HK1098082B - Integrated blood treatment module - Google Patents

Description

Integrated blood treatment module

Technical Field

The present invention relates to an integrated extracorporeal blood treatment circuit, and more particularly to an integrated extracorporeal blood treatment circuit that utilizes a filter for extracorporeal blood treatment.

Background

Filters are used for various extracorporeal treatments of blood, such as hemodialysis, hemofiltration, hemodiafiltration, plasmapheresis. The same type of filter, commonly referred to as a hemodialyzer or hemofilter, is used for hemodialysis, hemofiltration, hemodiafiltration. The main difference between a hemodialyzer and a plasmafilter (i.e. a filter used in plasmapheresis) is the different pore sizes of their respective membranes, the membrane used for plasmapheresis allowing the proteins contained in the blood to move through the membrane, whereas the membrane used for hemodialysis is the opposite.

A conventional filter for extracorporeal treatment of blood comprises a first compartment and a second compartment, which are separated by a membrane, the first compartment having an inlet and an outlet for the passage of blood therethrough, and the second compartment having an outlet and an inlet for the discharge of a treatment fluid (e.g. dialysis fluid) when the treatment (e.g. hemodialysis) requires the passage of the treatment fluid (e.g. dialysis fluid) in the second compartment. The membrane is enclosed in an elongated tubular housing closed at both ends by end caps with nozzles that are used as inlet/outlet ports for the first compartment.

During the above treatment, blood is withdrawn from the patient, flows through the first compartment of the filter, and then returns to the patient. During hemodialysis, the dialysis fluid flows through the second compartment of the filter, while metabolic discharges (urea, creatinine) contained in the blood move through the membrane into the second compartment by dialysis. During hemofiltration, a pressure differential is created between the two sides of the membrane so that plasma water flows through the membrane into the second compartment of the filter. At this time, the metabolic waste moves into the second compartment by convection. To compensate for the loss of fluid from the patient, the patient is concurrently infused with a sterile replacement solution. Hemodiafiltration is a combination of hemodialysis and hemofiltration, in which process a dialysis fluid is passed through a second compartment and a substitution fluid is infused into the patient. In plasmapheresis, a pressure differential is created across the membrane so that plasma (i.e., plasma water and proteins) flows through the membrane into the second compartment of the filter. Once processed, the plasma is returned to the patient.

A machine for performing any of the above treatments comprises a peristaltic pump for drawing blood from the patient through a so-called "arterial" line connected at one end to the vascular circuit of the patient and at the other end to the inlet of the first compartment of a filter for pumping the blood into the filter, and for returning the blood to the patient through a so-called "venous" line connected at one end to the outlet of the first compartment of the filter and at the other end to the vascular circuit of the patient. The processing machine typically further comprises: a first blood pressure sensor for measuring blood pressure in the arterial line upstream of the pump; a second blood pressure sensor for measuring blood pressure in the arterial line downstream of the pump; a third blood pressure sensor for measuring the blood pressure in the venous line; a bubble detector for detecting bubbles in the venous line; a clamp is used to close the venous line, for example when the bubble detector detects a bubble.

An arterial line generally comprises the following components connected together by lengths of flexible tubing: a first luer connection tube for connection to an arterial cannula; an arterial bubble trap; a pump hose for cooperation with a rotor of a peristaltic pump of a treatment machine; a second luer connection tube for connection with the inlet of the first compartment of the filter.

An intravenous line generally includes the following components connected together by lengths of flexible tubing: a first luer connection tube for connection to the outlet of the first compartment of the filter; a venous bubble trap; a second luer connection tube for connection to a venous cannula. Usually, when the treatment machine, the arterial line, the venous line and the filter are assembled together as a result of the treatment, the first and third blood pressure sensors of the machine are connected to an arterial bubble trap and a venous bubble trap, respectively.

A conventional bubble trap is essentially an elongated container that remains upright during use. The container has an inlet and an outlet for blood, the inlet and outlet being arranged non-adjacent. The container further comprises in its upper position: the pressure measurement port is used for connecting a pressure sensor; an input port for inputting a liquid (e.g., a drug or a sterile saline solution); an injection port for adding air to the bubble trap or for exhausting air from the bubble trap to regulate the blood level therein. During use, the bubble trap contains a large volume of blood in its lower portion, which temporarily stagnates in said lower portion, in order to let the bubbles and micro-bubbles escape under the effect of gravity and enter the upper portion of the container filled with air. Thus, in a conventional bubble trap, there is always a blood-air interface. For proper operation purposes, conventional bubble traps must contain a certain amount of blood (which conflicts with such long-term efforts to minimize extracorporeal blood volume in blood treatment). Furthermore, their use is limited to rather short treatment periods due to blood coagulation caused by the permanent blood-air interface. In this respect, they are suitable for the treatment of chronic diseases (for chronic patients, the treatment period usually lasts about four hours), but they cannot be used for intensive care treatment (treatment of acute patients may last several days).

The assembly of the extracorporeal blood circuit as described above (i.e. the connection of the arterial and venous lines to the filter) is thus installed on a blood treatment machine, and the setting of the liquid level in the bubble trap is rather time consuming.

Disclosure of Invention

It is an object of the present invention to design an integrated blood treatment module which can be mounted on a treatment machine faster than conventional extracorporeal blood circuits and which can be used for long-term treatment.

According to the invention, an integrated blood treatment module comprises:

a blood processing apparatus comprising:

a housing, the housing having a longitudinal axis,

a first end cap enclosing a first end of the housing, said first end cap having a blood inlet port,

a second end cap enclosing a second end of the housing,

a pump hose for a peristaltic pump, wherein the pump hose has a first end fixed to the housing and a second end connected to the blood inlet port, so that the pump hose extends in a position complementary to the orbital position of the peristaltic pump;

a degassing device connected to the second end cap, the degassing device comprising:

a first chamber having an inlet to receive liquid flowing into the second end cap,

a second chamber having an opening closed by a hydrophobic membrane and an outlet for discharging liquid,

wherein the first chamber has a downstream portion extending partially within the second chamber and communicating with the second chamber through a passageway, the second chamber having a downstream portion extending below the passageway and asymmetrically surrounding the downstream portion of the first chamber, the downstream portion of the second chamber having a sidewall surrounding a longitudinal axis of the degassing device and a bottom wall inclined relative to a longitudinal axis of the degassing device.

Other features are as follows:

the integrated blood processing module includes a first pressure measurement chamber secured to the blood processing device and connected to the first end of the pump hose, the first pressure measurement chamber having a pressure measurement port for connection to a pressure sensor, the pressure measurement port having a central axis parallel to a central axis of the at least one access port of the housing.

The integrated blood processing module includes a second pressure measurement chamber secured to the blood processing device and connected to the outlet of the blood degassing device, the second pressure measurement chamber having a pressure measurement port for connection to a pressure sensor, the pressure measurement port having a central axis parallel to a central axis of the at least one access port of the housing.

