Patent Application
20240216666
The present invention relates to the technical field of the devices for introducing media into the body, and in particular the invention concerns an infusion site of a blood tubing system.
During an extracorporeal blood treatment, like haemodialysis, infusion solutions or medicaments are mostly infused through the extracorporeal blood circuit, i.e., the utilized blood tubing system. For example, anticoagulation infusion solutions are regularly infused in an extracorporeal blood treatment to prevent a possible occlusion of the extracorporeal blood circuit.
In a Citrate-Calcium haemodialysis treatment, blood coagulation is prevented by injecting citrate in the blood stream, as soon as the blood enters the tubing system, so reducing calcium present in the blood. After filtration and prior to returning blood to the patient, the quantity of calcium is rebalanced by injecting in the stream a predetermined quantity of calcium, since too-low calcium concentrations influence nerves and muscles, the blood coagulation and functions of lung, heart and kidneys.
This treatment requires from the tubing system two permanent infusion sites located in the arterial (citrate infusion) and the venous (calcium infusion) portion of the tubing system, as near as possible to the entrance and exit of the tubing set respectively.
To reduce coagulation processes at the calcium-infusion site into the extracorporeal blood circuit an improved mixing of blood with the infusion solution is needed. A known solution to overcome possible mixing imbalance is the creation of a localized turbulence in correspondence of the infusion site with the consequent laminar flow disruption which will increase blood and calcium mixing.
WO2009/030973 discloses a blood line comprising an infusion site intended to inject into the line a solution. The blood line comprises a first main channel having a first passage section, a second main channel having a second passage section, and a turbulence generating area including a Venturi valve which is able to improve the mixing of blood with the infusion solution.
EP3645072, of the same Applicant, discloses a double flow mixing connector on the venous line, which forces a localized turbulence by separating the inlet blood flow in two circular streams and colliding them in the calcium injection point.
Several test conducted by the Applicant have shown a need to further increase the balance between calcium infused and the blood stream, both from the hydraulic (e.g. laminar flow separation, diffusion-driven mixing between the two species) and chemical (e.g. high calcium concentration) point of view.
A general object of the present disclosure is that of providing a solution to this need. This and other objects are achieved by the embodiments of the invention having the features recited in the independent claims. The dependent claims delineate preferred and/or especially advantageous aspects.
An embodiment of the disclosure provides an infusion site for a blood tubing set, comprising,
Further advantages and characteristics of the invention shall emerge from the following description, with reference to the attached drawings, wherein:
Reference will now be made in detail to the various embodiments of the invention, of which one or more examples are illustrated in the appended figures. Each example is provided merely by way of illustration of the invention and is not intended as a limitation thereof. For example, the technical features illustrated or described being part of an embodiment may be adopted on, or in association with, other embodiments for producing a further embodiment. It is to be understood that the present invention shall be inclusive of such modifications and variants.
It is also underlined that the present description is not limited in its application to the construction and arrangement details of the components as described below using the appended figures. The present description can envisage other embodiments and be realised or implemented with other technically equivalent features. The terms used below are merely descriptive and should not be considered limiting.
According to a first exemplary embodiment shown in
The infusion site 100 may comprise a second connection site 104 defining a second inlet 114 and a secondary channel 140 elongated along a second predetermined central axe Y-Y, the axe Y-Y being in a vertical or top-bottom direction in the figures. The secondary channel 140 may also comprise an outlet 142 arranged opposite to the inlet 114 and facing the first main channel 120. According to one of the embodiments of the present invention, the outlet 142 may a be a narrowed section of the secondary channel 140.
The infusion site 100 may comprise a third connection site 103 defining an outlet 113 and a second main channel 130, elongated along a third predetermined central axe X′-X′ which is parallel to the first predetermined axe X-X and offset thereto along the second predetermined axe Y-Y. Thus, the first main channel 120 is offset to the second main channel 130 in a vertical direction in the figures. All the three channels 120, 130 and 140 are in fluid communication to each other.
According to one of the embodiments of the present invention, the first 120 and the second 130 main channels may comprise a narrowed section 122, 132 arranged opposite to the first inlet 112 and to the outlet 113 respectively. Each of narrowed section 122, 132 has a narrowed internal circular section with respect to internal circular section of the first 120 and the second 130 main channels. Thus, the narrowed section 122 of the first main channel 120 is offset to the narrowed section 132 of second main channel 130 in a vertical direction in the figures.
