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EP-4577259-B1 - VACUUM PUMP

EP4577259B1EP 4577259 B1EP4577259 B1EP 4577259B1EP-4577259-B1

Inventors

  • SCHMITT, KARL-HEINZ
  • VISSER, Rudi
  • SHAHIM, CLINTON FREDERICK

Dates

Publication Date
20260506
Application Date
20230821

Claims (7)

  1. Apparatus (10) for controlling a negative pressure level prevailing at a wound site, the apparatus including an electric motor (42), a constant voltage source (24) which supplies current to the electric motor, an air pump (40) which is driven by the electric motor and which is configured to establish a negative pressure level in a region which encloses the wound site, a current monitor (26) which is configured to measure the amplitude of the current supplied to the motor while the pump is operable, a processor (22) which is configured to derive an operating current value of the motor which is dependent at least on said measured current amplitude, and a switch (56), responsive to the processor, to interrupt the supply of current to the motor when the operating current value equals a predetermined current value, characterised in that the apparatus includes a temperature sensor (48) which produces a signal, which is dependent on an operating temperature of the motor while the pump is operating, in that the processor (22) is operative, in response to said signal, to compensate for the effect of the operating temperature of the motor on the measured amplitude of the current supplied to the motor and in that the processor (22) is further operative to compensate for the effect of the no-load current of the motor on the measured amplitude of the current supplied to the motor, thereby to allow the processor to derive from the measured amplitude of the current supplied to the motor, an operating current value of the motor independently of the operating temperature of the motor and independently of the no-load current of the motor, whereby said derived operating current value determines said negative pressure value.
  2. Apparatus according to claim 1 which includes a first housing (12A) in which the constant voltage source and the processor are mounted, a second housing (16A) in which the electric motor and the air pump are mounted, and a connector arrangement (60, 20, 62) which connects the first housing to the second housing.
  3. Apparatus according to claim 1 which includes a housing (80) in which the constant voltage source (24), the processor (22), the electric motor (42) and the air pump (40) are mounted.
  4. An assembly comprising the apparatus of claim 3, an exudate collecting container (100), with which the housing (80) is releasably engageable, the air pump (40) including an inlet which is in air communication with an interior (160) of the container, and a suction port (154) which, in use, is connected to the wound site and which is in air communication with the interior of the container.
  5. An assembly according to claim 4 wherein the container (100) includes a lower part (102), an upper part (104) which is engageable with the lower part, an insert (114) at an interface between the lower part and the upper part whereby a manifold (150) is defined in the upper part, said manifold (150) being in air communication with an interior (160) of the lower part, a mechanism (124) which keeps the upper part engaged with the lower part, said inlet to the air pump being in air communication with an interior of the manifold, and said suction port being in air communication with the interior of the lower part.
  6. An assembly according to claim 5 which includes an odour neutralizing filter (152) inside the manifold.
  7. An assembly according to claim 5 wherein said insert (114) includes a plurality of air passages (148) which place the manifold (150) in air communication with the interior (160) of the lower part.

Description

BACKGROUND OF THE INVENTION This invention relates generally to negative pressure wound therapy and more particularly to the control of vacuum pressure (referred to as negative pressure) at a site which is subject to this form of therapeutic treatment. Negative pressure describes a pressure which is below normal atmospheric pressure and which is established at a wound site for therapeutic treatment purposes. The prior art is replete with devices used to establish negative pressure. Typically some form of pump, which may be chemical, electrical or mechanical, is used to lower the pressure at a wound site which is covered by a dressing. The benefits which are associated with this treatment regime are listed in many documents and are not repeated here. A device which is used on a patient to promote negative pressure therapeutic treatment should, to the extent which is possible, not adversely affect the patient. Ideally, the device should be small, light in weight, and not operate at a noise level which is uncomfortable to the patient. If the device is to be of a portable nature it should for example be battery-driven. In that case power consumption should be minimised so that battery lifetime is extended. Other factors which affect patient acceptability or tolerance of the device include ease of use and reliable and easy to understand indications of operation. If the treatment process is such that exudate is to be drawn from a wound site then provision must be made for directing the exudate into a container which can easily be connected to a negative pressure device. The container, once filled with exudate, must be disposed of and replacement thereof, with a fresh container, should be effected readily and hygienically. US 2021/121609 describes a therapy device which establishes a negative pressure at a wound site under the control of a processor. The device uses a constant voltage source which is connected to an air pump motor. No account is taken of the effect of voltage variations in the constant voltage source nor of the effect of the operating temperature of the air pump motor on the value of the negative pressure which is established. A similar observation is made in respect of the disclosure in US2020/376175 wherein an air pump motor is stopped when the amplitude of a current supplied to the motor is at a prescribed level. US2007/032763 and WO2021/024164 also link vacuum level at a wound site to the current drawn by an air pump motor. The aforementioned disclosures fail to recognise issues which can adversely affected the relationship between the current which is drawn by a motor and the negative pressure level which is established by an air pump driven by the motor. An object of the present invention is to provide a method of and an apparatus for controlling negative pressure at a wound site which, at least to a substantial extent, meet the aforementioned requirements and which, according to requirement, can be used with, or without, an exudate-collecting container. Additionally the present invention seeks to obtain a more accurate relationship between the amplitude of current supplied to an air pump motor and a negative pressure which is established by the air pump. SUMMARY OF THE INVENTION The invention is defined in the appended claims. In a negative pressure wound therapy system, a non-claimed embodiment of the disclosure provides a method of controlling a negative pressure level prevailing at a wound site which includes the steps of (a) using an electrical power supply to power an electric motor which drives an air pump, (b) using the pump to pump air from a region which encloses the wound site, (c) monitoring the amplitude of the current which is supplied by the electrical power supply to the electric motor while the pump is operable, (d) interrupting the power supply to the electric motor when the amplitude of the current reaches a predetermined value, and (e), after a time period, repeating steps (a), (b), (c) and (d). The electrical power supply may have a variable voltage but in a preferred embodiment the electrical power supply is configured to function as a constant voltage source. Techniques for establishing a constant voltage source are known in the art and are not repeated here. The pump may be of a type which is referred to as a micro-vacuum pump. By monitoring the amplitude of the current which is supplied to the electric motor, an indication is obtained of the vacuum level at the wound site i.e. of the negative pressure at the wound site. In this respect use may be made if desired of a look-up table which is established beforehand. A look-up table of this kind reflects the relationship between the current which is supplied to the electric motor when the pump is working at a known voltage, and the negative pressure level prevailing at the wound site. It has been established through experimentation that as the negative pressure level increases (i.e. as the vacuum level increases), the el