The integrated blood processing module includes a third pressure measurement chamber secured to the blood processing device and connected to the second end of the pump hose, the third pressure measurement chamber having a pressure measurement port for connection to a pressure sensor, the pressure measurement port having a central axis parallel to a central axis of the at least one access port of the housing.

The integrated blood treatment module according to the invention has several advantages. First, it is compact and facilitates a significant reduction in the amount of extracorporeal blood required in extracorporeal blood treatment. Secondly, it does not require any specific action for mounting it on a processing machine, nor does it require any specific action for setting it during use (in particular, it does not require level regulation of the air-blood interface in the degassing device). Third, the integrated blood circuit is particularly useful for long-term treatments (e.g., continuous renal replacement therapy) because the degassing device operates without an air-blood interface.

Some additional or alternative features of the invention are as follows:

the integrated blood treatment module includes a support structure having a plurality of conduits defined therein to which blood treatment devices are secured.

The support structure comprises a first conduit having a first end connected to a first access port of the casing and a second end constituted by an outlet nozzle for the waste liquid.

The support structure comprises a second conduit having a first end connected to a second access port of the housing and a second end constituted by an inlet nozzle for the dialysis liquid.

The support structure includes:

a third conduit having an inlet for connection to a blood withdrawal line and an outlet connected to the first end of the pump hose;

a fourth conduit having an inlet connected to the second end of the pump hose and an outlet connected to the blood inlet port of the first end cap.

The support structure includes a sixth conduit having a first end connected to the fourth conduit and a second end for connection to a pre-dilution input tube.

The integrated blood treatment module includes a first pressure measurement chamber defined in the support structure and connected to the third conduit for measuring pressure upstream of the pump hose.

The outlet of the third conduit and the inlet of the fourth conduit are arranged relative to each other such that the pump hose forms a loop extending in a plane substantially parallel to the longitudinal axis of the housing.

The outlet of the third conduit is arranged between the two end caps and the loop formed by the pump hose extends laterally with respect to the housing of the blood treatment device.

The outlet of the third conduit is disposed beyond the first end cap along the longitudinal axis of the housing, and the loop formed by the pump hose is offset relative to the housing of the blood processing device along the longitudinal axis of the housing.

The outlet of the third conduit and the inlet of the fourth conduit are arranged relative to each other such that the pump hose forms a loop extending in a plane which is inclined relative to a plane substantially perpendicular to the longitudinal axis of the housing.

The support structure comprises a fifth conduit having an inlet connected to the outlet of the blood degassing device and an outlet for connection to a blood return line.

The support structure includes a seventh conduit having a first end connected to the fifth conduit and a second end for connection to a post-dilution inlet.

The integrated blood treatment module comprises a second pressure measuring chamber defined in the support structure and connected to the fifth conduit for measuring the pressure downstream of the blood degassing device.

The first pressure measuring chamber has a port for connection to a pressure sensor and the second pressure measuring chamber has a port for connection to a pressure sensor, wherein the inlet nozzle, the outlet nozzle, the port of the first pressure measuring chamber and the port of the second pressure measuring chamber each have a central axis, the central axes being substantially parallel.

The central axes of the inlet nozzle, the outlet nozzle, the port of the first pressure measurement chamber and the port of the second measurement chamber are each substantially perpendicular to the longitudinal axis of the housing.

The downstream portion of the second chamber has a sidewall surrounding a longitudinal axis of the degassing device and a bottom wall that is inclined relative to a longitudinal axis of the degassing device.

The downstream portion of the first chamber has a sidewall that is concentric with the sidewall of the second chamber.

The side wall of the downstream portion of the first chamber and the side wall of the downstream portion of the second chamber are substantially cylindrical.

The downstream portion of the first chamber has a cross-section that is substantially the same as the cross-section of the passageway between the first chamber and the second chamber.

The first chamber includes an upstream portion having a decreasing cross-section.

The second chamber includes an upstream portion extending above the channel, the upstream portion having a decreasing cross-section with the larger cross-section being substantially flush with the channel and the smaller cross-section being substantially flush with the hydrophobic membrane.

The upstream portion of the second chamber is generally frusto-conical.

The outlet opens in a downstream portion of the second chamber at a location furthest from the passage.

The first chamber of the degassing device has a downstream portion having a cross-section selected according to the maximum flow of liquid in the module, so that the flow velocity of the liquid in the downstream portion of the first chamber is less than a predetermined velocity.

The cross-section of the downstream portion of the first chamber is selected based on a maximum flow of about 500 ml/min of liquid in the module such that the flow rate of the liquid in the downstream portion of the first chamber is less than about 3 m/min.

The cross-section of the second chamber of the degassing device at the level of the passage is chosen such that the ratio between the flow velocity of the liquid in the downstream part of the first chamber and the flow velocity of the liquid in the second chamber at the level of the passage exceeds a determined value.

The cross-section of the second chamber of the degassing device at the level of the passage is chosen such that the ratio between the flow velocity of the liquid in the downstream part of the first chamber and the flow velocity of the liquid in the second chamber at the level of the passage is at least about 2.

The downstream portion of the second chamber forms an overflow for fluid to flow from the first chamber into the second chamber.

The first chamber, the second chamber and the passage therebetween are arranged relative to each other such that a liquid flow pattern of the liquid from the first chamber, through the second chamber to the outlet includes a component tangential to the membrane.

The liquid flow pattern of the liquid from the first chamber, through the second chamber to the outlet comprises an umbrella-shaped component.

The first chamber, the second chamber and the passage therebetween are arranged relative to each other such that a flow of liquid from the first chamber, through the second chamber to the outlet, retains a quantity of gas bubbles during movement along an inner surface of the hydrophobic membrane.

The integrated blood treatment module comprises a protective element for protecting the hydrophobic membrane from external shocks and for limiting the deformation of the hydrophobic membrane when the pressure of the liquid in the degassing device exceeds a limit.

The hydrophobic membrane is disposed in a plane that is substantially perpendicular to a longitudinal axis of the degassing device.

The blood degassing device as part of the integrated blood treatment module according to the invention is very effective and remains effective for a long time. Furthermore, it allows for a compact structural design, i.e. a small internal volume. For example, such a degassing device may be designed such that its total internal volume is about half the amount of blood in a conventional bubble trap.

Drawings

Other features and advantages of the present invention will become apparent from the following detailed description. Referring to the drawings wherein:

FIG. 1 is a schematic perspective view of a first embodiment of an integrated blood treatment module according to the present invention;

FIG. 2 is a front view of the integrated blood processing module of FIG. 1;

FIG. 3 is a front view of the upper end cap assembly of the integrated blood treatment module of FIG. 1;

FIG. 4 is a schematic cross-sectional view taken along a plane of the upper end cap assembly of FIG. 3, the plane containing the central axis of the end cap;

FIG. 5 is a schematic cross-sectional view taken along a plane of a second embodiment of an upper end cap assembly, the plane containing the central axis of the end cap;

FIG. 6 is a schematic perspective view of a second embodiment of an integrated blood treatment module according to the present invention;

FIG. 7 is a rear view of the integrated blood processing module of FIG. 6;

FIG. 8 is a perspective view, partially cut away, of the upper portion of the integrated blood treatment module of FIG. 6;

FIG. 9 is a schematic cross-sectional view along a plane of the upper portion of the integrated blood treatment module of FIG. 6, the plane containing the longitudinal axis of the treatment device;

FIG. 10 is a schematic perspective view of a third embodiment of an integrated blood treatment module according to the present invention;

FIG. 11 is a rear view of the integrated blood processing module of FIG. 10;

FIG. 12 is a schematic perspective view of a fourth embodiment of an integrated blood treatment module according to the present invention;

FIG. 13 is a rear view of the integrated blood processing module of FIG. 12.

