SIMULATED BREATHING APPARATUS

Abstract

An apparatus (100) that simulates breathing, which is suitable for use when testing inhalers (14), comprises an inlet (22) to which, in use, an inhaler (14) can be connected, and a vacuum pumping system, which has a vacuum pump (106), a high-speed valve (102) and a flow sensing means (137, 112, 104, 114) interposed between the inlet (22) and the vacuum pump (106), and a controller (126). A user interface (134) enables a user to input a target flow profile (148, 150), which may correspond to human inspiration, such that, in operation, the controller (126) can control the operation of the vacuum pump (106) and the high-speed valve (102) so that the pressure and/or flow rate within the apparatus (100) matches the pressure (150) and/or flow rate (148) of the target flow profile in real-time or near-time.

Claims

1. A simulated breathing apparatus comprising: an inlet and a vacuum pumping system, the vacuum pumping system comprising: a vacuum pump; a high-speed valve interposed between the inlet and the vacuum pump; a flow sensing means interposed between the inlet and the pump; and a controller for controlling the operation of the vacuum pump and the high-speed valve, which comprises a user interface, via which a user can input a target flow profile, the target flow profile being a time-dependent flow profile, that is to say a target pressure and/or flow rate as a function of time, wherein the controller is configured to control the operation of the vacuum pump and the high-speed valve so that the actual pressure and/or flow rate within the apparatus is matched to the target flow profile in real-time or near-time.

2. The simulated breathing apparatus of claim 1, wherein controller is configured to control the vacuum pump and the high-speed valve in response to one or more outputs of the flow sensing means so as to create a flow within the apparatus that matches the user-inputted target flow profile.

3. The simulated breathing apparatus of claim 1, wherein the controller is operatively connected to the vacuum pump, the flow monitoring device and the high-speed valve, and wherein the controller is adapted, in use, to: monitor the pressure and/or flow rate within the device using the flow sensing means; and control the flow within the apparatus by controlling the operation of the vacuum pump and the high-speed valve.

4. The simulated breathing apparatus of claim 1, wherein the flow sensing means comprises a differential pressure sensor, which measures the pressure differential between any one or more of a group comprising: atmosphere and the inlet; and opposite sides of the high-speed valve.

5. The simulated breathing apparatus of claim 1, further comprising a temperature sensor, whose output is used by the controller to convert between mass flow and volumetric flow measurement.

6. The simulated breathing apparatus of claim 1, wherein the flow sensing means comprises a restriction interposed between the high-speed valve and the vacuum pump and a pressure sensor located upstream of the restriction and a pressure sensor located downstream of the restriction, whereby a pressure within the apparatus to be monitored using either or both of the upstream and downstream pressure sensors, and whereby a flow rate within the system can be monitored by monitoring a pressure differential between the upstream and downstream pressure sensors.

7. The simulated breathing apparatus of claim 1, wherein the flow sensing means comprises an impeller, and means for detecting a speed of rotation of the impeller in response to a flow of fluid.

8. The simulated breathing apparatus of claim 6, wherein the restriction comprises any one or more of the group comprising: an orifice plate; a Venturi; and an adjustable orifice plate of the high-speed valve.

9. The simulated breathing apparatus of claim 1, wherein controller is configured to measure the pressure and/or flow rate at any one or more of the group comprising: between 1 Hz to 1 MHz; and between 1 Hz to 1 MHz.

10. The simulated breathing apparatus of claim 1, wherein the target flow profile corresponds to a human inspiration process.

11. The simulated breathing apparatus of claim 1, wherein the high-speed valve is actuated via a high-speed actuator.

12. The simulated breathing apparatus of claim 1, wherein the controller is configured to determine a closed position of the high-speed valve, which corresponds to a valve position where the flow rate within the apparatus is zero or substantially zero.

13. The simulated breathing apparatus of claim 1, further comprising an actuator for automatically actuating an inhaler affixed, in use, to the inlet of the apparatus, and wherein the controller is adapted to detect the firing of the inhaler by the detection of a spike (peak or trough) in a flow measurement.

14. The simulated breathing apparatus of claim 1, further comprising a display and a human input device operatively connected to the controller for controlling and monitoring the operation of the apparatus.

15. The simulated breathing apparatus of claim 1, wherein the controller is adapted to control the pump and high-speed valve to produce a continuous flow, which can be used to obtain data over a period of time that is greater than 10 seconds.

Description

[0038] Preferred embodiments of the invention shall now be described, by way of example only, with reference to the accompanying drawings in which:

[0039] FIG. 1 is a schematic system diagram of a known breathing simulator utilising a water column;

[0040] FIG. 2 is a schematic diagram of a known breathing simulator using a vacuum pump; and

[0041] FIG. 3 is a schematic diagram of an embodiment of a breathing simulator in accordance with the invention.

[0042] Referring now to FIG. 3 of the drawings, an embodiment of a breathing simulator 100 in accordance with the invention comprises an inlet 12 to which an inhaler 14 is sealingly fitted. The inlet 12 leads to a tube 16, which connects in turn to an analyser, which in the illustrated embodiment, is an impactor 18, which comprises a number of stages 20. In other embodiments (not shown), the analyser is any piece of apparatus or equipment that could be used for dose collection and/or waste dose collection. In other embodiments, the analyser may simply be a tube for the purposes of calculating air flow resistance.

