Cardioplegia temperature indicator

• US 4,509,532 A
• Filed: 07/29/1982
• Issued: 04/09/1985
• Est. Priority Date: 07/29/1982
• Status: Expired due to Fees

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: DLM Incorporated (Medtronic Plc)
• Inventors: DeVries, James H.
• Primary Examiner(s): Cohen, Lee S.
• Assistant Examiner(s): Sykes, Angela D.
• Application Number:
  US06/403,124
• Time in Patent Office: 985 Days
• Field of Search: 128/736, 374/162, 374/163-164
• US Class Current: 600/549
• CPC Class Codes: G01K 1/18 for reducing thermal inertia
• CPC Class Codes: G01K 11/165 of organic liquid crystals
• CPC Class Codes: G01K 13/20 Clinical contact thermometers for use with humans or animals

Abstract

For use in monitoring the temperature of a heart during open heart surgery involving a cardioplegia system, the invention comprises a housing and mount for a temperature responsive liquid crystal chip or small panel which provides a visual temperature reading in various selected ranges. The housing includes an insulating shell enclosing a heat sink sheet associated with a highly conductive mounting pin which penetrates the wall of the heart and conducts the heart temperature to the heat sink underlying the liquid crystal panel.

Claims

1. A visual temperature monitor for use in open heart surgery and adapted to be used in connection with cardioplegia systems for reducing the temperature of the heart which comprises:

(a) a double walled housing providing between the walls a relatively thin chamber, one of the walls of said housing being transparent,

(b) a thin temperature sensitive liquid crystal chip disposed in said chamber and exposed to said transparent wall,

(c) a heat sink plate lying against said chip on a side of said chip opposite said transparent wall, and

(d) a heat transfer pin having a tapering shank projecting from said housing for removable insertion into heart tissue and having an end within said housing in heat conductive contact with said heat sink plate.

2. A temperature monitor as defined in claim 1 in which said housing comprises a transparent panel having a side flange, and a closing panel having edges confined within said side flange.

3. A temperature monitor as defined in claim 2 in which a layer of transparent material is lodged between said liquid crystal chip and said transparent panel.

4. A temperature monitor as defined in claim 2 in which the edges of said closing panel are lodged in a reentrant groove on said side flange.

5. A temperature monitor as defined in claim 1 in which said heat sink plate is formed with a depression and said pin has an enlarged head at said end lodged in said depression between said plate and said chip, the shank of said pin projecting through said heat sink plate and through a wall of said housing.

6. The monitor set forth in claim 5 wherein said housing is of generally flat planar construction, with said shank projecting orthogonally of the plane of said housing, and with said transparent wall being oriented oppositely of said shank.

7. A disposable monitor for visual indication of heart temperature during heart surgery accompanied by cardioplegia administration, said monitor comprising:

a housing having a transparent wall,

temperature sensitive display means disposed within said housing so as to be visible through said transparent housing wall, and

a pin of heat conductive construction having a tapering shank projecting from said housing for removable piercing insertion into heart tissue and a head disposed within said housing in heat transfer communication with said temperature sensitive display means.

8. The monitor set forth in claim 7 wherein said housing is of generally flat planar construction, with said shank projecting orthogonally of the plane of said housing, and with said transparent wall being oriented oppositely of said shank.

9. The monitor set forth in claim 7 further comprising means on said housing for removably suturing said housing to a heart with said shank inserted into heart tissue and said transparent wall facing outwardly of the heart.

10. A disposable monitor for visual indication of heart temperature during heart surgery accompanied by cardioplegia administration, said monitor comprising

a generally flat housing of plastic construction having a transparent wall facing orthogonally of said housing,

temperature sensitive digital liquid crystal display means disposed within said housing so as to be visible through said transparent wall,

a pin of heat conductive construction having a shank which projects and tapers narrowingly orthogonally of said housing oppositely of said transparent wall for piercing insertion into heart tissue, one end of said pin being disposed within said housing, and

means within said housing coupling said one end of said pin in heat transfer contact with said temperature sensitive liquid crystal display means.

11. The monitor set forth in claim 10 further comprising means on said housing for removably suturing said housing to a heart with said shank inserted into heart tissue and said transparent wall facing outwardly of the heart.