BLOOD-DEGASSING APPARATUS AND BLOOD-TREATMENT SYSTEM

Abstract

The invention relates to a degassing devive (25) for degassing blood, comprising a blood chamber (1, 1a, 1b) with a blood inlet (2) and a blood outlet (3), via which blood can be guided/is guided through the blood chamber (1, 1a, 1b), at least one underpressure chamber (11) with an underpressure attachment (8) via which the at least one underpressure chamber (11) is provided with an underpressure, at least one semipermeable membrane (4, 4a), which is arranged between the at least one underpressure chamber (11) and the blood chamber (1), wherein the blood chamber (1) comprises a first and a second sub-chamber (1a, 1b) which are arranged next to each other in a direction perpendicular to the direction of gravity, and a bridging region (9) which connects the two subchambers (1a, 1b) at their upper ends, wherein the blood inlet (2) is arranged in the lower region of the first subchamber (1a), and the blood outlet (3) is arranged in the lower region of the second subchamber (1b). The invention also relates to a system for extracorporeal treatment of blood.

Claims

1. A degassing apparatus for removing dissolved gas or gas bubbles from blood, the apparatus comprising: a blood chamber having a blood inlet and a blood outlet conducting blood conducted through the blood chamber; a subatmospheric-pressure chamber, having a subatmospheric-pressure connection; means connected to the connection for evacuating the subatmospheric-pressure chamber through the connection; and a semipermeable membrane between the subatmospheric-pressure chamber and the blood chamber that is in particular permeable to gas and impermeable to blood, the blood chamber having an upstream and a downstream subchamber that are next to one another in a direction perpendicular to the direction of gravity; and a bridging subchamber that is part of the subatmospheric-pressure chamber and that connects the upstream and downstream subchambers at upper ends thereof, the blood inlet being in a lower region of the upstream subchamber, and the blood outlet being in a lower region of the downstream subchamber.

2. The degassing apparatus according to claim 1, wherein the subchambers are relatively oriented such that the blood in the upstream subchamber flows at least on average parallel counter to the direction of gravity and, in the downstream subchamber, flows at least on average parallel in the direction of gravity.

3. The degassing apparatus according to claim 1, wherein a subregion of an upper wall region of the bridging subchamber is formed by a semipermeable flat membrane whose one side faces into the blood chamber and whose opposite side faces away from the subatmospheric-pressure chamber.

4. The degassing apparatus according to claim 1, further comprising: a gassing device generating oxygen bubbles at the blood inlet of the blood chamber.

5. The degassing apparatus according to claim 1, further comprising: a bundle of semipermeable fiber tubes in the blood chamber and having outer surfaces contacted by blood, and interiors connected to or forming a part of one of the subatmospheric-pressure chambers.

6. The degassing apparatus according to claim 1, further comprising: a bundle of semipermeable fiber tubes in the subatmospheric-pressure chamber and having outer surfaces acted upon by subatmospheric pressure and interiors contacted by blood, the interiors of the fiber tubes forming at least a portion of the blood chamber.

7. The degassing apparatus according to claim 1, further comprising: an oxygen supply opening into the subatmospheric-pressure chamber that in particular is configured to supply the subatmospheric-pressure chamber continuously with oxygen, while maintaining a subatmospheric pressure.

8. A system for the extracorporeal treatment of blood, comprising: a blood-drawing implement; a blood-return implement; a blood-conducting tube; a blood pump; an oxygenator between the implements such that blood can be pumped through the oxygenator by the blood pump; and a degassing apparatus according to claim 1 whose blood outlet opens into the blood-conducting tube between the implements, the system being configured to conduct a subflow of the overall blood flowing between the implements through the degassing apparatus.

9. The system according to claim 8, further comprising: an inflow line having a second blood pump that aspirates blood loaded with gas bubbles from a surrounding area of a surgical site, the inflow line opening into the blood inlet of the degassing apparatus.

10. The system according to claim 8, wherein the blood outlet of the degassing apparatus opens into a blood inlet of the oxygenator.

11. The system according to claim 8, further comprising: means for generating subatmospheric pressure in the subatmospheric pressure chamber of the degassing apparatus as a function of the operation of the second blood pump in the inflow line such that a subatmospheric pressure is automatically generated in the subatmospheric-pressure chamber as soon as, or before, the second blood pump starts to operate and an ambient pressure s formed in the subatmospheric-pressure chamber as soon as, or after the second blood pump has stopped operating.

Description

[0049] Preferred embodiments of the invention are described below with reference to the figures in which:

[0050] FIG. 1 shows a first possible embodiment of a degassing apparatus according to the invention, having a blood chamber 1 through which blood can be conducted from a blood inlet 2 to a blood outlet 3.

