Sensory monitoring apparatus and method

• US 4,570,640 A
• Filed: 04/16/1984
• Issued: 02/18/1986
• Est. Priority Date: 08/06/1981
• Status: Expired due to Fees

• Current Assignee: Staodynamics, Inc.
• Original Assignee: Staodynamics, Inc.
• Inventors: Barsa, John E.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US06/601,001
• Time in Patent Office: 673 Days
• Field of Search: 128/419 R, 128/421, 128/422, 128/423 R, 128/731, 128/734, 128/741
• US Class Current: 600/554
• CPC Class Codes: A61B 2505/05 Surgical care
• CPC Class Codes: A61B 2562/043 in a linear array
• CPC Class Codes: A61B 5/1106 to assess neuromuscular blockade, e.g. to estimate depth of anaesthesia
• CPC Class Codes: A61B 5/4035 Evaluating the autonomic nervous system
• CPC Class Codes: A61B 5/4041 Evaluating nerves condition
• CPC Class Codes: A61B 5/4047 afferent nerves, i.e. nerves that relay impulses to the central nervous system
• CPC Class Codes: A61B 5/411 Detecting or monitoring allergy or intolerance reactions to an allergenic agent or substance
• CPC Class Codes: A61B 5/4519 Muscles A61B5/389, A61B5/224 take precedence
• CPC Class Codes: A61B 5/4821 Determining level or depth of anaesthesia A61B5/1106 takes precedence
• CPC Class Codes: A61B 5/6823 Trunk, e.g., chest, back, abdomen, hip
• CPC Class Codes: A61N 1/36021 for treatment of pain

Abstract

Apparatus and method for monitoring the sensory system of a patient to enable determination of the level and depth of spinal and epidural nerve blocks, including those induced by anesthetics administered to a patient, which blocks affect the sympathetic and motor nervous systems. The anesthesia level is sequentially and repeatedly scanned at a plurality of spaced points to provide a continuous determination of the extent and depth of superficial and deep sensation and sympathetic and motor integrity. The electronic apparatus includes a stimulator that provides selective stimulation to each element of a multiple element transmitting unit the elements of which are non-invasively positioned contiguous to the skin of a patient, and a physiological response detector to detect patent responses to stimulation sensed by the elements of a multiple element sensing unit the elements of which are also non-invasively positioned contiguous to the skin of the patient. A multiple display is provided to facilitate monitoring, and an indication and/or termination of stimulation signal is provided whenever stimulation exceeds a reference level. The system and method are also shown to be usable for automatically controlling delivery of an anesthesic to a patient.

Claims

1. An apparatus for determining sensory system pathway blocks related to preselected areas of the body of a patient by stimulating predetermined anatomical skin areas, said apparatus comprising:

a stimulating and sensing unit including stimulating means for stimulating peripheral receptors at said predetermined anatomical skin areas to thereby stimulate segmental associated pathways at the input side of the central nervous system so that the central nervous system can receive said stimulation from said peripheral receptors through unblocked ones of said segmental associated pathways and can receive no said stimulation from said peripheral receptors through blocked ones of said segmental associated pathways, said stimulating and sensing means also including sensing means receiving responses from the output side of the central nervous system, and said stimulating and sensing means having a plurality of elements and positioning means for adapting said elements to be positioned contiguous to the body of a patient along said predetermined anatomical skin areas so that, upon actuation of said stimulating means, a response can be detected at said sensing means, with respect to said unblocked ones of said segmental associated pathways, indicative of at least one predetermined physiological characteristic of said preselected areas of the body of the patient;

means for activating said stimulating means of said stimulating and sensing means;

response processing means connected with said sensing means of said stimulating and sensing means for receiving said responses from said sensing means and providing an output indicative of the interruption pattern at said preselected areas of the body of the patient as determined by said sensed blocked and unblocked pathways; and

utilization means for receiving said output indicative of said interruption pattern from said response processing means and responsive thereto forming an indication thereof.

2. The apparatus of claim 1 wherein said plurality of elements are electrodes.

3. The apparatus of claim 2 wherein said positioning means non-invasively positions said electrodes contiguous to the body of a patient.

4. The apparatus of claim 1 wherein said stimulating and sensing means includes element selecting means for determining which of said plurality of elements is activated.

5. The apparatus of claim 4 wherein said activating means includes means for causing sequential activation of said plurality of elements.

6. The apparatus of claim 1 wherein said response processing means includes physiological response detecting means.

7. The apparatus of claim 1 wherein said utilization means includes display means connected with said response processing means for, displaying said output indicative of said interruption pattern.

8. An apparatus for determining sensory system pathway blocks, said apparatus comprising:

stimulating means having a plurality of elements and positioning means for adapting said elements to be positioned along predetermined anatomical skin areas of the body of a patient for stimulating peripheral receptors connected with segmental associated pathways of the input sensory system of the body of the patient when activated, said pathways of said input sensory system being connected with the central nervous system so that stimulation of said peripheral receptors causes stimulation of said central nervous system through unblocked ones of said segmental associated pathways with no stimulation of said central nervous system being caused through blocked ones of said segmental associated pathways;

element selecting means connected with said stimulating means for determining the selection of said plurality of elements to be activated;

sensing means having a portion to be positioned along said predetermined anatomical skin areas of the body of a patient for sensing a preselected physiological characteristic with respect to said unblocked ones of said segmental associated pathways responsive to stimulating of such a patient by said stimulating means, said sensing means including positioning means for adapting said portion to be positioned along said predetermined anatomical skin areas of the body of a patient;

physiological response detecting means connected with said sensing means for detecting said response sensed by said sensing means and providing an output indicative of the interruption pattern as determined by said sensed blocked and unblocked pathways; and

utilization means for receiving said output from said physiological response detecting means and responsive thereto forming an indication of said interruption pattern.

