Apparatus and method for testing integrity of an ultrafilter membrane

Abstract

An apparatus for an extracorporeal treatment of blood has a supply line, a waste line, and an ultrafilter inserted in the supply line. An air inlet line is connected to a first chamber of the ultrafilter. A pressure sensor is configured for detecting pressure in the waste line or a second chamber of the ultrafilter. A controller is configured to perform an integrity test procedure for detecting when an ultrafilter membrane of the ultrafilter has multiple or single fiber breaks. A method of testing the ultrafilter is also disclosed.

1 . A method for testing an integrity of a semipermeable membrane of an ultrafilter of an extracorporeal blood treatment apparatus, the extracorporeal treatment apparatus comprising:
 a supply line including an inlet end connected to a source of treatment liquid and an outlet end connected to an inlet port of a blood treatment device, wherein the ultrafilter is inserted in the supply line and the semipermeable membrane divides the ultrafilter into a first chamber and a second chamber, the ultrafilter including a first port connecting a first tract of the supply line to the first chamber, and a second port connecting the second chamber to a second tract of the supply line;   a waste line including an inlet end connected to an outlet port of the blood treatment device and an outlet end connected to a discharge of used treatment liquid;   an air inlet line connected to the first chamber of the ultrafilter or to the first tract of the supply line;   at least one waste pump located on the waste line; and   at least one pressure sensor configured to detect a pressure in one of:
 the second chamber of the ultrafilter, 
 the second tract of the supply line, or 
 the waste line, 
 
wherein the method comprises:
 filling the first chamber of the ultrafilter with air through the air inlet line, 
 verifying when, while the waste pump is running, the pressure sensed by the at least one pressure sensor reaches a set negative pressure threshold (Pt), and 
 determining that the ultrafilter semipermeable membrane has a multi-fiber break when the sensed pressure does not reach the set negative pressure threshold (Pt) within a set time interval (T), the pressure being considered relative to atmospheric pressure present in a location where the extracorporeal blood treatment apparatus operates. 
 
     
     
         2 . The method of  claim 1  wherein, after filling the first chamber with air, the waste pump is operated to make pressure in the second chamber more negative or to create a negative pressure in the second chamber. 
     
     
         3 . The method according to  claim 1 , wherein verifying the measured pressure does not reach the set negative pressure threshold (Pt) comprises detecting pressure by the pressure sensor after expiration of the set time interval (T). 
     
     
         4 . The method according to  claim 1 , wherein verifying the measured pressure does not reach the set negative pressure threshold (Pt) comprises detecting pressure by the pressure sensor and measuring an actual time interval at which the negative pressure threshold (Pt) is reached. 
     
     
         5 . The method according to  claim 1 , wherein filling the first chamber with air comprises opening an air valve or operating an air pump located on the air inlet line. 
     
     
         6 . The method according to  claim 1 , wherein operating the waste pump causes extracting or continuing to extract liquid from the second chamber of the ultrafilter, and wherein operating the waste pump after filling the first chamber with air makes pressure in the second chamber more negative or creates a negative pressure in the second chamber. 
     
     
         7 . A method for testing an integrity of a semipermeable membrane of an ultrafilter, wherein the semipermeable membrane separates the ultrafilter into a first and a second chamber, the method comprising:
 emptying the first chamber of the ultrafilter from liquid and filling the first chamber with air;   after the first chamber has been filled with air, extracting or continuing to extract liquid from the second chamber of the ultrafilter;   verifying, while extracting liquid from the second chamber of the ultrafilter, when the pressure in the second chamber of the ultrafilter reaches a set negative pressure threshold (Pt);   determining that the semipermeable membrane has a multi-fiber break when the pressure in the second chamber during the step of extracting liquid does not reach the set negative pressure threshold (Pt) within a set time interval (T), 
 wherein the pressure in the second chamber is considered relative to atmospheric pressure present in a location where the ultrafilter operates. 
     
     
         8 . The method according to  claim 7 , wherein verifying the measured pressure does not reach the set negative pressure threshold (Pt) comprises detecting the pressure in one of:
 the second chamber of the ultrafilter, or   a line connected to the second chamber of the ultrafilter, after expiration of the set time interval (T).   
     
     
         9 . The method according to  claim 7 , wherein verifying the measured pressure does not reach the set negative pressure threshold (Pt) comprises detecting the pressure in one of:
 the second chamber of the ultrafilter, and   a line connected to the second chamber of the ultrafilter; and   measuring an actual time interval at which the negative pressure threshold (Pt) is reached.   
     
     
         10 . The method according to  claim 7 , wherein an air inlet line is connected to the first chamber of the ultrafilter, and wherein the steps of emptying the first chamber of the ultrafilter from liquid and filling the first chamber with air comprise opening an air valve or operating an air pump located on the air inlet line. 
     
