METHOD AND DEVICE FOR THE EXTRACTION OF A BODY FLUID

• US 20080108910A1
• Filed: 10/07/2007
• Published: 05/08/2008
• Est. Priority Date: 04/07/2005
• Status: Active Grant

• Current Assignee: Roche Diabetes Care Inc. (Roche Holding AG)
• Original Assignee: Roche Diagnostics Operations Incorporated (Roche Holding AG)
• Inventors: Calasso, Irio, Korner, Stephan, Griss, Patrick, Abt, Reto, Sarofim, Emad, Hein, Heinz-Michael, Jaeggi, Rainer
• Granted Patent: US 7,833,172 B2
• Time in Patent Office: Days
• US Class Current: 600/583
• CPC Class Codes: A61B 5/0531 Measuring skin impedance
• CPC Class Codes: A61B 5/150022 for capillary blood or interstitial fluid
• CPC Class Codes: A61B 5/150068 by tissue compression, e.g. with specially designed surface of device contacting the skin area to be pierced
• CPC Class Codes: A61B 5/150167 Adjustable piercing speed of skin piercing element, e.g. blade, needle, lancet or canula, for example with varying spring force or pneumatic drive
• CPC Class Codes: A61B 5/150175 Adjustment of penetration depth
• CPC Class Codes: A61B 5/150358 Strips for collecting blood, e.g. absorbent optical reagent test strips G01N21/8483; chemical reagent test strips G01N33/4875, G01N33/52
• CPC Class Codes: A61B 5/150435 Specific design of proximal end
• CPC Class Codes: A61B 5/150503 Single-ended needles hollow piercing element tip design A61B5/150396, needle sets for catheters A61M25/06, needles for bringing media into the body A61M5/32
• CPC Class Codes: A61B 5/15107 Piercing being assisted by a triggering mechanism
• CPC Class Codes: A61B 5/15117 comprising biased elements, resilient elements or a spring, e.g. a helical spring, leaf spring, or elastic strap
• CPC Class Codes: A61B 5/15123 comprising magnets or solenoids
• CPC Class Codes: A61B 5/15186 Devices loaded with a single lancet, i.e. a single lancet with or without a casing is loaded into a reusable drive device and then discarded after use; drive devices reloadable for multiple use

Abstract

The present invention provides a method and a device for piercing a body part and determining whether a sufficient volume of blood has been withdrawn. A lancing element is rapidly inserted into a body part in a forward phase and retracted quickly to a lesser puncturing depth. Subsequently, the lancing element is retracted slower than during the first retraction movement and the distance retracted during the second retraction is shorter than the first retraction movement. During the second retraction movement, body fluid is collected in a collection phase by a capillary structure of the lancing element. Contact between the lancing element and the body fluid is detected after the forward phase at the beginning and the end of a waiting period.

Claims

1. A method of collecting body fluid with a lancing element having a tip and a capillary structure, comprising:

inserting the tip of the lancing element into the skin of a body part to a puncture depth;

retracting the tip from the puncture depth to a lesser depth than the puncture depth;

detecting contact between the lancing element and the body fluid after the tip has been retracted to the lesser depth; and

determining from the detecting step whether a sufficient volume of body fluid has been collected by the lancing element.

2. The method of claim 1, further comprising:

detecting contact between the lancing element and the body fluid when the tip is located at about the puncture depth; and

the determining step comprising comparing a first signal generated from the detecting of contact when the tip is located at about the puncture depth to a second signal generated from the detecting of contact after the tip has been retracted to the lesser depth.

3. The method of claim 2, wherein a sufficient volume of body fluid is determined to have been collected by the lancing element when the first signal and the second signal are substantially the same.

4. The method of claim 2, further comprising triggering an error state when the first signal and the second signal are substantially different.

5. The method of claim 1, further comprising:

forming a lancing channel in the skin during the retraction of the tip from the puncture depth to the lesser depth;

at least partially evacuating the lancing channel during the retraction of the tip from the puncture depth to the lesser depth;

waiting an amount of time after the retracting of the tip to the lesser depth to allow the body fluid to enter the lancing channel; and

then performing the step of detecting contact between the lancing element and the body fluid.

6. The method of claim 1, further comprising applying a contact element against the skin, wherein the lancing element comprises electrically conductive material and the contact between the lancing element and the body fluid is detected by monitoring an electrical parameter between the contact element and the lancing element.

7. The method of claim 6, wherein the detecting step comprises measuring an electrical parameter.

8. The method of claim 7, wherein the electrical parameter comprises impedance.

9. The method of claim 7, further comprising detecting contact between the lancing element and the body fluid during the step of retracting the tip from the puncture depth to the lesser depth, wherein the electrical parameter reaches a reference value when the tip is located at about the puncture depth, then deviates from the reference value after the tip is retracted from the puncturing depth, and then substantially returns to the reference value after the tip reaches the lesser depth.