[0051] A plurality of semipermeable fiber tubes 4 are in the blood chamber 1, the outsides of the fiber tubes being in contact with the blood in the blood chamber 1, and the tube interiors being placed under subatmospheric pressure by at least one vacuum pump 5. For this purpose, all open ends of the fiber tubes can collectively open into a chamber that is at subatmospheric pressure that here, in particular, is placed under subatmospheric pressure via at least one subatmospheric-pressure connection 8, two subatmospheric-pressure connections being shown here, per vacuum pump 5. The sum of all inner volumes of the fiber tubes 4 and of the described chamber into which these open forms the subatmospheric-pressure chamber within the meaning of the invention. Each fiber tube 4 forms a semipermeable membrane.

[0052] In addition, here a semipermeable, and preferably microporous, flat membrane 4a is in the blood inlet region of the blood chamber 1 and separates the blood chamber 1 from a further subatmospheric-pressure chamber 11 evacuated by a further vacuum pump 5. The flat membrane 4a can have a longitudinal extension that corresponds to the lengths of the fiber tubes 4.

[0053] It is furthermore shown here that oxygen is introduced into the subatmospheric-pressure chamber via an oxygen supply 7 so that the subatmospheric atmosphere predominantly contains oxygen, having the advantages described above.

[0054] The apparatus shown in FIG. 1 can be formed by an oxygenator or a dialyzer, to which a vacuum pump 5 is connected, for example at the gas outlet or outlets 8. This gas outlet 8 thus forms the subatmospheric-pressure connection 8.

[0055] FIG. 2 shows a preferred embodiment in which the blood supply 2 and the connections of the vacuum pump 5 and the oxygen supply 7 are reversed. Accordingly, compared to FIG. 1, the blood moves through inside the fiber tubes 4 here, and the subatmospheric pressure is present on the outside of the fiber tubes 4. Otherwise, the function is identical to FIG. 1. In this respect, the blood chamber 1 here is formed by the sum of the inner volumes of the fiber tubes 4, and the subatmospheric-pressure chamber 11 is formed by surrounding volume that in particular is delimited by the outer housing of the apparatus.

[0056] FIG. 3 shows an embodiment in which the blood chamber 1 of the degassing apparatus is divided into two subchambers 1a and 1b offset transversely to the direction of gravity, that is horizontally, next to one another, and the blood flow in each of the subchambers takes place on average parallel to the direction of gravity, namely upwardly from the blood inlet opposite the direction of gravity in the subchamber 1a, and in the direction of gravity to the blood outlet 3 in the subchamber 1b.

[0057] The upper ends of the subchambers 1a and 1b are connected by a substantially horizontal bridging subchamber 9 in which the blood is transferred basically horizontally from the upstream subchamber 1a to the downstream subchamber 1b.

[0058] This bridging subchamber 9 is divided by a semipermeable membrane 10, for example a flat membrane, into a lower region that is part of the blood chamber, that is through which blood flows, and an upper region that forms the subatmospheric-pressure chamber 11 to which the vacuum pump 5 is connected.

[0059] As a result of the subatmospheric pressure, the membrane 10 is upwardly curved and, in the upper region of the curvature, forms the highest point of blood flow in the blood chamber. Existing gas bubbles will thus collect here, due to buoyancy, and are eliminated. Gas bubbles not eliminated continue to be prevented from flowing out of the blood chamber in that the gas bubbles, by virtue of the buoyancy thereof, are prevented from flowing downward in the downstream subchamber 1b, and thus remain in the blood chamber until these are completely eliminated.

[0060] FIG. 4 shows a refinement of the embodiment of FIG. 3. In this embodiment, semipermeable fiber tubes 4 are at least in the downstream subchamber 1b as already described with regard to FIG. 1. Subatmospheric pressure is applied to them internally, and blood flows outside around them.

[0061] Accordingly, this degassing apparatus comprises a blood chamber including the two subchambers 1a and 1b and the bridging subchamber 9, as well as two subatmospheric-pressure chambers, namely one subatmospheric-pressure chamber 11 above the membrane 10 in the bridging subchamber 9, and one that is formed of the sum of the inner volumes of the fiber tubes 4, and where applicable also in a chamber region into which the open ends of the fiber tubes 4 lead.

[0062] Both subatmospheric-pressure chambers can be evacuated by separate vacuum pumps or another subatmospheric pressure source.

[0063] It may also be in the embodiments of FIGS. 3 and 4 that oxygen is supplied to the subatmospheric-pressure chamber(s) so as to form therein an atmosphere that predominantly, or exclusively, contains oxygen.