Detailed Description

Figures 1 and 2 show an integrated blood treatment module comprising a blood treatment device in the form of a hollow fibre filter 1, the hollow fibre filter 1 having a tubular housing 2 closed at one end by a lower end cap assembly 4 and closed at its other end by an upper end cap assembly 5 (the integrated blood treatment module being held in a substantially upright position during use and the end cap assemblies being designated herein by their respective positions taken along a vertical line when the integrated blood treatment module is in use). A tubular housing 2 having a longitudinal axis 3 contains a semi-permeable membrane consisting of a bundle of hollow fibers which extends inside the housing 2 and is fixed thereto at its two ends by means of a potting compound in which the two ends are embedded. The potting compound forms a disc which extends perpendicularly to the longitudinal axis 3 of the housing 2. The ends of the fibers are open on an outer surface of the disc of insert-cast material.

The hollow fiber filter 1 is constructed to include a first compartment and a second compartment, which are separated from each other by a semi-permeable membrane. The first compartment comprises the interior of the hollow fibres and the space defined at each end of the filter between the outer surface of the disc impregnated with the compound and the inner surface of the end cap assembly 4, 5, and the second compartment comprises the space outside the hollow fibres, which space is defined by the inner surface of the housing and the inner surface of the disc made of the potting material. The housing 2 is fitted at both ends with nozzles 6 which provide access to the second compartment. The central axis of the nozzle 6 is perpendicular to the longitudinal axis 3 of the housing 2.

A first disk-shaped blood pressure measuring chamber 7 and a second disk-shaped blood pressure measuring chamber 8 are fixed to the housing 2 in the vicinity of the two nozzles 6, respectively. Each blood pressure measuring chamber 7, 8 comprises a blood compartment and an air compartment, which are separated by a circular flexible membrane. The blood compartment comprises an inlet 10 and an outlet 11. An inlet port 29 for medication or medicinal liquid is connected to the blood compartment of the first blood pressure measuring chamber 7. The air compartment comprises a measurement port 12 for connection to a pressure sensor. The blood pressure measuring chambers 7, 8 are fixed to the housing 2 so that the measuring port 12 and the nozzle 6 are open in the same direction. The central axis of the nozzle 6 and the central axis of the measurement port 12 are substantially parallel and they are substantially perpendicular to the longitudinal axis 3 of the housing 2.

The lower end cap assembly 4 includes a circular end wall 13 connected to a tubular peripheral wall 14 by which the end cap 4 is secured to the housing 2. The end wall 13 is substantially perpendicular to the longitudinal axis 3 of the filter 1 and the tubular peripheral wall 14 is concentric with the housing 2. The end wall 13 is fitted with an inlet nozzle 15 which is connected to the end wall 13 so that the central axis of the nozzle 15 coincides with the longitudinal axis 3 of the housing 2. The lower end cap assembly 4 further comprises a third blood pressure measurement chamber 9, similar to the first and second blood pressure measurement chambers 7, 8. The outlet of the blood compartment of the third blood pressure measuring chamber 9 is physically and fluidly connected to the inlet nozzle 15, and the inlet of the blood compartment is physically and fluidly connected to a tubular connection 19, said tubular connection 19 being dimensioned to receive a downstream end 16 of a pump hose 17. The measurement port 12 of the air compartment of the pressure measurement chamber 9 is oriented the same as the measurement ports 12 of the nozzle 6 and the first and second pressure measurement chambers 7, 8, i.e. its axis is perpendicular to the longitudinal axis 3 of the housing 2.

A first tube 21 for the infusion of an anticoagulant (e.g. heparin) and a second tube 22 for the infusion of a drug or medicinal liquid are connected to the pump hose connection 19.

The upstream end 18 of the pump hose 17 is connected to a tubular connector 20, which tubular connector 20 is fixed to the housing 2 just above the lower nozzle 6. The two pump hose connections 19, 20 are oriented such that a pump hose 17 connected thereto forms a U-shaped loop which extends in a plane which is perpendicular to a plane containing the axis of the nozzle 6 and which is inclined relative to the longitudinal axis 3 of the filter 1.

As shown schematically in fig. 2, the annular pump hose 17 is adapted to cooperate rapidly with a rotary peristaltic pump comprised in a treatment machine, for example a dialysis machine. Recall that a conventional rotary peristaltic pump 55 comprises a rotor 51 which normally supports two rollers 52 at its periphery. The rotor 51 is mounted in a support 53 having a semi-circular wall 54, said semi-circular wall 54 partially surrounding the rotor and defining a track against which a pump hose 17 can be received. As the rotor rotates, the rollers 52 alternately engage the pump hose 17 while moving along the circular path and press the pump hose 17 against the semicircular track 54, thereby pushing the liquid contained in the pump hose 17 toward its downstream end 16.

An extraction vessel (or arterial line) comprises a first section 23 and a second section 24, said first section 23 being connected to the inlet 10 of the first pressure measuring chamber 7, said second section 24 connecting the outlet 11 of the first pressure measuring chamber 7 to the tubular connection 20, i.e. the outlet 11 to the pump hose 17. The first pressure measuring chamber 7 is therefore used to measure the blood pressure upstream of the pump hose (the so-called "arterial" pressure).

The upper end cap assembly 5 includes an annular end wall 25 which is connected to a tubular peripheral wall 26 by which the end cap 5 is secured to the housing 2. The end wall 25 is substantially perpendicular to the longitudinal axis 3 of the filter 1 and the tubular peripheral wall 26 is concentric with the housing 2. The upper end cap assembly 5 also comprises a blood degassing device 30 connected to the annular end wall 25. The blood degassing device 30 comprises an outlet port 35 connected to the inlet 10 of the second pressure measuring chamber 8 via the first section 27 of a blood return line (or venous line), said blood degassing device 30 being shown in detail in figures 3 and 4. The blood return tube comprises a second section 28 which is connected to the outlet 11 of the second pressure measuring chamber 8. The first pressure measurement chamber 7 is therefore used to measure the blood pressure downstream of the filter (the so-called "venous" pressure).

As shown in fig. 3 and 4, the degassing device 30 includes: a first chamber 31 for receiving liquid flowing from the first compartment of the filter 1 and into the end cap assembly 5; a second chamber 32 in flow communication with the first chamber 31 and having an opening 33 closed by a hydrophobic membrane 34; an outlet port 35 connected to the second chamber 32 for discharging liquid.

