Vaporizer for inhalation anesthetics during high-frequency jet ventilation and associated method

• US 5,072,726 A
• Filed: 05/11/1990
• Issued: 12/17/1991
• Est. Priority Date: 10/09/1987
• Status: Expired due to Fees

• Current Assignee: University of Pittsburgh of The Commonwealth System of Higher Education
• Original Assignee: University of Pittsburgh of The Commonwealth System of Higher Education
• Inventors: Mazloomdoost, Manoochehr, Foon, Wilfred L.
• Primary Examiner(s): Burr, Edgar S.
• Assistant Examiner(s): Lewis, Aaron J.
• Application Number:
  US07/613,981
• Time in Patent Office: 585 Days
• Field of Search: 128/200.14, 128/200.18, 128/200.21, 128/203.12, 128/203.25
• US Class Current: 128/200.14
• CPC Class Codes: A61M 11/06 of the injector type
• CPC Class Codes: A61M 16/0096 High frequency jet ventilation
• CPC Class Codes: A61M 16/147 the respiratory gas not passing through the liquid container
• CPC Class Codes: A61M 16/18 Vaporising devices for anaesthetic preparations

Abstract

A vaporizer that may be used in high-frequency jet ventilation (HFJV) is closed. The vaporizer operates on the principle of airblast atomization. The vaporizer provides inhalation anesthesia and is adaptable to the high pressure requirements of a high frequency jet ventilator. The apparatus consists of a main tube or body which defines a passageway. Vaporization occurs by the principle of airblast atomization inside the passageway. The open end of the main body adapts to a connector of the endotracheal tube. A gas supply needle extends into and is centered within the lumen of the main body and directed along the axis of the body. The gas supply needle may be positioned horizontally and gas is jetted through it from a high-frequency jet ventilator. An inhalation anesthetic supply needle intersects the main body in general proximity to the gas supply needle. Preferably the inhalation anesthetic supply needle intersects the main body in a generally perpendicular manner to the gas supply needle. At the point of intersection of the inhalation anesthetic supply needle and the gas supply needle airblast atomization occurs. Inhalation anesthetic is drawn up into the inhalation anesthetic supply needle by the negative pressure that is created by the high velocity flow of the gas at the tip of the gas supply needle.

Claims

1. A vaporizer used for high-frequency jet ventilation comprising:

a main body portion defining a passageway that extends therethrough and having an open end connectable to an endotracheal tube,

a gas supply needle which extends into said passageway, and being operatively associated with a high-frequency jet ventilator for introducing said gas supply into said passageway of said main body portion at a desired frequency,

an inhalation anesthetic supply needle operatively associated with infusion pump means for introducing liquid inhalation anesthetic fluid into said inhalation anesthetic supply needle at a controlled flow rate, and

said inhalation anesthetic supply needle and said gas supply needle being disposed generally perpendicular relative to each other,

said arrangement and the construction of said inhalation anesthetic needle and said gas supply needle being such that when a jet of gas is introduced into said passage-way the high velocity of said gas produces a negative pressure which draws said inhalation anesthetic fluid out of said inhalation anesthetic supply needle and airblast atomization occurs at the point of intersection of said gas from said gas supply needle and said fluid from said inhalation anesthetic supply needle whereby said fluid is reduced to small fluid droplets, said airblast atomization immediately followed by vaporization due to the increased surface area of said small droplets and further contact of said jet of gas with said droplets of said inhalation anesthetic such that a vaporized substance with only a gas phase containing molecules of said inhalation anesthetic exists in said passageway of said vaporizer with a controllable percentage of an inspired anesthetic concentration, and

said construction of said passageway of said main body of said vaporizer being unobstructed along the path of travel of said vaporized gas such that said vaporized gas flows freely through said passageway out of said vaporizer into said endotracheal tube.

2. The vaporizer of claim 1, wherein said gas supply needle is generally larger in gauge than said inhalation anesthetic supply needle.

3. The vaporizer of claim 2, wherein said gas supply needle is about 8 to 14-gauge.

4. The vaporizer of claim 3, wherein said gas supply needle is about 14-gauge.

5. The vaporizer of claim 2, wherein said inhalation anesthetic supply needle is about 18 to 22-gauge.

6. The vaporizer of claim 5, wherein said inhalation anesthetic supply needle is about 20-gauge.

7. The vaporizer of claim 1, wherein the distance between said gas supply needle and said inhalation supply needle is about 0.3 to 1.0 millimeters.