[0064] FIG. 4 furthermore shows that there is the option of integrating an oxygen supply 12 into the region of the blood inlet 2 so that oxygen bubbles 13 for oxygenation of the blood can be formed. For example, a frit filter passing incident oxygen flow may be provided here. Remaining oxygen bubbles are then removed again in the upper transition region.

[0065] FIG. 5 shows an embodiment in which semipermeable fiber tubes 4 are provided both in the upstream subchamber 1a and in the downstream subchamber 1b. Otherwise, the embodiment is identical to that of FIG. 4, however without oxygen supply into the blood chamber that, however, could also be provided.

[0066] This embodiment thus results in a total of 3 subatmospheric-pressure chambers that can be evacuated by three vacuum pumps 5.

[0067] Instead of the blood flowing around the fiber tubes 4, and the subatmospheric pressure prevailing in the fiber tubes 4, it is also possible in the embodiments of FIGS. 4 and 5 for the blood to flow in the fiber tubes 4, and the subatmospheric pressure to be present around the outside of the fiber tubes. The latter is the preferred embodiment of the designs of FIGS. 4 and 5. This does not result in any visual difference in FIGS. 4 and 5.

[0068] FIGS. 6a and 6b show a possible system that can be used when carrying out surgery on a creature, such as a human. [The system comprises]

[0069] The system comprises a blood-drawing implement, for example a cannula 20 through which venous blood is withdrawn from the patient P and conducted in a blood-conducting tube 21 through a blood pump 22 and an oxygenator 23 to a blood-return implement, for example another cannula 24. In this way, a blood circuit is formed for oxygenating the pumped blood.

[0070] A subflow of the blood is withdrawn from the tube 21 upstream of the oxygenator 23 and conducted through the degassing apparatus according to the invention that is denoted here generally by reference numeral 25 and corresponds to one of the apparatuses described with respect to FIGS. 1 to 5, even though the apparatus according to FIG. 5 is shown here.

[0071] The degassed blood is returned into the tube 21 here, and more particularly, in this embodiment, downstream of the oxygenator. The degassing apparatus thus forms a bypass and blood flows through it continuously.

[0072] FIG. 6a shows an application in which the degassing apparatus 25 is not evacuated by the vacuum pump 5. It is not connected to the subatmospheric-pressure chamber, for example.

[0073] FIG. 6b shows an application in which blood is drawn off from a surgical site using a blood pump 26 and an inflow line 27 that can thus contain gas bubbles of ambient air. This blood is conducted via the inflow line 27 into the blood inlet 2 of the degassing apparatus 25 and is there stripped of gas bubbles, whereupon the blood is conducted out of the blood outlet 3 downstream of the oxygenator into the tube 21. The degassed blood is thus conducted past the oxygenator.

[0074] Only one blood pump 22 is required in the circuit of the tube 21 for this embodiment, since the bypass flow through the degassing apparatus 25 is achieved by the pressure drop across the oxygenator 23.

[0075] Also, a blood-storing reservoir 21a can be configured in the tube 21 in the system; however this is not essential for the invention.

[0076] FIGS. 7a and 7b show a system like that of FIG. 6, however with the difference that the subflow of the blood conducted in the circuit that is conducted through the degassing apparatus 25 is returned back into the tube 21 downstream of the degassing apparatus 25, upstream of the oxygenator 23. For this reason, the subflow through the degassing apparatus has to be pumped through the degassing apparatus 25 using an additional blood pump 28, but offers the advantage that the degassed blood can also be enriched with oxygen by the oxygenator 23.

[0077] FIG. 7a again shows the application in which the degassing apparatus is only operated in the partial through-flow, without subatmospheric pressure in the subatmospheric-pressure chamber being switched on. FIG. 7b shows the blood being pumped off the surgical site, as in FIG. 6b. Accordingly, the aspirated blood containing bubbles is conducted via the inflow line 27 into the blood inlet 2 of the degassing apparatus 25 here as well.

[0078] FIG. 7b also shows an embodiment in which a controller 29 is provided that can operate the blood pump 26 for aspirating blood from the surgical site and the vacuum pump 5 for generating the subatmospheric pressure in the subatmospheric-pressure chamber of the degassing apparatus 25 independently of one another.

[0079] Such a controller can be configured in such a way that the blood pump 26 for example does not start to suction, that is, does not start to operate, until the vacuum pump 5 has already started to operate and a subatmospheric pressure for eliminating bubbles has already been reliably formed in the degassing apparatus. The controller can also cause the vacuum pump to only stop operating when the blood pump 26 is switched off and is no longer pumping. Other operating dependencies can also be stored in this regard. Such a controller can also be provided in the system according to FIG. 6; however this is not shown there.