In certain embodiments, the second predeterminate axe Y-Y of the secondary channel 140 may not be perpendicular to the axes X-X and X′-X′ of the first 120 and the second 130 main channel respectively.
In use, the infusion site 100 acts between three tubes of a blood tubing set.
An addition line, here a line 207 for citrate solution, opens upstream of the blood pump 301 into the blood withdrawal line 203. The line 207 is operatively connected to, or comprises, a citrate pump 307.
Downstream of the hemofilter 201, a further addition line, here a line 209 for an electrolyte solution, in particular a calcium solution according to the present invention, opens into the blood return line 205. The infusion site 100 according to the present invention is operatively connected to a calcium pump 309 or comprises the latter. It is supplied by a source for infusion solution which is not shown in
The operative connection to the calcium pump 309 is to be understood herein as an example. Arranging the infusion site 100 behind another pump than a calcium pump, i.e. for example downstream of a citrate pump like the citrate pump 307 of
The hemofilter 201 is connected to a line 311 for fresh dialysis liquid and to a line 315 for spent dialysate or filtrate. The line 311 is connected to, or comprises, a dialysis liquid pump 313. The line 315 is connected to, or comprises, a filtrate pump 317.
The arrowhead indicates the flow direction when using the blood tubing set 200 as intended.
The blood tubing set 200 shown in
The first connection site 102 may be connected in fluid communication to a first tubing portion 205a of the blood tubing set 200, for example the blood-return line 205, so that a liquid, preferably blood, enters the infusion site 100 at the first inlet 112 conducted by the first main channel 120 in the direction of the arrow B.
The second connection site 104 may be connected in fluid communication to a tubing portion of the line for calcium solution 209, so that an infusion solution, enters the infusion site 100 at the second inlet 114 conducted by the secondary channel 140 in the direction of the arrow S, and enter into the first main channel 120 through the outlet 142. The infusion solution may be a liquid comprising a calcium-substitution solution, or any other type of solution used in haemodialysis treatment, or even a medicament.
The third connection site 103 may be connected in fluid communication to a second tubing portion 205b of the blood tubing set 200, for example the blood return line 205, so that a third liquid, preferably the infusion of blood and infusion solution, exits the infusion site 100 at the outlet 113 conducted by the third main channel 130 in the direction of the arrow I.
The infusion site 100 comprises an inlet deflector 160 suitable to deflect the fluids entering the infusion site 100. In particular, the inlet deflector comprises an inclined wall 160 of the first main channel 120. More particularly, the inclined wall 160 is obtained at an end of the narrowed section 122 of the first main channel 120 opposite to the first connection site 102 and facing the narrowed section 132 of the second main channel 130.
According to this configuration, the inclined wall 160 is positioned at and faced to the outlet 142 of the secondary channel 140.
The infusion site 100 further comprises a re-circulator 170 suitable to recirculate the fluid inside the infusion site 100. In particular, the re-circulator comprises a curved wall 170 of the second main channel 130. More particularly, the curved wall 170 is obtained at an end of the narrowed section 132 of the second main channel 130 opposite to the third connection site 103 and facing the narrowed section 122 of the first main channel 120.
The term “inclined wall” is used herein to indicate a surface defining a plane which forms with the first axe X-X of the first main channel 120 an angle α comprised between 40° and 90°. The term “curved wall” is used therein to indicate a curved surface wherein the tangent plane to the curved surface defines a plane which forms with the second axe X′-X′ of the second main channel 130 an angle different from zero. According to the embodiments shown in the figures, the “curved wall” defines a concavity. Different embodiments of the present invention may comprise a different combination of inclined and curved walls for the inlet deflector 160 and the re-circulator 170.
For example, the value of the angle α of the inclined wall 160 is preferably comprised between 45° and 90°. The distance between the first predetermined central axe X-X and the third predetermined central axe X′-X′, i.e. the offset between the first main channel 130 and the second main channel 130, is preferably comprised between 1 and 2.5 mm. The radius of the curved surface 170 is preferably comprised between 2° and 10°.
The infusion site 100 comprises an inner turbulence chamber 150, located downstream from and in fluid communication to the first main channel 120 and with the secondary channel 140, and located upstream from and in fluid communication to the second main channel 130. According to the flow path of the liquids inside the infusion site 100, the inner turbulence chamber 150 is thus defined by the narrowed section 122 arranged downstream of the inlet 112 of the first main channel 120, by the inclined wall 160 arranged downstream the narrowed section 122, by the curved wall 170 arranged downstream the inclined wall 160, and by the narrowed section 132 of the second main channel 130 arranged downstream the curved wall 170. The outlet 142 of the secondary channel 140 is arranged at and faces the inner turbulence chamber 150.
