Device and method for flow-through temperature control of liquids in medical devices

Description

[0001] It is known to irrigate body cavities in various medical endoscopy procedures, such as arthroscopy, (endo)urology, or hysteroscopy. In this case, an irrigation fluid is typically pumped into a body cavity using a pump, e.g., a roller pressure pump. It has proven advantageous to adjust the irrigation fluid to body temperature during application in order to avoid local hypothermia of the patient's body—for example, in (endo)urology and hysteroscopy. Various solutions for this are known in the prior art (e.g., US 6,480,257, US 8,790,303, US 7,153,285, US 2003 / 0216689 A1), although they have various disadvantages. Further prior art devices are known from US 2002 / 0045851 A1 and DE 10 2010 036 295 A1.

[0002] In arthroscopy, it may be beneficial to cool the joint with the irrigation fluid to reduce inflammatory processes, avoid bleeding and / or reduce local metabolic activity during the operation.

[0003] The present invention is a new device intended to overcome various disadvantages of the prior art.

[0004] The present invention therefore relates to a device for flow-through tempering of medical rinsing liquids according to claim 1.

[0005] Advantageous embodiments of the invention are explained below and are the subject of the dependent claims.

[0006] The device according to the invention therefore consists of a heat exchanger body, e.g. in the form of a cassette, through which the liquid to be tempered flows, and a flat tempering element adapted to the shape of the heat exchanger body.

[0007] In the preferred embodiment of the invention, the liquid to be tempered is heated from room temperature to body temperature, e.g., from 20°C to 37°C. In this case, the flat tempering element is designed as a flat heating element.

[0008] In an alternative embodiment of the invention, the liquid to be tempered is cooled from room temperature, e.g., from 20°C to 3-5°C. In this case, the flat tempering element is designed as a flat cooling element. This alternative embodiment is described in detail below.

[0009] The heat exchanger body can have different geometric shapes.

[0010] As shown in the accompanying figures, a preferred embodiment is the shape of a flat cuboid. The interior of the cuboid is essentially hollow and can accommodate rinsing liquid. The cuboid has an inlet at one location and an outlet at another location. The inlet and outlet can, as shown in Figure 2 As shown, it can be arranged on a cuboid surface. As liquid flows into the inlet, the heat exchanger body is filled with the liquid until it exits again at the outlet. In the operating position, the outlet is preferably located higher than the inlet so that the air originally contained can escape more easily. Alternatively, the heat exchanger body can also have other geometric shapes, such as round, oval, hexagonal, octagonal, etc.

[0011] The heat exchanger body is preferably made of plastic (e.g. polycarbonate (PC), polyethylene terephthalate (PET), polyethylene terephthalate glycol (PETG), polyvinyl chloride (PVC), polypropylene (PP), polyethylene (PE) or mixtures of these plastics. The plastics can also be filled with ceramic powder. It is also possible to manufacture the heat exchanger body from metal, in particular from metal foils (e.g. aluminum foil). The individual components of the heat exchanger body can also be made of different materials. In this case, at least one heat exchanger body wall is manufactured in such a way that good heat transfer is ensured. The heat transfer coefficient of this wall (also called heat conducting wall) should be at least 1 W / (cm 2 < K), preferably greater than 2.5 W / (cm 2 < K).

[0012] The "heat transfer coefficient a" is the coefficient that describes the heat transport (P = ΔQ / Δt) per unit area (P = ΔQ / Δt) across an interface as a function of the temperature difference between the two sides of the interface according to the following equation: P = α · ΔA · ΔT

[0013] In general, all heat-conducting materials are suitable for this purpose. A metal foil, particularly aluminum foil, is preferred. Alternatively, a ceramic powder-filled plastic can also be used. Advantageously, the largest surfaces of the heat exchanger body are used for heat transfer, e.g., the top surface or base surface of a flat cuboid. In special embodiments, multiple surfaces can also be configured in this way, e.g., the top surface and base surface of a cuboid-shaped heat exchanger body.

[0014] According to the invention, the heat exchanger body contains two flow paths: The majority of the heat exchanger body is heated by the heating element, while at the same time, a "bypass" is provided, through which fluid can flow directly from the inlet to the outlet without being heated. The bypass is formed according to the invention by appropriately shaping the heat exchanger body base within the heat exchanger body, as exemplified in Figure 2 is shown.

