BREATHING TUBE ARRANGEMENT FOR A LUNG FUNCTION DIAGNOSTICS DEVICE COMPRISING A DISTAL FILTER ELEMENT

Abstract

The disclosure relates to a breathing tube arrangement for a lung function diagnostics device, comprising a breathing tube defining a guiding path for breathing air to be analyzed by a lung function diagnostics device, the breathing tube having a proximal end, a distal end and an analysis zone located between the proximal end and the distal end. According to an aspect of the disclosure, the breathing tube arrangement comprises a filter element having a filter material, a breathing air releasing region arranged distally of the filter material, and a diffusor zone arranged proximally of the filter material, wherein the diffusor zone comprises a proximal end having a first proximal cross-sectional area and a distal end having a first distal cross-sectional area that is bigger than the first proximal cross-sectional area, and wherein the breathing air releasing region has a second distal cross-sectional area, wherein the second distal cross-sectional area is bigger than the first proximal cross-sectional area and at least as big as the first distal cross-sectional area, wherein a ratio between the first proximal cross-sectional area and the second distal cross-sectional area lies in a range of between 1:2 to 1:20.

Claims

1. A breathing tube arrangement for a lung function diagnostics device, comprising a breathing tube defining a guiding path for breathing air to be analyzed by a lung function diagnostics device, the breathing tube having a proximal end, a distal end and an analysis zone located between the proximal end and the distal end, wherein the proximal end is designed to face a subject whose lung function is to be analyzed and to receive exhaled breathing air from the subject, wherein the analysis zone serves for allowing an analysis of breathing air flowing through the breathing tube, and wherein the distal end serves for releasing analyzed breathing air to an environment of the breathing tube, wherein the breathing tube arrangement comprises a filter element having a filter material, a breathing air releasing region arranged distally of the filter material, and a diffusor zone arranged proximally of the filter material, wherein the diffusor zone comprises a proximal end having a first proximal cross-sectional area and a distal end having a first distal cross-sectional area that is bigger than the first proximal cross-sectional area, wherein the proximal end of the diffusor zone is connected to the distal end of the breathing tube such that breathing air flowing from the breathing tube through the distal end of the breathing tube towards an environment of the breathing tube has to pass the filter element, and wherein the breathing air releasing region has a second distal cross-sectional area, wherein the second distal cross-sectional area is bigger than the first proximal cross-sectional area and at least as big as the first distal cross-sectional area, wherein a ratio between the first proximal cross-sectional area and the second distal cross-sectional area lies in a range of from 1:2 to 1:20.

2. The breathing tube arrangement according to claim 1, wherein a distal end of the breathing air releasing region does not comprise a connector for connecting further elements of a breathing gas flow path to the breathing air releasing region.

3. The breathing tube arrangement according to claim 1, wherein the diffusor zone has sidewalls that diverge in a direction from the proximal end of the diffusor zone towards the distal end of the diffusor zone at least in a section between the proximal end of the diffusor zone and the distal end of the diffusor zone at an angle lying in a range of from 5° to 30°.

4. The breathing tube arrangement according to claim 1, wherein the filter material is arranged in a filter material support, wherein the filter material support and/or the filter material have a circular base area having a diameter lying in a range of from 30 mm to 160 mm.

5. The breathing tube arrangement according to claim 1, wherein the filter material is arranged in a filter material support, wherein the filter material support further comprises a plurality of ribs arranged distally of the filter material and keeping the filter material within the filter material support.

6. The breathing tube arrangement according to claim 5, wherein at least some ribs of the plurality of ribs lie upon corresponding fins, wherein the filter material is clamped between the ribs and the fins.

7. The breathing tube arrangement according to claim 4, wherein the filter material is clamped in the filter material support such that a circumferential edge area of the filter material is more proximally or more distally arranged than a central area of the filter material.

8. The breathing tube arrangement according to claim 7, wherein an angle between i) a first line intersecting a center of the central area of the filter material on a proximal surface of the filter material and a first support point on which a proximal surface of the circumferential edge area abuts a support surface of the filter material support and ii) a second line extending from the first support point through an axis running through the center of the central area of the filter material along a longitudinal extension direction of the breathing tube arrangement to a second support point on which the proximal surface of the circumferential edge area abuts the support surface of the filter material support lies in a range of from 1° to 10°.

9. The breathing tube arrangement according to claim 4, wherein the filter material support comprises a filter material support body and a filter material support cover, wherein one of the filter material support body and the filter material support cover comprises at least one cam and the other of the filter material support body and the filter material support cover comprises at least one notch for receiving the at least one cam.

10. The breathing tube arrangement according to claim 1, wherein the filter material comprising a filtering layer comprising blended synthetic fibers.