     
         11 . The method according to  claim 7 , wherein extracting or continuing to extract liquid from the second chamber of the ultrafilter after filling the first chamber with air makes pressure in the second chamber more negative or creates a negative pressure in the second chamber. 
     
     
         12 . The method according to  claim 7 , wherein:
 the ultrafilter is inserted in a supply line including an inlet end connected to a source of treatment liquid and an outlet end connected to an inlet port of a blood treatment device, the ultrafilter having a first port connecting a first tract of the supply line to the first chamber of the same ultrafilter, and a second port connecting the second chamber of the ultrafilter to a second tract of the supply line;   a waste line including an inlet end is connected to an outlet port of the blood treatment device and an outlet end is connected to a discharge of used treatment liquid;   a waste pump is positioned on the waste line; and   an air inlet line is connected to the first chamber of the ultrafilter or to the first tract of the supply line,   wherein said step of extracting liquid from the second chamber is achieved by operating the waste pump, and   wherein said step of verifying takes place while the waste pump is running.   
     
     
         13 . A method for testing an integrity of a semipermeable membrane of an ultrafilter of an extracorporeal blood treatment apparatus, the extracorporeal treatment apparatus comprising:
 a supply line including an inlet end connected to a source of treatment liquid and an outlet end connected to an inlet port of a blood treatment device, wherein the ultrafilter is inserted in the supply line and the semipermeable membrane divides the ultrafilter into a first chamber and a second chamber, the ultrafilter including a first port connecting a first tract of the supply line to the first chamber, and a second port connecting the second chamber to a second tract of the supply line;   a waste line including an inlet end connected to an outlet port of the blood treatment device and an outlet end connected to a discharge of used treatment liquid; and   a waste pump located on the waste line, 
the method comprising the following steps:
 emptying the first chamber of the ultrafilter from liquid and filling the first chamber with air, 
 operating the waste pump to extract or to continue extracting liquid from the second chamber of the ultrafilter, 
 verifying, while the waste pump is operating, when the pressure in the second chamber of the ultrafilter reaches a set negative pressure threshold (Pt), and 
 determining that the semipermeable membrane has a fiber break when, while operating the waste pump, the pressure in the second chamber does not reach the set negative pressure threshold (Pt) within a set time interval (T), the pressure being considered relative to atmospheric pressure present in a location where the extracorporeal blood treatment apparatus operates. 
 
     
     
         14 . The method according to  claim 13 , wherein verifying the measured pressure does not reach the set negative pressure threshold (Pt) comprises detecting the pressure in one of:
 the second chamber of the ultrafilter, or   a line connected to the second chamber of the ultrafilter, after expiration of the set time interval (T).   
     
     
         15 . The method according to  claim 13 , wherein verifying the measured pressure does not reach the set negative pressure threshold (Pt) comprises detecting pressure in one of:
 the second chamber of the ultrafilter, or   a line connected to the second chamber of the ultrafilter; and 
 and measuring an actual time interval at which the negative pressure threshold (Pt) is reached. 
     
     
         16 . The method according to  claim 13 , wherein an air inlet line is connected to the first chamber of the ultrafilter, and wherein the steps of emptying the first chamber of the ultrafilter from liquid and filling the first chamber with air comprise opening an air valve or operating an air pump located on the air inlet line. 
     
     
         17 . The method according to  claim 13 , wherein operating the waste pump to extract or to continue extracting liquid from the second chamber of the ultrafilter takes place until after the first chamber has been filled with air. 
     
     
         18 . The method according to  claim 17 , wherein operating the waste pump after filling the first chamber with air makes pressure in the second chamber more negative or creates a negative pressure in the second chamber. 
     
     
         19 . The method according to  claim 16 , wherein the method further includes:
 while filling the first chamber of the ultrafilter with air, operating the waste pump based on a first set negative pressure value (P1), which is a desired set value to be reached by the pressure sensed by the at least one pressure sensor; and   after the step of filling the first chamber of the ultrafilter with air, once the first chamber has been emptied from liquid and filled with air, operating the waste pump based on a second set negative pressure value (P2), which is a desired set value to be reached by the pressure sensed by the at least one pressure sensor and which is more negative than the first pressure value,   wherein the set negative pressure threshold (Pt), which is checked during the verifying step, has a negative value intermediate between the first set pressure value (P1) and the second set pressure value (P2).   
     
     
         20 . The method according to  claim 19 , wherein:
 the first set pressure value (P1) is selected in a pressure range between -150 mmHg and -450 mmHg; and   the second set pressure value (P2) is selected in a pressure range between -300 mmHg and -700 mmHg, with the condition that the second pressure value be at least 100 mmHg more negative than the first set pressure value.