An apparatus for extracorporeal blood treatment

Apparatus for the treatment of extracorporeal blood

Background of the invention

The present invention relates to an apparatus for the treatment of extracorporeal blood.

5 Specifically, but not exclusively, the invention can be usefully applied in an apparatus for treating renal insufficiency (hemodialysis and / or heme (day) filtration).

In particular, the invention relates to an extracorporeal blood treatment apparatus as defined in the preamble of claim 1.

In US 4371385 and US 4348280 an apparatus of this type is disclosed, which describes a machine of

10 dialysis equipped with means for the continuous preparation of dialysate by mixing water with dialysis concentrate. The dialysis machine includes a device for removing and minimizing gas in the dialysis fluid, as well as means for controlling the pressure and flow rate of the dialysate in the dialyzer. The means for controlling comprise a first flow rate limiter that is located upstream of the dialyzer and a second flow limiter located downstream of the dialyzer. The degassing device comprises a degassing tank that

fifteen It is continuously at a negative pressure supplied by two pumps: the first pump that removes gas from the tank and the second one that removes degassed water from the tank. Therefore, the pressure in the degassing tank is not related to the speed of dialysate. The first gas pump is a constant speed pump that produces a negative pressure in the degassing tank that is not affected by the flow rate of the liquid to be degassed. The first gas pump is arranged in the drain pipe that connects the day outlet

twenty Lizer to download. Therefore, the first pump is useful both to apply a negative pressure in the degassing tank and to aspirate the dialysis fluid used from the dialyzer. The prior art machine mentioned above has the disadvantage that it cannot allow a precise control over the amount of gas that has been removed from the dialysis liquid, nor a regulation of the percentage of gas contained in the dialysis liquid that operates within of the dialyzer. An additional drawback is that it cannot estimate the variation in flow rate

25 of fluid through the vent tube of the degassing tank.

Summary of the invention

One purpose of the invention is to provide an apparatus for the treatment of extracorporeal blood provided with a system for fluid aspiration, an apparatus that is independent of the operating conditions (particularly pressure and flow rate of treatment fluid) in the treatment device. of blood.

30 A further purpose of the invention is to provide a device that is simple and economical from a construction point of view.

An advantage of the invention is that it provides an apparatus whose operating conditions are not affected by the situation (especially by the pressure level) in the discharge of the used treatment fluid.

The invention also has the advantage of providing, in a blood treatment apparatus, an aspiration system

35 of fluid that is highly versatile, reliable, efficient, easily adaptable to many possible uses, among which the evacuation of the liquid used for cleaning by tangential discharge of the ultrafilters, or the evacuation of fluids from various parts of the apparatus (such as the gas evacuation of the degassing system upstream and / or downstream of the blood treatment device, or the evacuation of liquid and gas from the extracorporeal circuit during the priming phase).

40 An additional advantage of the invention is that it provides a device that is equipped with a protection system for the hydraulic circuit against any possible pressure change in the discharge of used treatment fluid.

All these objectives and more are achieved by the invention as characterized in one or more of the following claims.

The additional features and advantages of the present invention will be better apparent from the following description.

Four. Five detailed of at least one preferred but not exclusive embodiment of the invention, which is described by way of non-limiting example in the accompanying figures of the drawings.

Brief description of the drawings

Reference is made in the following description to the accompanying drawings, which are provided by way of example and therefore do not have a limiting purpose and in which Figure 1 schematically shows the apparatus of the invention.

Detailed description

In figure 1, 1 indicates in its entirety an apparatus for the treatment of extracorporeal blood. In this specific case, the apparatus is an apparatus for treating renal failure, more particularly a hemodialysis apparatus. The invention can be used in any kind of hemodialysis and / or heme (dia) filtration apparatus. In this specific case, in order to provide a clear and simple explanation, not all components of a hemodialysis or heme (dia) filtration apparatus, such as the disinfection system, the blood loss detection system, will be explicitly described. , the monitoring and control system for the various parameters of the device (such as temperature, conductivity, pH, pressure, etc. in the dialysis fluid), the replacement fluid infusion system in case of heme (day) filtration, etc.