11. The breathing tube arrangement according to claim 1, wherein the filter material comprises a filtering layer and a top layer laminated onto the filtering layer.

12. The breathing tube arrangement according to claim 11, wherein the top layer is a scrim layer.

13. A filter element for a breathing tube of a breathing tube arrangement according to claim 2, wherein the filter element has a proximal opening that can be connected to a distal end of a breathing tube, wherein a distal end of the breathing air releasing region does not comprise a connector for connecting further elements of a breathing gas flow path to the breathing air releasing region.

14. A lung function diagnostics device comprising a breathing tube arrangement according to claim 1, wherein the breathing tube arrangement is inserted into the lung function diagnostics device such that i) a sensor of the lung function diagnostics device is able to analyze breathing air flowing through an analysis zone of a breathing tube of the breathing tube arrangement, ii) a proximal end of the breathing tube is arranged proximally of the sensor, and iii) a filter element of the breathing tube arrangement is arranged distally of the sensor.

15. The lung function diagnostics device according to claim 14, wherein the sensor is an ultrasonic sensor.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0043] Further details of aspects of the present disclosure will be described in the following making reference to exemplary embodiments and accompanying Figures. In the Figures:

[0044] FIG. 1A shows a perspective view of a first embodiment of a filter element;

[0045] FIG. 1B shows a frontal view onto the distal end of the filter element of FIG. 1A;

[0046] FIG. 1C shows a longitudinal section through the filter element of FIG. 1A along the line indicated with “C” in FIG. 1B;

[0047] FIG. 1D shows a perspective exploded view of the filter element of FIG. 1A;

[0048] FIG. 1E shows a detail of the filter material of the filter element of FIG. 1A;

[0049] FIG. 2A shows a perspective view of a second embodiment of a filter element;

[0050] FIG. 2B shows a frontal view onto the distal end of the filter element of FIG. 2A;

[0051] FIG. 2C shows a longitudinal section through the filter element of FIG. 2A along the line indicated with “C” in FIG. 2B;

[0052] FIG. 2D shows a longitudinal section through the filter element of FIG. 2A along the line indicated with “D” in FIG. 2B;

[0053] FIG. 3A shows a breathing tube arrangement known from prior art;

[0054] FIG. 3B shows a graphic depiction of the breathing resistance over the flow rate of the breathing tube arrangement of FIG. 3A;

[0055] FIG. 4A shows an embodiment of a breathing tube arrangement comprising a distal filter element; and

[0056] FIG. 4B shows a graphic depiction of the breathing resistance over the flow rate of the breathing tube arrangement of FIG. 4A.

DETAILED DESCRIPTION

[0057] FIG. 1A shows an embodiment of a filter element 1 comprising an inlet 2 at its proximal end and an outlet 3 at its distal end. A plurality of ribs 4 is provided for holding a filter material (not shown in FIG. 1A) in place so that breathing air entering the filter element 1 through the inlet 2 and exiting the filter element 1 through the outlet 3 has to pass the filter material. For illustration purposes, only some of the ribs 4 are marked with the according numeral reference.

[0058] FIG. 1B shows a frontal view onto the outlet 3 of the filter element 1 of FIG. 1A. In this and in all following Figures, similar elements will be denoted with the same numeral reference.

[0059] FIG. 1C shows a longitudinal section through the filter element 1 of FIG. 1A along the line indicated with “C” in FIG. 1B. Here, it can well be seen that the inlet 2 is proximal of a diffusor 5 having a proximal end 6 and a distal end 7. The inlet 2 is realized at a connecting element 20 that is arranged proximal to the proximal end 6 of the diffusor 5. The connecting element 20 is intended to be connected to a distal end of a breathing tube. Upon such connection, the distal end of the breathing tube will be inserted into the proximal end region of the connecting element 20 up to a stop. An interior cross-section of the connecting element 20 is shaped such that no diameter offset between an interior of the distal end of the breathing tube and an interior of the proximal end 6 of the diffusor 5 is formed. Rather, the interiors of the distal end of the breathing tube and of proximal end 6 of the diffusor 5 will be flush. This reduces the risk of the occurrence of vortices and allows a laminar flow of gas through the breathing tube and the filter element 1.

[0060] Breathing air flowing through the breathing tube and further through the filter element 1 will then be guided through an interior of the diffusor 5 and through a filter material 9 that is kept in place by a filter material support 10. The ribs 4 form part of this filter material support 10.

[0061] A first side wall 51 and a second side wall 52 of the diffusor 5 diverge from each other in a continuous manner. A first line 53 extending along the first side wall 51 and a second line 54 extending along the second side wall 52 intersect each other at an angle α lying at approximately 12.5°.

