System and method for measuring the pressure of a fluid system within a patient

• US 9,220,424 B2
• Filed: 07/02/2009
• Issued: 12/29/2015
• Est. Priority Date: 12/29/2004
• Status: Active Grant

• Current Assignee: Integra LifeSciences Switzerland Sàrl
• Original Assignee: Depuy Synthes Products Incorporated (Johnson & Johnson)
• Inventors: Wilson, Stephen F., Dextradeur, Alan J.
• Primary Examiner(s): DOUGHERTY, SEAN PATRICK
• Application Number:
  US12/496,871
• Publication Number:
  US 20090270759A1
• Time in Patent Office: 2,371 Days
• Field of Search: 600/561, 600/300, 600/555, 600/560, 600/587, 604/8, 604/9, 702/138, 702/139, 702/140
• US Class Current: 1/1
• CPC Class Codes: A61B 2090/064 for measuring force, pressure or mechanical tension
• CPC Class Codes: A61B 2562/0247 Pressure sensors
• CPC Class Codes: A61B 5/031 Intracranial pressure
• CPC Class Codes: A61B 5/032 Spinal fluid pressure
• CPC Class Codes: A61B 5/742 using visual displays A61B5/339 takes precedence
• CPC Class Codes: A61M 2202/0464 Cerebrospinal fluid

Abstract

A pressure sensing apparatus has a pressure sensor component that includes a pressure sensing port, a pressure sensor for sensing a pressure of a fluid in the pressure sensing port, and a digital processor communicating with the pressure sensor for performing calculations involving fluid pressures sensed. The pressure sensing apparatus further includes a first chamber in fluid contact with the pressure sensing port, a second chamber fluidically connectable with a patient'"'"'s cerebrospinal fluid system, and a membrane located between the first and second chambers so as to transmit fluid pressure from the second chamber to the first chamber.

Claims

1. A pressure sensor component comprising:

a pressure sensing port for containing a fluid for pressure sensing; and

a pressure sensor for measuring a pressure of the fluid in the pressure sensing port, wherein the pressure measured is indicative of a patient'"'"'s cerebrospinal fluid pressure;

wherein the pressure sensor component includes a digital processor in electrical communication with the pressure sensor, the pressure sensor component being configured to calculate at least two selected from the group consisting of resting pressure, outflow resistance, and pressure volume index based on the cerebrospinal fluid pressure.

2. The pressure sensor component of claim 1, wherein the pressure sensor component includes a display.

3. The pressure sensor component of claim 2, wherein the pressure sensor component is configured to display a graph of fluid pressures sensed over time.

4. The pressure sensor component of claim 1, wherein the pressure sensor component is configured to calculate at least one selected from the group consisting of resting pressure, outflow resistance, and pressure volume index in multiple iterations with selective calculation of mean results.

5. The pressure sensor component of claim 1, wherein the pressure sensor component is configured to calculate each of a resting pressure, an outflow resistance, and a pressure volume index.

6. The pressure sensor component of claim 1, wherein the pressure sensor component is an integral, hand-held component.

7. The pressure sensor component of claim 6, further comprising a pressure transmission medium in fluid contact with the pressure sensing port.

8. The pressure sensor component of claim 7, wherein the pressure transmission medium is a liquid.

9. The pressure sensor component of claim 8, wherein the liquid is other than cerebrospinal fluid.

10. The pressure sensor component of claim 6, further comprising a catheter connected to the pressure sensing port.

11. The pressure sensor component of claim 10, wherein the catheter includes a membrane that divides the catheter into a first chamber in fluid contact with the pressure sensing port and a second chamber fluidically connectable with a patient'"'"'s cerebrospinal fluid system, the membrane transmitting fluid pressure from the second chamber to the first.

12. The pressure sensor component of claim 11, wherein the first chamber is filled with a liquid.

13. The pressure sensor component of claim 10, wherein the catheter includes a port for adding a liquid bolus to a patient'"'"'s cerebrospinal fluid system.

14. The pressure sensor component of claim 13, wherein the port is a three-way stopcock.

15. The pressure sensor component of claim 2, wherein the pressure sensor component includes at least one button for operating the component.

16. The pressure sensor component of claim 15, wherein the processor is configured to calculate at least one selected from the group consisting of outflow resistance and pressure volume index.

17. The pressure sensor component of claim 16, wherein the pressure sensor component is configured to prompt a user through a sequence of measurement steps, the measurement steps including the injection of a bolus into the fluid system being measured.

18. The pressure sensor component of claim 17, wherein the pressure sensor component is configured to prompt a user to infuse the fluid system being measured with a measured volume of fluid.

19. The pressure sensor component of claim 18, wherein the pressure sensor component is configured to prompt a user to wait for a predetermined amount of time.

20. The pressure sensor component of claim 18, wherein the pressure sensor component is configured to prompt a user to wait for a predetermined pressure reading.

21. The pressure sensor component of claim 18, further comprising a catheter connected to the pressure sensing port.

22. The pressure sensor component of claim 21, wherein the catheter includes a port for adding a liquid bolus to a patient'"'"'s cerebrospinal fluid system.

23. The pressure sensor component of claim 1, wherein the pressure sensor component is configured to calculate the pressure volume index (PVI) as a pressure change resulting from a rapid injection or withdrawal of a bolus fluid from a patient'"'"'s CSF space.

24. The pressure sensor component of claim 23, wherein the pressure sensor component is further programmed configured to calculate the PVI as:

PVI=V_o/Log(P_p/P_o)

where;

V_o is the volume of the bolus;

P_o is the resting pressure; and

P_p is the peak pressure resulting from the addition of the bolus.

25. The pressure sensor component of claim 1, wherein the pressure sensor component is programmed configured to calculate the outflow resistance (R_o) as indicative of a return trajectory of a patient'"'"'s CSF pressure following the addition of a bolus fluid to a patient'"'"'s CSF space.

26. The pressure sensor component of claim 25, wherein the pressure sensor component is further configured to calculate R_o as:

R_o=t₂×

P_o/PVI×

Log {(P₂/P_p)(P_p−

P_o)/(P₂−

P_o)}

where;

t₂ is a measured time;

P_o is the resting pressure;

PVI is the pressure volume index;

P₂ is a measured pressure reading at time t₂ after the bolus addition; and

P_p is the peak pressure resulting from the addition of the bolus.