10. The method of claim 1, wherein the detecting contact comprises an optical measurement.

11. The method of claim 1, wherein the lesser depth is located in the region of the stratum corneum.

12. The method of claim 1, further comprising:

removing the tip of the lancing element from the skin after the tip is retracted to the lesser depth;

reinserting the tip into the skin; and

wherein, the detecting contact between the lancing element and the body fluid after the tip reaches the lesser depth is performed after the reinsertion.

13. The method of claim 1, wherein the body fluid is collected via the capillary structure, the capillary structure being vacated when the tip moves from the puncture depth to the lesser depth.

14. A lancing device for collecting body fluid, comprising:

a housing;

a lancing element reciprocably mounted in the housing, the lancing element including a tip that is exposed for puncturing a body part and a capillary structure adapted to collect body fluid;

a lancing drive connected to the lancing element, the lancing drive configured to move the lancing element in a forward phase, a retraction phase and a collection phase; and

a detection mechanism adapted to detect contact between the lancing element and the body fluid by measuring a signal that varies as a function of contact between the lancing element and the body fluid, the detection mechanism configured to measure and compare the signal at the beginning and at the end of a waiting period that is initiated after the forward phase.

15. The lancing device of claim 14, wherein the detection mechanism is configured to determine from the comparison whether a sufficient volume of body fluid has been collected.

16. The lancing device of claim 14, wherein the detection mechanism initiates an error signal if it is determined that a sufficient volume of body fluid has not been collected.

17. The lancing device of claim 14, wherein the detection mechanism comprises an electrically insulated contact element configured for contact with the body part.

18. The lancing device of claim 17, wherein the contact element comprises a ring.

19. The lancing device of claim 17, wherein the lancing element comprises a first electrode and the contact element comprises a second electrode.

20. The lancing device of claim 19, wherein the detection mechanism measures impedance.

21. The lancing device of claim 14, wherein the detection mechanism measures an optical parameter.

22. A method of collecting body fluid with a lancing element having a tip and a capillary structure, comprising:

inserting the tip of the lancing element into the skin of a body part to a puncture depth;

retracting the tip by a first distance during a retraction phase, the first distance being measured from the puncture depth to a lesser depth than the puncture depth;

retracting the tip by a second distance during a collection phase, the second distance being measured from the lesser depth to the skin surface; and

the retraction phase being faster than the collection phase and the first distance being greater than the second distance.

23. The method of claim 22, further comprising collecting body fluid during the collection phase.

24. The method of claim 22, wherein the collection phase is about 10 to 10,000 times longer than the retraction phase.

25. The method of claim 22, wherein the retracting the tip during the collection phase is performed at substantially uniform speed.

26. The method of claim 22, further comprising decelerating the lancing element during the collection phase.

27. The method of claim 22, further comprising temporarily stopping the lancing element during the collection phase.

28. The method of claim 22, wherein the second distance is about 0.1 mm to about 2 mm.

29. The method of claim 22, wherein the tip is located in the stratum corneum during at least part of the collection phase.

30. The method of claim 22, further comprising controlling movement of the lancing element as a function of time.

31. The method of claim 22, further comprising controlling movement of the lancing element as a function of distance.

32. The method of claim 22, wherein the collection phase comprises collecting body fluid through the capillary structure.

33. The method of claim 32, further comprising creating a channel in the skin extending from the puncture depth to the lesser depth and through which the body fluid moves after the tip has reached the lesser depth.

34. The method of claim 33, wherein the channel is initially evacuated after the retraction from the puncture depth to the lesser depth.

35. The method of claim 22, further comprising:

mechanically controlling movement of the lancing element during the inserting the tip to a puncture depth and during the retracting the tip by a first distance; and

electrically controlling movement of the lancing element during the collection phase.

36. The method of claim 22, further comprising maintaining the tip of the lancing element at the lesser depth while collecting body fluid with the capillary structure.

37. The method of claim 22, further comprising collecting body fluid with the capillary structure while the lancing element is being retracted from the lesser depth.

38. The method of claim 37, further comprising decelerating the lancing element while the lancing element is being retracted from the lesser depth.

39. A lancing device for collecting body fluid, comprising:

a housing;

a lancing element reciprocably mounted in the housing, the lancing element including a tip that is exposed for puncturing a body part and a capillary structure adapted to collect body fluid;

a lancing drive connected to the lancing element, the lancing drive configured to move the lancing element in a forward phase, a retraction phase and a collection phase; and

the lancing drive further configured to retract the lancing element by a first distance during the retraction phase and to retract the lancing element by a second distance during the collection phase, wherein the retraction phase is faster than the collection phase and the first distance is greater than the second distance.

40. The lancing device of claim 39, wherein the lancing drive moves the lancing element at a substantially uniform speed during the collection phase.

41. The lancing device of claim 39, wherein the lancing drive decelerates the lancing element during the collection phase.

42. The lancing device of claim 39, wherein the lancing drive temporarily stops the lancing element during the collection phase.

43. The lancing device of claim 39, wherein the lancing drive comprises two components, the first component moving the lancing element during the forward and retraction phases and the second component moving the lancing element during the collection phase.

44. The lancing device of claim 43, wherein the first component comprises a mechanical drive and the second component comprises an electrical drive.