Infiltration detection system using pressure measurement

• US 4,816,019 A
• Filed: 03/03/1987
• Issued: 03/28/1989
• Est. Priority Date: 03/04/1986
• Status: Expired due to Term

• Current Assignee: Deka Products Limited Partnership
• Original Assignee: Dean Kamen
• Inventors: Kamen, Dean L.
• Primary Examiner(s): Rosenbaum, C. Fred
• Assistant Examiner(s): Reilly, Colleen M.
• Application Number:
  US07/021,294
• Time in Patent Office: 756 Days
• Field of Search: 604/65, 604/902, 604/131, 604/141, 604/50, 604/118, 604/66, 604/67, 73/149, 128/DIG. 13
• US Class Current: 604/65
• CPC Class Codes: A61M 2005/1403 Flushing or purging
• CPC Class Codes: A61M 2205/15 Detection of leaks
• CPC Class Codes: A61M 39/26 Valves closing automatically on disconnecting the line and opening on reconnection thereof check valves A61M39/24
• CPC Class Codes: A61M 5/16809 by repeated filling and emptying of an intermediate volume pressure infusion using positive displacement pumps A61M5/142
• CPC Class Codes: A61M 5/16813 by controlling the degree of opening of the flow line
• CPC Class Codes: A61M 5/16859 Evaluation of pressure response, e.g. to an applied pulse
• CPC Class Codes: A61M 5/365 Air detectors A61M5/1684 takes precedence; in extracorporeal blood circuits A61M1/3626
• CPC Class Codes: F04B 43/043 Micropumps
• CPC Class Codes: F16K 31/005 Piezoelectric benders
• CPC Class Codes: G01F 11/086 using an auxiliary pressure to cooperate with the diaphragm or bellows
• CPC Class Codes: G01P 13/0066 by using differences of pressure in the fluid
• CPC Class Codes: Y10S 128/12 Pressure infusion
• CPC Class Codes: Y10S 128/13 Infusion monitoring
• CPC Class Codes: Y10T 137/7782 With manual or external control for line valve
• CPC Class Codes: Y10T 137/7796 Senses inlet pressure
• CPC Class Codes: Y10T 137/88005 Biased valve

Abstract

A system is provided for detecting the presence of an infiltration condition in a line delivering fluid to a patient. Stepping means subjects the fluid in the line to a negative pressure step. The pressure of the fluid is monitored, and processing means then determines whether an infiltration condition is present by determining whether the function of line pressure over time in response to the occurrence of a negative pressure step exhibits a relative slow return to the pre-step pressure, such relatively slow return being characteristic of the presence of infiltration.

Claims

1. A system for detecting the presence of infiltration of fluid being delivered through a line to a patient, the system comprising:

stepping means for subjecting the fluid in the line to a negative pressure step;

pressure monitoring means for monitoring fluid pressure in the line; and

processing means, in communication with the pressure monitoring means and the stepping means, for actuating the stepping means and for determining whether the function of line pressure over time in response to the occurrence of a negative pressure step exhibits a markedly slow return to the pre-step pressure, such markedly slow return being characteristic of the presence of infiltration.

2. A system according to claim 1, wherein

the processing means includes means (i) for determining the duration of time required for the line pressure to decrease in absolute value to a predetermined fraction of the absolute value of such pressure step, and (ii) for entering an alarm state in the event that the duration is substantially greater than a predetermined maximum limit.

3. A system according to claim 1, wherein

the stepping means includes means for subjecting the fluid in the line to a pressure step that may be selectably either positive or negative;

and

the processing means includes means for identifying whether the function of line pressure over time in response to the occurrence of a negative pressure step is lacking in substantial symmetry with respect to the function of pressure over time in response to the occurrence of a positive pressure step.

4. A system according to claim 3, wherein the processing means includes means (i) for determining, in the event of either a positive or negative pressure step, the duration of time, up to a predetermined limit, required for the line pressure to decrease in absolute value to a predetermined fraction of the absolute value of such pressure step, (ii) for comparing the durations determined respectively for a positive and for a negative pressure step, and (iii) for entering an alarm state in the event that the duration for a negative pressure step is substantially greater than for a positive pressure step.

