Patent Application
20080169047
1. Field of the Invention
The present invention relates generally to medical apparatus and methods. More particularly, the present invention relates to methods and hand-held apparatus for delivering therapeutic gases at a low-flow rate suitable for patient administration.
Gas delivery systems for inhalation therapies are well-known. Drugs, mists, vapors, and the like, can and be delivered from a wide variety of hand-held and other apparatus. For example, heated liquids have been used to provide vapors for delivering a wide variety of drugs and therapies. Hand-held devices have also been developed for both oral and nasal inhalation delivery. For example, powders may be delivered using disc inhalers where the patient inspires powder medicine from a receptacle on a disc. Metered-dose inhalers (MDI's) rely on a pressurized propellant in a cartridge for delivering pressurized doses of a drug to a patient. Most if not all of these drug delivery devices are intended to provide a relatively high gas flow rate compatible with a patient's inhalation rate.
Recently, a new therapy relying on the non-inhalation administration of therapeutic gases at relatively low-flow rates on the order of 0.5 cc/sec to 20 cc/sec has been proposed. As described in U.S. Pat. No. 7,017,573, carbon dioxide and a variety of other therapeutic gases are suffused through a patient's nasal and/or oral cavities without inhalation. Typically, the gases are introduced from a dispenser to a patient's nostril and allowed to flow through the nasal cavity while exiting through the other nostril or the mouth. The gases, such as substantially pure carbon dioxide, can be irritating to the throat and lungs if inhaled, and flow rates higher than 10 cc/sec to 20 cc/sec can be uncomfortable to the patient.
U.S. Pat. No. 7,017,573 describes a hand-held dispenser suitable for delivering such low-flow rates, where the particular flow rate is patient adjustable. The device relies penetrating a needle through a septum on a cartridge of the carbon dioxide or other therapeutic gas. The flow rate is controlled by rotating a cap which holds the needle, where such rotation axially translates the needle in and out the hole which was originally formed. The flow rate is thus controlled by the annular opening between the needle and the hole in the septum where the area of the annular varies depending on the axial position of the needle.
While this is a workable system, the dimensions of the needle and other system components must be carefully controlled in order to assure both the ability to stop flow entirely as well as the ability to carefully adjust the flow rate between the desired minimum and maximum ranges. The need to provide such close tolerances on system components complicates the manufacturing and raises the price of the hand-held dispenser considerably.
For these reasons, it would be desirable to provide improved hand-held, low-flow therapeutic gas dispensers which are both reliable and relatively simple to operate. Such hand-held dispensers should allow for relatively low manufacturing costs, be convenient for held-held patient use, provide stable, low-flow rates on the order of a fraction of a cc/sec while being adjustable to higher flow rates from 5 cc/sec to 20 cc/sec or even higher. At least some of these objectives will be met by the inventions described hereinbelow.
2. Description of the Background Art
A list of relevant U.S. Patent documents and foreign patent documents is provide below. U.S. Pat. No. 7,017,573 has been discussed above.
The present invention provides improved hand-held, low-flow therapeutic gas dispensers which are both economical to manufacture and easy to use by the patient. The dispenser utilizes a high pressure gas cartridge, and separate mechanisms are used for opening the gas cartridge and for controlling the flow rate of gas to the patient. The opening mechanism penetrates a septum on the gas cartridge to form an opening having a sufficient clearance with the penetrating mechanism so that flow through the penetration will not limit the rate of flow to the patient. The separate flow control mechanism allows the user to repeatably and stably adjust flow at very low-flow rates, typically from rates of from 0.5 cc/sec or lower to rates of from 5 cc/sec, 10 cc/sec, 15 cc/sec, 20 cc/sec, or higher. Moreover, the flow control mechanism will allow the user to provide a complete shut-off of the gas flow with minimum risk of leakage and maintenance of high gas pressure over extended time periods. In the exemplary embodiments, the flow control valve will typically be calibrated to deliver gas in the range from 1 cc/sec to 50 cc/sec
In a first aspect of the present invention, a hand-held, low-flow gas dispenser comprises an enclosure having a gas outlet. The enclosure is adapted to receive a pressurized gas cartridge having a penetrable septum. A pin having a tip for penetrating the septum is carried in a pin carrier having an “advanced” configuration for penetrating the pin through septum to form a hole or other opening (including round and other shapes) in the septum and a “retracted” configuration for withdrawing the pin from the hole to allow gas flow from the cartridge.