[0043] The outlet of the analyser is connected to a vacuum tube 22, which has a high-speed valve 102, a restriction 104 (e.g. an orifice plate) and a vacuum pump 106. An outlet 108 of the system 100 is optionally connected to an outlet filter system 110, but this is not essential.

[0044] In certain embodiments of the invention, the high-speed valve 102 and the restriction 104 are integrally formed, that is to say, with the restriction being adjustable, for example, using a servo. By placing pressure sensors 112, 114 upstream and downstream (respectively) of the adjustable restriction, the functions of the high-speed valve 102 and the restriction 104 can be combined into a single unit, but this is optional.

[0045] An upstream pressure sensor 112 is located within the tube 22 upstream of the restriction 104; and a downstream pressure sensor 114 is located in the tube 22 downstream of the restriction 104. The restriction, in the illustrated embodiment, comprises a simple orifice plate, but it could be of a more complex design, such as a venturi, if required. Control lines 116, 118, 120, 122 connect the high-speed valve 102, the upstream pressure sensor 112, the downstream pressure sensor 114 and the pump 106, respectively, to an 1/01/0 bus 124 of a controller 126. An actuator 128, which actuates the inhaler 14 on-command is also provided and this too interfaces with the controller 126 via a further control line 129.

[0046] An optional temperature sensor 131 is provided at the inlet 12, which also interfaces 133 with the I/O bus 124, to measure the temperature at or near to the inflow airstream. This temperature measurement can be used to convert between mass flow and volumetric flow, as will be well-understood by the skilled reader.

[0047] The controller 126 comprises a processing unit 130, which interfaces with the I/O bus 124 to control the inhaler actuator 128, the high-speed valve 102 and the pump 106. In certain embodiments, the processor 130 also monitors the pressures obtained by the upstream 112 and the downstream 114 pressure sensors and can deduce therefrom, in addition, a flow rate within the tube 22.

[0048] A differential pressure sensor 135, which also interfaces with the I/O bus 124, measures the pressure differential between the ambient atmospheric pressure and the inlet 12 pressure. A flow meter 137, which also interfaces with the I/O bus 124 is provided in the conduit 22, upstream of the valve 102 and the orifice plate 104.

[0049] In certain embodiments, flow is measured using the aforedescribed flow meter 137. In other embodiments, flow is measured using a combination of the flow meter 137, and the upstream 112 and the downstream 114 pressure sensor measurements.

[0050] The controller 126 can be controlled by a user (not shown) via a HID interface 132, which connects to a display unit 134 and a human input device 136, 138, which, in the illustrated embodiment, is a keyboard and a touch-screen, respectively.

[0051] The display system 134 comprises a touch-screen monitor which displays a target flow profile area 140, a numerical display area 142 and a chart display area 146.

[0052] A user can input a target flow profile using the human interface devices 138, 136 to set a target flow rate 148 and/or a target pressure 150 as a function of time (t). Using the human interface devices 136, 138, a user can also set a trigger point 152, that is to say a point in time (t) at which the inhaler actuator 128 is actuated to trigger firing of the inhaler at a certain point in the cycle.

[0053] The display unit 134 also has a start button 154, which when pressed by a user, initiates the test procedure.

[0054] In use, the system 100 is set up as shown below with a clean analyser (impactor) 18 and an inhaler 14 affixed to the inlet 12 of the tube 16. The high-speed valve 102 is initially set at a closed position, which is a position where the measured flow within the tube 22 is 0 with the pump 106 switched on. The high-speed valve 102 is simply closed to a point at which the flow within the tube is measured to be 0, or substantially 0, which need not necessarily be a point at which the high-speed valve 102 is completely closed or tightened-down.

[0055] The test then proceeds.

[0056] The pump 106 and the high-speed valve 102 are controlled by the processor 130 of the controller 126 to ensure that the pressures and flowas measured by pressure sensors 112 and 114 and/or the flow meter 137, match the inputted flow 148 and pressure 150 profile as inputted by the user via the input device 134. After the predetermined period of time, as set by the trigger point 152, the processor 130 sends a signal, via the I/O bus 124 and control line 129 to actuate the inhaler actuator 128, which causes the inhaler 14 to release a cloud 42 of particulate and/or vapour medicament into the inlet 16/12 of the system 100. The vacuum drawn by the vacuum pump causes the cloud 42 to flow into the analyser (impactor) 18, where it is collected to different degrees by the various stages 20 thereof. During the procedure, the pressure and flow within the tube 22 is continuously monitored by the flow sensor 137 and/or the pressure sensors 112,114 and the I/O bus 124. The processor 130 calculates the optimum pump 106 and high-speed valve 102 settings to keep the pressure and flow, as a function of time, in accordance with the target flow 148 and pressure 150 as inputted by the user.

[0057] At the end of the test, the pump 106 can either be switched off and/or the high-speed valve closed in accordance with the target flow profile as set by the user of the system.

[0058] Once there is no flow in the tube 22, the analyser (impactor) 18 can be removed and disassembled so that the medicament captured by the analyser, or stages 20 of the impactor 20 thereof can be analysed as necessary.

[0059] The sampling rate of the I/O bus 124 is typically high-speed sampling so that the actual pressure and flow rates within the tube 22 match, as closely as possible, the target flow rate 148 and pressure 150 in the time domain as specified by the user of the system 100.

[0060] The invention is not restricted to the details of the foregoing embodiment, which are merely exemplary of the invention.