The first chamber 31 is defined by a funnel-shaped wall 36, which funnel-shaped wall 36 has a first end of larger cross-section, which is connected by its larger cross-section to the end wall 25 of the end cap 5, and a second end of smaller cross-section, which defines a passage 38 between the first chamber 31 and the second chamber 32. The funnel-shaped wall 36 is centered about a longitudinal axis 37 of the degassing device 30. Thus, in the direction of flow, the first chamber 31 has an upstream portion with a decreasing cross section and a downstream portion with a constant cross section (unless otherwise specified, "cross section" means here and in the following a transversal cross section with respect to the longitudinal axis 37; furthermore "direction of flow" means the direction of flow from the first compartment of the filter 1 to the outlet port 35 through the first and second chambers 31, 32 of the degassing device 30).

In the flow direction, the second chamber 32 of the degassing device 30 comprises a disc-shaped upstream portion extending above the channel 38 and a downstream portion extending below the channel 38 and partially and asymmetrically surrounding the downstream portion of the first chamber 31. The downstream portion of the second chamber 32 is defined by a cylindrical wall 39 and a substantially flat bottom wall 40, said cylindrical wall 39 being concentric with the cylindrical portion of the wall 36 of the first chamber 31, said bottom wall 40 being inclined at an angle of about 45 degrees with respect to the axis 37. The uppermost point of the inclined bottom wall 40 abuts the edge of the cylindrical wall 39. Due to the respective structural arrangement of the downstream portions of the first chamber 31 and the second chamber 32, the second chamber 32 forms an overflow for the liquid to flow from the first chamber 31 to the second chamber 32.

The outlet port 35 of the degassing device 30 is constituted by a tubular wall which is connected to the inclined wall 40 of the second chamber 32 at the low point of the inclined wall. The central axis of the outlet 35 is substantially perpendicular to the longitudinal axis 37 of the degassing device 30. The outlet port 35 extends inwardly, i.e. below the inclined wall 40 of the second chamber 32, and tangentially to the upper cylindrical portion of the wall 36 of the first chamber 31.

Due to the shape of the second chamber 32 (cylindrical wall 39 connected to an inclined bottom wall 40) and due to the connection of the outlet port 35 at the lowest point of the bottom wall 40, two particularly advantageous features are for the degassing device for blood: the structural design shown in the figures allows for a degassing device with minimum internal volume, in which there are no areas of relative stagnation for the liquid circulating through the degassing device, in contrast to a second chamber which surrounds the first chamber completely and symmetrically or even only the upstream cylindrical part of the first chamber, with a bottom wall substantially perpendicular to the longitudinal axis of the degassing device. During the research work of the present invention it was observed that in the case where the second chamber completely surrounds the first chamber and the bottom wall is substantially perpendicular to the longitudinal axis of the degassing device, a relatively stagnant zone occurs in the second chamber opposite the outlet.

The disc-shaped upstream portion of the second chamber 32 is defined within a cap-shaped cover 41, which cover 41 is mounted on the upper edge of the cylindrical wall 39 of the second chamber 32. More specifically, the disc-shaped upstream portion of the second chamber 32 is defined by an inner peripheral wall 42 of the cover 41, said inner peripheral wall 42 having a frustoconical inner surface, and by a circular hydrophobic membrane 34, said circular hydrophobic membrane 34 closing, inside the cover 41, an opening of the second chamber 32 defined by an internal annular shoulder 33. The hydrophobic membrane 34 is fixed (e.g. by gluing) at its periphery to the shoulder 33 and perpendicular to the axis 37 of the degassing device 30. In more detail, the cap-shaped lid 41 comprises a circular flat top wall 45 connected to the inner peripheral wall 42 and to an outer peripheral wall 43. The inner peripheral wall 42 and the outer peripheral wall 43 define between them a recess corresponding to the upper edge of the cylindrical wall 39 of the second chamber 32, so that the lid 41 can be engaged in the edge of the cylindrical wall 39 and can be fixed there, for example by gluing. The lid 41 also includes a vent 46 centrally located in the circular flat top wall 45 through which air removed from the liquid in the degassing device 30 can escape. Annular shoulder 33 is spaced from top wall 45 of cover 41 so that hydrophobic membrane 34 is deformable under positive pressure. The top wall 45 of the cover 41 essentially serves to protect the hydrophobic membrane from external impacts.

Due to the respective structural arrangement of the first chamber 31 and the second chamber 32, the liquid flowing through the degassing device 30 has an umbrella-shaped pattern with a longitudinal component in the first chamber 31 and a radial component in the upstream portion of the second chamber 32. The radial component of the flow sweeps tangentially across the hydrophobic membrane 34 and helps to prevent the formation of blood bubbles along its inner surface, while keeping the bubbles and microbubbles constantly moving along the membrane until they escape there through.

The efficiency of the degassing device of the invention can be optimized by selecting the diameter of the downstream cylindrical portion (wall 36) of the first chamber 31 with respect to the maximum flow rate of blood inside the integrated blood treatment module and the size of the second chamber 32 (diameter of the cylindrical wall 39) with respect to the size of the first chamber 31 (diameter of the cylindrical wall 36), so that:

the maximum flow rate of liquid in the first chamber 31 (corresponding to the maximum flow rate in the blood treatment module) is not high enough to prevent bubbles and microbubbles from moving towards the hydrophobic membrane 34 and to expel these bubbles to the outlet port 35;

the flow rate of liquid into the second chamber is reduced to such an extent that bubbles and microbubbles can move under gravity towards the hydrophobic membrane 34.

For example, for a maximum blood flow of about 500 ml/min in the blood treatment module, it was determined during the study of the present invention that the optimal flow rate of blood in the downstream portion of the first chamber 31 (cylindrical wall 36) should be less than about 3 m/min, and that the optimal ratio of the flow rate of blood in the downstream portion of the first chamber 31 and the flow rate of blood in the second chamber 32 at the level of the channel 38 should be at least about 2.

Fig. 5 shows a second embodiment of an upper end cap assembly 5, which is a variation of the end cap assembly shown in fig. 3 and 4.

In this second embodiment, the upstream portion of the second chamber 32 is defined by a lid 41 having a lower edge which is machined so as to tightly engage an outer annular notch of the upper edge of the cylindrical wall 39. The cover 41 comprises a first frustoconical wall 47 connected to a second cylindrical wall 48, the first wall 47 being connected to the second wall 48 via a smaller area thereof. It should be noted that the first wall 47 in fact comprises two truncated-cone-shaped portions, the lower portion having an angle slightly greater than the angle of the upper portion. Thus, the upstream portion of the second chamber 32 has a decreasing cross-section. The lid 41 also comprises an internal annular shoulder 44 extending at the junction between the truncated-cone-shaped wall 47 and the cylindrical wall 48. The aperture defined by the internal annular shoulder 44 forms an opening 33 of the second chamber 32, which is closed by the hydrophobic membrane 34. The membrane 34 is secured to the annular shoulder 44 by an O-ring 50, said O-ring 50 being supported at the periphery of the membrane 34 and against which a disc-shaped plug 49 is tightly engaged. A plug 49, which fits snugly within a cylindrical wall 48 of the lid 41, includes in its center a vent 46 through which air removed from the liquid in the degassing device 30 can escape. It should be noted that the membrane 34 is close to the inner surface of the plug 49, rather than abutting against it. Thus, the membrane 34 is deformable to some extent. However, when the positive pressure in the filter exceeds a certain value, the membrane 34 abuts against the plug 49 and there is no risk of rupture.