5. A system according to claim 1, wherein the stepping means includes:

a region in pressure communication with the line;

fluid housing means means for housing auxiliary fluid in communication with the region such that a change in line pressure causes a corresponding change in auxiliary fluid pressure and vice versa; and

displacement means for displacing a predetermined volume increment of auxiliary fluid, such that displacement of the predetermined volume increment causes a change in the auxiliary fluid pressure,

whereby the negative pressure step may be created by the displacement means.

6. A system according to claim 2, wherein the stepping means includes:

a region in pressure communication with the line;

auxiliary fluid housing means means for housing auxiliary fluid in communication with the region such that a change in line pressure causes a corresponding change in auxiliary fluid pressure and vice versa; and

displacement means for displacing a predetermined volume increment of auxiliary fluid, such that displacement of the predetermined volume increment causes a change in the auxiliary fluid pressure,

whereby the pressure step will be negative or positive according as the displacement means displaces a positive or negative volume increment of auxiliary fluid into the auxiliary fluid housing means.

7. A system according to claim 5, wherein

the auxiliary fluid housing means is disposed in relation to the region so as to define collectively therewith a fixed volume that is varied by the displacement means, and wherein the region includes a flexible interface surface defining a boundary with the auxiliary fluid.

8. A system according to claim 6, wherein

the auxiliary fluid housing means is disposed in relation to the region so as to define collectively therewith a fixed volume that is varied by the displacement means, and wherein the region includes a flexible interface surface defining a boundary with the auxiliary fluid.

9. A system according to claim 7, wherein

the region includes a substantially hemispherical rigid enclosure with an input and an output.

10. A system according to claim 8, wherein

the region includes a substantially hemispherical rigid enclosure with an input and an output.

11. A system according to claim 5, wherein

the processing means includes means (i) for determining the duration of time, up to a first predetermined limit, required for the line pressure to decrease in absolute value to a predetermined fractions of the absolute value of such pressure step, and (ii) for entering an alarm state in the event that the duration is substantially greater than a second predetermined limit.

12. A system according to claim 6, wherein

the processing means includes means (i) for determining, in the event of either a positive or negative pressure step, the duration of time, up to a predetermined limit, required for the line pressure to decrease in absolute value to a predetermined fraction of the absolute value of such pressure step, (ii) for comparing the durations determined respectively for a positive and for a negative pressure step, and (iii) for entering an alarm state in the event that the duration for a negative pressure step is substantially greater than for a positive pressure step.

13. A system according to claim 5, wherein the auxiliary fluid is air.

14. A system according to claim 6, wherein the auxiliary fluid is air.

15. A system according to claim 12, wherein the auxiliary fluid is air.

16. A system for detecting the presence of infiltration of fluid being delivered though a line to a patient, the system comprising:

a region in pressure communication with the line, such region having a flexible interface surface;

auxiliary fluid housing means, for housing auxiliary fluid, such means disposed in relation to the region so as to define collectively therewith a volume that is normally fixed, and wherein the interface surface is disposed to define a boundary with the auxiliary fluid;

displacement means for displacing a predetermined volume increment of auxiliary fluid, such that displacement of the predetermined volume increment causes a change in the normally fixed volume and in the auxiliary fluid pressure, so that the displacement means upon actuation will subject fluid in the line to a pressure step that may be negative or positive according as the volume increment in the fixed volume is positive or negative respectively; and

processing means (i) for determining, in the event of either a positive or negative pressure step, the duration of time, up to a predetermined limit, required for the line pressure to decrease in absolute value to a predetermined fraction of the absolute value of such pressure step, (ii) for comparing the durations determined respectively for a positive and for a negative pressure step, and (iii) for entering an alarm state in the event that the duration for a negative pressure step is substantially greater than for a positive pressure step.

17. A system according to claim 16, wherein the auxiliary fluid is air.

18. A system according to claim 16, further comprising:

means for actuating the displacement means and the processing means repetitively in the course of delivery of fluid through the line.