[0015] Alternatively, in non-claimed embodiments, the bypass can be formed outside the heat exchanger body, for example, by a hose running parallel to the heat exchanger body. In each case of this embodiment, control devices, such as valves (e.g., in the form of pinch valves), are provided that direct the fluid flow either into the main chamber or into the bypass. Preferably, the bypass runs within the heat exchanger body through an area that has no contact with the surface temperature control element described below (see Figure 2This design allows the outlet temperature of the rinsing fluid to be regulated quickly and effectively, particularly in applications where the flow is very uneven. Should the fluid temperature in the chamber become too high, e.g., due to a temporary flow stoppage, unheated rinsing fluid can be metered in via the bypass to keep the outlet temperature constant. Furthermore, this can be used to achieve a sufficient control speed of the outlet temperature, which guarantees a reliable temperature setting even with strong fluctuations in the flow rate.

[0016] In order to be able to control the fluid flow through the heat exchanger body and bypass, parts of the heat exchanger body are made of elastic material (e.g. silicone) in order to regulate the fluid flow through the heat exchanger body or the bypass (like a pinch valve) using actuators integrated into the heater housing. Depending on the wall material used, local material weakening or shaping (e.g. in the manner of a bellows) may be sufficient to ensure the necessary flexibility in the sense of reversible deformability. The actuators are preferably set so that when at rest, in the event of failures or malfunctions, flow passes through the bypass and no fluid flows through the heating section. This ensures that the fluid is never supplied to the patient when it is too hot.

[0017] According to the invention, the heat exchanger body described above is used together with a correspondingly adapted temperature control element, e.g., a heating element. The heating element is shaped so that at least one wall of the heat exchanger body can be heated across its entire surface. Such heating elements in the form of a flat heating foil are available commercially and consist of a generally single-layer, flatly arranged ohmic heating coil embedded in an insulating plastic film, e.g., made of silicone or polyimide (trade name Kapton®).

[0018] Alternatively, the heating element can also be designed as a heating surface with a wire-shaped heating conductor that is pressed into ceramic powder (= electrical insulation), which in turn is pressed into a metallic outer sleeve / housing.

[0019] Temperature sensors can be arranged at one or more locations in close thermal contact with the heating element, e.g. the heating foil, in order to measure the temperature of the heating foil and to carry out temperature control based on the measurements.

[0020] As a special embodiment, this heating foil can also be made of a PTC thermistor, which increases its electrical resistance with increasing temperature. In this way, temperature control can be omitted under certain circumstances, because the increasing resistance with increasing temperature causes a decrease in heating output. Such PTC thermistors and the associated controls are state of the art and require no further explanation here.

[0021] The heating element is expediently arranged inside a housing, which can have practically any external shape. Crucial for the use according to the invention is a housing opening for receiving the described heat exchanger body, e.g. in the form of a slot. The geometry of the opening is of course designed so that the heat exchanger body can be inserted into the opening. The flat heating element, e.g. in the form of a heating foil, is located on one side of the cavity accessible through the opening, e.g. the underside. The heat exchanger body described above must be inserted into the opening in such a way that the side that ensures heat transfer comes into contact with the heating element. The temperature of the rinsing liquid can be regulated by adjusting the heating output.

[0022] As has been shown, the heat exchanger body is preferably heated from below. Due to thermal convection, thermal mixing of the fluid in the heat exchanger body occurs. In the case of the operating mode described below, in which the fluid is cooled, the cooling element is preferably arranged at the top. Since, in principle, two walls of the heat exchanger body can also be formed from heat-conducting material, e.g., the bottom surface and the top surface, heating or cooling can also occur from two sides.

[0023] In a further embodiment of the invention, it is possible to provide both a heating surface and a cooling surface in the housing. Depending on the device's settings, heating or cooling can thus be achieved.

[0024] Preferably, the shape of the aforementioned inlet opening is designed geometrically so that incorrect positioning of the heat exchanger body can be largely eliminated. Additional symbols or color coding can be helpful in this regard.

[0025] The device according to the invention can be operated as follows: A hose leads from a reservoir containing medical rinsing fluid to the inlet of the heat exchanger body. Another hose connects the outlet of the heat exchanger body to the inlet of a medical pump, e.g., a roller pump. A further hose leads from the pump outlet to a medical instrument, such as an endoscope. Alternatively, the device according to the invention can also be operated without a pump using pure gravity feed; in this case, the outlet-side hose leads directly from the heat exchanger body to the instrument, with all other features of the invention remaining unchanged. The heat exchanger body is inserted into the heating device. The fluid, preheated to the desired temperature (e.g., the patient's body temperature) by the heating device according to the invention, is fed into the patient's body by the rinsing pump.

