DEVICE FOR WITHDRAWING AND FOR TRANSPORTING A BREATHING GAS STREAM

Abstract

A device 10 withdraws a breathing gas stream (A) from a ventilation system (B) and transports the breathing gas stream (A) to a gas analysis system (G). The device 10 has a tubular configuration with an inner side (41) and with an outer side (42) and includes two tube sections (11, 11′) and a drying stage (12, 14, 22) with an inner side (43, 43′) and with an outer side (44, 44′), and at least one liquid storage device (13, 21). The drying stage (12, 14, 22) includes a gas-tight and moisture-permeable material that transports moisture from the inner side (43, 43′) of the drying stage (12, 14, 22) through the gas-tight and moisture-permeable material to the outer side (42) of the tubular device (10). The drying stage (12, 14, 22) and/or the liquid storage device (13, 21) is arranged at least partially between the two tube sections (11, 11′).

Claims

1. A device for withdrawing a breathing gas stream from a ventilation system and for transporting the breathing gas stream to a gas analysis system the device comprising: a tubular configuration with an inner side and with an outer side and has comprising at least two tube sections at least one drying stage with an inner side and with an outer side; and at least one liquid storage device wherein: the drying stage comprises a gas-tight and moisture-permeable material such that moisture can be transported from the inner side of the drying stage through the gas-tight and moisture-permeable material to the outer side of the tubular configuration; and the at least one drying stage or the at least one liquid storage device is arranged at least partly between two tube sections or both the at least one drying stage and the at least one liquid storage device are arranged at least partly between two tube sections.

2. A device in accordance with claim 1, wherein the at least one liquid storage device is selected from among a hydrophilic porous sintered plastic material, a nonwoven, a plasma-treated granular polyethylene (PE) or a matrix of microstructured plastic particles.

3. A device in accordance with claim 1, wherein the at least one liquid storage device is arranged between a first tube section and a second tube section, so that the breathing gas stream passes through the device in the sequence of a. first tube section b. liquid storage device, and c. second tube section.

4. A device in accordance with claim 1, wherein the at least one tube section is configured as a drying stage.

5. A device in accordance with claim 1, further comprising at least one additional drying stage to provide a first drying stage and at least one second drying stage wherein the liquid storage device is arranged between the first drying stage and the second drying stages such that the breathing gas stream passes through the device in the sequence of a. first drying stage, b. liquid storage device, and c. second drying stage.

6. A device in accordance with claim 1, wherein the at least one liquid storage device has a tubular configuration.

7. A device in accordance with claim 1, wherein a desiccant zeolite, silica gel or the like, is applied to the outer side of at least one drying stage.

8. A device in accordance with claim 1, wherein the at least one liquid storage device is arranged in the at least one drying stage, so that the at least one drying stage forms a part of a drying element.

9. A device in accordance with claim 1, wherein the at least one liquid storage device has a wick-shaped configuration.

10. A device in accordance with claim 1, wherein the at least one drying stage has a membrane based on polyether imides, polyether block amides or polyurethanes.

11. A device in accordance with claim 10, wherein the material of which the membrane is formed is a material based on polyurethane, wherein the membrane material has: a density of 0.5 g/cm.sup.3 to 1.8 g/cm.sup.3; or a melting range between 100° C. and 200° C.; or or a water vapor permeability greater than 500 g/m.sup.2 per 24 hours; or any combination of a density of 0.5 g/cm.sup.3 to 1.8 g/cm.sup.3 and a melting range between 100° C. and 200° C. and a water vapor permeability greater than 500 g/m.sup.2 per 24 hours.

12. A device in accordance with claim 10, wherein membrane is applied to a polyethylene carrier.

13. A device in accordance with claim 1, further comprising a hydrophobic bacteria filter, wherein the bacteria filter has a PTFE membrane with a pore size of 0.45 μm or less and with a water penetration pressure of 100 kPa or higher.

14. A device in accordance with claim 13, wherein the liquid storage device, and the bacteria filter form a single component.

