Methods of and apparatus for monitoring respiration and conductive composition used therewith

• US 5,329,932 A
• Filed: 10/31/1991
• Issued: 07/19/1994
• Est. Priority Date: 11/09/1989
• Status: Expired due to Fees

• Current Assignee: Oregon State University (Oregon University System)
• Original Assignee: Oregon Health & Science University
• Inventors: Yount, John E.
• Primary Examiner(s): Sykes, Angela D.
• Application Number:
  US07/786,214
• Time in Patent Office: 992 Days
• Field of Search: 128/721-723, 128/774, 128/782, 324/691, 324/699, 338/80, 338/94, 338/99, 338/114, 338/231
• US Class Current: 600/534
• CPC Class Codes: A61B 5/1135 by monitoring thoracic expansion
• CPC Class Codes: H01B 1/20 Conductive material dispersed in non-conductive organic material organic macromolecular compounds or compositions C08
• CPC Class Codes: H01M 6/22 Immobilising of electrolyte

Abstract

An apparatus for measuring respiration includes a first gauge for positioning around a patient'"'"'s chest and a second gauge for positioning around the patient'"'"'s abdomen. Each gauge is comprised of a compliant tube, e.g., natural or silicone rubber filled with a conductive gel. The conductive gel is a composition comprising glycerol, water, and, e.g., sodium chloride. Upon securing the gauges about the patient, signals indicative of absolute volume are immediately available, providing a new and improved method of measuring and/or monitoring respiration.

Claims

1. A stretchable tube comprising a length, wall thickness and inside diameter whereby the tube is useful as a respiratory gauge having minimal response to proximate high frequency electromagnetic fields and containing a composition of 35-90% by volume glycerol, 65-10% by volume water and an amount of a salt in a concentration of from about 20 g per 100 ml to saturated which is effective as an electrolyte, wherein said salt is one of sodium chloride, potassium chloride, potassium acetate, potassium bromide, calcium lactate and a mixture thereof.

2. A tube of claim 1 which is a silicone or natural rubber tube.

3. A tube according to claim 2, wherein all the salts of the composition are present as a saturated solution thereof in a higher concentration than when formulated with water alone.

4. A tube according to claim 2, further comprising a gel-forming concentration of magnesium sulfate.

5. A tube of claim 2, the composition being a fluid.

6. A tube of claim 2, the composition being a gel.

7. A tube of claim 2, wherein the composition further comprises one of an amount of an iodide salt effective to enhance the imageability of the composition to X-rays. An amount of a paramagnetic ion chelate effective to enhance the imageability of the composition to MRI, an amount of a magnetic particle effective to enhance the imageability of the composition to MRI, and a mixture of the X-ray imageability enhancer and at least one of the MRI imageability enhancers.

8. A process for measuring respiration of a patient comprising:

calibrating first and second tubular gauges each comprising a tube of stretchable composition filled with a conductive gel or fluid by stretching the gauges and storing voltage readings indicative of changes in impedance in a microprocessor, and

tensioning the first tubular gauge and securing the tensioned gauge about the patient'"'"'s chest, tensioning the second tubular gauge and securing the tensioned gauge about the patient'"'"'s abdomen, and measuring changes in impedance in each gauge as the gauge expands and contracts in length due to respiration of the patient in order to monitor the patient'"'"'s respiration.

9. A process of claim 8, wherein each tube is a natural rubber tube.

10. The process of claim 9, wherein a measurement of absolute volume of respiratory effort is available immediately because the gauges are calibrated prior to attachment to the patient.

11. An apparatus for monitoring respiration of mammals comprising first tubular gauge means for surrounding the chest of the mammal and second tubular gauge means for surrounding the abdomen of the mammal, each gauge means comprising at least one stretchable tube filled with conductive gel or fluid, the conductive gel or fluid being in electrical contact with a pair of electrical contacts disposed within opposite ends of the at least one tube, means for applying signals indicative of changes in impedance of the at least one tube as the at least one tube stretches to signal processing means wherein immediate, absolute calculation of the thoracic volume is achieved, the at least one tube being of a length and wall thickness and the conductive gel or fluid being of a composition which are each selected to provide a substantially linear change in impedance per unit of stretch.

12. An apparatus of claim 11, wherein the at least one tube is a silicone or natural rubber tube.

13. The apparatus of claim 12, wherein in each case the at least one tube has a length in the range of 16 to 36 cm, a wall thickness in the range of 1 to 6 mills, and an inside diameter in the range of 1 to 3 mm, and wherein the conductive gel within each tube is a composition comprising 35 to 90% by volume glycerol, 65-10% by volume water, and an electrolytic salt in a concentration of from about 20 g per 100 ml to saturation.

14. An apparatus of claim 12, wherein in at least one of said tubes the composition further comprises one of an amount of an iodide salt effective to enhance the imageability of the composition to X-rays, an amount of a paramagnetic ion chelate effective to enhance the imageability of the composition to MRI, an amount of a magnetic particle effective to enhance the imageability of the composition to MRI, and a mixture of the X-ray imageability enhancer and at least one of the MRI imageability enhancers.

15. The apparatus of claim 11, wherein the first and second tubular gauge means each comprise a pair of tubes filled with a conductive gel.

16. The apparatus of claim 15, wherein in each case the at least one tube has a length in the range of 16 to 36 cm, a wall thickness in the range of 1 to 6 mills, and an inside diameter in the range of 1 to 3 mm, and wherein the conductive gel within each tube is a composition comprising 35 to 90% by volume glycerol, 65-10% by volume water, and an electrolytic salt in a concentration of from about 20 g per 100 ml to saturation.

17. An apparatus according to claim 16, wherein the salt in the composition of the tubes is one of sodium chloride, potassium chloride, potassium acetate, potassium bromide, calcium lactate and a mixture thereof.

18. An apparatus for monitoring respiration of mammals comprising first tubular gauge means for surrounding the chest of the mammal and second tubular gauge means for surrounding the abdomen of the mammal, each gauge means comprising at least one stretchable tube filled with conductive gel or fluid, the at least one tube comprising the gauge means each having a length in the range of 16 to 36 cm, a wall thickness in the range of 1 to 6 mills, and an inside diameter in the range of 1 to 3 mm, the conductive gel or fluid within each tube being a composition comprising 35 to 90% by volume glycerol, 65-10% by volume water, and an electrolytic salt in a concentration of from about 20 g per 100 ml to saturation, the conductive gel or fluid being in electrical contact with a pair of electrical contacts disposed within opposite ends of the at least one tube, signal processing means, and means for applying signals indicative of changes in impedance of the at least one tube to said signal processing means wherein immediate, absolute calculation of thoracic volume is achieved.

19. An apparatus of claim 18, wherein the at least one tube is a silicone or natural rubber tube.

20. The apparatus of claim 19, wherein the first and second tubular gauge means each comprise a pair of silicone or natural rubber tubes filled with a conductive gel wherein said salt is one of sodium chloride, potassium chloride, potassium acetate, potassium bromide, calcium lactate and a mixture thereof.

21. The apparatus of claim 20, wherein the composition is about 40% by volume glycerol.

22. An apparatus of claim 20, wherein in at least one of said tubes the composition further comprises one of an amount of an iodide salt effective to enhance the imageability of the composition to X-rays, an amount of a paramagnetic ion chelate effective to enhance the imageability of the composition to MRI, an amount of a magnetic particles effective to enhance the imageability of the composition to MRI, and a mixture of the X-ray imageability enhancer and at least one of the MRI imageability enhancers.