second controllable valve and then to a second gas pressure sensor. Via a second tube and a second trocar, the sensor line also leads into the body cavity. During operation, a discontinuous, pulsatile gas flow through the sensor line can be set via the second controllable valve, as described in [reference missing]. Figure 1b This is illustrated. For example, a single pressure pulse of 20–50 mmHg can be applied to the sensor line for 1 to 3 seconds, followed by a pulse pause of 3 to 20 seconds. Due to the comparatively low gas flow through the sensor line, the gas flow through the sensor line has virtually no effect on the pressure in the cavity. During a gas pulse, however, the pressure measured by the second gas pressure sensor in the sensor line rises significantly and then falls again after the second controllable valve closes, until it is identical to the pressure in the body cavity. The actual pressure in the body cavity therefore corresponds to the equilibrium pressure during the pulse pauses. In the event of occlusion of the sensor line, the pressure measured by the second gas pressure sensor rises and remains at the elevated pressure level for a longer period (see Figure 1 b)Such pressure behavior clearly indicates an occlusion of the sensor line. In this case, an alarm signal is triggered if the elevated pressure measured at the second gas pressure sensor lasts longer than twice the pulse width.

[0012] For the detection of an occlusion of the sensor line, the pulsatile gas flow through the sensor line is therefore crucial. Without these gas flow pulses, detection of a sensor line occlusion is not possible in this embodiment of the invention. Furthermore, the comparison of the measured values ​​from the first gas pressure sensor (5) and the second gas pressure sensor (12) is essential for the inventive function of the described device and the insufflation methods carried out with it.

[0013] The triggered alarm signal can be visual and / or audible. It is also possible to automatically limit the gas flow during insufflation to prevent excessive pressure in the cavity.

[0014] The design of the insufflator according to the invention also allows for a modified operating mode, which is described below: In this operating mode, a continuous gas flow through the sensor line is established by a constant opening of the second controllable valve. With a constant gas flow through the sensor line, a pressure can be read at the second gas pressure sensor, which depends on the pressure in the cavity. However, the pressure measurement at the second gas pressure sensor must be corrected for the pressure loss in the line and the trocar between the second gas pressure sensor and the cavity. The following equation 1 applies for this purpose: p Kavität = p Sensor − p Sensorleitung

[0015] The pressure loss in the sensor line is approximately constant at the aforementioned low gas flow through the line and can be determined by measurement or calculation.

[0016] In this operating mode, the pressure measured by the second gas pressure sensor increases when an occlusion occurs. The pressure rise of at least 20 mmHg occurs within one to two seconds and drops almost as quickly once the occlusion is resolved, for example, in the case of a temporarily kinked hose. Such a rapid pressure rise or fall can only occur if the sensor line is occluded. The pressure rise in the body cavity in the event of a malfunction in the gas supply line would be significantly slower.

[0017] In a further embodiment of the invention, the sensor line between the second trocar and the second gas pressure sensor includes a check valve that opens at a low back pressure of 8-12 mmHg from the cavity. In specific embodiments of the invention, the check valve can open at even lower back pressures, for example, 3 to 5 mmHg, or even 1 to 3 mmHg. This allows verification that the sensor line is properly connected to the cavity and that no occlusion is present. If there is no connection to the cavity or if an occlusion occurs between the cavity and the second sensor, the check valve remains closed. This situation can be recognized by the fact that opening the second controllable valve results in a rapid increase in the measured pressure at the second gas pressure sensor, but not at the first gas pressure sensor (see [reference]). Figure 2bWith a proper connection, the measured pressure at the second gas pressure sensor rises significantly more slowly. Simultaneously, the measured pressure at the first gas pressure sensor also rises. In this embodiment as well, generating a pulsatile gas flow through the sensor line is necessary. Without these gas flow pulses, detection of a sensor line blockage is not possible.

[0018] Furthermore, in this case too, knowledge of the pressure loss through the sensor line is necessary in order to correct the measurement at the second pressure sensor accordingly (see Figure 2b ).