The apparatus 1 comprises a blood treatment device 2 (dialyzer or heme (dia) filter) having a blood chamber 3, a fluid chamber 4 and a semipermeable membrane 5 separating the blood chamber 3 from the chamber 4 fluid.

The apparatus 1 comprises a circuit of extracorporeal blood of the prior art that is known and indicated in its entirety by 6, to connect the blood chamber 3 to a vascular access of a patient (not shown) during the treatment. The extracorporeal circuit 6 comprises any extracorporeal circuit that can be used for blood circulation in a hemodialysis and / or heme (dia) filtration apparatus. In particular, the extracorporeal blood circuit comprises an arterial blood tube to remove blood to be treated from the vascular access and send it to chamber 3, and a venous blood tube to return the treated blood from the blood chamber 3 to the vascular access Each blood tube (arterial or venous) comprises a device end with a connection to the blood chamber 3 and a patient end with a connection to the vascular access. Each blood tube (arterial and venous) also has the various elements (expansion chambers, clamping elements, service tubes, syringe accesses, etc.) of which a blood tube is normally provided; This description does not describe these elements in order to provide a short and clear explanation. Figure 1 shows circuit 6 of extracorporeal blood in a priming configuration.

The apparatus 1 comprises a fluid tube 7 used to connect the fluid chamber 4 to a used fluid discharge. A first actuator is predisposed in the used fluid tube. The first actuator is in particular a first fluid circulation pump 8 which, when it works, can change the pressure and flow rate of the fluid flowing through the fluid chamber 4. This first pump 8 is a positive displacement pump (for example, a gear pump).

A second actuator is disposed in the fluid tube 7 used downstream of the first actuator. The second actuator is, in this case, a second fluid circulation pump 9, in particular a positive displacement pump (for example, a gear pump). The second actuator, which is arranged in series with the first actuator along the tube 7, can, in particular, vary a pressure in an intermediate section of the used fluid tube 7, that is, in the section between the first and the second actuator

The apparatus 1 comprises a first pressure sensor 10 designed to emit a pressure signal indicating pressure in the aforementioned intermediate section of the used fluid tube 7. In the specific case, the pressure sensor 10 is arranged along the fluid tube 7 used upstream of the second pump 9.

The apparatus 1 comprises a control unit (not shown) programmed to control the second pump 9 according to the pressure signal described above. In particular, the control unit controls the second pump 9 in feedback to maintain the pressure upstream of the second pump 9 at a desired value; the desired value may change according to the need, situation or mode of operation of the device; In addition, the desired pressure value can be constant or can be changed according to predetermined criteria.

The apparatus comprises a new fluid tube 11 for connecting a source of a treatment fluid to the fluid chamber 4 and / or to the extracorporeal blood circuit 6 (depending on whether the treatment is hemodialysis or heme (dia) filtration). In this particular case, the new fluid tube 11 is connected to a device for preparing a treatment fluid, which is shown schematically and is globally referred to as 12. The preparation device can be any device for preparing a treatment fluid (such as a substitute or dialysis fluid). In particular, the preparation device 12 is specially designed to prepare a treatment fluid by mixing water with liquid and / or solid concentrates. The new fluid tube 11, in this case, has an initial section that connects the preparation device 12 to a water source. The initial section is equipped with a first ultrafilter 13 having a retention chamber (upstream chamber) connected to a source of a fluid to be ultrafiltered (water), a filtration chamber (downstream chamber) connected to chamber 4 of fluid through the preparation device 12, and a semipermeable membrane, for example, of the type of hollow fiber bundle that separates the retention chamber from the filtering chamber. The apparatus 1 comprises a pressure regulator (not shown) predisposed in the new fluid tube 11 before the first ultrafilter 13. The pressure regulator controls the downstream pressure at a predefined pressure. The pressure regulator maintains the downstream pressure at the preset pressure regardless of the upstream pressure (i.e., the pressure in the water source). The pressure regulator can control the downstream pressure by restricting the flow. The pressure regulator can be manually adjusted to the predefined downstream pressure. The device 1 buy

furthermore an inlet valve (not shown) disposed in the new fluid tube 11 between the pressure regulator and the first ultrafilter 13. The inlet valve is normally closed and opens to allow water supply.

