Apparatus for detecting a blockage between a tissue site and a reduced pressure source fluidly connected to the tissue site , comprising: a first sensing device including a first sensor positioned proximate the tissue site and a first processor configured to measure a tissue-site pressure (PTS) corresponding to a pressure of a fluid to which the tissue site is exposed; a second sensing device including a second sensor positioned proximate to the reduced pressure source and a second processor configured to measure a source-pressure (PS) corresponding to the output pressure provided by the reduced pressure source; and a control processor coupled to the first processor and the second processor for receiving the tissue-site pressure (PTS) and the source pressure (PS), the control processor having a first input adapted to be set at a target pressure (TP) corresponding to a pressure desired for therapy at the tissue site and having a second input adapted to be set at a first maximum differential pressure (DP1) greater than the target pressure (TP), the control processor being configured to (i) determine if the target pressure (TP) is greater than the tissue-site pressure (PTS), (ii) calculate a differential pressure (DP) as the difference between the source pressure (PS) and the target pressure (TP), and (iii) determine if the differential pressure (DP) is greater than or equal to the first maximum differential pressure (DP1), (iv) determine a blockage between the reduced pressure source and the tissue site by determining whether a change in the source pressure (PS) results in a directionally corresponding change in the tissue-site pressure (PTS), and (v) provide an alarm signal to alert a user of a blockage condition between the reduced pressure source and the tissue site when a change in the source pressure (PS) does not result in a directionally corresponding change in the tissue-site pressure (PTS). a first sensing device including a first sensor positioned proximate the tissue site and a first processor configured to measure a tissue-site pressure (PTS) corresponding to a pressure of a fluid to which the tissue site is exposed; a second sensing device including a second sensor positioned proximate to the reduced pressure source and a second processor configured to measure a source-pressure (PS) corresponding to the output pressure provided by the reduced pressure source; and a control processor coupled to the first processor and the second processor for receiving the tissue-site pressure (PTS) and the source pressure (PS), the control processor having a first input adapted to be set at a target pressure (TP) corresponding to a pressure desired for therapy at the tissue site and having a second input adapted to be set at a first maximum differential pressure (DP1) greater than the target pressure (TP), the control processor being configured to (i) determine if the target pressure (TP) is greater than the tissue-site pressure (PTS), (ii) calculate a differential pressure (DP) as the difference between the source pressure (PS) and the target pressure (TP), and (iii) determine if the differential pressure (DP) is greater than or equal to the first maximum differential pressure (DP1), (iv) determine a blockage between the reduced pressure source and the tissue site by determining whether a change in the source pressure (PS) results in a directionally corresponding change in the tissue-site pressure (PTS), and (v) provide an alarm signal to alert a user of a blockage condition between the reduced pressure source and the tissue site when a change in the source pressure (PS) does not result in a directionally corresponding change in the tissue-site pressure (PTS). <EOS>