15. A system for monitoring the breathing gas of a patient, the system comprising a device for withdrawing a breathing gas stream from a ventilation system and for transporting the breathing gas stream to a gas analysis system, the device comprising: a tubular configuration with an inner side and with an outer side and comprising at least two tube sections; at least one drying stage with an inner side and with an outer side; and at least one liquid storage device, wherein: the drying stage comprises a gas-tight and moisture-permeable material such that moisture can be transported from the inner side of the drying stage through the gas-tight and moisture-permeable material to the outer side of the tubular configuration; and the at least one drying stage or the at least one liquid storage device is arranged at least partly between two tube sections or both the at least one drying stage and the at least one liquid storage device are arranged at least partly between two tube sections.

16. A system in accordance with claim 15, wherein the at least one liquid storage device is selected from among a hydrophilic porous sintered plastic material, a nonwoven, a plasma-treated granular polyethylene (PE) or a matrix of microstructured plastic particles.

17. A system in accordance with claim 15, wherein the at least one liquid storage device is arranged between a first tube section and a second tube section, so that the breathing gas stream passes through the device in the sequence of a. first tube section, b. liquid storage device, and c. second tube section.

18. A system in accordance with claim 15, wherein the at least one tube section is configured as a drying stage.

19. A system in accordance with claim 15, further comprising at least one additional drying stage to provide a first drying stage and at least one second drying stage, wherein the liquid storage device is arranged between the first drying stage and the second drying stage such that the breathing gas stream passes through the device in the sequence of a. first drying stage, b. liquid storage device, and c. second drying stage.

20. A device in accordance with claim 19, wherein the desiccant comprises zeolite, silica gel or both zeolite and silica gel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In the drawings:

[0053] FIG. 1 is a schematic view of a first embodiment of the present invention;

[0054] FIG. 2 is a schematic view of a second embodiment of the present invention; and

[0055] FIG. 3 is a schematic view of a third embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0056] Referring to the drawings, the embodiment variant of a device 10 according to the present invention shown in FIG. 1 has two tube sections 11, 11′ and a liquid storage device 13 arranged between the two tube sections 11, 11′. The liquid storage device 13 has a tubular configuration corresponding to FIG. 1 in the exemplary embodiment.

[0057] Both the first tube section 11 and the second tube section 11′ are configured as a drying stage 12, 14. In other words, the device 10 has a first drying stage 12 and a second drying stage 14, the drying stages 12, 14 having each a tubular configuration. The device 10 has, furthermore, an inner side 41 and an outer side 42. The drying stages 12, 14 also have an inner side 43 each and an outer side 44 each. It can be seen in this connection that the inner side 43 of the drying stages 12, 14 corresponds in the example being shown in FIG. 1 to the inner side 41 of the device 10 and that the outer side 44 of the drying stages 12, 14 corresponds to the outer side 42 of the device 10.

[0058] The drying stages 12, 14 have a gas-tight, moisture-permeable material. Suitable materials for the embodiment variant described in FIG. 1 and for all other (described or non-described) embodiment variants will hereinafter be mentioned in the example “testing of different membrane materials.”

[0059] The device 10 further has a first end 16 and a second end 17. A breathing gas stream A, which arrives from a ventilation system B, can flow through the first end 16 into the device 10. The breathing gas stream A can flow out of the device 10 through the second end 17 and towards a gas analysis system G. It is seen that while flowing through the device 10, the breathing gas stream A first flows through the first drying stage 12. Moisture contained in the breathing gas stream A is transported here from the inner side 43 of the drying stage 12 and hence from the inner side 41 of the device 10 to the outer side 44 of the drying stage 12, i.e., to the outer side 42 of the device 10. If large droplets of moisture are contained in the breathing gas stream A, these can subsequently be absorbed by the liquid storage device 13. At the same time, the liquid storage device 13 may also release moisture in the form of water vapor to the breathing gas stream A. To prevent the breathing gas stream A from being greatly rehumidified in the process, moisture can once again be transported from the inner side 43 of the drying stage 14 and hence from the inner side 41 of the device 10 to the outer side 44 of the drying stage 14, i.e., to the outside 42 of the device 10 while the breathing gas stream A is passing through the second drying stage 14.

