Negative pressure wound therapy system with detection of full absorbant dressing

A method for detecting a state of a dressing, comprising:

• measuring the air pressure within a tube, the tube providing airflow between a pump device and the dressing;
• determining whether the air pressure differs from a pressure setpoint by more than a preset limit;
• in response to a determination that the air pressure differs from the pressure setpoint by more than the preset limit, running the pump to cause the air pressure to approach the pressure setpoint;
• and
• in response to a determination that the air pressure does not differ from the pressure setpoint by more than the preset limit:
• determining a duration of time since a last running of the pump;
• determining whether the duration of time since the last running of the pump exceeds a threshold duration;
• and
• in response to a determination that the duration of time since the last running of the pump exceeds the threshold duration, generating an alert that indicates that the dressing is full.

A dressing comprising:

• a drape sealable over a wound bed;
• an absorbent layer coupled to the drape and configured to absorb fluid from the wound bed;
• a first manifold layer abutting the absorbent layer, the first manifold layer allowing the flow of air and fluid therethrough, the absorbent layer positioned between the first manifold layer and the drape;
• a first opening extending through the drape;
• a first conduit extending though the absorbent layer and pneumatically communicable with the first opening and the manifold layer;
• a connection pad positioned on the drape at the first opening, the connection pad configured to couple a tube to the dressing in pneumatic communication with the first opening, the tube coupled to a pump that provides a negative pressure to the wound bed;
• a second manifold layer positioned between the absorbent layer and the drape, the second manifold layer allowing the flow of air therethrough;
• a plurality of perforations extending through the absorbent layer and allowing airflow between the first manifold layer and the second manifold layer;
• a second opening extending through the drape and aligned with the second manifold layer;
• and
• a sensing port pneumatically communicable with the second opening, the sensing port facilitating measurement of a pressure of the second manifold layer.

A method for detecting a state of a dressing, comprising:

• measuring a first pressure in a pump tube, the pump tube pneumatically communicable with a pump and a dressing to allow the pump to create a negative pressure at the dressing;
• measuring a second pressure in a sensor tube, the sensor tube pneumatically communicable with a sensing port of the dressing;
• comparing the first pressure and the second pressure to determine a pressure difference;
• determining whether the pressure difference is greater than a threshold difference;
• and
• in response to a determination that the pressure difference is greater than a threshold difference, generating an alert that indicates that the dressing is full.

A negative-pressure wound therapy system, comprising:

• a dressing, comprising:
• a drape sealable over the wound bed;
• an absorbent layer that absorbs fluid;
• and
• a manifold layer that provides a volume of air between the absorbent layer and the wound bed;
• a tube coupled to the dressing to allow airflow from the manifold layer to the tube, the airflow restricted when the absorbent layer absorbs a threshold amount of fluid;
• and
• a pump coupled to the tube and operable to provide negative pressure to the volume of air by pumping air out of the volume of air;
• and
• a therapy unit configured to detect whether the absorbent layer absorbs the threshold amount of fluid by:
• measuring a pressure response ripple in the tube induced by noise in the pump;
• determining whether the pressure response ripple exceeds a limit.