8. The vaporizer of claim 7, wherein the distance between said gas supply needle and said inhalation anesthetic supply needle is 0.6 mm.

9. The vaporizer of claim 8, wherein said inhalation anesthetic is selected from the group consisting of enflurane, fluothane, and isoflurane.

10. The vaporizer of claim 9, wherein said inhalation anesthetic is enflurane.

11. The vaporizer of claim 1, including

a scavenging tube which is disposed generally perpendicular to the main body portion that contains a passageway that extends therethrough whereby a respirator may be attached to the end of said scavenging tube.

12. The vaporizer of claim 11, including a scavenging system for evacuation of exhaled gases.

13. The vaporizer of claim 12, including a respirometer means for measuring minute volume.

14. The vaporizer of claim 1, wherein the inside diameter of the passageway of said main body is about 5/8 inches.

15. The vaporizer of claim 1, including a window in the wall of said main body portion disposed near the tips of said gas supply needle and said inhalation anesthetic supply needle.

16. The vaporizer of claim 1, including pin means associated with said gas supply needle for stabilizing said gas supply needle.

17. The vaporizer of claim 1, including pin means associated with said inhalation anesthetic supply needle for stabilizing said inhalation anesthetic supply needle.

18. The vaporizer of claim 1, wherein the tip of said inhalation anesthetic supply needle is oriented generally aligned with the longitudinal axis of the center of the opening of said gas supply needle.

19. The vaporizer of claim 18, wherein the center of the opening of said inhalation anesthetic supply needle is positioned within half of the radius of said gas supply needle.

20. The vaporizer of claim 1, wherein the distance between said needles may be adjusted by adjustment means.

21. The vaporizer of claim 1, including a reinspired gas tube for providing access for reinspired gases into said main body passageway.

22. A method of ventilating the lungs of a patient comprising:

providing a vaporizer having a main body portion defining a passageway, and a gas supply needle and an inhalation anesthetic supply needle, the tips of each said needle being disposed generally perpendicular relative to each other in said passageway,

jetting gas through said gas supply needle by means of a high frequency jet ventilator and introducing said gas into said main body portion of said vaporizer at a desired frequency,

infusing an inhalation anesthetic fluid through said inhalation anesthetic supply needle at a controlled flow rate,

causing airblast atomization to occur at the point of intersection of said gas from said gas supply needle and said fluid from said inhalation anesthetic supply needle, whereby said fluid is reduced to small fluid droplets, said airblast atomization being a result of the high velocity of said jetting of said gas producing a negative pressure which draws said inhalation anesthetic fluid out of said tip of said inhalation anesthetic supply needle, thereby entraining said fluid into the stream of gas in said passageway of said body portion of said vaporizer,

after said airblast atomization, immediately causing vaporization of said entrained anesthetic fluid in said passageway prior to the introduction of the resultant vaporized gas into the lungs of a patient, and

for said vaporization step, causing further contact of said jet of gas with said small droplets of said inhalation anesthetic such that a vaporized substance with only a gas phase containing molecules of said inhalation anesthetic exists in said passageway of said vaporizer with a controllable percentage of inspired anesthetic concentration, and causing said vaporized gas to flow freely along its path of travel through said passageway in said vaporizer without any obstructions and into the lungs of said patient.

23. The method of claim 22, including infusing said inhalation anesthetic through said inhalation anesthetic supply needle by means of an infusion pump means.

24. The method of claim 23, including employing enflurance as said inhalation anesthetic.

25. The method of claim 22, including measuring minute volume by means of respirometer means.

26. The method of claim 25, including evacuating expired gases by means of scavenging means.

27. The method of claim 22, including providing a reinspired gas tube for accessing expired gases into said passageway.

28. The method of claim 22, including providing 8 to 14-gauge needles as said gas supply needles and 18 to 22-gauge needles as said inhalation anesthetic supply needles.

29. The method of claim 28, including providing a 14-gauge needle as said gas supply needle and a 20-gauge needle as said inhalation anesthetic supply needle.

30. The method of claim 29, including employing a distance of about 0.3 to 1.0 mm between said needles.

31. The method of claim 30, including employing a distance of 0.6 mm between said needles.

32. The method of claim 31, including stabilizing said first and said second needles by means of stabilizing means.

33. The method of claim 22, including measuring the concentration of expired gases by means of mass spectrometer means.