Blood parameter measurement system with compliant element

• US 5,048,525 A
• Filed: 06/18/1990
• Issued: 09/17/1991
• Est. Priority Date: 01/30/1987
• Status: Expired due to Fees

• Current Assignee: Terumo Cardiovascular Systems Corporation (Terumo Corporation)
• Original Assignee: Minnesota Mining and Manufacturing Co (3M Company)
• Inventors: Maxwell, Thomas P.
• Primary Examiner(s): Jaworski, Francis
• Assistant Examiner(s): MANUEL, GEORGE C
• Application Number:
  US07/539,602
• Time in Patent Office: 456 Days
• Field of Search: 128/637, 128/692, 128/632, 128/634, 128/635, 128/673
• US Class Current: 600/311
• CPC Class Codes: A61B 5/1459 invasive, e.g. introduced into the body by a catheter A61B5/1464 takes precedence
• CPC Class Codes: A61B 5/6852 Catheters

Abstract

An assembly for the measurement of a blood parameter comprising a catheter having a lumen extending therethrough and a sensor mounted in the lumen. A conduit couples the lumen to a source of anti-clotting solution, and a compliant element is coupled to the conduit to allow the volume of the introducing system to be expanded and contracted. The compliance of the compliant element can be adjusted to thereby adjust the compliance of the assembly.

Claims

1. An assembly for the measurement of a blood parameter comprising:

first means for withdrawing blood from a patient into the first means;

said first means comprising a catheter adapted to be received in a patient'"'"'s cardiovascular system and having a lumen for receiving blood from the patient'"'"'s cardiovascular system;

said first means further comprising means for introducing a fluid into the lumen so as to form a blood-fluid interface in the first means;

said first means being compliant whereby the patient'"'"'s heartbeats tend to move the interface;

said first means having a first compliance and a second compliance and comprising means for selecting the first compliance or the second compliance, said first and second compliances being different; and

a sensor in communication with the lumen.

2. An assembly as defined in claim 1 wherein the introducing means has a natural compliance which provides the first compliance and the first means includes a compliant element for use in providing the second compliance, said second compliance being greater than the first compliance.

3. An assembly as defined in claim 2 including means for selectively switching the compliant element into and out of communication with the lumen of the catheter.

4. An assembly as defined in claim 1 wherein the first means has a compliant element and means for adjusting the compliance of said compliant element to thereby provide said first and second compliances.

5. An assembly as defined in claim 4 wherein the compliant element includes an elastic membrane and said adjusting means includes means for limiting maximum elastic movement of the membrane to thereby provide said first and second compliances.

6. An assembly as defined in claim 5 wherein the limiting means is infinitely adjustable to provide an infinite number of compliances for the introducing means.

7. An assembly as defined in claim 5 comprising a housing having a passage in communication with the lumen, said membrane being mounted on said housing and said limiting means including a movable member mounted for movement on the housing to provide an adjustable stop for limiting movement of the membrane.

8. An assembly for the in vivo measurement of a blood parameter comprising:

a catheter comprising a lumen extending therethrough, a proximal end, a distal end and a distal opening at the distal end, said catheter being adapted to be received in a patient'"'"'s cardiovascular system;

a sensor for sensing the blood parameter and providing a signal in response thereto;

means for mounting the sensor on the catheter with the sensor being within the lumen;

a conduit for coupling the lumen to a source of fluid whereby the fluid can be supplied to the lumen;

a compliant element coupled to said conduit to allow the volume of the assembly to be expanded and contracted;

said compliant element including a membrane; and

means for adjustably limiting movement of the membrane to adjust the compliance of the compliant element.

9. An assembly for the measurement of a blood parameter comprising:

first means for withdrawing blood from a patient into the first means;

said first means comprising a catheter adapted to be received in a patient'"'"'s cardiovascular system and having a lumen for receiving blood from the patient'"'"'s cardiovascular system;

said first means further comprising means for introducing a fluid into the lumen so as to form a blood-fluid interface in the first means;

said first means having a natural compliance whereby the patient'"'"'s heartbeats tend to move the interface;

said first means further comprising compliance means for providing the introducing means with a plurality of different compliances other than said natural compliance; and

a sensor in communication with the lumen.

10. An assembly as defined in claim 9 wherein the introducing means includes a conduit communicable with the lumen of the catheter and the compliance means includes an elastic membrane and means for adjustably limiting movement of the membrane to provide said plurality of different compliances.

11. A method of sensing a parameter of blood comprising:

withdrawing blood from a patient into an elongated passage of a system having a plurality of different compliances;

introducing an anti-clotting solution into the passage to provide an interface between the blood and the solution;

selecting one of said compliances;

moving the interface back and forth in the passage with the system having said one compliance, said step of moving including allowing the patient'"'"'s heartbeats to move the interface; and

sensing a parameter of the blood in the passage.

12. A method as defined in claim 11 wherein said different compliances include a natural compliance of the system, wherein there is a compliant element in said system for use in providing a second of said compliances, and wherein said step of selecting includes selecting said natural compliance or said second compliance.

13. A method as defined in claim 11 wherein said different compliances include a natural compliance of the system, wherein there is a compliant element in said system for use in providing a plurality of other different compliances, and wherein said step of selecting includes using said compliant element to provide one of said other compliances.