As the pin is intended to open the gas cylinder but not to control flow therethrough, it is advantageous that the pin be prevented from reentering the hole that is created after it is retracted. This can be accomplished, for example, by mounting the pin on a “bistable” mechanism which carries the pin in both an advanced configuration or position and a retracted configuration or position. By mounting the bistable carrier so that it automatically switches from the advanced configuration to the retracted configuration after the pin has penetrated the septum, the pin can be withdrawn from the hole and maintained in the retracted configuration. As illustrated in the specific embodiments below, the bistable carrier will typically comprise a spring having both an advanced and retracted stable configuration where the pin or spring engages a stop or other mechanism to push the spring from the advanced to the retracted configuration as the pin carrier is advanced. A variety of other mechanical elements or components could also be provided to effect such advancement and retraction of the pin.
A flow control system is placed in series with pin and pin carrier to receive and adjust the flow rate of therapeutic gas released from the penetration in the septum of the gas cartridge. The flow control system, however, will form a separate component or assembly and will be separately adjustable from the pin and pin carrier used to penetrate the septum of the cartridge. The flow control system will typically include at least one flow control valve which acts as a hybrid valve/regulator, as described in greater detail below in connection with the specific embodiments.
Usually, the pressured gas cartridge will form a non-removable component of the hand-held gas dispenser. In other embodiments, however, the gas cartridge may be removably received within the enclosure to allow removal and replacement of the gas cartridge after gas has been depleted.
The pin in the septum-penetrating structure will usually have a solid core, allowing very small pin widths to be utilized, typically in the range from 0.5 mm to 2 mm, with a tip radius less than 0.1 mm. The use of such narrow width pins is advantageous since it reduces the force necessary to penetrate the septum. The pins will typically have circular cross-sections, but could have a variety of non-circular cross-sections, such as having a narrow, triangular tip. Additionally, although solid core needles are preferred, hollow core needles could be used although they are generally less preferable. Prior art designs have often used hollow needles in order to both penetrate the septum and provide a flow path for pressurized gas leaving the cartridge. The need to provide a hollow passage within the penetrating needle requires use of a larger needle which can increase the necessary needle penetration force and render manufacturer and use of the dispenser more difficult.
In the exemplary embodiments, the septum-penetrating pin is carried on a spring-loaded carrier, such as a spring disc, having a concave or other retracted configuration and a convex or other advanced configuration. As the carrier and pin are advanced forwardly to penetrate the septum, they will engage a stop or other structure surrounding the septum which will push the carrier back to the retracted (concave) configuration after the septum has been fully penetrated. In the concave configuration, the spring is abruptly withdrawn from the hole or other opening that it just created, thus creating a flow path around the pin from the cartridge and through the septum. This flow path will be relatively unobstructed as the pin has been withdrawn to provide a large clearance area. The septum will remain open (with the pin retracted) throughout the use of the gas dispenser until the cartridge is depleted. Turning the flow of gas on and off as well as regulating the flow rate will be accomplished using the flow control system which is a separate component of the gas dispenser.
In the exemplary embodiments, the flow control system will comprise a spring-loaded valve with an axial valve stem for pushing a ball or other closure element against the spring force. In its unloaded configuration, the valve element closes against a valve seat under the spring force and pressurized gas. When the valve element is pushed by the stem, an opening will be formed between the valve seat and the ball valve to permit a controlled flow of gas, where the flow rate is typically in the ranges described above. As a particular advantage of the present invention, the gas pressure and spring force both tend to close the ball valve against the valve seat, thus providing a fail-safe mechanism for shutting off the gas flow when it is desired to stop using the dispenser. The valve seat may be rigid or compliant. Rigid valve seats may be preferable as they provide more repeatable flow performance in response to temperature and other environmental changes.