Further, in the second embodiment of the upper end cap assembly 5 shown in fig. 5, two inlets 56, 57 are connected to the first chamber 31. The two inlets 56, 57 can be used for the input of various liquids (e.g. for the input of substitution liquids or drugs when the filter is a blood filter) and can be used for connection to a pressure sensor.

The prototype (prototype) of the degasser 30 shown in fig. 5 was made of molded polycarbonate: the downstream portion of the first chamber 31 (the cylindrical portion of the wall 36) has a diameter of 16 mm; the internal diameter of the second chamber 32 at the level of the channel 38 is 19 mm; the outer diameter of the second chamber 32 at the level of the channel 38 is 32 mm; the diameter of the hydrophobic membrane 34 (effective surface) is 27 mm; the distance between channel 38 and hydrophobic membrane 34 is 5 mm. The membrane was made of polytetrafluoroethylene and had a thickness of 0.13 millimeters and a pore size of 0.2 microns.

The retarded blood circulates at a rate of 500 ml/min in a closed loop comprising a blood filter connected to the prototype of the degassing device 41. The flow rate of the blood in the degassing device was:

-2.5 meters/min in the downstream cylindrical portion of the first chamber 31;

2 meters/minute between channel 38 and hydrophobic membrane 34;

-1 meter/min in the downstream part of the second chamber 32, just below the level of the channel 38;

in the downstream portion of the second chamber 32, just upstream of the outlet port 35, at 2 meters/minute.

The pressure in the degassing apparatus was 50 mm hg. After four hours, 5 ml of air were injected into the circuit upstream of the hemofilter. After 15 minutes, the air injected into the circuit has been completely removed by the degassing device 30.

The end caps 25, 26, the walls 36, 39, 40 defining the downstream portions of the first and second chambers 31, 32 and the ports 25(56, 57) connected thereto may be manufactured in one piece from a moldable material by molding. Biologically inert materials such as polycarbonate are suitable when the filter is used for medical purposes. The cover 41 may also be made in one piece from the same material as the end caps 25, 26, the walls 36, 39, 40 by moulding. The hydrophobic membrane 34 may be made of polytetrafluoroethylene.

The operation of the integrated blood treatment module 1 is as follows.

Prior to the treatment session, the integrated blood treatment module 1 is secured to a treatment machine in a generally upright position with the degassing device 30 in the upper position. The two nozzles 6 of the second compartment of the filter are connected to a dialysis liquid supply conduit and a waste liquid conduit, respectively, of the treatment machine. The pressure measurement ports 12 of the first, second and third blood pressure measurement chambers 7, 8, 9 are connected to an arterial pressure sensor, a rear pump/pre-filter pressure sensor and a venous pressure sensor of the treatment machine, respectively. The pump hose 17 is engaged between the circular track 54 of the peristaltic pump 55 of the treatment machine and the rotor 51. A bag of sterile saline solution is connected to the blood withdrawal line 23 and an empty waste bag is connected to the blood return line 28. The sterile saline solution is then pumped by the peristaltic pump 55 into the blood withdrawal vessel 23 and through the first pressure measuring chamber 7, the pump hose 17, the third pressure measuring chamber 9, the first compartment of the filter 1, the degassing device 30, the second pressure measuring chamber 8 and the blood return line 28, in order to purge the extracorporeal blood circuit, fill it with sterile saline solution and remove air from it (these preparatory steps are called "priming" the extracorporeal blood circuit). At the end of this process, there is no more air in the integrated blood treatment module 1, in particular in the degassing device 30. The blood withdrawal line 23 is then connected to a blood vessel of the patient, and the saline solution flowing out of the venous line 28 is collected in a waste bag while the blood is pumped into the extracorporeal circuit. When the blood reaches the end of the blood return tube 28, which is in turn connected to the blood vessel of the patient, the treatment in a strict sense can be started.

In the filter 1, blood flows within the hollow fibers, enters the end cap assembly 5, flows through the first chamber 31, floods the second chamber 32, and exits the degassing device 30 via the outlet port 35. Since the cross-section of the second chamber 32 at the level of the channel 38 is substantially larger than the cross-section of the channel 38 itself, the blood flow is substantially reduced when blood enters the second chamber 32. This helps bubbles and microbubbles that may be present in the blood to move upward toward the hydrophobic membrane 34 under the force of gravity. Furthermore, the overall flow pattern of the blood is umbrella-shaped with a component tangential to the hydrophobic membrane 34, since the blood is directed towards the hydrophobic membrane 34 via the funnel-shaped wall 36 and then from there towards the truncated conical wall 42 (indicated at 47 in fig. 5) of the cover 41. Thus permanently skimming the membrane, preventing a static blood foam layer from being created on the inner surface of the membrane 34. Instead, the bubbles and microbubbles are kept in permanent movement near the membrane 34 through which they pass shortly after entering the second chamber 32.

Fig. 6-9 show a second embodiment of an integrated blood treatment module according to the present invention. Such an integrated blood treatment module comprises: a support structure 60 having a plurality of conduits defined therein; a filter 100; a blood degassing device 30 secured to the structure 60.

The filter 100 has the same general construction as the filter 1 described above, except for the same end caps 101, which end caps 101 close the housing 2 at both ends of the filter 100. Each end cap 101 comprises a circular end wall 102 connected to a tubular peripheral wall 103 by which the end cap 101 is secured to the housing 2. The end wall 102 is substantially perpendicular to the longitudinal axis 3 of the filter 100 and the tubular peripheral wall 103 is concentric with the housing 2. The end cap assembly 101 also includes an inlet nozzle 104 (or outlet nozzle 105) that is connected to the end wall 102 so as to extend radially relative to the longitudinal axis 3 of the housing 2. The end cap 101 is mounted on the housing 2 such that the inlet and outlet nozzles 6, 104, 105 of the first and second compartments of the filter 100 extend parallel to each other on the same side of the filter 100, with the inlet nozzle 104 of the first compartment adjacent to the outlet nozzle 6 of the second compartment and the outlet nozzle 105 of the first compartment adjacent to the inlet nozzle 6 of the second compartment.