The apparatus 1 also comprises a heat exchanger 14 predisposed after the first ultrafilter 13 in order to recover heat from the used treatment fluid. After the heat exchanger 14 the new fluid tube 11 has a degassing loop (and heating) of the fluid (water) that includes a heater 15, a degassing pump 16, and a first liquid-gas separator 17 (degassing chamber ). A temperature sensor (not shown) controls the heater 15. A degassing shutter (not shown) causes a reduction in water pressure and subsequently an easier degassing of water in the separator 17. In the main tube (new fluid tube 11) a check valve 18 prevents fluid flow from a first branch point (removal of water to be degassed) from the degassing loop to a second branch point (water return degassed) of the same loop located upstream of the first branch. The new fluid tube 11 is further provided with a supply pump 19 (for example, of the gear pump type) for circulating fluid in the same tube to the fluid chamber 4. A second liquid-gas separator 20 (degassing chamber) is disposed in the tube 11 downstream of the preparation device 12 for degassing the treatment fluid. A first flow sensor 21 is located downstream of the second separator 20 to emit a signal indicating the flow rate in the new fluid tube 11. A second ultrafilter 22 is arranged before the fluid chamber 4 in order to ultrafiltrate the treatment fluid. A first diversion tube 23 is disposed upstream of the second ultrafilter 22, while a second diversion tube 24 is disposed downstream of the second ultrafilter 22. Each diversion tube 23 and 24 avoids the fluid chamber 4 and puts the new fluid tube 11 in communication with the used fluid tube 7. Each bypass tube 23, 24 is provided with a bypass valve (in this particular case a three-way valve in order to selectively open or close the bypass tube and the main tube). An upstream pressure sensor 25 and a downstream pressure sensor 26 are predisposed to measure the pressure respectively at the inlet and outlet of the fluid chamber 4. An all-nothing valve 27 can close the outlet of the fluid chamber 4 at the order of the control unit.

A second flow sensor 28 is predisposed to send to the control unit a signal indicating the fluid flow rate in the used fluid tube 7. The control unit operates the first pump 8 according to the flow rate signal emitted by the second sensor 28 in order to achieve a desired fluid balance in the treatment device 2. The fluid balance depends, as is known, on the fluid flow rate through the membrane 5 (ultrafiltration rate), which results from the difference between the flow rates measured by the flow sensors 28 and 21 . In order to achieve the desired fluid balance, the speed signal emitted by the first sensor 21, as is known, can be used to control the supply pump 19 or the first pump 8. A third liquid-gas separator 29 (degassing chamber) is disposed in the fluid tube 7 used upstream of the second flow sensor 28. The used fluid tube 7 is also provided with an all-nothing valve 30 located downstream of the second pump 9.

The apparatus 1 comprises a fluid balance control device or fluid balance system to control the ultrafiltration rate through the membrane 5. The fluid balance system includes, in this case, the first flow meter 21, the second flow meter 28 and the first pump 8. In other embodiments (not shown) the fluid balance system may be of a different type (known), for example, a system comprising a compensation device (with volumetric compensation chambers or with compensation flow meters or other type) and an ultrafiltration tube that avoids the compensation device.

