Background of the Invention
The present invention relates to a modification of an inhalation therapy device for use with a patient ventilator.
U.S. Pat. No. 3,771,721 issued Nov. 13, 1973, relates to inhalation therapy in the medical art of treating with oxygen or a mixture of oxygen and air having a high moisture content. Several classes of devices including atomizers and humidifiers are adapted for such treatments. With respect to atomizers and nebulizers as they are frequently called, a heretofore known system for inhalation therapy comprises a container for pure water which has means enabling operation of the container in one of several modes.
U.S. Pat. No. 4,110,419 issued Aug. 29, 1978, and U.S. Pat. No. 4,172,105 issued Oct. 23, 1979, relate to a cartridge type humidifier apparatus that includes a separate heater module with a cylindrical opening for replaceably receiving therein disposable cylindrical humidifier cartridge modules. The cartridge modules each have a tubular metal main body adapted for a sliding fit within a complimentary tubular walled heater. The metal tubular body has a rigid plastic top and bottom end portions with a separate transverse gas delivery pipe, the cap forming a closed air space over a pool of humidifying liquid. The gas to be humidified is dispersed within a hollow chamber formed between the gas inlet pipe projecting concentrally into the cartridge and the radially spaced wall of the main cartridge body and absorption column. The inlet tube terminates above the water. The subject matter of the above patents are incorporated herein by reference. The instant device is a modification of the disclosure in these patents to provide an improved cartridge humidifier.
Summary of the Invention
The present invention relates to a waterfeed circuit for delivering water from a reservoir to a humidifying apparatus connected within a ventilation system wherein the ventilation system produces a cycling pressure within the humidifier. The circuit maintains a constant water volume within the humidifier while isolating the compliance of the reservoir from the system. The circuit includes a level sensing tube positioned in the humidification apparatus. The top of the level sensing tube is connected by means of an air flow conduit having a check valve positioned therein that connects to an air space in the top of the reservoir of an aseptic liquid. Water is fed to the humidifying apparatus by means of a conduit connecting the reservoir with the cylindrical cartridge of the apparatus. A check valve is positioned in this conduit.
Although this system can be used for adult as well as pediatric humidification, to simplify the discussion, this apparatus will be described as a modification of U.S. Pat. No. 4,110,419 and, more specifically, U.S. Pat. No. 4,172,105 that provide breathable inhaled gases that are moisture laden with a large quantity of water for pediatric use. The elements of the device that are not mentioned above are identical with the structure shown in U.S. Pat. No. 4,172,105.
Brief Description of the Drawings
FIG. 1 is a perspective view of the assembled humidifying apparatus according to one form of the invention.
FIG. 2 is another perspective view of the invention with a portion of the structure shown in cross section.
FIG. 3 is a cross sectional view of the valve and stop elements of the structure in more detail.
Detailed Description of the Preferred Embodiment
Since the instant application covers the modification of high volume disposable and semi-disposable cartridge humidifiers with self-contained cartridge sterilizing means disclosed and claimed in U.S. Pat. No. 4,172,105 and U.S. Pat. No. 4,110,419, only the essential portions of this modified apparatus will be discussed in detail.
Reference is made to FIGS. 1 and 2 wherein the modification of the humidifier and nebulizer assembly is generally indicated by the member 11. The assembly comprises a combined heater cartridge supporting means 12 with a disposable or semi-disposable cartridge module 30 as shown in FIG. 2, preferably with a non-metallic top body cap 13. The details of the heater and cartridge supporting module are described in detail in U.S. Pat. No. 4,110,419 and will not be repeated here.