[0060] The device 10 has a diameter D. This diameter D corresponds to the internal diameter of the tube sections 11, 11′. The drying stages 12, 14 thus have the same diameter D as the entire device 10. The diameter D is selected to be such that the breathing gas stream A will have a minute volume of 50 mL/minute at a gas velocity higher than 1 m/sec. The diameter D is about 1 mm in a preferred embodiment variant.

[0061] A bacteria filter 15 is arranged as an additional protection at the second end 17 of the device 10. The bacteria filter 15 is hydrophobic and consists of a PTFE membrane with a pore size of 0.45 μm or less and with a water penetration pressure of 100 kPa or higher.

[0062] On the whole, a device 10 for withdrawing breathing gas stream A from a ventilation system B and for transporting the breathing gas stream A to a gas analysis system G is seen in FIG. 1, the device 10 having a tubular configuration with an inner side 41 and with an outer side 42 and two tube sections 11, 11′ as well as two drying stages 12, 14 with an inner side 43 and an outer side 44 each, and a liquid storage device 13, the drying stages 12, 14 consisting at least partly of a gas-tight and moisture-permeable material, such that moisture can be transported from the inner side 43 of the drying stages 12, 14 through the gas-tight and moisture-permeable material to the outer side 42 of the tubular device 10, and the liquid storage device 13 being arranged between two tube sections 11.

[0063] The breathing gas stream A typically has a temperature of about 37° C. in this exemplary embodiment when it enters the first tube section 11 through the end 16. It cools while flowing through the tube section 11, as a result of which the dew point drops and water can be removed by condensation. However, this condensed water can be brought through the drying stage 12 to the outer side 42 of the device and thus removed. If water drops have formed during the cooling or have already been present in the breathing gas stream before, these are absorbed by the liquid storage device 13 during the further flow of the breathing gas stream A. However, the gas temperature can decrease further as a result and condensation of moisture may occur due to the temperature dropping below the dew point. This is likewise transported during the flow through the tube section 11′, which is likewise configured as a drying stage 14, to the outer side 42 of the device 10. In addition, the condensation can be avoided by means of the drying stage 14 by the dew point of the gas being lowered by means of the drying stage 14 to below the ambient temperature. The breathing gas stream A, upon reaching the end 17, no longer has disturbing moisture present for entry into the gas analysis system G.

[0064] The device 10 has a first tube section and a second tube section 11, 11′, respectively, as well as a diameter D that is selected as was already described for FIG. 1 in the exemplary embodiments shown in FIGS. 2 and 3 as well. It is seen here as well that the device 10 has a first end 16, through which a breathing gas stream A arriving from a ventilation system B flows into the device, and a second end 17, through which the breathing gas stream A flows out of the device 10 and flows towards a gas analysis system G. The device 10 shown in FIGS. 2 and 3 also has a liquid storage device 21. This liquid storage device 21 has a wick-shaped configuration. It forms a drying element 20 together with a drying stage 22.

[0065] The wick, i.e., the liquid storage device 21, has the shape of a circular disk with a hold 214 in the center, with a circular surface 213, with an inner edge 211 and with an outer edge 212. The area of the circular surface 213 and the outer edge 212 are arranged within the drying element 22. The inner edge 211 is arranged between the first tube section 11 and the second tube section 11a. The liquid storage device 21 is thus arranged at least partly between two tube sections 11, 11′. The breathing gas stream A now flows through the hole 214. It is thus seen that at least one liquid storage device 21 is arranged in one of the drying stages 22 in the exemplary embodiment according to FIG. 2, just like in the example shown in FIG. 3, so that it forms only a part of a drying element 20. The breathing gas stream A flowing through the device 10 now flows first through the first tube section 11, then through the liquid storage device 21, namely, through the hole 214 in the liquid storage device 21, and finally through the second tube section 11′. It is thus seen that the liquid storage device 13, 21 is arranged between the first tube section and a second tube section, 11, 11′, respectively, in all the exemplary embodiments shown in FIGS. 1, 2 and 3, so that the breathing gas stream A passes through the device 10 in the sequence of [0066] a. first tube section 11, [0067] b. liquid storage device 13, 21, and [0068] c. second tube section 11′.