The intermediate section of the tube 7 between the first pump 8 and the second pump 9 is maintained at a desired pressure by controlling the second pump 9 according to the signal emitted by the pressure sensor 10. The intermediate section is connected or designed to be connected to various elements of the apparatus 1. First, the intermediate section mentioned above is connected to an outlet of the retention chamber of the first ultrafilter 13 through a tangential discharge cleaning tube 31 . The discharge cleaning tube 31 is used for the tangential washing of the first ultrafilter

13. A discharge cleaning valve 32, arranged in the discharge cleaning tube 31, is periodically opened in order to carry out the tangential washing. Secondly, the intermediate section is connected to a gas outlet (ventilation) of the first separator 17 through a first ventilation tube 33 provided with a first ventilation valve 34. The intermediate section is further connected to a gas outlet (ventilation) of the second separator 20 through a second ventilation tube 35, provided with a second ventilation valve 36. The intermediate section mentioned above is also connected to a gas outlet (ventilation) of the third separator 29 through a third ventilation tube 37 provided with a third ventilation valve 38. The various ventilation tubes 33, 35, 37 are connected to the intermediate section through a single limiting shutter 39, which serves all the tubes. The shutter 39 is formed by a fixed precalibrated section constraint. The various ventilation tubes 33, 35, 37 are attached to the discharge cleaning tube 31 to form a single main branching tube 40 that branches from a branching point of the used fluid tube 7, the branching point of the fluid tube 7 used between the second flow sensor 28 and the second pump 9. Each ventilation valve 34, 36, 38 opens and closes according to a predetermined rule (for example, periodically or depending on the level of liquid or the pressure level in the corresponding separator 17, 20, 29). The branching tube 40 is provided with a check valve 44 to prevent return flow to the separators and the ultrafilter.

The intermediate section between the pump 8 and pump 9 is further connected to a connection hole 41 suitable for connection to an access hole 42 to the extracorporeal circuit 6. The connection between hole 41 and hole 42 is a co

hermetic connection The connection between hole 41 and hole 42 is removable. The connection between hole 41 and hole 42 includes the connection disclosed in US Patent No. 5,041,215 between drain 32 and, respectively, priming plug 44 (reference numbers as mentioned in US Pat. No. 5,041,215). (The connection between the hole 41 and the hole 42 may include, in other embodiments not shown, a screw connection, particularly of the luer type, or other known removable connections). The connection hole 41 is arranged in the external panel of the hemodialysis or heme (dia) filtration apparatus. The access hole 42 comprises, in this particular case, a connection located at a patient end of one of the blood tubes of the extracorporeal circuit 6, for example, the arterial tube or the venous tube. Alternatively, the access hole 42 may be a connection arranged in a branching relationship with the arterial or venous blood tube. The access opening 42 may be, for example, a connection arranged in a service tube connected to the arterial tube or to the venous tube; in particular, the service tube can be connected to an arterial or venous blood expansion chamber. The configuration in which the holes 41 and 42 are connected to each other (as in Figure 1) is particularly used in the priming phase of the extracorporeal circuit in order to carry out the evacuation of fluid (air and part of the priming liquid used) through the discharge of the treatment apparatus 1. In this case, the second pump 9 is used for the aspiration of both the air and the used priming liquid. The connection hole 41 is connected to a discharge tube 43 that branches from a branch point of the used fluid tube 7, the branch point being located between the second flow sensor 28 and the second pump 9. The priming liquid can be obtained by connecting the extracorporeal circuit to a priming liquid container (for example, a saline bag), or by retro-filtering a sterile liquid (eg, dialysis fluid) from the fluid chamber 4 to the chamber 3 of blood. In the case of retrofiltration, a difference in pressure is generated between the fluid chamber 4 and the blood chamber 3, for example, by aspiration by means of the second pump 9 and / or by aspiration using a blood pump associated with the 6 extracorporeal circuit.