[0019] In a simplified embodiment of the invention (not shown in the figures), the sensor line with the connected second gas pressure sensor leads into the cavity via a second trocar, without the sensor line being connected to the first pressure and flow control unit. The second controllable valve is unnecessary in this case. In this embodiment, occlusion of the sensor line can only be achieved by comparing the measured values ​​between the first and second gas pressure sensors. For this purpose, the first controllable valve in the supply line must be closed so that the measured value of the first gas pressure sensor is not influenced by the gas flow. With the first valve closed, i.e., during an insufflation pause, both gas pressure sensors must indicate the same pressure, possibly taking into account the gas pressure losses through the lines (see above).If the pressure values ​​deviate by more than 5 mmHg (in special cases more than 1 mmHg), an occlusion of the pipe or another disturbance of the gas flow should be assumed. Description of the characters

[0020] Figure 1 shows the device according to the invention as described at the beginning. Figure 1a Figure 1 shows the basic structure with the components of claim 1. Only the computing unit is not shown. The second controllable valve (11) enables a pulsatile gas flow into the cavity (8). Figure 1b shows the result of the pressure measurement of the second pressure sensor ( p 12 ) compared to the actual pressure in the cavity ( p 8 ) depending on the gas flow in the sensor line. The upper line shows the position of the second controllable valve (11), "on" or "off". The lower lines show the measured pressure at the second pressure sensor (12) and in the body cavity, respectively. The gas pulse in the sensor line results in a corresponding pressure pulse at the second pressure sensor (12) with approximately the same pulse width. In the event of a blockage of the sensor line (right in the image), a pressure increase occurs at the second pressure sensor (12), which lasts significantly longer than the pulse width of the pressure pulse. The actual pressure in the body cavity ( p 8 ) is constant in this example. If the measured pressure increase lasts significantly longer than the pulse width of the pressure pulse from the second controllable valve (11), without a corresponding pressure increase being registered by the first pressure sensor (5), a blockage of the sensor line (9) can be assumed and an alarm triggered. Figure 1cFigure 1 shows the pressure profile in the case of occlusion, namely the removal of the sensor line (9) from the second trocar without pulsation of the second controllable valve. The pressure measured at the second pressure sensor remains constant in this case, even if the pressure p 8 in the cavity (8) increases. Figure 2a shows the embodiment of the invention with a check valve (15). Figure 2b The measurement results show that, with the sensor line (9) not connected to the second trocar (13), a short pressure pulse through the second controllable valve (11) leads to a longer-lasting pressure increase ( p 12 ) at the second pressure sensor (12). Once the sensor line (9) is properly connected to the second trocar (13), the pressure measured at the second pressure sensor (12) p 12 ) parallel to the actual pressure in the cavity (8). The pressure difference shown in the diagram ΔpThis results from the volume flow rate of the sensor line (9). With the valve (11) closed, the pressure difference would be lower, but not zero due to the pressure loss in the line (see Equation 1). This embodiment of the invention is also possible without the second controllable valve (11), which is therefore optional. However, without the second controllable valve (11), only an improper connection between the sensor line (9) and the second trocar (13) can be detected, not an occlusion between the cavity (8) and the second gas pressure sensor (12).

[0021] The reference symbols used in the figures have the following meaning: (1) Gas connection for a gas cylinder or house gas (2) First pressure and flow control unit equipped with proportional valve (3) Supply line (4) First controllable valve (5) First gas pressure sensor (6) First gas flow sensor (7) First trocar (8) Cavity (9) Sensor line (10) Throttle (optional) (11) Second controllable valve (12) Second gas pressure sensor (13) Second trocar (14) Computing unit (15) Check valve

Claims

1. Insufflator for minimally invasive surgery, comprising a) gas connection for a gas cylinder or domestic gas (1) b) first pressure and flow control unit (2) equipped with a proportional valve, c) supply line (3) with a cross-section of 5.5 to 15 mm, designed for a gas flow of 0-50 L / min at 2-3 bar, with a first controllable valve (4), first gas pressure sensor (5), first gas flow sensor (6), and connection to a first trocar (7) in a cavity (8), characterized in that the insufflator further comprises d) a sensor line (9) with a cross-section of 2 to 5 mm with an optional throttle (10), designed for a gas flow of less than 1 L / min at 2-3 bar, with a second controllable valve (11) and a second gas pressure sensor (12), and connection to a second trocar (13) in the cavity (8), e) a computing unit (14) for controlling the insufflation and evaluating the measurement data from the first gas pressure sensor (5) and the second gas pressure sensor (12), wherein the sensor line (9) is connected to the first pressure and flow control unit (2) and wherein the second controllable valve (11) enables a pulsatile gas flow into the cavity (8) controlled by the computation unit (14).

2. Insufflator for minimally invasive surgery according to claim 1, further comprising a check valve (15) which opens at a low back pressure of 8 to 12 mmHg from the cavity, and which is positioned in the sensor line between the second trocar (13) and the second gas pressure sensor (12).

3. Insufflator for minimally invasive surgery according to claim 1, wherein the computing unit (14) is designed to correct the pressure losses of the supply line (3) with the first trocar (7) and the sensor line (9) with the second trocar (13) and to compare the corrected measured values of the first pressure sensor (5) and the second pressure sensor (6).

Images