[0069] The wick-shaped liquid storage device shown in FIGS. 2 and 3 may also have another shape, e.g., with a polygonal outer contour or the like, in an alternative embodiment (not shown). It is essential that it have a section that is arranged between the first and second tube sections 11, 11′ and that its main surface be arranged within the drying stage 22.

[0070] The drying element 20 formed from the liquid storage device 21 and the drying stage 22 is arranged on the outer side 42 of the device 10. The outer side 44′ of the drying stage 22 forms a part here of the outer side 42 of the device 10. The moisture flowing in with the breathing gas stream A is sent from the liquid storage device 21 to the inner side 43′ of the drying stage 22 and reaches from the inner side 43′ of the drying stage 22 the outer side 42 of the device, which corresponds in the area of the drying element 20 to the outer side 44′ of the drying stage 22.

[0071] As was already described for FIG. 1, the breathing gas stream A entering the FIG. 2 typically also has a temperature of 37° C. at the first end 16. While the breathing gas stream is moving through the first tube section 11, the temperature drops here as well and water is removed by condensation. This is absorbed by the liquid storage device 21 and is sent to the drying stage 22 by means of capillary forces in order to be removed from there from the device 10 by the liquid being brought from the inner side 43′ of the drying stage 22 to the outer side 42 of the device 10. After flowing through the liquid storage device 21, the cooled and dried breathing gas stream A is moved further through the second tube section 11′. The drying element 20 is ideally arranged here at the device 10 such that the breathing gas stream A is already cooled when reaching the liquid storage device 21 to the extent that no more water will be removed by condensation from the breathing gas stream A in the second tube section 11′, or that the dew point of the breathing gas stream A has already decreased to the extent that no more water can be removed by condensation.

[0072] In addition to the drying element 20, the tube sections 11, 11′ are configured in the exemplary embodiment shown in FIG. 3 as drying stages 12, 14, as was already explained in reference to FIG. 1. As was described for FIG. 1, these remove condensed water and/or gaseous water vapor from the breathing gas stream A to the outside to the outer side 42 of the device 10 before and after flowing through the liquid storage device 21. It is thus seen that at least one tube section 11 is configured as a drying stage 12, 14 in the exemplary embodiments shown in FIGS. 1 and 3. In particular, the device 10 has a first drying stage and at least one second drying stage 12, 14, respectively, in these embodiments, the liquid storage device 13, 21 being arranged between the first and second drying stages 12, 14 such that the breathing gas stream A passes through the device 10 in the sequence of [0073] d. first drying stage 12, [0074] e. liquid storage device 13, 21, and [0075] f. second drying stage 14.

[0076] The liquid storage device 13, 21 is selected from among a hydrophilic porous sintered plastic element, a nonwoven, a plasma-treated granular PE material (granular polyethylene) or a matrix of microstructured plastic particles in both the tubular liquid storage device 13 shown in FIG. 1 and the liquid storage device 21 integrated in the drying element 20 according to FIGS. 2 and 3.

[0077] It is conceivable in yet another exemplary embodiment that the device 10 has a first tube section 11 and a plurality of additional tube sections 11′. The first tube section 11 may be a simple plastic tube section, and a second tube section 11′ directly adjoining same may be configured as a drying stage 12. Another tube section 11″, which is configured as a liquid storage device 13 or again as a simple plastic tube, may adjoin this downstream. One or more drying elements corresponding to the drying element 20 shown in FIGS. 2 and 3 may also now be arranged downstream or also upstream. Likewise downstream, additional tube sections may follow, which are optionally configured as a drying stage, as a liquid storage device or as a simple plastic tube. It is seen here that a drying stage 12 corresponding to the present invention may also be arranged between two tube sections 11, 11′.

