Methods and systems for detecting an occlusion in a blood circuit of a dialysis system
The present specification describes systems and methods for detecting an occlusion in a tubing carrying a patient's blood through a manifold and into a dialyzer in a dialysis system. A controller measures pressures value of the blood at a predetermined point after exiting the manifold and before entering the dialyzer, calculates a historical running average, calculates a weighted sum of the most recent pressure values, and determines whether to trigger an occlusion alarm based on a function of the historical running average and the weighted sum of the most recent pressure values.
1. A dialysis system comprising:
a manifold comprising an enclosed blood flow path, wherein said blood flow path comprises a blood inlet port, a blood outlet port, and a flexible tube positioned between said blood inlet port and blood outlet port;
a pressure sensor in physical communication with manifold at a position proximate said blood outlet port;
a non-transient memory in data communication with said pressure sensor and configured to store pressure values generated and transmitted by said pressure sensor;
at least one pump in physical contact with said flexible tube and configured to pump blood from a patient's body, through a tube, and through said blood flow path; and
a controller in data communication with said pressure sensor, said non-transient memory, and said at least one pump, wherein said controller is configured to execute a plurality of programmatic instructions in order to:
receive said pressure values;
determine an average of n pressure values, where n is a subset of said pressure values;
determine a sum of m pressure values, where m is a subset of said pressure values and where m<n;
apply a function of said average of n pressure values and said sum of m pressure values to generate an occlusion indicator value; and
based upon said pressure difference value, determine if an alarm should be triggered.
2. The dialysis system of claim 1 further comprising a housing that encloses said controller, the at least one pump, and the pressure sensor, wherein said housing is adapted to detachably receive said manifold.
3. The dialysis system of claim 1 further comprising a dialyzer in fluid communication with the blood output port of said manifold.
4. The dialysis system of claim 3 wherein the pressure sensor is positioned between the blood outlet port and the dialyzer.
5. The dialysis system of claim 1 wherein n is in a range of 10 to 20 pressure values.
6. The dialysis system of claim 1 wherein m is in a range of 3 to 10 pressure values.
7. The dialysis system of claim 1 wherein pressure values in the sum of m pressure values include pressure values that are more recent than pressure values in the average of n pressure values.
8. The dialysis system of claim 1 wherein pressure values in the m subset of pressure values include pressure values sensed later in time than pressure values in the n subset of pressure values.
9. The dialysis system of claim 1 wherein said controller is configured to execute a plurality of programmatic instructions in order to apply a weight to said average of n pressure values.
10. The dialysis system of claim 9 wherein said weight is in a range of 3 to 10.
11. The dialysis system of claim 1 wherein said controller is configured to execute a plurality of programmatic instructions in order to apply a weight to each pressure value in said sum of m pressure values.
12. The dialysis system of claim 11 wherein said weight is in a range of 1 to 5.
13. The dialysis system of claim 1 wherein said function takes a difference between said average of n pressure values and said sum of m pressure values to generate the occlusion indicator value.
14. The dialysis system of claim 13 wherein said controller is configured to determine an alarm should be triggered when said occlusion indicator value is greater than or equal to a predefined threshold number.
15. The dialysis system of claim 14 wherein said predefined threshold number is in a range of 200 to 450 mmHg.
16. The dialysis system of claim 13 wherein said controller is configured to determine an alarm should be triggered when said occlusion indicator value is less than or equal to a predefined threshold number.
17. The dialysis system of claim 16 wherein said predefined threshold number is in a range of 200 to 450 mmHg.
18. A dialysis system comprising:
a manifold comprising an enclosed blood flow path, wherein said blood flow path comprises a blood inlet port, a blood outlet port, and a flexible tube positioned between said blood inlet port and blood outlet port;
a pressure sensor in physical communication with manifold at a position proximate said blood outlet port;
a non-transient memory in data communication with said pressure sensor and configured to store pressure values generated and transmitted by said pressure sensor;
at least one pump in physical contact with said flexible tube and configured to pump blood from a patient's body, through a tube, and through said blood flow path; and
a controller in data communication with said pressure sensor, said non-transient memory, and said at least one pump, wherein said controller is configured to execute a plurality of programmatic instructions in order to:
receive said pressure values;
determine an average of n pressure values, where n is a subset of said pressure values;
determine a sum of m pressure values, where m is a subset of said pressure values, m<n, and pressure values in the m subset of pressure values include pressure values sensed later in time than pressure values in the n subset of pressure values;
obtain a difference of said average of n pressure values and said sum of m pressure values to generate an occlusion indicator value;
compare said occlusion indicator value to a predefined threshold number; and
based upon said comparison, determine if an alarm should be triggered.
19. The dialysis system of claim 18 further comprising a housing that encloses said controller, the at least one pump, and the pressure sensor, wherein said housing is adapted to detachably receive said manifold and wherein upon inserting and installing said manifold and closing said housing, said at least one pump is placed into physical contact with the flexible tube.
20. The dialysis system of claim 18 further comprising a dialyzer in fluid communication with the blood output port of said manifold, wherein the pressure sensor is positioned between the blood outlet port and the dialyzer.
21. The dialysis system of claim 18 wherein n is in a range of 10 to 20 pressure values.
22. The dialysis system of claim 21 wherein m is in a range of 3 to 10 pressure values.
23. The dialysis system of claim 18 wherein said controller is configured to execute a plurality of programmatic instructions in order to apply a weight to said average of n pressure values.
24. The dialysis system of claim 23 wherein said weight is in a range of 3 to 10.
25. The dialysis system of claim 23 wherein said controller is configured to execute a plurality of programmatic instructions in order to apply a weight to each pressure value in said sum of m pressure values.
26. The dialysis system of claim 25 wherein said weight is in a range of 1 to 5.
27. The dialysis system of claim 18 wherein said predefined threshold number is in a range of 200 to 450 mmHg.
28. The dialysis system of claim 18 wherein said predefined threshold number is 325 mmHg.
29. The dialysis system of claim 18 wherein at least five pressure values in them subset of pressure values include pressure values sensed later in time than pressure values in the n subset of pressure values.
30. The dialysis system of claim 18 wherein said controller is configured to execute a plurality of programmatic instructions in order to determine if a dialysis process should be suspended or terminated based upon said comparison.