LOW-FLOW OXYGEN THERAPY HUMIDIFIER AND METHOD
FIG8 depicts a side view of humidification system 800, which is an embodiment of humidification system 100 of FIG2
In some embodiments, another structural adaptation the enables reservoir 202 to adapt its volume to the amount of liquid water present is an arrangement that applies a constant positive pressure to reservoir 202 (see, e.g., FIG8). In addition to its applicability to the aforementioned embodiments of reservoir 202, embodiments that include an arrangement for applying positive pressure can utilize a reservoir formed from two spaced-apart membranes and a frame wherein the upper membrane comprises a resilient material. The membrane will be capable of expanding to accommodate a maximum volume of water and, as liquid water in the reservoir decreases, the surface of the membrane will be capable of being forced "downward" (i.e., toward the "bottom" of the reservoir) due to the positive pressure, thereby reducing the volume of the reservoir. FIG8 depicts humidification system 800, which is a further embodiment of humidification system 100. The salient features of system 800 include, in addition to the elements present in other embodiments discussed herein (e.g., reservoir 202, WVP membrane 206, an enclosure or housing, such as housing 420, 420', or 420", etc.), means 860 for applying positive pressure to the upper surface of reservoir 202. This is a further structural adaptation that may be used to promote collapse of reservoir 202 so that WVP membrane 206 remains in contact with liquid water. In the embodiment depicted in FIG8, means 860 for applying positive pressure to reservoir 202 includes pressure plate 862 and resilient elements 864. The resilient elements are preloaded by compressing them between pressure plate 864 and the inside of the housing. The resilient elements therefore apply a force against pressure plate 864. Because liquid water is non-compressible, the water resists the applied pressure. However, as water evaporates and passes into WVP membrane 206, the pressure applied against reservoir 202 ensures that the volume of the reservoir will be no greater than is required to accommodate the remaining water. This is particularly useful for maintaining minimum reservoir volume when the reservoir is in a vertical or otherwise not horizontal orientation.
side view
634
surface
860
means
206
membrane
204
water
642
fill port
632
"bottom" surface
423
port
864
resilient elements pressure plate
800
system
631
frame
['1. A humidification system for use with low-flow oxygen therapy, the humidification system comprising: a reservoir, wherein the reservoir receives a volume of liquid water, and further wherein a liquid capacity of the reservoir is alterable such that instantaneous liquid capacity of the reservoir is substantially equal to instantaneous volume of liquid water in the reservoir; and a tube comprising a water-vapor-permeable (WVP) membrane, wherein a major portion of the tube is contained in the reservoir.', '3. The humidification system of claims 1 or 2 wherein the reservoir comprises two spaced-apart liquid-water-impermeable membranes, wherein a first one of the two membranes comprises a greater surface area than a second one of the two membranes.', '14. The humidification system as in any of the preceding claims wherein the reservoir comprises a fill port for filling the reservoir with water.']