9. The apparatus of claim 8 wherein said plurality of elements are electrodes, and wherein said stimulating means includes electronic means for stimulating the body of a patient through said electrodes.

10. The apparatus of claim 9 wherein said element selecting means includes automatic sequencing means for causing sequential activation of said electrodes.

11. The apparatus of claim 9 wherein said element selecting means includes manual means for activating said electrodes.

12. The apparatus of claim 8 wherein said element selecting means includes stimulator control means, pulse stimulating means controlled by said stimulator control means, element selector means, and element selector control means connected with said element selector means and said stimulator control means.

13. The apparatus of claim 8 wherein said sensing means are electrodes.

14. The apparatus of claim 8 wherein said utilization means includes display means connected with said physiological response detecting means for displaying said output therefrom indicative of said detected physiological responses.

15. The apparatus of claim 8 wherein said apparatus includes means for automatically terminating stimulation of said plurality of elements.

16. The apparatus of claim 15 wherein said stimulation terminating means includes reference means and comparator means connected with said reference means, said physiological response detecting means and said element selecting means, said comparator means comparing the outputs from said reference means and said physiological response means and terminating operation of said element selecting means when said output from said physiological reference means exceeds said output from said reference means.

17. The apparatus of claim 16 wherein said apparatus includes display means for indicating said termination of stimulation.

18. A method for determining sensory system pathway blocks at preselected areas of the body of a patient, said method comprising;

electrically stimulating peripheral receptors to thereby stimulate segmental associated pathways at the input side of the sensory system of the body of a patient leading to the central nervous system so that the central nervous system can receive said stimulation from said peripheral receptors through unblocked ones of said segmental associated pathways and can receive no said stimulation from said peripheral receptors through unblocked ones of said segmental associated pathways;

receiving responses from the output side of the central nervous system of the body of the patient with respect to unblocked ones of said segmental associated pathways that are indicative of a predetermined physiological characteristic of said preselected areas of the body of the patient; and

determining from said sensed blocked and unblocked pathways the interruption pattern of pathway blocks at said preselected areas of the body of the patient.

19. The method of claim 18 wherein said step of stimulating peripheral receptors of the body of the patient includes sequentially and repeatedly stimulating said peripheral receptors of the body of the patient.

20. The method of claim 19 wherein said method includes progressively applying increasing levels of stimulation to said predetermined areas of the body of the patient.

21. The method of claim 19 wherein said method includes terminating sequential stimulation of said predetermined areas when a predetermined condition is sensed.

22. The method of claim 21 wherein said method includes comparing the received response with a reference to sense said predetermined condition.

23. The method of claim 18 wherein said method includes displaying an indication of said interruption pattern after determination of the same.

24. A method for continuously determining the extent of sensory and sympathetic blocks in the sensory system of the body of a patient, said method comprising:

sequentially and repeatedly stimulating peripheral receptors to thereby stimulate segmental associated pathways at the input side of the sensory system of the body of a patient leading to the central nervous system so that the central nervous system can receive said stimulation from said peripheral receptors through unblocked ones of said segmental associated pathways and can receive no said stimulation from said peripheral receptors through blocked ones of said segmental associated pathways;

monitoring the sensory system of the patient to sense responses with respect to unblocked ones of said segmental associated pathways that are indicative of at least one predetermined physiological characteristic to thereto provide an interruption pattern;

establishing a reference pattern for correlating said received response to said interruption pattern;

comparing said interruption pattern with said reference pattern to thereby continuously determine the extent of sensory and sympathetic blocks sensed to exist in the body of the patient; and

utilizing said continuous determination to indicate the extent of sensory and sympathetic blocks.

25. The method of claim 24 wherein said method includes progressively increasing the level of stimulation at each of said predetermined areas.

26. The method of claim 24 wherein said step of monitoring the sensory system of the patient includes monitoring predetermined dermatomal sites of the body of the patient.

27. The method of claim 26 wherein said step of monitoring the sensory system of the patient includes selecting sensors capable of sensing at least phychogalvanic skin responses, and utilizing said sensors to sense at least phychogalvanic skin responses in response to said electrical stimulation of said predetermined dermatomal sites.

28. The method of claim 24 wherein said step of monitoring the sensory system of the patient includes sensing responses indicative of spinal and epidural nerve blocks as said predetermined physiological characteristic, and wherein said step of comparing includes determining the extent of spinal and epidural nerve blocks affecting the sympathetic and motor nervous system of the patient.

29. The method of claim 24 wherein said step of monitoring the sensory system of a patient includes sensing responses indicative of administered regional anesthetics as said predetermined physiological characteristic, and wherein said step of comparing includes determining the extent of regional anesthesia administered to a patient during surgery.

30. The method of claim 29 wherein said method includes providing an anesthetic administering means for administering anesthetics to a patient, and utilizing said determined extent of anesthesia of a patient to regulate the level and depth of anesthetic administered the patient.