The support structure 60 basically comprises an elongated flat body 61, a lower bracket 62 and an upper bracket 63 extending from the same side of the body 61 at both ends of the body 61. The elongated body 61 has an overall rectangular shape. It is slightly longer and narrower than the filter 100. The function of the brackets 62, 63 is to mechanically and fluidly connect the filter 100 to the structure 60. Each bracket 62/63 includes an upper and lower recess having parallel axes designed to receive a pair of adjacent inlet/outlet nozzles (104/6 or 105/6) of filter 100. The distance between the two recesses 62, 63 corresponds to the distance between the two pairs of nozzles 104/6 and 105/6 of the filter 100 so that the nozzles can be engaged in the brackets to secure the filter 100 to the structure 60.

The support structure 60 includes: a plurality of conduits defined therein, a first pressure measurement chamber 7 and a second pressure measurement chamber 8.

A first conduit 64 extending through the lower tray 62 and the main body 61 connects the upper recess of the lower tray 62 to an outlet nozzle 65 for used liquid (e.g. ultrafiltrate and/or used dialysis liquid), said outlet nozzle 65 being connected to the side of the main body 61 opposite to the filter 100.

A second conduit 66 extending through the upper bracket 63 and the body 61 connects the lower recess of the upper bracket 63 to an inlet nozzle 67 for fresh treatment liquid (e.g. fresh dialysis liquid), said inlet nozzle 67 being connected to the side of the body 61 opposite the filter 100.

A third conduit 68 extending through the body 61 has a first section connecting an extraction vessel 69 to an inlet 10 of the blood chamber of the first pressure measuring chamber 7 and a second section connecting the outlet 11 of the blood chamber of the first pressure measuring chamber 7 to the first (upstream) end 18 of the pump hose 17. The air chamber of the first pressure measuring chamber 7 is defined by a circular cover having a central opening 12 for connection to a pressure sensor.

A fourth conduit 70 extending through the lower bracket 62 and the main body 61 connects the lower recess of the lower bracket 62 to the second (downstream) end 16 of the pump hose 17. The third and fourth conduits 68, 70 are defined within the body 60 such that the pump hose 17 connected thereto forms a U-shaped loop which extends in the same plane as the flat body 61 and is ready to engage the rotor of a peristaltic pump.

A fifth conduit 71 extending through the body 61 has a first section connecting the outlet port 35 of the blood degassing device 30 to an inlet 10 of the blood chamber of the second pressure measuring chamber 8 and a second section connecting the outlet 11 of the blood chamber of the second pressure measuring chamber 8 to a blood return tube 72. The air chamber of the second pressure measuring chamber 8 is defined by a circular cover having a central opening 12 for connection to a pressure sensor. It should be noted that the central axes of the inlet and outlet nozzles 65, 67 extend in the same plane as the central axes of the measurement ports 12 of the pressure measurement chambers 7, 8, which central axes are parallel and perpendicular to the elongated body 61 of the support structure 60.

A sixth conduit 73 extending through the body 61 connects an input tube 74 to the fourth conduit 70. The inlet line 74 is therefore connected to the blood circuit upstream of the filter 100 and serves for the introduction of what is known as pre-dilution.

A seventh conduit 75 extending through the body 61 connects an input tube 76 to the fifth conduit 71. The inlet line 76 is therefore connected to the blood circuit downstream of the filter 100 and is used for the introduction of what is known as post-dilution.

An eighth conduit 78 extending through body 61 connects an anticoagulant tube 79 to fourth conduit 70.

These inlets open on the upper and lower sides of the main body 61 (when the integrated blood treatment module is in an operating state) in addition to the inlet of the fifth conduit 71 and the inlets of the sixth and eighth conduits 73, 78, respectively, and the inlets/outlets of the third, fourth and seventh conduits 68, 70, 75 and the outlet of the fifth conduit 71 open on the same side of the main body 61. It should also be noted that the two pressure measurement chambers 7, 8 are embedded in the body 61 and are located between the inlet and outlet nozzles 65, 67 for the second compartment of the filter 100. Furthermore, since the third conduit 68 is embedded in the body 61 at a distance from both ends of the body 61 (i.e., of the filter 100), the loop formed by the pump hose 17 extends laterally with respect to the filter 100. Due to these different configurations, the integrated blood treatment module in fig. 6 and 7 is exceptionally compact.

The body 61 and the catheter defined therein may be manufactured in one piece from a moldable material by molding. Only the membranes of the two pressure measuring chambers 7, 8 and the covers defining the air compartments thereof have to be manufactured as separate components and subsequently mounted on the body 61.

The blood degassing device 30 is connected to the upper recess of the upper bracket 63 by a conduit 77. As shown in fig. 8 and 9, the blood degassing device 60 is identical to the device shown in fig. 5, except for the upstream portion of the first chamber 31 of the blood degassing device 60, which is tapered and has an increasing cross section in the direction of flow.

Figures 10 and 11 show a third embodiment of an integrated blood treatment module according to the present invention. Such an integrated blood treatment module comprises: a support structure 80 having a plurality of conduits defined therein; a filter 100; a blood degassing device 30 secured to the structure 80.

This third embodiment differs from the second embodiment basically in that: the shape of its support structure 80, the position of the third conduit 68 and the first pressure measuring chamber 7 determining the position of the pump hose 17. The overall function of the blood processing device and its various components remains the same.

More specifically, some of the features specific to the integrated blood processing module of fig. 10 and 11 are as follows:

the flat elongate body 81 is substantially longer than the filter 100 and it is secured to the filter so that a substantial portion thereof extends beyond the filter relative to the lower end cap 101 of the filter 100.

The third conduit 68 and the first pressure measuring chamber 7 are arranged in the lowermost part of the body 81, while the fourth conduit 70 is adjacent to the lower end cap of the filter. Due to this structural arrangement, the loop formed by the pump hose 17 extends laterally below the filter 100 with respect to the longitudinal axis 3 of the filter.

The inlet of the third conduit 68 connected to the blood evacuation tube 69 opens on the lowermost side of the elongate body 81.

A ninth conduit 82 extending through the body 81 connects an inlet pipe 83 to the third conduit 68 upstream of the pump hose 17.

The inlet of the ninth conduit 82 opens on the opposite side of the elongated body 81 to the side to which the pump hose 17 is connected.

The inlet of the sixth conduit 73, which is connected to the inlet conduit 74, opens on the opposite side of the elongated body 81 to the side where the pump hose 17 is connected.

Fig. 12 and 13 show a fourth embodiment of an integrated blood treatment module according to the invention. Such an integrated blood treatment module comprises: a support structure 90 having a plurality of conduits defined therein; a filter 100; a blood degassing device 30 secured to the structure 90.

This fourth embodiment basically differs from the second embodiment in that: the shape of its support structure 90, the position of the third conduit 68 and the first pressure measuring chamber 7 determining the position of the pump hose 17. The overall function of the blood processing device and its various components remains the same.

