Fluid sampling method

• US 5,301,686 A
• Filed: 08/31/1992
• Issued: 04/12/1994
• Est. Priority Date: 05/02/1991
• Status: Expired due to Term

• Current Assignee: Gambro Renal Products, Inc. (Baxter International Inc.)
• Original Assignee: COBE Laboratories Incorporated (Terumo Corporation)
• Inventors: Newman, David P.
• Primary Examiner(s): HINDENBURG, MAX F
• Application Number:
  US07/938,407
• Time in Patent Office: 589 Days
• Field of Search: 128/760, 128/763-766, 128/770, 604/52, 604/181, 604/182, 604/229, 604/233, 604/236, 604/240, 604/246, 604/249
• US Class Current: 600/573
• CPC Class Codes: A61B 5/15003 for venous or arterial blood
• CPC Class Codes: A61B 5/150221 Valves
• CPC Class Codes: A61B 5/150992 Blood sampling from a fluid line external to a patient, such as a catheter line, combined with an infusion line; blood sampling from indwelling needle sets, e.g. sealable ports, luer couplings, valves tubing connectors and couplings A61M39/00
• CPC Class Codes: G01N 1/2035 by deviating part of a fluid stream, e.g. by drawing-off or tapping

Abstract

A fluid sampling method in which a variable volume chamber between a needle site and a syringe creates a negative pressure at the tip on its removal from the needle site to reduce the exposure to liquid at the time of removal.

Claims

1. A method for withdrawing a sample of a fluid from a sample site on a fluid container, said method being adapted to reducing the amount of excess fluid at the sample site, said method comprising:

engaging a sampling device with the sampling site, said sampling device defining a variable volume passage with a relatively larger volume position and a relatively smaller volume position and having a tip at one end of the variable volume passage and a valve at another end of the variable volume passage opposite the one end;

sealing the tip of the sampling device to the sampling site;

decreasing the volume of the variable volume passage by moving the variable volume passage to a relatively smaller volume position;

releasing air from the variable volume passage through the valve;

withdrawing the sample of fluid from the sample site through the variable volume passage in the sampling device;

increasing the volume of the variable volume passage by moving the variable volume passage to a relatively larger volume position to create a negative pressure in the variable volume passage;

closing the valve to prevent entry of air into the variable volume passage through the valve;

drawing the excess fluid into the variable volume passage by action of the negative pressure; and

disengaging the sampling device from the sampling site.

2. A method as defined in claim 1 wherein:

further includes a resilient member to bias the variable volume passage toward the relatively larger volume position;

the decreasing step further comprises;

compressing the resilient member of the sampling device to decrease the volume of the variable volume passage against biasing action of the resilient member; and

the increasing step further comprises;

decompressing the resilient member of the sampling device to increase the volume of the variable volume passage by moving the variable volume passage to the relatively larger volume position by the biasing action of the resilient member.

3. A method as defined in claim 2 wherein:

the valve is a check valve; and

the closing step further comprises;

closing the check valve by action of the negative pressure to prevent entry of air into the variable volume passage through the check valve.

4. A method as defined in claim 3 wherein:

the engaging step further comprises;

threadably connecting the sampling device to the sampling site; and

the disengaging step further comprises;

threadably disconnecting the sampling device from the sampling site.

5. A method as defined in claim 4 wherein:

the compressing step is performed simultaneously with the engaging step; and

the resilient member is compressed by the action of threadably connecting the sampling device to the sampling site.

6. A method as defined in claim 4 wherein:

the decompressing step is performed simultaneously with the disengaging step; and

the resilient member is decompressed by the action of threadably disconnecting the sampling device from the sampling site.

7. A method as defined in claim 2 wherein:

the sealing step further comprises;

urging the tip of the sampling device into contact with the sampling site by biasing action of the resilient member.

8. A method as defined in claim 3 wherein:

the variable volume passage is defined by a plurality of members each defining a plurality of bores in a coaxial telescoping relationship;

the decreasing step further comprises;

moving at least one of the plurality of members defining a bore telescopingly with respect to at least one other member defining a bore from the relatively larger volume position to the relatively smaller volume position; and

the increasing step further comprises;

moving the one member defining a bore telescopingly with respect to the other member defining a bore from the relatively smaller volume position to the relatively larger volume position.

9. A method as defined in claim 8 wherein:

the resilient member is an elastomeric barrel;

said method further comprising;

sealing the one member defining a bore to the other member defining a bore by compressing the elastomeric barrel against a surface of the one member defining a bore and the surface of the other member defining a bore.

10. A method for withdrawing a sample of a fluid from a sample site on a fluid container, said method being adapted to reducing the amount of excess fluid at the sample site, said method comprising:

engaging a sampling device with the sampling site, said sampling device defining a variable volume passage having a relatively larger volume position and a relatively smaller volume position and having a tip at one end of the variable volume passage and a check valve at another, opposite, end of the variable volume passage and further having a resilient member for biasing the variable volume passage toward the relatively larger volume position;

sealing the tip of the sampling device to the sampling site;

compressing the resilient member of the sampling device;

decreasing the volume of the variable volume passage by moving the variable volume passage to the relatively smaller volume position against biasing action of the resilient member;

releasing air from the variable volume passage through the check valve;

withdrawing the sample of fluid from the sample site through the variable volume passage in the sampling device;

decompressing the resilient member of the sampling device;

increasing the volume of the variable volume passage by moving the variable volume position to the relatively larger volume position by the biasing action of the resilient member to create a negative pressure in the variable volume passage;

closing the check valve by action of the negative pressure to prevent entry of air into the variable volume passage through the check valve;

drawing the excess fluid into the variable volume passage by action of the negative pressure; and

disengaging the sampling device from the sampling site.