In use, a first liquid, preferably blood, enters the inner turbulence chamber 150 coming from the first connection site 102 conducted by the first main channel 120 in the direction of the arrow B.
A second liquid, preferably an infusion solution, enters the inner turbulence chamber 150 coming from the second connection site 104 conducted by the secondary channel 140 in the direction of the arrow S.
The blood entered from the first connection site 102 enters the narrowed section 122 of the first main channel 120 and encounters the inlet deflector 160, which acts as an obstacle to the stream of blood disrupting the fluid vein and allowing a pre-mixing of blood with the infusion solution coming from the inlet 142 of the secondary channel 140 and generating a premixed flow.
The premixed flow is then deflected according to the inclination of the inclined wall 160 towards the curved wall 170 of the narrowed section 132 of the second main channel 130. Reaching the curved wall 170, part of the premixed flow is redirected to the narrowed section 122 of the first main channel 120 and part of the premixed flow is discharged towards the second main channel 130.
The part of the premixed flow redirected to the narrowed section 122 of the first main channel 120 is mixed with blood which enters the first connection site 102 and that is not yet mixed with the infusion solution. Then, the premixed blood mixed with the blood encounters the inlet deflector 160 and the inlet 142 of the secondary channel 140 allowing a new mixing cycle begin.
According to the previous configuration, two mixing area inside the inner turbulence chamber 150 can be identified:
The inclined wall 160 and the curved wall 170 allow the creation of a vortex that recirculates the premixed blood into blood entering the infusion site 100. The offset between the first 120 and the second 130 main channels permits the integration of the inclined wall 160 and the curved wall 170 in the inner turbulence chamber 150, creating a space where the vortex can develop.
Moreover, thank to this configuration, the inlet 142 of the infusion solution is positioned at the edge of the vortex, so that the infusion solution hits the blood vortex at the point of highest velocity and the mixing of the infusion solution and the premixed blood is optimized.
Several tests conducted by the Applicant has shown how the present invention definitively increases the mixing capability of an infusion site of a blood tubing system. Some of the results of these tests are herein below provided merely by way of examples of embodiments of the invention and they are not intended as a limitation thereof.
Some prototypes of the present invention have been produced, with different parametric values of the single components thereof.
Internal geometry quotes were optimized with a Design of Experiment where each test was a CFD (Computational Fluid Dynamics) simulation, and where the influence of each parameter on the mixing efficiency was considered. A set of critical parameter, intended as the parameter with a statistical effect on the response, was identified and their value was set in correspondence of the highest response.
The transfer function of the optimized design was also computed and can directly links changes in the critical parameters to a change in response.
For the purpose of this design development, mixing efficiency was defined as
computed on a cross section of the tube on the outside of the component, where:
Mixing efficiency gamma moves from 0 to 1, where 0 correspond to no mixing and 1 correspond to complete mixing.
The present invention has been also analysed with a computational fluid dynamic simulation at different blood and calcium feed flow condition and for different distances from the outlet of the component. Results where then used with an ANOVA (ANalysis Of VAriation) calculation to establish a relationship between mixing efficiency and blood feed rate, calcium feed rate and distance from the component.
Results from CFD and ANOVA computation showed that for predetermined flow rates range, moving along distances from the infusion site to the patient reinfusion site, the mixing efficiency is always above 0.7.
An empirical relationship can be established between the distance from the infusion site (L), the blood flow rate (Q blood) and the γ mixing efficiency, while the calcium flow rate appeared to be not statistically significant after the ANOVA analysis.
A similar comparative CFD analysis has been performed for a standard T Hep connector and for the connector of the present invention. The results were retrieved at a two different distances (L) from the infusion site and showed that the mixing efficiency of the present invention is always above compared to the efficiency of the other one. Table 1 shows the result of the test comparison.
In addition to the increased mixing capability, the test results showed that the present invention provides several advantages. The infusion site can be produced in PVC and can be easily integrated in a bloodline using current gluing technique. The present invention can be easily moulded with no impact on the actual production processes and with lower costs. The present invention has the same encumbrance as current designs, and, thus, it has no impact on an assembly procedure. The present invention can be produced as one-piece component.
| Number | Date | Country | Kind |
|---|---|---|---|
| 21173535.2 | May 2021 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/062729 | 5/11/2022 | WO |