[0078] A desiccant, preferably zeolite, silica gel or the like, may be applied on the outer side 44, 44′ of one or more drying stages 12, 14, 22 in all the embodiments shown and not shown. It is also conceivable in another, alternative exemplary embodiment, not shown, that the liquid storage device 13, 21 and the bacteria filter 15 form a single component.

[0079] The breathing gas stream A typically has a temperature of about 37° C. on entry into the device 10 through the end 16 in both the exemplary embodiment shown in FIG. 1 and in the exemplary embodiment shown in FIGS. 2 and 3 and in the exemplary embodiments that are not shown. This corresponds to the body temperature of a patient who has exhaled the breathing gas stream A. The breathing gas stream A cools due to the transport through the device 10 to the second end 17 and water can be removed by condensation from the breathing gas stream A. The dew point of the breathing gas stream A is optionally reduced here by the first drying stage 12 or 22 to the extent that it is at or below the room temperature, e.g., at about 25° C., about 20° C. or even about 15° C. Droplets may be removed by condensation in the process, and they are then taken up by the downstream liquid storage device 13 or by the hydrophobic bacteria filter 15 and stored or are sent to the drying stage 22 and released to the outside. The dew point rises again due to the removal of the droplets from the breathing gas stream A.

Testing of Different Membrane Materials

[0080] The drying stage 12, 14, 22 of the above-described exemplary embodiments consists of a gas-tight, moisture-permeable material.

[0081] Different such membrane materials were tested in Table 1 with respect to their interactions with anesthetics. A mixture of 2 vol. % of isoflurane in air was drawn alternatingly with pure air through tubes that had the corresponding membrane material, and the rise and fall times (Tup=rise time, Tdown=fall time (always T10-90 times; Trise=arithmetic mean) of anesthetics detected by a gas sensor were determined.

TABLE-US-00001 Water vapor Thickness permeability* T.sub.up T.sub.down T.sub.rise Material (μm) g/m.sup.2 [g/m.sup.2 per 24 hours] [msec] [msec] [msec] Reference without membrane — — — 424 460 442 Copolyester 15 21 1,100/2,500 496 607 557 Polyether block amide 15 10 1,200/2,550 479 635 557 Polyether block amide 22 25 1,170/2,200 449 528 489 Polyurethane-based 15 16 1,350/2,500 521 710 616 Polyurethane-based 25.4 32 720/720 458 524 491 Polyurethane-based 20 27 1,200/2,200 474 568 521 Polyurethane-based 15 17 1,200/2,200 433 496 465 *Permeation without/permeation with contact with liquid water

[0082] Materials with the properties correspondingly listed in the table are available, for example, under the following trademarks: Collano V 842-1, Epurex Platilon, API MZ 1001, Collano Tex., Arnitel VT308. The list of these materials is, of course, incomplete; other materials with corresponding properties are, of course, likewise suitable for carrying out the present invention.

[0083] It is possible in all embodiments shown that the at least one drying stage 12, 14, 22 has a membrane based on polyether imides, polyether block amides or polyurethanes. In especially preferred embodiments, the membrane consists of a material based on thermoplastic polyurethane. The membrane material has a density of 0.5 g/cm.sup.3 to 1.8 g/cm.sup.3, preferably 0.7 g/cm.sup.3 to 1.5 g/cm.sup.3, especially preferably 1 g/cm.sup.3 to 1.3 g/cm.sup.3 and especially preferably 1.2+0.1 g/cm.sup.3; a melting range between 100° C. and 200° C., preferably between 120° C. and 180° C., especially preferably between 140° C. and 170° C. and especially preferably between 150° C. and 160° C.; and a water vapor permeability greater than 500 g/m.sup.2 per 24 hours, preferably greater than 1,000 g/m.sup.2 per 24 hours, especially preferably greater than 1,500 g/m.sup.2 per 24 hours and especially preferably greater than 2,000 g/m.sup.2 per 24 hours. For better processability, the membrane is applied to a polyethylene carrier (PE carrier).

[0084] While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.