Method and apparatus for judging a depth of anesthesia

• US 5,906,208 A
• Filed: 04/04/1997
• Issued: 05/25/1999
• Est. Priority Date: 04/05/1996
• Status: Expired due to Fees

• Current Assignee: Nihon Kohden Corporation
• Original Assignee: Nihon Kohden Corporation
• Inventors: Ishikawa, Norio, Ono, Kohei, Nakaichi, Katsumi, Hosaka, Hidehiro, Suda, Shin, Ochiai, Ryoichi
• Primary Examiner(s): Yu, Mickey
• Assistant Examiner(s): Nguyen, Dinh X.
• Application Number:
  US08/832,797
• Time in Patent Office: 781 Days
• Field of Search: 600/300, 600/306, 600/301, 600/547, 600/544, 128/200.24, 128/897, 128/898
• US Class Current: 128/898
• CPC Class Codes: A61B 5/0531 Measuring skin impedance
• CPC Class Codes: A61B 5/1106 to assess neuromuscular blockade, e.g. to estimate depth of anaesthesia
• CPC Class Codes: A61B 5/2415 Measuring direct current [DC] or slowly varying biopotentials
• CPC Class Codes: A61B 5/4821 Determining level or depth of anaesthesia A61B5/1106 takes precedence
• CPC Class Codes: A61B 5/6824 Arm or wrist

Abstract

The apparatus has: electrodes (E₁ to E₆) which are to be attached to a predetermined region of a living body; a skin potential measuring unit (1) which detects the skin potential from the electrodes; a judging unit (3) which detects and stores the skin potential before administration of an anesthetic agent, which detects and stores that after administration of the anesthetic agent, which sets a threshold to be an arbitrary level, on the basis of a change from the stored skin potential before administration of the anesthetic agent to the stored skin potential after administration of the anesthetic agent, and which compares the time-varying skin potential with the threshold, thereby judging the depth of anesthesia; and an alarm unit (6) which raises an alarm in accordance with instructions from the judging unit.

Claims

1. A method of judging a depth of anesthesia comprising:

detecting a pre-anesthesia skin potential from a predetermined region of a living body before administration of an anesthetic agent;

detecting a post-anesthesia skin potential after administration of the anesthetic agent;

setting a threshold level on the basis of at least said pre-anesthesia skin potential;

judging said depth of anesthesia by comparing said post-anesthesia skin potential levels with said threshold level; and

activating an alarm on the basis of a result of said judging step.

3. The method according to claim 1, wherein said step of detecting said post-anesthesia skin potential comprises detecting said post-anesthesia skin potential from said predetermined region of the living body after administration of the said anesthetic agent;

wherein said step of setting said threshold level comprises setting said threshold level on the basis of a change from said pre-anesthesia skin potential to said post-anesthesia skin potential after administration of said anesthetic agent; and

wherein said step of judging said depth of anesthesia comprises judging said depth of anesthesia by comparing subsequent post-anesthesia skin potential levels with said threshold level.

4. The method according to claim 1, wherein said predetermined region of the living body comprises at least one of a palm of a hand, a position at least proximate to a wrist, a position at least proximate to an ankle, and soles of feet.

2. An apparatus for judging a depth of anesthesia, comprising an electrode to be attached to a predetermined region of a living body;

a skin potential measuring unit for detecting a skin potential from said electrode;

a judging unit for detecting a pre-anesthesia skin potential before administration of an anesthetic agent, for detecting a post-anesthesia skin potential after administration of the anesthetic agent, for setting a threshold level on the basis of at least said pre-anesthesia skin potential, and for judging said depth of anesthesia by comparing said post-anesthesia skin potential levels with said threshold level and

an alarm unit for activating an alarm in accordance with an output signal from said judging unit.

5. The apparatus according to claim 2, wherein said judging unit sets said threshold level on the basis of a change from said pre-anesthesia skin potential to said post-anesthesia skin potential after administration of the anesthetic agent, and judges said depth of anesthesia by comparing subsequent post-anesthesia skin potential levels with said threshold level.