Monitoring subcortical responsiveness of a patient

• US 20060004296A1
• Filed: 06/30/2004
• Published: 01/05/2006
• Est. Priority Date: 06/30/2004
• Status: Active Grant

• Current Assignee: Instrumentarium Dental Incorporated (Envista Holdings Corporation)
• Original Assignee: Instrumentarium Dental Incorporated (Envista Holdings Corporation)
• Inventors: Huiku, Matti Veli, Korhonen, Iikka Kimmo
• Granted Patent: US 7,447,541 B2
• Time in Patent Office: Days
• US Class Current: 600/513
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/02405 Determining heart rate variability
• CPC Class Codes: A61B 5/0531 Measuring skin impedance
• CPC Class Codes: A61B 5/145 Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissuemeasuring of blood pressure or blood flow A61B5/02; non-radiation detecting or locating of foreign bodies in blood A61B5/06
• CPC Class Codes: A61B 5/352 Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
• CPC Class Codes: A61B 5/377 using evoked responses
• CPC Class Codes: A61B 5/383 Somatosensory stimuli, e.g. electric stimulation
• CPC Class Codes: A61B 5/389 Electromyography [EMG]
• CPC Class Codes: A61B 5/4035 Evaluating the autonomic nervous system
• CPC Class Codes: A61B 5/4821 Determining level or depth of anaesthesia A61B5/1106 takes precedence

Abstract

To monitor subcortical responsiveness of a patient at least one first measurement signal is acquired from a patient and at least one second measurement signal is derived from the at least one first measurement signal. The second measurement signal is indicative of pain-related activity in the patient. A predetermined stimulus signal is then supplied to the patient and a response caused by the stimulus signal in the at least one second measurement signal is monitored in synchronization with the supplying of the stimulus signal. Based on the monitoring step, an indicator of subcortical responsiveness is determined, the indicator being indicative of the patient'"'"'s level of antinociception.

Claims

1. A method for monitoring subcortical responsiveness of a patient, the method comprising the steps of:

acquiring at least one first measurement signal from a patient;

deriving at least one second measurement signal from the at least one first measurement signal, said at least one second measurement signal being indicative of pain-related activity in the patient;

supplying a predetermined stimulus signal to the patient;

monitoring a response caused by the stimulus signal in the at least one second measurement signal, wherein the monitoring step is synchronized with the supplying step; and

determining, based on the monitoring step, an indicator of subcortical responsiveness, said indicator being indicative of the patient'"'"'s level of antinociception.

2. A method according to claim 1, further comprising a step of synchronizing the supplying step with at least one of the at least one second measurement signal.

3. A method according to claim 1, further comprising a step of synchronizing the supplying step with an external synchronization signal.

4. A method according to claim 1, wherein the supplying step includes supplying a stimulus signal comprising a sequence of stimuli to the patient.

5. A method according to claim 4, further comprising a step of synchronizing the supplying step with a spontaneous rhythm regulated by the autonomous nervous system of the patient.

6. A method according to claim 5, wherein the synchronizing step includes synchronizing the supplying step with a respiration of the patient.

7. A method according to claim 1, wherein the acquiring step includes acquiring a single first measurement signal from the patient, whereby a single second measurement signal is obtained in the deriving step.

8. A method according to claim 7, wherein the acquiring step includes measuring a physiological signal from the patient, the physiological signal being one of the signals in a group including an RRI signal, a plethysmographic signal, an EMG signal, a blood pressure signal, and a signal representing skin conductivity.

9. A method according to claim 1, wherein the acquiring step includes a step of measuring a set of physiological signals from the patient.

10. A method according to claim 9, wherein the acquiring step further includes calculating the at least one first measurement signals based on the set of physiological signals.

11. A method according to claim 9, wherein the measuring step includes measuring at least two physiological signals from the patient, the at least two physiological signals belonging to a group including an RRI signal, a plethysmographic signal, an EMG signal, a blood pressure signal, and a signal representing skin conductivity.

12. A method according to claim 1, wherein

the acquiring steps includes a step of measuring a set of physiological signals from the patient;

and

the deriving step includes a step of calculating the at least one second measurement signal based on the set of physiological signals.

13. A method according to claim 12, wherein the measuring step includes measuring at least two physiological signals from the patient, the at least two physiological signals belonging to a group including an RRI signal, a plethysmographic signal, an EMG signal, a blood pressure signal, and a signal representing skin conductivity.

14. A method according to claim 12, wherein the calculating step includes calculating an index signal indicative of pain experienced by the patient.

15. A method according to claim 1, wherein

the monitoring step includes detecting changes caused by the stimulus signal in a plurality of second measurement signals;

and

the determining step includes a step of calculating the indicator of subcortical responsiveness based on the changes detected.

16. A method according to claim 4, wherein

the monitoring step includes detecting changes caused by each of said stimuli in the at least one second measurement signal;

and

the determining step includes defining the indicator of subcortical responsiveness based on the changes detected.

17. A method according to claim 1, wherein the deriving step includes filtering at least one of the at least one first measurement signal.

18. A method according to claim 1, wherein the deriving step includes deriving at least one second measurement signal being indicative of activity in the sympathetical branch of the autonomous nervous system of the patient.

19. An apparatus for monitoring the subcortical responsiveness of a patient, the apparatus comprising:

first means for acquiring at least one first measurement signal from a patient;

second means for deriving said at least one second measurement signal from the at least one first measurement signal, second measurement signal being indicative of pain-related activity in the patient;

stimulator means for supplying a predetermined stimulus signal to the patient;

third means for monitoring a response caused by the stimulus signal in the at least one second measurement signal, the third means being synchronized with the stimulator means; and

fourth means, responsive to the third means, for determining an indicator of subcortical responsiveness, said indicator being indicative of the patient'"'"'s level of antinociception.

20. An apparatus according to claim 19, further comprising means for synchronizing the stimulator means with a predetermined signal.

21. An apparatus according to claim 20, wherein the predetermined signal is indicative of a body function regulated by the autonomous nervous system of the patient.

22. An apparatus according to claim 19, wherein the stimulator means comprise control means for controlling the characteristics of the stimulus signal.

23. An apparatus according to claim 19, wherein the second means comprise filtering means for filtering the at least one first measurement signal.