[0062] Due to the diverging side walls 51, 52, the interior of the diffusor 5 acts as expansion. This design facilitates flowing of breathing air towards and through the filter material 9 and finally exiting the filter element 1 through the outlet 3.

[0063] The diverging side walls 51, 52 also cause that a proximal cross-sectional area 61 (corresponding to a first proximal cross-sectional area) is smaller than a distal cross-sectional area 71 (corresponding to a first distal cross-sectional area).

[0064] The filter element 1 does not comprise any connector on its distal end side (i.e., on the side of the outlet 3). Rather, the connecting element 20 is the only connector of the filter element 1. Therefore, it is not necessary that breathing air that has passed the filter material 9 needs again to flow through a connector having a comparatively small diameter. Rather, the whole area of the outlet 3 can be used by the breathing air upon exiting the filter element 1. The outlet 3 forms part of a breathing air releasing region 30, a cross-sectional area 31 of which is significantly larger than the proximal cross-sectional area 61 and the distal cross-sectional area 71 of the diffusor 5.

[0065] The sectional view of FIG. 1C illustrates that the filter element 1 has a particularly small dead space. Many lung function measuring standards require small dead spaces so that the filter element 1 is appropriate to be used for many different measurements according to such standards. Furthermore, the analysis of breathing gas of children requires particularly small dead spaces since otherwise the breathing of the children would be changed.

[0066] The filter material support 10 comprises a filter material support base 101 and a filter material support cover 102. The filter material support base 101 and the filter material support cover 102 receive the filter material 9 between them. This will be illustrated in FIG. 1D in more detail.

[0067] FIG. 1 D shows an exploded perspective view of the filter element 1 already shown in FIGS. 1A to 1C. In this depiction, it can well be seen that the filter material support base 101 and the filter material support cover 102 form the filter material support 10. The ribs 4 are formed in the filter material support cover 102, whereas at least for some of the ribs 4 corresponding fins 40 are formed within the filter material support base 101. When the filter material 9 is placed between the filter material support base 101 and the filter material support cover 102, only those seven supporting ribs 4 that directly extend from the circular center rib 4 to the circumference of the filter material support cover 102 will abut the filter material 9. These seven supporting ribs 4 are supported by correspondingly arranged fins 40 in the filter material support base 101. Thus, the filter material 9 will be clamped between the seven supporting ribs 4 and the corresponding seven fins 40. The other ribs 4 in the filter material support cover 102 do not directly abut the filter material 9, but increase the mechanic stability of the filter material cover 102 and reduce the possibility for a user to contact the filter material 9 with her or his fingers.

[0068] In order to achieve an alignment of the seven supporting ribs 4 and the corresponding seven fins 40, the filter material support cover 102 needs to be placed upon the filter material support base 101 in a specific orientation. To particularly easily achieve this orientation, the filter material support base 101 comprises seven cams 103 (only one of these cams 103 is marked with the respective numeral reference), and the filter material support cover 102 comprises seven notches 104 (also here, only one of these notches 104 is marked with the respective numeral reference). Each of these notches 104 is intended to receive a corresponding cam 103. Once all cams 103 are received by corresponding notches 104, the filter material support cover 102 is tightly connected to the filter material support base 101.

[0069] Due to an equal distribution of the cams 103 and the notches 104, the filter material support cover 102 can be connected with the filter material support base 101 in seven different positions. Due to the symmetric design of the filter material support base 101 and the filter material support cover 102, each of these seven positions will result in the same final design of the filter material support 10.

[0070] FIG. 1E shows a detail of the filter material 9 of the filter element 1 illustrated in FIGS. 1A to 1D. Here, a proximal offset of a circumferential edge area 90 of the filter material 9 with respect to a central area 91 of the filter material 9 is visible. This proximal offset is achieved by clamping the filter material 9 between the filter material support base 101 and the filter material support cover 102 (cf. FIG. 1D). Due to this proximal offset, a surface 92 of the filter material 9 becomes particularly flat and smooth, thus increasing the reliability and repeatability of measurements performed when using the filter element 1.

[0071] The proximal offset can be defined by an angle between a first line 93 and a second line 94. The first line 93 intersects a proximal surface of the central area 91 of the filter material 9 at a central axis A running through a center of the central area 91 along a longitudinal direction of extension of the filter element 1 (and thus of a longitudinal direction of extension of the breathing tube arrangement comprising this filter element 1). The first line 93 further intersects a first support point 95 at which a proximal surface of the circumferential edge area 90 abuts a part of the filter material support. The second line 94 runs from this first support point 95 through the central axis a to a second support point lying opposite to the first support point 95 at the most distant part of the circumferential edge area 90 of the filter material support 9. The second support point is not shown in FIG. 1E. An angle β between the first line 93 and the second line 94 has a value of approximately 4° in the embodiment shown in FIG. 1E.