[0026] Preferred embodiments of the invention are described below: The heat exchanger body is preferably designed as a disposable article and is therefore disposed of after one-time use. The heat exchanger body is preferably made of plastic (e.g. polycarbonate (PC), polyethylene terephthalate (PET), polyethylene terephthalate glycol (PETG), polyvinyl chloride (PVC), polypropylene (PP), polyethylene (PE) or mixtures of these plastics), which is formed by deep drawing. Alternatively, other techniques can of course also be considered, such as injection molding or 3D printing. In this way, the cover side of the heat exchanger body can be easily covered with an adhesively bonded or welded aluminum foil (thickness e.g. 20-90 micrometers, preferably 60 micrometers). In a preferred embodiment, the aluminum foil is coated on the side that forms the inside of the heat exchanger body with a plastic layer (e.g.1-5 micrometers, preferably 2 micrometers polypropylene). This prevents direct contact of the fluid with aluminum without disrupting the necessary heat transfer.

[0027] In order to transfer the necessary heat output, the base area of ​​the heat exchanger body is generally between 100 and 1,600 cm 2 (e.g. 10 by 10 cm to 40 by 40 cm).

[0028] The hose connectors are, for example, injection-molded parts or other plastic molded parts and are preferably made of the same plastic as the base part of the heat exchanger body. The hose connectors are inserted into appropriately prepared openings and welded or glued to the heat exchanger body. Alternatively, the hose connectors can also be directly molded using deep drawing, extrusion, or 3D printing.

[0029] The heat exchanger body is preferably flat, with a height of 5-20 mm. The housing opening is designed accordingly. The housing opening is preferably dimensioned so that operating personnel cannot insert their fingers into the opening, to avoid accidents caused by burns.

[0030] Furthermore, by appropriate shaping of the heat exchanger body and the housing opening, it can be ensured that the heat exchanger body is inserted into the housing in the correct way, e.g. by slight trapezoidal deviation from the cuboid shape ( Figure 6 above) with appropriate shaping of the housing opening or by forming guide strips on the heat exchanger body side ( Figure 6 (below) with corresponding guide slots in the housing. Alternatively or additionally, symbols or color coding applied to the heat exchanger body and housing can prevent incorrect operation.

[0031] Furthermore, the temperature control device preferably contains a temperature sensor for monitoring the outlet temperature of the rinsing liquid. For this purpose, a temperature sensor can be integrated, for example, into the outlet of the heat exchanger body.

[0032] It turns out that when aluminum foil is used for heat transfer, its thermal conductivity is so good that a contact thermometer positioned near the outlet of the heat exchanger body is sufficient to measure the temperature accurately enough. This allows the temperature sensor to be incorporated into the housing and is reusable.

[0033] In a further development of the described invention, the housing comprises a vacuum pump. The generation of a vacuum on the heat transfer side enables the heat exchanger body to be pressed against the temperature control element, thus improving heat transfer. The intake port(s) of the pump will be located in the area of ​​the heating element. It is recommended that a sealing material (e.g., a silicone seal in the form of a circumferential sealing cord) be arranged around the flat heating element so that the vacuum can be easily maintained. In this embodiment of the invention, a pressure between the heat exchanger body and the heating or cooling surface of 0.3–0.05 bar is desired, preferably approximately 0.1 bar. At this pressure, the heat-conducting wall of the heat exchanger body (e.g., the aluminum foil) is drawn to within less than 1 µm of the heating or cooling surface. At the same time, a pressure of 0.3–0.05 bar ensures excellent heat transfer.

[0034] In a further embodiment of the invention, one or more inner sides of the heat exchanger body inner walls contain a structuring, e.g. in the form of a wave-shaped, sawtooth-like or herringbone-like structured design of the inner surfaces ( Figure 4 ). It has been shown that such structuring contributes to turbulence in the fluid passing through it and thus to thermal homogenization of the flow and the temperature of the heat exchanger body. Structuring the inner wall opposite the wall with heat transfer has proven particularly advantageous.

[0035] Depending on the size of the heat exchanger body and the elasticity of the heat exchanger material, support elements (e.g., cylindrical) may also be installed inside to prevent the heat exchanger body from collapsing. The heat exchanger body walls may also contain stiffening devices (e.g., ribs).