In addition to controlling flow rate, the flow control system will also provide for a pressure reduction where the small aspect ratio between the ball or other closure element and the size of the piston (described in more detail below) contribute greatly to the pressure reduction characteristics.
In the exemplary embodiments, the flow control valve is located in the enclosure between the gas cartridge and the outlet, typically having the septum-opening pin therebetween. In alternate embodiments, the flow control valve may be located in the neck of the gas cartridge. Having the control valve located in the gas cartridge would be particularly advantageous in embodiments where the gas cartridge is replaceable so that a fresh flow control element is provided each time the cartridge is replaced.
The hand-held, low-flow gas dispenser of the present invention is particularly useful for delivering carbon dioxide and other therapeutic gases to a patient's nasal and/or oral cavities, typically in the absence of inhalation, as described in U.S. Pat. No. 7,071,573, the full disclosure of which has been previously incorporated herein by reference. For such use, the gas outlet of the enclosure is typically adapted to seal against a nostril of the patient.
In a second aspect of the present invention, methods for dispensing a low-flow rate gas from a hand-held dispenser comprise pushing a spring-loaded pin through a septum on a gas cartridge in the dispenser to create a hole or other opening. The pin is allowed to spring back or otherwise retract from the opening to permit gas flow through a clearance surrounding the pin in the hole to an outlet on the dispenser, and a separate valve assembly is adjusted on the dispenser to control the flow rate of the gas. Typically, the gas will be a therapeutic gas, more typically being carbon dioxide. Carbon dioxide therapeutic gases will usually comprise at least 50% carbon dioxide by volume, often being substantially pure carbon dioxide. The valve will be adjusted to control flow at a desired rate, typically from 1 cc/sec to 50 cc/sec, more typically from 0.5 cc/sec to 20 cc/sec Adjusting the flow usually comprises turning a nose piece or other dial on the enclosure which adjusts the position of a spring-loaded ball valve, where the ball valve is usually located between the gas cartridge and the outlet within the enclosure. Although the flow control valve is typically adjusted using a nose piece on the hand-held dispenser, it will be appreciated that other control interfaces, such as sliding actuators, pushing actuators, other rotating actuators, and the like, could be provided for adjusting the flow rate.
In a third aspect of the present invention, a low-flow rate gas dispenser is manufactured by providing an enclosure having an outlet, a septum-penetrating pin, and a control valve stem. A gas cartridge is provided having a penetrable septum and a spring-loaded valve. The gas cartridge and the enclosure are assembled so that the pin is located adjacent the septum, and the control valve can engage the spring-loaded valve after the septum has been penetrated. Optionally, the assembly may be performed by a user who is replacing a spent cartridge with a new cartridge.
As illustrated in
Referring now to
Referring now to
The nose piece 18 carries a regulator piston 62 having the valve stem 60 depending from its lower end. The regulator piston 62 is adapted to travel up and down in a receptacle 64 formed in the upper end of the regulator body 40. The regulator piston 62 has wings, bosses, or other features which travel in slots 68 surrounding the receptacle 64. The regulator piston 62 is biased downwardly by a spring 70 and seals against the inside of the receptacle 64 with 0-ring 66. A lower cam 72 rides against an upper cam 74 formed in the inside of the nose piece 18 so that rotation of the nose piece 18 relative to the remainder of the lower assembly 14 will cause the regulator piston to axially translate upwardly and downwardly, depending on the direction of rotation. In this way, the valve stem 60 can be caused to lower against the ball 50 of the regulator valve assembly to allow the user to rotate the nose piece to both turn on and off the flow as well as to regulate the flow to a desired rate, generally within the ranges set forth above. Additional over-pressure failure modes may be provided in the nose piece in order to prevent gas to flow through the fitted end 20 when exposed to excess pressure. For example, the O-ring 66 may be selected to have properties which will fail in response to pressure above a pre-determined threshold. Alternatively, the O-ring 43 (
Referring now to
Flow from the cartridge, however, will continue to be blocked by ball valve 50 so long as it remains seated in seat 56, as shown in
While the above is a complete description of the preferred embodiments of the invention, various alternatives, modifications, and equivalents may be used. Therefore, the above description should not be taken as limiting the scope of the invention which is defined by the appended claims.
