Pressure applicator devices particularly useful for non-invasive detection of medical conditions

• US 6,461,305 B1
• Filed: 04/28/2000
• Issued: 10/08/2002
• Est. Priority Date: 06/07/1998
• Status: Expired due to Term

• Current Assignee: Itamar Medical Ltd. (Asahi Kasei Corporation)
• Original Assignee: Itamar Medical Ltd. (Asahi Kasei Corporation)
• Inventors: Schnall, Robert P.
• Primary Examiner(s): Nasser, Robert L.
• Application Number:
  US09/485,302
• Time in Patent Office: 893 Days
• Field of Search: 600/342, 600/481, 600/483, 600/485, 600/500, 600/503, 600/504, 600/507
• US Class Current: 600/485
• CPC Class Codes: A61B 5/02007 Evaluating blood vessel condition, e.g. elasticity, compliance
• CPC Class Codes: A61B 5/1073 Measuring volume, e.g. of limbs
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6838 Clamps or clips

Abstract

A probe for application to a body part particularly a finger of a patient to detect a change in the physical condition of the patient includes a housing defining a compartment closed at one end and open at the opposite end for receiving the distal end of the patient'"'"'s finger and a medium wholly self-contained within the probe for applying a static pressure field substantially uniformly around the distal end of the patient'"'"'s finger, of a predetermined magnitude sufficient to substantially prevent distention of the venous vasculature, uncontrolled venous backflow, and retrognade shockwave propagation into the distal end, and to partially unload the wall tension of, but not to occlude, the arteries in the distal end when at heart level or below. A sensor senses changes in the distal end of the patient'"'"'s finger related to changes in arterial blood volume therein.

Claims

1. A device for application to a body part of a patient to determine the physiological condition of the patient, comprising a probe including:

a housing defining a compartment closed at one end and open at an opposite end for receiving a distal end of the body part including a terminal-most extremity;

pressurizing means for applying a static pressure field substantially uniformly around the distal end of the body part, when received in said compartment, including the terminal-most extremity, which static pressure field is of a predetermined magnitude sufficient to substantially prevent distention of venous vasculature, uncontrolled venous backflow, and retrognade shockwave propogation into said distal end, and to partially unload wall tension of, but not to occlude, arteries in said distal end when at heart level or below;

and a sensor for sending changes in said distal end of the body part related to changes in volume thereof due to changes in instantaneous blood volume related to arterial blood volume therein,

wherein said pressurizing means for applying said static pressure substantially uniformly around the distal end of the body part, including the terminal-most extremity, comprises a medium wholly self-contained within said probe.

2. The device according to claim 1, wherein said pressurizing means includes an inner resilient membrane within said housing and defining therewith an inner chamber to be filled with a fluid for applying said static pressure via said membrane substantially uniformly around the distal end of the body part including the terminal-most extremity.

3. The device according to claim 2, wherein said pressurizing means further includes an outer resilient membrane attached to said housing externally thereof and defining therewith an outer chamber communicating with said inner chamber via openings in said housing for enlarging an effective volume of said inner chamber such as to cause said inner membrane to apply substantially the same static pressure around the distal end of the body part despite changes in volume thereof.

4. The device according to claim 3, wherein said housing includes a port having a one-way valve for filling said inner chamber to a desired predetermined pressure.

5. The device according to claim 3, wherein said outer resilient membrane is of annular configuration and is applied around an annular portion of the housing formed with said openings providing communication between said inner and outer chambers.

6. The device according to claim 3, wherein said outer resilient membrane is of tubular configuration and is attached around an outer tip of the housing, said outer tip being formed with said openings providing communication between said inner and outer chambers.

7. The device according to claim 6, wherein said housing includes an annular ring spaced from the outer resilient membrane attached to the housing for receiving an open end of a syringe to be used for enlarging said outer chamber by shifting the fluid from said inner chamber to said outer chamber to facilitate insertion of the body part into said compartment.

8. The device according to claim 6, wherein said outer resilient membrane includes a finger piece graspable by a user for enlarging said outer chamber by shifting the fluid from said inner chamber to said outer chamber to facilitate insertion of the body part into said compartment.

9. The device according to claim 8, wherein said finger piece includes a knob extending externally of the outer membrane for grasping by the user and fixed to a backing member engageable with an inner surface of the outer membrane.

10. The device according to claim 3, wherein said housing is made of two sections hinged together to assume open and closed conditions, and including at least one fastening element for fastening the two sections in their closed condition.

11. The device according to claim 10, wherein said at least one fastening element is “

Velcro”

(T.M.) hook and loop fastener strips carried by the two housing sections.

12. The device according to claim 10, wherein said at least one fastening element is tongue and recess formations integrally formed in the two housing sections.

13. The device according to claim 10, wherein said housing includes a tubular side wall closed at one end by an end wall and open at the opposite end, said tubular housing being split into two half-sections and hinged together at said end wall.

14. The device according to claim 10, wherein said housing includes a tubular side wall closed at one end by an end wall and open at the opposite end, said housing being split into two half sections and hinged together along said tubular side wall.

15. The device according to claim 13, wherein said hinge is an integral hinge integrally formed with said two half sections of the housing.

16. The device according to claim 13, wherein said hinge is a strip of flexible strechable material attached to the two housing half-sections.

17. The device according to claim 13, wherein:

said inner membrane includes a membrane strip joined to the side wall and end wall of each housing section;

and said outer membrane includes another membrane strip attached to an outer surface of each housing section.

18. The device according to claim 1, wherein said pressurizing means includes an adhesive layer within said compartment to be contacted by the body part received within the device.

