APPARATUS AND METHOD FOR SPECTROPHOTOMETRIC MEASUREMENTS OF BLOOD PARAMETERS

• US 20120108981A1
• Filed: 05/25/2010
• Published: 05/03/2012
• Est. Priority Date: 05/26/2009
• Status: Abandoned Application

• Current Assignee: B. Braun Avitum AG (B. Braun Holding GmbH & Co. KG)
• Original Assignee: B. Braun Avitum AG (B. Braun Holding GmbH & Co. KG)
• Inventors: Porro, Giampiero, Pozzi, Roberto, Torinesi, Alessandro
• Application Number:
  US13/322,756
• Publication Number:
  US 20120108981A1
• Time in Patent Office: Days
• US Class Current: 600/476
• CPC Class Codes: A61B 5/14535 for measuring haematocrit
• CPC Class Codes: A61B 5/14557 specially adapted to extracorporeal circuits

Abstract

An apparatus for measuring the blood parameters in an extracorporeal circuit comprises: a seat (23) suitable for containing a duct (14) for the blood flow of said extracorporeal circuit; emitting means (16) and detecting means (18) of electromagnetic radiation that face the seat (23); a control unit (38) to which said emitting means (16) and detecting means (18) are connected. The apparatus according to the invention is characterised in that the emitting means (16) are suitable for producing electromagnetic radiation at different wavelengths, and the detecting means (18) are suitable for detecting the electromagnetic radiation diffused in the blood at said wavelengths. Moreover, the apparatus is characterised in that the control unit (38) is suitable for calculating values of blood parameters through a correlation between reference values and ratios obtained from values of the light intensity of the radiation detected at at least two different wavelengths.

Claims

1-22. -22. (canceled)

23. Apparatus for measuring the blood parameters in an extracorporeal circuit, comprising:

a seat (23) suitable for containing a duct (14) for the blood flow of said extracorporeal circuit;

electromagnetic radiation emitting means (16);

electromagnetic radiation detecting means (18), said means (16, 18) facing the seat (23); and

a control unit (38) to which said emitting means (16) and said detecting means (18) are connected;

wherein

said electromagnetic radiation emitting means (16) are suitable for producing electromagnetic radiation at different wavelengths, said electromagnetic radiation detecting means (18) are suitable for detecting the electromagnetic radiation diffused in the blood at said wavelengths, and in that the control unit (38) is suitable for calculating values of blood parameters through a correlation between reference values and ratios obtained from values of the light intensity of the radiation detected at at least two different wavelengths.

24. Apparatus according to claim 23, wherein said emitting means (16) are suitable for emitting electromagnetic radiation at wavelengths corresponding to the water absorption peaks.

25. Apparatus according to claim 23, wherein said emitting means (16) are suitable for emitting electromagnetic radiation at four different wavelengths.

26. Apparatus according to claim 25, wherein said emitting means (16) are suitable for emitting electromagnetic radiation at wavelengths:

A=805 nm, B=660 nm, C=1450 nm, D=1550 nm.

27. Apparatus according to claim 23 further comprising:

a temperature detector (28) facing the seat (23) and connected to the control unit (38).

28. Apparatus according to claim 27, wherein said temperature detector (28) is an infrared temperature sensor having a wide band reception in the range of middle-infrared electromagnetic radiation up to 15000 nm.

29. Apparatus according to claim 23 further comprising:

a first temperature sensor (32) suitable for measuring the operating temperature of the detecting means (18).

30. Apparatus according to claim 29 further comprising:

a second temperature sensor (34) suitable for measuring the blood temperature.

31. Apparatus according to claim 23, wherein said emitting means (16) emit a train of impulses of constant width and frequency at at least one wavelength.

32. Apparatus according to claim 23, further comprising:

a central body (20) comprising the seat (23);

a base (13), associated with the central body (20), to which the emitting and detecting means (16, 18) are connected so that they are contained inside a space located between body (20) and base (13); and

holes (24, 26), formed on the seat (23) and distributed in a substantially axial direction, for the optical connection between the duct (14) and the emitting means (16) and detecting means (18), respectively.

33. Apparatus according to claim 30, further comprising:

holes (30, 36) formed on the seat (23) and distributed in a substantially axial direction, for the optical connection between the duct (14) and the temperature detector (28) and for the contact between the second sensor (34) and the duct (14), respectively.

34. Method for measuring blood parameters comprising the steps of:

emitting electromagnetic radiation in the form of a sequence of pulses of at least two different wavelengths;

detecting the radiation diffused in the blood by said at least two wavelengths;

calculating the values of the blood parameters correlating reference values to the ratio between the intensity of the electromagnetic radiation detected at said at least two different wavelengths.

35. Method according to the claim 34, wherein an oxygen saturation value (sO₂%) is obtained by correlating to calibration curves the ratio R₂=I_λ

(A)/I_λ

(B) between a first intensity of detected electromagnetic radiation I_λ

(A) and a second intensity of detected electromagnetic radiation I_λ

(B).

36. Method according to claim 34, wherein an oxygen saturation value (sO₂%) is obtained by correlating the ratio R₂=I_λ

(A)/I_λ

(B) between intensity of detected electromagnetic radiation to calibration values approximated with a mathematical function of the second order.

37. Method according to claim 34, wherein a hematocrit value (Ht %) is obtained by correlating to calibration curves the ratio R₁=I_λ

(A)/[I_λ

(C)+I_λ

(D)] between the intensities of electromagnetic radiation detected I_λ

(A), I_λ

(C) and I_λ

(D)

38. Method according to claim 34, wherein a hematocrit value (Ht %) is obtained by correlating the ratio R₁=I_λ

(A)/[I_λ

(C)+I_λ

(D)] between the intensities of electromagnetic radiation detected to calibration values approximated with a mathematical function of the third order.

39. Method according to claim 34, wherein the values of the blood parameters calculated are corrected based on the blood temperature.

40. Method according to claim 34, wherein the values of the blood parameters calculated are corrected based on a value of an operating temperature of an electromagnetic radiation detecting means (18).

41. Method according to claim 35, wherein the calculated oxygen saturation value of the blood (sOhd 2%) is corrected based on a hematocrit value (Ht %).

42. Method according to claim 37, wherein the calculated hematocrit value (Ht %) of the blood is corrected based on an oxygen saturation value (sO₂%).

43. Method according to claim 34, comprising the steps of:

emitting a train of pulses at constant intensity and frequency;

detecting the train of pulses;

processing the detected train of pulses; and

associating the presence and size of an embolus with the time period in which the variation in intensity of the detected radiation exceeds a certain threshold.

44. Method according to claim 43, wherein a computation of a volume of air accumulated both as single embolus and as a sum of microemboli is carried out and consequently an alarm and/or a stop of the blood flow is generated if a risk threshold determined for the patient is exceeded.