Method and apparatus for releasing a controlled amount of aerosol medication over a selectable time interval

• US 5,392,768 A
• Filed: 01/29/1993
• Issued: 02/28/1995
• Est. Priority Date: 03/05/1991
• Status: Expired due to Fees

• Current Assignee: Aradigm Corporation
• Original Assignee: Aradigm Corporation
• Inventors: Rubsamen, Reid M., Johansson, Eric T., Ritson, Carl
• Primary Examiner(s): Burr, Edgar S.
• Assistant Examiner(s): Lewis, Aaron J.
• Application Number:
  US08/011,351
• Time in Patent Office: 760 Days
• Field of Search: 128/200.14, 128/200.23, 128/204.21, 128/204.23, 128/204.26
• US Class Current: 128/200.14
• CPC Class Codes: A61J 7/0418 with electronic history memory
• CPC Class Codes: A61M 15/00 Inhalators drug delivery in endotracheal tubes A61M16/04
• CPC Class Codes: A61M 15/0021 Mouthpieces therefor
• CPC Class Codes: A61M 15/0066 with means for varying the dose size
• CPC Class Codes: A61M 15/008 Electronic counters
• CPC Class Codes: A61M 15/009 using medicine packages with incorporated spraying means, e.g. aerosol cans pocket atomiser of the injector type A61M11/08
• CPC Class Codes: A61M 15/0091 mechanically breath-triggered
• CPC Class Codes: A61M 16/0858 Pressure sampling ports
• CPC Class Codes: A61M 16/202 electrically actuated
• CPC Class Codes: A61M 2016/0021 with a proportional output signal, e.g. from a thermistor
• CPC Class Codes: A61M 2016/0036 in the breathing tube and used in both inspiratory and expiratory phase
• CPC Class Codes: A61M 2016/0039 in the inspiratory circuit
• CPC Class Codes: A61M 2205/50 with microprocessors or computers
• CPC Class Codes: A61M 2205/60 with identification means
• CPC Class Codes: A61M 2205/6018 providing set-up signals for the apparatus configuration
• CPC Class Codes: A61M 2205/6027 Electric-conductive bridges closing detection circuits, with or without identifying elements, e.g. resistances, zener-diodes
• CPC Class Codes: A61M 2205/6036 characterised by physical shape, e.g. array of activating switches
• CPC Class Codes: A61M 2205/6045 having complementary physical shapes for indexing or registration purposes
• CPC Class Codes: A61M 2205/8206 battery-operated
• CPC Class Codes: A61M 2205/8212 with means or measures taken for minimising energy consumption
• CPC Class Codes: B01F 23/2132 : using nozzles
• CPC Class Codes: B01F 35/71 : Feed mechanisms with proportioning B01F35/80
• CPC Class Codes: B01F 35/7179 : using sprayers, nozzles or jets
• CPC Class Codes: F16H 35/00 : Gearings or mechanisms with other special functional features
• CPC Class Codes: G01F 1/363 : with electrical or electro-mechanical indication G01F1/37 and G01F1/38 take precedence
• CPC Class Codes: G01F 1/40 : Details of construction of the flow constriction devices
• CPC Class Codes: G01F 1/44 : Venturi tubes
• CPC Class Codes: G01F 1/50 : Correcting or compensating means
• CPC Class Codes: G01F 13/006 : measuring volume in function of time
• CPC Class Codes: G01F 15/002 : for gases
• CPC Class Codes: G01F 25/10 : of flowmeters
• CPC Class Codes: G01F 7/005 : by measuring pressure or differential pressure, created by the use of flow constriction

Abstract

A portable, battery powered, hand-held system for releasing a controlled dose of aerosol medication for inhalation by a patient including a durable body and a medication cassette inserted in the durable body. The cassette includes a housing for containing a canister of medication, bears an identification code, and permits the canister to be manually depressed to release a dose, e.g., a metered dose, when out of the durable body. The durable body includes an actuator mechanism for engaging an inserted cassette and its canister, and an actuator release mechanism for controlling the actuator mechanism to depress the canister for a selected period of time to release the desired dose of medication and then the release the canister. The actuator mechanism, includes a compression spring for depressing the canister and a torsion spring for reloading the compression spring. The torsion spring is reloaded by rotating the cassette from an open position for delivering aerosol to a closed position. The actuator release mechanism includes a motor and trigger pin assembly that controls the release of the compression spring and the torsion spring, and, hence, the time that the canister is depressed. The motor operates in response to sensed flow satisfying a selected delivery threshold. The durable body includes a flow sensor having an asymmetrical orifice that is calibrated, independent of the cassette, to convert the sensed pressure due to flow into a flow rate. The orifice is separately calibrated for an inhalation flow rate range and an exhalation flow rate range over a selected number of known flow rates. The sensed pressure value is corrected for transducer offset drift and converted to a flow rate using the calibration data and piecewise linear interpolation.

Claims

1. Apparatus for providing a timed release of an amount of aerosol medication comprising:

a flow sensor for detecting inspiratory flow;

a canister of medication having a body and a valve stem, the valve stem being spring biased closed and depressible relative to the canister body to open and release a dose of aerosol medication;

a housing having a valve stem receptacle for receiving the valve stem and a nozzle for releasing an aerosol into an inhalation flow path, the valve stem receptacle having an inner dimension terminating in the nozzle;

a drive element for depressing the canister body relative to the valve stem receptacle, thereby to release a dose of aerosol medication;

a release actuator for moving the drive element to depress the canister body relative to the valve stem receptacle and maintain the body depressed for a selected period of time so that a controlled dose of medication is released through the valve stem receptacle inner dimension and out the nozzle;

a first compression spring fixed at one end and secured to the drive element and movable from a loaded condition to a released condition for moving the drive element to depress the canister body;

a second spring fixed at one end and secured to the drive element and moveable from a loaded condition to a released condition for allowing the drive element to release the canister body from a depressed condition;

a trigger pin having a first position for maintaining the first and second springs in the loaded condition, a second position for allowing the first spring to release and maintaining the second spring in a loaded condition, and a third position for allowing the second spring to release;

a motor for allowing the pin to move from the first to the second to the third positions; and

means for operating the motor so that the trigger pin is maintained in the second position for the selected period of time.

2. The apparatus of claim i wherein the time period is selected from between 0.1 and 2.0 seconds.

3. The apparatus of claim I wherein the canister further comprises a metering chamber for producing a metered dose in response to depressing the canister body for the selected period.