[0072] FIG. 2A shows a perspective view of another embodiment of a filter element 1 that has a very similar design like the filter element shown in FIGS. 1A to 1C. However, the diffusor 5 surrounding the inlet 2 has a substantially rectangular cross section, whereas the cross-section of the diffusor 5 of the filter element of FIGS. 1A to 1D has a cylindrical cross-section. The other elements of the filter element 1 are highly similar or identical to the corresponding elements of the filter element shown in FIGS. 1A to 1C so that reference is made to the above given explanations.

[0073] FIG. 2B shows a front view on the outlet 3 of the filter element 1 of FIG. 2A. Also here, reference is made to the explanations given above with respect FIG. 1B.

[0074] FIGS. 2C and 2D show longitudinal sections along the lines indicated with “C” or “D”, respectively, in FIG. 2B.

[0075] Due to the rectangular cross section of the diffusor 5, the longitudinal sections of FIG. 2C and FIG. 2D deviate from each other. The most prominent difference is a different angle between opposite side walls. Whereas a first side wall 51 and a second side wall 52 diverge at an angle α of approximately 20°, a third side wall 55 and a fourth side wall 56, as shown in FIG. 2D, diverge at an angle γ of approximately 8°. However, even though the opening angle between the opposing sidewalls differs, the diffusor 5 still has the design of a diffusor or expansion. As a result, air being introduced through the inlet 2 into the filter element 1 can be easily flow towards and through the filter material 9 experiencing only a very low breathing resistance. Thus, the sidewalls 51, 52, 55, 56 diverging from the proximal end 6 to the distal end 7 of the diffusor 2 together with the big area of the outlet 3 serve for a particularly low respiratory resistance of the filter element 1.

[0076] FIG. 3A shows a breathing tube arrangement not falling under the present disclosure, but serving as comparative example. This breathing tube arrangement comprises a breathing tube 11 and a filter 12 located distally of an analysis zone 13 of the breathing tube 11. The filter 12 has an active filter area of approximately 60 cm.sup.2. However, it does not comprise a diffusor zone. Furthermore, it has an outlet having a smaller area then the area of the filter element.

[0077] FIG. 3B indicates the evolution of the breathing resistance with increasing flow of the breathing tube arrangement of FIG. 3A. The maximum desired breathing resistance of 1.5 cm H.sub.2O/L/s (corresponding to approximately 1.5 hPa/L/s) to comply with the ATS/ERS guidelines is indicated as reference value (dashed horizontal curve). It can be clearly seen from FIG. 3B that the breathing resistance (individual measuring points fitted with the dashed ascending curve) linearly increases with increasing flow. The recommended maximum breathing resistance is already reached at a flow of approximately 11 L/s. At a flow of 14 L/s, the breathing resistance has reached a value of approximately 1.75 hPa/L/s and thus lies significantly over the recommended maximum breathing resistance. Thus, this comparative breathing tube arrangement is not able to comply with the recommended breathing resistance.

[0078] FIG. 4A shows a breathing tube arrangement 14 comprising a breathing tube 15 and a filter element 1 with a diffusor zone. The breathing tube 15 comprises a proximal end 16 and a distal end 17 as well as an analysis zone 18 located between the proximal end 16 and the distal end 17. The filter element 1 is the same filter element as illustrated in more detail in FIGS. 1A to 1D. It is located at the distal end 17 of the breathing tube 15 and has an active filter area of approximately 45 cm.sup.2.

[0079] FIG. 4B shows the breathing resistance of the breathing tube arrangement 14 of FIG. 4A over the flow rate. The same filter material as in the setup of the comparative example of FIG. 3A was used. Once again, the recommended maximum breathing resistance of approximately 1.5 hPa/L/s is indicated as reference value (dashed horizontal curve). Here, it can clearly be seen that the breathing resistance of the breathing tube arrangement 14 with the distally positioned filter element 1 having a diffusor zone exhibits a breathing resistance that is significantly lower than the maximum recommended breathing resistance (individual measuring points fitted with the dashed ascending curve). At a flow rate of 14 L/s, the breathing resistance is approximately 0.75 hPa/L/s and thus less than half of the breathing resistance of the comparative breathing tube arrangement depicted in FIG. 3A (cf. also the experimental results of FIG. 3B). This clearly shows the superiority of a distally positioned filter element having a diffusor zone like in case of the breathing tube arrangement 14 shown in FIG. 4A.