[0036] It is recommended that the flat heating element of the heating device reach a maximum temperature slightly above the patient's body temperature (e.g., 39°C). For safety reasons, the temperature of the flat heating element is monitored by appropriate temperature sensors. Furthermore, the outlet temperature of the rinsing fluid from the heat exchanger body is monitored by a temperature sensor. This can be part of the heat exchanger body, as shown above. For cost reasons, it would be advisable to make the temperature sensor part of the heating device, e.g., in the form of a contact sensor that measures the temperature of the surface of the aluminum foil.

[0037] It has been found that in order to optimise temperature control it is advantageous to measure the flow through the heat exchanger body. If the device according to the invention is operated in combination with a pump, e.g. a medical roller pump, then it is generally sufficient to determine the flow rate of the pump. If the flow rate is not determined by any other means and is available, the device according to the invention can also be set up for simultaneous flow measurement. The flow measurement can be carried out, for example, according to the Venturi principle. For this purpose the flow cross-section must be narrowed, for example in the area of ​​the liquid inlet or outlet. The flow can be determined by measuring the differential pressure (in the narrowing and after the narrowing). Appropriate sensors are required to measure the pressure. The pressure sensors can be installed directly in the heat exchanger body, i.e. in its inlet or outlet.Output, integrated. Alternatively, a flexible membrane can be arranged at the measuring points, the deflection of which is used for pressure measurement by corresponding pressure sensors in the housing.

[0038] Alternatively, the flow rate can also be measured thermally: For this purpose, a temperature sensor must be installed at a suitable location on the heat exchanger, e.g., near the fluid inlet or outlet. A heating element, e.g., a resistance heater, must be located in the immediate vicinity of the temperature sensor. The heating element can heat continuously or discontinuously, whereby the heating power is determined. The temperature increase achieved in the vicinity of the heating element, which is measured by the temperature sensor, is a measure of the flow rate. At a high flow rate, no significant temperature increase will occur, whereas at a low flow rate, a temperature increase will be measured by the thermometer.The advantage of this type of flow measurement is that both the heating element and the temperature sensor do not have to be part of the heat exchanger body, but can perform the measurement through contact with the surface of the heat exchanger body. This allows the heat exchanger body to be manufactured in the simplest and therefore most cost-effective way.

[0039] The device according to the invention is capable of heating up to 800 ml / min of aqueous rinsing liquid from room temperature (20°C) to 38°C.

[0040] The device according to the invention has several advantages over the prior art. First, the device according to the invention is easy to integrate into existing medical equipment. The device can be used in addition to existing pump systems (e.g., a roller pump), which can continue to be operated in the usual way. Alternatively, the device according to the invention can also be used as a " stand-alone "-solution can be used. In this case, the liquid flows from an elevated storage container through the heat exchanger body to the medical instrument, e.g. endoscope, solely by gravity ("gravitational conveyance").

[0041] By using disposable heat exchanger bodies, the necessary safety, especially sterility, can be easily ensured. The manufacturing costs of the heat exchanger bodies are relatively low.

[0042] Furthermore, the device according to the invention only heats the portion of the rinsing liquid that is immediately ready for use. The device according to the invention thus avoids, for example, the need to heat the entire rinsing liquid reservoir, which would negatively impact the stability of the solution.

[0043] In particular, the design with integrated bypass also enables highly precise regulation of the liquid temperature even with strongly alternating liquid flow.

[0044] As already mentioned above, the device according to the invention can also be used for flow-through cooling. Such cooling is advantageous, for example, for use in arthroscopy in order to minimize swelling, bleeding, and the patient's perception of pain. For this purpose, the rinsing fluid can be cooled to a few degrees above freezing point (e.g. 1-10°C, preferably 2-5°C). In this embodiment of the invention, a flat cooling element is used instead of a flat heating element. This can be a flat, compressor-driven cooler. Alternatively, a coolant can also be used for cooling. In a further embodiment of the invention, a Peltier element can also be used. In the embodiment with such a Peltier element, both cooling and heating can be achieved by reversing the current flow (polarity reversal).

[0045] As mentioned above, the cooling of the heat exchanger body preferably takes place from above. Of course, it is also possible to cool multiple sides, e.g., the base and top surfaces of a cuboid heat exchanger body. The other alternative embodiments of the invention described above can be used in a completely analogous manner in the cooling embodiment, such as temperature measurement and / or flow measurement. A "bypass" design is also possible in a similar manner to admix flushing fluid at room temperature if necessary.