19. The device according to claim 18, wherein said adhesive layer is on an inner surface of a plastic strip, an outer surface of the plastic strip having another adhesive layer, said plastic strip further including a protective layer covering the adhesive layer on an inner surface thereof and strippable therefrom to enable said inner surface to contact and firmly adhere to the body part when received within the device.

20. The device according to claim 1, further including an annular pressure cuff applied around the body part contiguous to said housing on a heart side of the patient to extend the static pressure field past the sensor on the heart side of the patient.

21. The device according to claim 1, wherein said pressurizing means includes a body of resilient sponge material formed with a recess defining said compartment for receiving the body part when inserted therein.

22. The device according to claim 21, wherein:

said housing is made of two sections hinged together to assume open and closed conditions;

said body of resilient sponge material is also made of two sections, one carried on each of the two sections of the housing;

and said two housing sections further include at least one fastening element for fastening the two housing sections in their closed condition.

23. The device according to claim 22, wherein each of said two sections of the body of resilient sponge material includes a layer of a gel material exposed for contact with the body part when inserted into the two housing and the housing sections are in their closed condition.

24. The device according to claim 1, wherein a pressure sensing device is located within said housing to sense the pressure applied to the patient'"'"'s body part by said pressurizing means.

25. The device according to claim 1, wherein said sensor is an optical sensor and includes a light source carried within said housing on one side of the body part when inserted therein, and a light detector carried within said housing on an opposite side of the body part.

26. The device according to claim 1, wherein said sensor is a Hall effect sensor and includes a permanent magnet carried within said housing on one side of the body part when inserted therein, and a magnetic field detector carried within said housing on an opposite side of the body part.

27. The device according to claim 1, wherein said sensor comprises a combination of an optical sensor device and a volumetric sensing device.

28. The device according to claim 1, wherein said sensor is a pulse oximeter sensor for sensing oxygen saturation of blood.

29. The device according to claim 1, further including electrical conductors leading from said sensor to an electrical circuit carried by a band applied to another body part of the patient.

30. The device according to claim 29, wherein said electrical circuit includes a storage device for storing an output of said sensor.

31. The device according to claim 1, wherein the body part is a finger.

35. The device according to claim 22, wherein the body part is a finger.

32. A device for application to a body part of a patient to determine the physiological condition of the patient, comprising:

a first housing defining a first compartment closed at one end and open at the opposite end for receiving a distal end of the body part including a terminal-most extremity;

pressurizing means for applying a static pressure field substantially uniformly around the distal end of the body part, when received in said compartment, including the terminal-most extremity, which static pressure field is of a predetermined magnitude sufficient to substantially prevent distention of venous vasculature, uncontrolled venous backflow, and retrograde shockwave propagation into said distal end, and to partially unload wall tension of, but not to occlude, arteries in said distal end when at heart level or below;

a sensor for sensing changes in said distal end of the body part related to changes in volume thereof due to changes in instantaneous blood volume related to arterial blood volume therein;

and a second housing separate and apart from said first housing and defining a second compartment having a fluid connection to said first compartment, said sensor being located within said second housing in operative position with respect to said second compartment.

33. The device according to claim 32, wherein said second housing includes a presettable pressure source for presetting a predetermined pressure inside said second housing.

34. The device according to claim 32, wherein said second housing is vented to atmosphere.

36. A device for application to a body part of a patient to determine the physiological condition of the patient, comprising:

a housing defining a compartment closed at one end and open at the opposite end for receiving a distal end of the body part;

a first membrane defining a first chamber containing a pressurized fluid to apply a static pressure field to the body part when received within the housing;

a second membrane defining a second chamber communicating with said first chamber and of a volume such that combined volumes of the first and second chambers maintain a relatively constant pressure despite changes in volume according to the Laplace Law;

and at least one sensor element in at least one of said first and second chambers for sensing changes in said distal end of the body part related to changes in volume therein.

37. The device according to claim 36, wherein said second membrane encloses at least a portion of said housing to define said second chamber with an outer surface of an enclosed portion of the housing, said second chamber communicating with said first chamber via openings through said housing.

38. The device according to claim 37, wherein said at least one sensor element is carried by said first membrane in said first chamber.

39. The device according to claim 37, wherein said second membrane is of annular configuration and is applied around an annular portion of the housing formed with said openings providing communication between said inner and outer chambers.

40. The device according to claim 37, wherein said second membrane is of tubular configuration and is attached around an outer tip of the housing, the outer tip being formed with said openings providing communication between said first and second chambers.

41. The device according to claim 36, wherein said second chamber defined by said second membrane is located in a second housing and is connected to said first chamber by a fluid tube.

42. The device according to claim 41, wherein said at least one sensor element is located in said second housing in operative position with respect to said second chamber.

43. The device according to claim 42, wherein said second membrane is subject to differential pressure with respect to the pressure in said second chamber and ambient pressure in said second housing.

44. The device according to claim 43, wherein said second housing includes a pressure presetting device for presetting the pressure within said second housing acting on said second membrane.

45. The device according to claim 44, wherein said second housing includes a pressure sensor for sensing the ambient pressure within said second housing.

46. The device according to claim 36, wherein the body part is a finger.

47. The device according to claim 42, wherein said at least one sensor translates volume changes in said second chamber into an electronic signal.

48. The device according to claim 47, wherein said at least one sensor comprises a light source and an optical detector.

49. The device according to claim 48, wherein said light source is mounted on a movable membrane which defines one wall of said second chamber and said optical detector is mounted on a fixed base which forms another wall of said second chamber, or vice versa, and wherein when said membrane shifts with respect to said fixed base said optical detector emits a signal which is indicative of an amount of movement of said membrane and is correlated to a volume change within said first and second chambers.