More specifically, some of the features specific to the integrated blood processing module of fig. 12 and 13 are as follows:

the flat elongated body comprises a first long branch tube 91 and a second short branch tube 92, which are parallel and connected via a third transverse branch tube 93, the longitudinal axis of the third branch tube 93 being slightly inclined with respect to the longitudinal axis of the first and second branch tubes 91, 92. The longitudinal axes of the three branch pipes 91, 92, 93 lie in the same plane. The first branch pipe 91 has a length substantially the same as that of the filter 100 and is connected at its lower end portion to the lateral branch pipe 93 at the middle thereof. The third transverse branch 93 is slightly longer than the diameter of a loop of a U-shaped pump hose 17, said U-shaped pump hose 17 being used for a peristaltic pump suitable for pumping blood. The second short branch tube 92 is connected by its upper end to the lower end of the third branch tube 93.

The third conduit 68 extends in the second branch 92 and the third branch 93 along the longitudinal axis of the second branch 92 so that its outlet opens in the lower end of the transverse branch 93 and is located on the surface of the body 91, 92, 93 opposite to the filter 100.

The fourth conduit 70 extends in the first branch 91 and the third branch 93 so that its inlet opens in the upper end of the transverse branch 93 and is located on the surface of the body 91, 92, 93 opposite to the filter 100.

The pump hose 17 with a first (upstream) end 18 and a second (downstream) end 16 forms a loop, the first end 18 being connected to the outlet of the third conduit 68 and the second end 16 being connected to the inlet of the fourth conduit 70, the loop extending in a plane perpendicular to the plane of the body of the structure 90 containing the longitudinal axes of the three branches 91, 92, 93. It should be noted that when the blood treatment module is held in its operating position, i.e. in a vertical position, the inlet end 18 of the pump hose 17 is lower than its outlet end 16. The purpose of this arrangement is to help vent air from the pump hose during priming of the blood treatment module.

The inlet of the third conduit 68 to the blood evacuation tube 69 opens on the lowermost side of the elongated bodies 91, 92, 93.

A ninth conduit 82 extending through a short branch 92 of the main body connects an inlet pipe 83 to the third conduit 68 upstream of the pump hose 17.

The seventh conduit 75 is connected to the fifth conduit 71 upstream of the second pressure measurement chamber 8.

The inlet of the ninth conduit 83 opens on one side of the elongated body 91, 92, 93 and the inlet of the seventh conduit 75 and the outlet of the fifth conduit 71 open on the other side of the elongated body 91, 92, 93.

The various embodiments of the invention described above are only some examples of the invention. Thus, the scope of the invention is not limited to any one embodiment.

Claims (37)

1. An integrated blood processing module comprising:

a blood treatment device (1, 100) comprising:

a housing (2) having a longitudinal axis (3),

a first end cap (4) closing a first end of the housing (2), said first end cap having a blood inlet port (15, 104),

a second end cap (5) closing a second end of the housing (2),

-a pump hose (17) for a peristaltic pump, wherein the pump hose (17) has a first end (18) fixed to the housing (2) and a second end (16) connected to the blood inlet port (15, 104), so that the pump hose (17) extends in a position complementary to the orbital position of the peristaltic pump;

-a degassing device (30) connected to the second end cap (5), said degassing device having:

a first chamber (31) having an inlet for receiving liquid flowing into the second end cap (5),

a second chamber (32) having an opening (33) closed by a hydrophobic membrane (34) and an outlet port (35) for discharging liquid,

wherein the first chamber (31) has a downstream portion extending partially within the second chamber (32) and communicating with the second chamber through a passage (38), the second chamber (32) having a downstream portion extending below the passage (38) and asymmetrically surrounding the downstream portion of the first chamber (31), the downstream portion of the second chamber (32) having a side wall (39) surrounding a longitudinal axis (37) of the degassing device (30) and a bottom wall (40) inclined with respect to a longitudinal axis (37) of the degassing device.

2. Integrated blood treatment module according to claim 1, further comprising a first pressure measurement chamber (7) fixed to the blood treatment device (1) and connected to the first end (18) of the pump hose (17), the first pressure measurement chamber (7) having a first pressure measurement port (12) for connection of a pressure sensor, said first pressure measurement port having a central axis parallel to a central axis of the at least one access port (6) of the housing (2).

3. Integrated blood treatment module according to claim 1 or 2, further comprising a second pressure measuring chamber (8) fixed to the blood treatment device (1) and connected to the outlet port (35) of the degassing device (30), the second pressure measuring chamber (8) having a second pressure measuring port (12) for connection of a pressure sensor, said second pressure measuring port (12) having a central axis parallel to a central axis of the at least one access port (6) of the housing (2).

4. Integrated blood treatment module according to claim 1, further comprising a third pressure measuring chamber (9) fixed to the blood treatment device (1) and connected to the second end (16) of the pump hose (17), the third pressure measuring chamber (9) having a third pressure measuring port (12) for connection of a pressure sensor, said third pressure measuring port (12) having a central axis parallel to a central axis of the at least one access port (6) of the housing (2).

5. Integrated blood treatment module according to claim 1, further comprising a support structure (60, 80, 90) with a plurality of conduits (64, 66, 68, 70, 71, 73, 75, 78, 82) defined therein, the blood treatment device (100) being fixed to the support structure (60, 80, 90).

6. Integrated blood treatment module according to claim 5, wherein the support structure (60, 80, 90) comprises a first conduit (64) having a first end connected to a first access port (6) of the housing (2) and a second end constituted by an outlet nozzle (65) for discharging the waste liquid.

7. Integrated blood treatment module according to claim 5 or 6, wherein the support structure (60, 80, 90) comprises a second conduit (66) having a first end connected to a second access port (6) of the housing (2) and a second end constituted by an inlet nozzle (67) for the entry of a dialysis liquid.

8. Integrated blood treatment module according to claim 5, wherein the support structure (60, 80, 90) comprises:

-a third conduit (68) having an inlet for connection to a blood withdrawal vessel (69) and an outlet, the outlet of the third conduit being connected to the first end (18) of the pump hose (17); and

-a fourth conduit (70) having an inlet connected to the second end (16) of the pump hose (17) and an outlet connected to the blood inlet port (15) of the first end cap (4).

9. Integrated blood treatment module according to claim 8, wherein the support structure (60, 80, 90) comprises a sixth conduit (73) having a first end and a second end, the first end of the sixth conduit being connected to the fourth conduit (70), the second end of the sixth conduit being adapted for connection to a pre-dilution feed tube (74).

10. Integrated blood treatment module according to claim 8, further comprising a first pressure measurement chamber (7) defined in the support structure (60, 80, 90) and connected to the third conduit (68) for measuring the pressure upstream of the pump hose (17).

11. Integrated blood treatment module according to claim 8, wherein the outlet of the third conduit (68) and the inlet of the fourth conduit (70) are arranged with respect to each other such that the pump hose (17) forms a loop extending in a plane substantially parallel to the longitudinal axis (3) of the housing (2).

12. Integrated blood treatment module according to claim 11, wherein the outlet of the third conduit (68) is arranged between the two end caps (4, 5) and the loop formed by the pump hose (17) extends laterally with respect to the housing (2) of the blood treatment device (100).