The second fluid circulation pump 9 is disposed along the main path of the treatment fluid used. The second pump 9 is arranged in series with the first pump 8. The inlet of the second pump 9 is designed to receive the used fluid (all the amount or essentially all the amount of the fluid used, possibly less weight loss) from the output of the first pump 8. The second pump 9 does not control ultrafiltration through the membrane 5. The second pump 9 is not responsible for fluid balance. The second pump 9 is not part of the fluid balance system of the apparatus. The second pump 9 is located downstream of the first pump 8. The second pump 9 is located between the discharge of used fluid and the first pump 8. The second pump 9 is used to protect the hydraulic circuit of the apparatus 1 from any possible pressure change in the discharge of used fluid. In particular, the second pump 9 has a protective role of the fluid balance system, the gas evacuation system of the circuit, the ultrafilter discharge cleaning system and the used priming liquid evacuation system. In summary, the second pump 9 acts to disengage the discharge of the used fluid tube 7 (whose conditions are sometimes uncontrollable, unpredictable, considerably changing from one clinic to another) of the various operating elements of the apparatus 1, so that any Change of discharge pressure does not disturb the rest of the device 1. For example, the second pump 9 can maintain the pressure measured by the sensor 10 at a constant level (for example, about 0 mmHg during the treatment), or it can act so that a pressure change occurs according to a predetermined sequence (in in particular, with negative values, that is, values ​​below 0 mmHg, in the priming phase of the extracorporeal circuit 6). The second pump 9 operates in order to maintain a constant pressure, particularly at a predetermined value (for example, approximately 0 mmHg), at the branch point of the communicating fluid tube (s). with one or more operating elements of the apparatus, wherein the operating elements may comprise a gas liquid separator of the treatment fluid circuit, a blood tube or an extracorporeal circuit service tube, an ultrafilter of the treatment fluid circuit, etc.

In a further embodiment (not shown), the heat exchanger 14 is also arranged upstream of the second pump 9, so that it disengages from, and therefore is not disturbed by, what happens in the discharge.

The second pump 9 facilitates the ventilation of the separators 17, 20, 29. This keeps the pressure at a relatively low level in the entire hydraulic circuit of the apparatus. In particular, this keeps the pressure at a relatively low level at the inlet of the new fluid tube 11 (which is located upstream of the first ultrafilter 13, after the inlet connection connected to the municipal water supply that provides water at a relatively pressure high). The inlet pressure is set by a pressure regulator (usually a known pressure reducer, not shown in Figure 1) at a constant preset value that is high enough to allow the above-mentioned separators to let air pass. The suction action of the second pump 9 makes it possible to preset a relatively low value in the pressure regulator.

In a further embodiment (not shown), the supply pump 19 is disposed in the new fluid tube 11 downstream of the second gas-liquid separator 20. The supply pump 19 is disposed between the separator 20 and the first bypass tube 23, or between the separator 20 and the first flow sensor 21, or between the separator 20 and the fluid balance system, or between the first sensor 21 of flow (or the fluid balance system) and the first bypass tube 23, or between the fluid balance system and the first bypass tube 23.

Legend:

extracorporeal blood treatment apparatus

blood treatment device

blood chamber

fluid chamber

semipermeable membrane

extracorporeal blood circuit

used fluid tube

first fluid circulation pump

second fluid circulation pump

first pressure sensor

new fluid tube

treatment fluid preparation device

first ultrafilter

heat exchanger

heater

degassing pump

first gas-liquid separator

retention valve

supply pump

second gas-liquid separator

first flow sensor

second ultrafilter

first deflection tube

second deflection tube

upstream pressure sensor

downstream pressure sensor

all-nothing valve

second flow sensor

third gas-liquid separator

all-nothing valve

tangential discharge cleaning tube

discharge cleaning valve

first vent tube

first vent valve

second vent tube

second vent valve

<dl><dt>37 </dt><dd>third vent tube </dd></dl>

<dl><dt>38 </dt><dd>third vent valve </dd></dl>

<dl><dt>39 </dt><dd>limiting shutter </dd></dl>

<dl><dt>40 </dt><dd>branching tube </dd></dl>

<dl><dt>5 </dt><dd>41 connection hole </dd></dl>

<dl><dt>42 </dt><dd>access hole </dd></dl>

<dl><dt>43</dt><dd> discharge tube </dd></dl>

<dl><dt>44 </dt><dd>retention valve</dd></dl>