Self-normed brain state monitoring

• US 4,545,388 A
• Filed: 06/09/1983
• Issued: 10/08/1985
• Est. Priority Date: 06/09/1983
• Status: Expired due to Fees

• Current Assignee: New York University
• Original Assignee: New York University
• Inventors: John, E. Roy
• Primary Examiner(s): Cohen, Lee S.
• Assistant Examiner(s): Sykes, Angela D.
• Application Number:
  US06/502,568
• Time in Patent Office: 852 Days
• Field of Search: 128/731-733
• US Class Current: 600/544
• CPC Class Codes: A61B 5/377 using evoked responses
• CPC Class Codes: A61B 5/4064 Evaluating the brain A61B5/031, A61B5/369, A61B5/14553 take precedence
• CPC Class Codes: A61B 5/4821 Determining level or depth of anaesthesia A61B5/1106 takes precedence

Abstract

Disclosed are a method and an apparatus for monitoring the brain state of a patient during a medical procedure relative to a self-norm established at an earlier time, when the patient is in a state selected for medical relevance to the planned procedure. To establish the pre-procedure self-norm, electrical measurements are taken of brain functions which are selected for medical relevance to the procedure, and are processed to produce, for each brain function of interest, a respective statistically and medically significant mean and variance. During the procedure, the same brain functions are electrically measured at each of a sequence of time intervals selected for medical relevance to the procedure. Each new set of measurements is tested for statistically amd medically significant change from the self-norm and, if a test shows such a change, a tangible indication is produced, showing not only that a change has occurred but also showing the ascribed medical significance of the change itself and the persistence of a change.

Claims

1. A machine-implemented method for monitoring the occurrence and ascribed medical significance of changes in a patient undergoing a medical procedure relative to a prior state of the patient at a time selected for medical relevance to the planned procedure after administration of anesthesia, comprising:

electrically measuring brain functions of the patient which are selected for medical relevance to a medical procedure which the patient is to undergo, at said time at which the patient is in a state selected for medical relevance to the procedure, said selected state being after administration of anesthesia;

processing the measurements to produce a self-norm comprising, for each brain function, a respective statistically and medically significant mean measurement and a respective statistically and medically significant standard deviation or variance measurement;

electrically measuring the same brain functions of the same patient during the said procedure, at each of a sequence of time intervals selected for medical relevance to the procedure;

testing each new set of measurements for statistically and medically significant change from the self-norm;

converting each significant change to a dimensionless probability of significant deviation and combining at least two of the said probabilities through vector addition into a single vector-form indication of said medically significant change; and

producing a tangible indication of the vector-form indication of the significant change, said tangible indication conveying information both as to the occurrence of a change and as to the ascribed medical significance of the change itself and the persistence of the change.

2. A method of monitoring the occurrence and ascribed medical significance of changes in a patient undergoing a medical procedure relative to a prior state of the patient at a time selected for medical relevance to the planned procedure, comprising the steps of:

selecting a patient state at a time after administration of anesthesia selected for medical relevance to a future medical procedure and electrically measuring brain functions of the patient which are also selected for medical relevance to the procedure;

processing the measurements to produce a self-norm comprising, for each brain function, a respective statistically significant mean measurement and a respective statistically significant standard deviation or variance measurement;

electrically measuring the same brain functions at each of a sequence of time interevals selected for medical relevance to the procedure, and testing each new set of measurements with respect to the self-norm to obtain significant changes;

converting each significant change to a dimensionless probability of significant deviation and combining at least two of the said probabilities through vector addition into a single vector-form indication of said medically significant change; and

in case said vector-form indicates the occurrence of a change which is statistically significant and has an ascribed medical significance, producing a tangible indication of the change and, if the test based on the measurements taken in the subsequent time interval indicates that a significant change persists, escalating the nature and ascribed medical significance of the change tangible indication, with each consecutive test which indicates persistence of the change, up to a selected escalated level, but if a new test indicates the absence of a significant change, de-escalating the tangible indication to the one level per test, to a lower level tangible indication of change or to a tangible indication of no change, as the case may be.