Apparatus and method for controlling the negative pressure in a wound

An apparatus for treating a wound with negative pressure, said apparatus comprising:

• a wound cover;
• a first pump for providing said negative pressure at a chosen pressure level to the wound;
• a canister;
• a first conduit between the wound cover and the canister, wherein the first conduit is arranged to connect the wound with the canister during use of the apparatus;
• first means for measuring the pressure within the canister;
• a second conduit that connects the canister with the first pump;
• a circulating pump;
• and
• a third conduit that connects the canister and a wound region of the wound, wherein the circulating pump is arranged to intermittently transport a gas volume from the canister to the wound region via the third conduit and back to the canister via the first conduit in order to press out possible exudates from the first conduit to the canister, wherein a second means is arranged to analyze the pressure curve over time of said pressure in the canister, said pressure curve being intermittently influenced by said transport of the gas volume, and wherein a third means is arranged to indicate by an alarm when said pressure curve differs from a normal cyclical form, wherein the alarm is visible, audible, or visible and audible.