Additionally, the supporting means 12 is provided with a bracket means 14 to support therewith a suitably prepared water supply thermoplastic bottle 15 with which the system hereof is designed to work as aseptically prefilled bottles known as Concha.RTM. preferably the Concha.RTM. 1500 (1500 ml) marketed by Respiratory Care, Inc., of Arlington Heights, Ill. The bottle is provided with breachable seals 24 and 25 for accommodating piercing members 32 and 53 in a manner shown in FIG. 2. The cap 13 is provided with a gas delivery port 21. A flexible tubing 22 is shown fragmentarily in connection with a gas delivery port 21 and is adapted to deliver the treated gas to the patient. A liquid water bottle reservoir means shown in the drawing is preferably the aforesaid Concha.RTM. unit placed in upright position adjacent to the supporting means 12. The unit is a disposable sealed plastic container of aseptic water. The container comprises a principal chamber 23 which is shown in the drawing as provided with breachable seals 24 and 25 and connecting tubes 26 and 27. The essential feature of this invention resides in the method of connecting the bottle 15 with the humidifier cartridge 30 and in the elements designed to control the water level in the humidifier cartridge 30.
The tube 26 is connected to the bottom of the bottle 15 through the connector 25 having the piercing member 32. The other end of the tube 26 is connected through the connector 34 to the bottom of the humidifier cartridge 30. The tube 27 is connected to the top of the bottle through the connector 24 having a piercing member 53 attached thereto. The other end of the tube 27 is connected through the connector 38 to the level sensing tube 31 positioned in the humidifier cartridge 30.
FIG. 3 is a cross-sectional view of the check valves 28 and 29 in FIGS. 1 and 2. The valves consist of an elastomeric disk 39 that moves between positions 54 and 60. When the disk is in position 54, water can flow through the conduit 26 and air can flow through the conduit 27. When the disk is in position 60, the valve is closed and water cannot flow through the conduit 26 and air cannot flow through the conduit 27.
In operation of the system the check valves 28 and 29 control the flow of the water from the reservoir 15 through the humidifier cartridge 30 and the air from the air space 40 to the level sensing tube 31. Referring again to FIG. 1, clip means 50 are positioned onto 26 and 27. The apparatus includes an on and off switch 51 and a controllable member 52.
In operation of the system when the humidifier cartridge is first connected, water will flow by gravity from the bottle 15 to the humidifier cartridge 30 through the connectors 25 and 34. The water will rise in the humidifier cartridge 30 and will eventually close off the air supply to the level sensing tube 31.
The water will continue to rise in the level sensing tube 31 and create a negative pressure in the bottle air space 40. At equilibrium the level in the sensing tube 31 will be equal to the level in the bottle 15. The negative pressure in the bottle will equal the hydrostatic pressure equivalent to the difference in levels between the water in the bottle and the water in the humidifier cartridge 30.
When used for noncycling, continuous flow applications evaporation will cause a drop in the level of water in the humidifier cartridge 30 and will expose the bottom of the level sensing tube 31 to air. Some of the water in the sensing tube will drain and be replaced by air from within the humidifier cartridge 30. This will create an imbalance so that water will flow from the bottle 15 through the connector 25, tube 26, and connector 34 into the humidifier cartridge 30. The cycle will repeat as the water in the humidifier cartridge is used up and a constant water level will be maintained.
During the inspiration portion of a ventilator cycle, the pressure in the humidifier cartridge 30 will increase relative to the reservoir 15 and if the water level in the cartridge 30 is above the control level, the water will be forced into conduit 27 and check valve 28 will open. If the water level in the cartridge 30 is below the control level, air will move through the conduit 27 and into the reservoir 15. Water forced into conduit 26 will cause check valve 29 to close during the expiration portion of the cycle, the pressure in the humidifier cartridge 30 will decrease substantially relative to the reservoir 15. This will cause check valve 28 to close and check valve 29 to open and water to move from the reservoir 15 through conduit 26 into cartridge 30. The system will constantly try to reach equilibrium. The pressure in the reservoir 15 will increase until the air supply is cut off and then will decrease until the air supply is reopened. The check valve 29 in conduit 26 prevents water from being forced back into the bottle during inspiration and allows water to flow during expiration. The check valve 28 in conduit 27 prevents the pressure in the reservoir 15 from being relieved during expiration but also allows the air or excess water to be forced through conduit 27 during inspiration. Another fact is that a fairly constant water level is maintained and the compliance (expansion and contraction of the reservoir) is significantly reduced.
While one preferred embodiment has been illustrated and described in detail it is apparent that other modifications and changes may be made by those skilled in the art without departing from the inventive spirit thereof. Reference should be made to the appending claims for the inventive scope of this invention.