13. Integrated blood treatment module according to claim 11, wherein the outlet of the third conduit (68) is arranged beyond the first end cap (4) along the longitudinal axis (3) of the housing (2) and the loop formed by the pump hose (17) is offset with respect to the housing (2) of the blood treatment device (100) along the longitudinal axis (3) of the housing (2).

14. Integrated blood treatment module according to claim 8, wherein the outlet of the third conduit (68) and the inlet of the fourth conduit (70) are arranged with respect to each other such that the pump hose (17) forms a loop (17) extending in a plane inclined with respect to a plane substantially perpendicular to the longitudinal axis (3) of the housing (2).

15. Integrated blood treatment module according to claim 5, wherein the support structure (60, 80, 90) comprises a fifth conduit (71) having an inlet connected to the outlet port (35) of the degassing device (30) and an outlet for connecting a blood return tube (72).

16. Integrated blood treatment module according to claim 15, wherein the support structure (60, 80, 90) comprises a seventh conduit (75) having a first end and a second end, the first end of the seventh conduit being connected to the fifth conduit (71), the second end of the seventh conduit being adapted for connection to a post-dilution inlet tube (76).

17. Integrated blood treatment module according to claim 15, further comprising a second pressure measuring chamber (8) defined in the support structure (60, 80, 90) and connected to the fifth conduit (71) for measuring the pressure downstream of the degassing device (30).

18. Integrated blood treatment module according to claim 6, wherein the support structure (60, 80, 90) comprises:

a second conduit (66) having a first end connected to a second access port (6) of the housing (2) and a second end constituted by an inlet nozzle (67) for the entry of the dialysis liquid;

a third conduit (68) having an inlet for connection to a blood withdrawal line (69) and an outlet, the outlet of the third conduit being connected to the first end (18) of the pump hose (17);

a fourth conduit (70) having an inlet connected to the second end (16) of the pump hose (17) and an outlet connected to the blood inlet port (15) of the first end cap (4); and

a fifth conduit (71) having an inlet connected to the outlet port (35) of the degassing device (30) and an outlet for connection to a blood return tube (72),

said integrated blood treatment module further comprising a second pressure measuring chamber (8) defined in said support structure (60, 80, 90) and connected to a fifth conduit (71) for measuring the pressure downstream of the degassing device (30),

the first pressure measuring chamber (7) has a port (12) for connection to a pressure sensor, the second pressure measuring chamber (8) has a port (12) for connection to a pressure sensor, and wherein the inlet nozzle (67), the outlet nozzle (65), the port (12) of the first pressure measuring chamber (7) and the port (12) of the second pressure measuring chamber (8) have respective central axes which are substantially parallel.

19. Integrated blood treatment module according to claim 18, wherein the respective central axes of the inlet nozzle (67), the outlet nozzle (65), the port (12) of the first pressure measurement chamber (7) and the port (12) of the second measurement chamber (8) are substantially perpendicular to the longitudinal axis (3) of the housing (2).

20. Integrated blood treatment module according to claim 1, wherein the downstream portion of the first chamber (31) has a side wall (36) concentric with a side wall (39) of the second chamber (32).

21. Integrated blood treatment module according to claim 20, wherein the side wall (36) of the downstream portion of the first chamber (31) and the side wall (39) of the downstream portion of the second chamber (32) are substantially cylindrical.

22. Integrated blood treatment module according to claim 1, wherein the downstream portion of the first chamber (31) has a cross-section substantially identical to the cross-section of the passage (38) between the first chamber (31) and the second chamber (32).

23. Integrated blood treatment module according to claim 1, wherein the first chamber (31) comprises an upstream portion having a decreasing cross section.

24. Integrated blood treatment module according to claim 1, wherein the second chamber (32) comprises an upstream portion extending above the channel (38), the upstream portion having a decreasing cross-section, wherein the larger cross-section is substantially flush with the channel (38) and the smaller cross-section is substantially flush with the hydrophobic membrane (34).

25. Integrated blood treatment module according to claim 24, wherein the upstream portion of the second chamber (32) is substantially frusto-conical.

26. Integrated blood treatment module according to claim 1, wherein the outlet port (35) opens in a downstream portion of the second chamber (32) at a position furthest from the channel (38).

27. Integrated blood treatment module according to claim 1, wherein the downstream portion of the first chamber (31) of the degassing device (30) has a cross-section selected with respect to the maximum flow of liquid in the module such that the flow rate of liquid in the downstream portion of the first chamber (31) is less than a predetermined flow rate.

28. Integrated blood treatment module according to claim 27, wherein the cross section of the downstream portion of the first chamber (31) is selected with respect to a maximum flow of liquid in the module of 500 ml/min, such that the flow rate of liquid in the downstream portion of the first chamber (31) is less than 3 m/min.

29. Integrated blood treatment module according to claim 1, wherein the cross section of the second chamber (32) of the degassing device (30) at the level of the passage (38) is chosen such that the ratio of the liquid flow rate in a downstream portion of the first chamber (31) to the liquid flow rate in the second chamber (32) at the level of the passage (38) is greater than a certain value.

30. Integrated blood treatment module according to claim 29, wherein the cross section of the second chamber (32) of the degassing device (30) at the level of the passage (38) is chosen such that the ratio of the liquid flow rate in the downstream portion of the first chamber (31) to the liquid flow rate in the second chamber (32) at the level of the passage (38) is at least 2.

31. Integrated blood treatment module according to claim 1, wherein the downstream portion of the second chamber (32) forms an overflow for fluid to flow from the first chamber (31) into the second chamber (32).

32. Integrated blood treatment module according to claim 1, wherein the first chamber (31), the second chamber (32) and the channel (38) therebetween are arranged with respect to each other such that the liquid flow pattern of the liquid from the first chamber (31), through the second chamber (32) to the outlet port (35) comprises a component tangential to the membrane.

33. Integrated blood treatment module according to claim 32, wherein the liquid flow pattern of the liquid from the first chamber (31), through the second chamber (32) to the outlet port (35) comprises an umbrella-shaped component.

34. Integrated blood treatment module according to claim 1, wherein the first chamber (31), the second chamber (32) and the channel (38) therebetween are arranged with respect to each other such that a flow of liquid from the first chamber (31), through the second chamber (32) to the outlet port (35) retains some bubbles during movement along an inner surface of the hydrophobic membrane (34).

35. Integrated blood treatment module according to claim 1, further comprising a protective element (45, 49) for protecting the hydrophobic membrane (34) against external shocks and for limiting the deformation of the hydrophobic membrane (34) when the pressure of the liquid in the degassing device exceeds a limit.

36. Integrated blood treatment module according to claim 1, wherein the hydrophobic membrane (34) is arranged in a plane substantially perpendicular to a longitudinal axis (37) of the degassing device (30).

37. Integrated blood treatment module according to claim 1, wherein the blood treatment device (1, 100) is a hemodialyzer, a hemofilter or a plasmafilter.