Method and apparatus for determining an indicator of autonomic nervous system state

An apparatus for determining an indicator of the level of nociception of a subject, the apparatus comprising:

• a parameter unit configured to generate a parameter indicative of sympathetic activation in a subject;
• a monitoring unit configured to monitor changes in the parameter, thereby to detect a stable state of the parameter;
• a scaling unit configured to define a subject-specific scaling transformation intended to transform the parameter to an index on a predetermined index scale, wherein the scaling unit is configured to make the scaling transformation dependent on at least one value detected for the parameter in connection with detection of the stable state, and wherein the index serves as the indicator of the level of nociception;
• an index determination unit configured to apply the scaling transformation to subsequent values of the parameter, thereby to transform the subsequent values to index values indicative of the level of nociception.

A computer program product for determining an indicator of the level of nociception of a subject, the computer program product comprising:

• a first program product portion configured to generate a parameter indicative of sympathetic activation in a subject;
• a second program product portion configured to monitor changes in the parameter, thereby to detect a stable state of the parameter;
• and
• a third program product portion configured to define a subject-specific scaling transformation intended to transform the parameter to an index on a predetermined index scale, wherein the third program product portion is configured to make the scaling transformation dependent on at least one value detected for the parameter in connection with detection of the stable state, and wherein the index serves as the indicator of the level of nociception;
• and
• a fourth program product portion configured to apply the scaling transformation to subsequent values of the parameter, thereby to transform the subsequent values to index values indicative of the level of nociception.