[0046] In a further possible embodiment of the invention, the heat exchanger body can also be heated and cooled from two different sides (e.g., base and top). For example, it is conceivable to equip the housing with a heating element on one side (e.g., the underside) and a cooling element on another side (e.g., the top). When using a heat exchanger body with two heat-conducting walls, cooling or heating can occur depending on the operating mode. Under certain circumstances, it may even be expedient to operate a device according to the invention with the ability to cool and heat in order to be able to regulate the fluid temperature more quickly, more effectively, and / or more precisely. Explanation of the figures

[0047] Figure 1shows the basic shape of a heat exchanger body (1) according to the invention in plan view (top) and perspective view (bottom). The heat exchanger body housing is essentially cuboid-shaped, with two connections shown as inlets (2) and outlets (3). Figure 2shows a special embodiment of the heat exchanger body (1) with a bypass (11). The bypass is separated from the rest of the volume within the body by a partition (7). The heat exchanger body has deformable elements (8, 9) at at least two points, which regulate the flow through the main part and the bypass, respectively, in the manner of a pinch valve. Temperature sensors are also provided to measure the temperature of the inlet (6) and the outlet (10). Furthermore, a flow meter based on the Venturi principle is shown: for this purpose, a constriction (4) is formed in the inlet. Pressure sensors in or downstream (5) of the constriction allow the fluid flow to be calculated by determining the differential pressure. Figure 3This diagram schematically shows the use of the device according to the invention: The fluid reservoir is fed into the heat exchanger body via a hose, which is located in the housing with the surface heating device. Another hose is connected to the outlet of the heat exchanger body, which leads to the roller pump. The instruments leading to the patient are located at the outlet of the roller pump. The figure clearly shows that the device according to the invention is suitable as a simple supplement to existing medical equipment. Figure 4 shows a cross-section of a heat exchanger body with a sawtooth-shaped design of the top surface (top) or a wave-shaped design of the bottom (bottom). The flow through such a heat exchanger body leads to a swirling of the liquid, resulting in better heat transfer. Figure 5shows a cross-section of a heat exchanger body with a trapezoidal shape (top) and molded-on guide rails (14) (bottom). In combination with the complementary housing opening, faulty insertions can be reliably prevented. Figure 6 shows heat exchange bodies with different geometries, such as round (top) or hexagonal (bottom).

Claims

1. A device for tempering the flow of medical irrigation liquids, including a heat exchange body (1) with at least one inlet and outlet (6, 10) each having a tube port, wherein the heat exchange body forms a closed cavity through its heat exchange body walls, wherein at least one heat exchange body wall has a heat transfer coefficient greater than 1W / (cm2 K), wherein the heat exchange body has two current paths, wherein the two current paths are formed on the inside of the heat exchange body through shaping of the heat exchange body base, wherein one current path has no thermal contact with the tempering element, wherein the heat exchange body walls are reversibly shaped at least in places so that the current paths are controllable depending on the shape, wherein the device includes a temperature sensor for controlling the outlet temperature of the irrigation liquid, wherein, via the current path that has no thermal contact with the tempering element, untempered irrigation liquid can be added in a targeted manner in order to maintain a constant temperature at the heat exchange body outlet, the device further including at least one surface tempering element which matches the heat exchange body, wherein the surface tempering element is integrated into a housing with an opening, wherein the heat exchange body wall with a heat transfer coefficient greater than 1W / (cm2 K) is in contact with the surface tempering element in the operating position.

2. The device according to Claim 1, characterized by a substantially parallelepiped shape of the heat exchange body.

3. The device according to Claim 1, characterized in that the wall providing the heat transfer is formed by an aluminum foil.

4. The device according to Claim 1, characterized in that the surface tempering element is formed by a heating foil.

5. The device according to Claim 1, characterized in that the housing has at least one contact thermometer which, in the operating position of the device, rests on the wall providing the heat transfer.

6. The device according to Claim 1, characterized in that the housing has a vacuum pump which generates an underpressure between the heat exchange body wall and the tempering element.

7. The device according to Claim 6, characterized in that said underpressure between the heat exchange body wall and the tempering element is 0.05 to 0.3 bar, preferably 0.1 bar.

8. The device according to Claim 1, characterized in that at least one heat exchange body wall has superficial structuring.

9. The device according to Claim 1, characterized in that the heat exchange body has a constriction of the current cross-section in the area of the inlet and / or outlet, wherein one measuring location for pressure measurement is set up in each of the constriction as well as before and / or after the constriction.

10. The device according to Claim 1, characterized in that the housing has at least one sensor for thermal flow measurement in the area of the inlet and / or outlet of the heat exchange body in the operating position, wherein the sensor for thermal flow measurement includes a heating element and a temperature sensor.