Filter assembly for a therapeutic gas delivery device

1 . A filter assembly for a therapeutic gas delivery device, the assembly comprising:

a filter apparatus comprising an inlet, an outlet, and at least one reservoir and at least one filter membrane between the inlet and the outlet, wherein the filter apparatus is operable to remove water vapor from a sample gas and collect a condensate in the at least one reservoir;

a water-permeable tubular membrane fluidly connected to the outlet of the filter apparatus, and

a ventilated cap connected to the filter apparatus and surrounding the outlet, the ventilated cap comprising a ventilation aperture.

2 . The assembly of claim 1 , wherein the water-permeable tubular membrane is configured to humidity condition the sample gas.

3 . The assembly of claim 1 , wherein the ventilated cap comprises a plurality of ventilation apertures.

4 . The assembly of claim 1 , wherein the ventilated cap is configured to contain and secure the water-permeable tubular membrane.

5 . The assembly of claim 1 , wherein the water-permeable tubular membrane is formed of a sulfonated tetrafluoroethylene based fluoropolymer-copolymer.

6 . The assembly of claim 1 , wherein the water-permeable tubular membrane is tubing comprising a sulfonated tetrafluoroethylene based fluoropolymer-copolymer.

7 . The assembly of claim 1 , wherein the filter apparatus comprises:

a housing inlet operable to receive a sample gas from a sample line connected to an inspiratory line of the therapeutic gas delivery device;

a first chamber disposed in the housing, the first chamber comprising:

a first filter membrane; and

a first reservoir disposed between the inlet and the first filter membrane; and

a second chamber disposed in the housing, the second chamber comprising:

a second filter membrane; and

a second reservoir disposed between the first filter membrane and the outlet.

8 . The assembly of claim 7 , wherein the first reservoir and the second reservoir are oriented axially such that the filter apparatus is operable to be used in any axial orientation.

9 . The assembly of claim 7 , wherein the housing, each of the chambers, and each of the filter membranes have a substantially circular cross-section.

10 . The assembly of claim 1 , wherein the at least one reservoir is large enough to accommodate water for 12 hours of continuous use.

11 . The assembly of claim 1 , wherein the at least one reservoir has a volume of at least 10 cubic centimeters.

12 . The assembly of claim 1 , wherein the assembly is configured to be installed in the therapeutic gas delivery device with one hand.

13 . A method for humidity conditioning and filtering a sample gas in a therapeutic gas delivery device, the method comprising:

passing the sample gas through a filter apparatus of an assembly;

collecting a condensate from the sample gas in the filter apparatus; and

passing a filtered sample gas through a water-permeable tubular membrane of the assembly, wherein the sample gas leaving the water-permeable tubular membrane is a humidity conditioned sample gas.

14 . The method of claim 13 , wherein the sample gas leaving the water-permeable tubular membrane is a humidity conditioned sample gas.

15 . The method of claim 13 , further comprising exposing outer surfaces of the water-permeable tubular membrane to an ambient air flow.

16 . The method of claim 13 , wherein the humidity conditioned sample gas is substantially free of saline.

17 . The method of claim 13 , further comprising reducing or preventing production of HCl within the therapeutic gas delivery device.

18 . The method of claim 13 , further comprising reducing or preventing a blockage of a sample line connected to the assembly, a blockage of a pump connected to the sample line, corrosion of the filter apparatus, and/or corrosion in the therapeutic gas delivery device.

19 . The method of claim 13 , wherein the assembly maintains the condensate at a pH of about 5.0 to about 6.0.

20 . A method for preventing degradation or corrosion in a therapeutic gas delivery device, the method comprising:

passing a sample gas through a filter apparatus of an assembly;

collecting a condensate from the sample gas in the filter apparatus;

passing a filtered sample gas through a water-permeable tubular membrane of the assembly, wherein the sample gas leaving the water-permeable tubular membrane is a humidity conditioned sample gas, and

preventing the sample gas from contacting a sensor without first being humidity conditioned and/or maintaining the condensate at a pH of about 5.0 to about 6.0.