Method and Apparatus Based on Combination of Physiological Parameters for Assessment of Analgesia During Anesthesia or Sedation

• US 20080167540A1
• Filed: 03/20/2008
• Published: 07/10/2008
• Est. Priority Date: 07/07/2003
• Status: Active Grant

• Current Assignee: Instrumentarium Dental Incorporated (Envista Holdings Corporation)
• Original Assignee: Instrumentarium Dental Incorporated (Envista Holdings Corporation)
• Inventors: Paloheimo, Markku, Van Gils, Marcus Johannis, Huiku, Matti Veli Tapani, Yli-Hankala, Arvi, Korhonen, Ilkka
• Granted Patent: US 8,463,370 B2
• Time in Patent Office: Days
• US Class Current: 600/301
• CPC Class Codes: A61B 2505/05 Surgical care
• 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 5/412 Detecting or monitoring sepsis
• CPC Class Codes: A61B 5/4821 Determining level or depth of anaesthesia A61B5/1106 takes precedence

Abstract

The invention relates to a method for monitoring a condition of a patient under anesthesia or sedation, whereupon one, two, three or more signals are acquired, and the signal(s) represent(s) cardiovascular and/or combined electrical biopotential on skull activity of the patient. From said signal or signals are derived or calculated at least two parameter values related to a quantity like waveform amplitude, waveform periodicity, waveform morphology, waveform variability, energy, power, signal complexity and frequency content. A predetermined mathematical index for probability of patient comfort is used, in which function said parameters are variables, and successively changing probability index values of said mathematical index is calculated.

Claims

1-22. -22. (canceled)

23. A method for monitoring a condition of a patient under anesthesia or sedation, the method comprising the steps of:

acquiring at least a first signal and a third signal representing a cardiovascular and respectively a combined electrical biopotential on skull activity of the patient;

—

deriving, from said first signal, at least a first parameter value;

calculating, from said third signal, at least a fourth parameter value;

applying a predetermined mathematical index for probability of patient comfort, in which index said at least first and fourth parameters are variables;

calculating successively changing values of said mathematical index; and

indicating said successive index values.

24. A method according to claim 23, wherein at least first parameter value is related to a quantity selected from a group of quantities including waveform amplitude, waveform periodicity, waveform morphology, and waveform variability.

25. A method according to claim 23, wherein said at least fourth parameter value related to a quantity selected from a group of quantities including energy, power, signal complexity and frequency content, each over a predetermined time period.

26. A method according to claim 23, wherein said first signal concerning cardiovascular activity is a blood volume signal measured non-invasively using photoplethysmography.

27. A method according to claim 26, wherein:

the quantity for said first parameter value is a pulse wave amplitude, or a dicrotic notch height in the pulse wave;

and the quantity for said second parameter value is a pulse rate, or a heart beat interval, or a temporal position of the dicrotic notch.

28. A method according to claim 23, wherein said third signal is a non-invasive measurement concerning neuromuscular and brain activity.

29. A method according to claim 28, wherein said neuromuscular and brain activity measurement comprises electromyography and electroencephalogram.

30. A method according to claim 29, further comprising the step of extracting electric myographic component from said third signal as an EMG partial signal, and electroencephalographic component as an EEG partial signal.

31. A method according to claim 30, wherein the quantity for said fourth parameter value is a spectral power calculated from said EMG partial signal.

32. A method according to claim 29, wherein the quantity for said fourth parameter value is a subtraction of a response entropy, calculated from said third signal as a whole, and a state entropy, calculated from said EEG partial signal.

33. A method according to claim 23, wherein said first signal concerning cardiovascular activity is a cardiac excitation measured non-invasively using electrocardiogram.

34. A method according to claim 33, wherein the quantity for said first parameter value is a heart rate or inter beat interval of the electrical excitation.

35. A method according to claim 23, further comprising the steps of:

acquiring online a second signal representing a cardiovascular activity of the patient;

deriving, from said and second signal, a third parameter value related to a quantity selected from a group of quantities including waveform amplitudes, waveform periodicity, waveform morphology, and waveform variability; and

introducing said at least third parameter in said predetermined mathematical index as an additional variable.

36. A method according to claim 35, wherein the quantity for said first parameter value is a heart rate or inter beat interval of the electrical excitation.

37. A method according to claim 23, wherein said mathematical index for probability is a nonlinear equation.

38. A method according to claim 23, wherein said mathematical index for probability is a neural network algorithm.

39. A method according to claim 23, wherein said mathematical index for probability is based on a defined or fuzzy rule-based reasoning procedure.

40. A method according to claim 23, further comprising the step of normalizing said first and fourth parameter values on the basis their respective parameter values acquired over a predetermined fixed time window including or excluding the latest real-time parameter value.

41. A method according to claim 40, wherein said normalized parameter values are acquired from:

said patient prior to incision, or prior to intubation, or prior to starting anesthesia or sedation, or

group of patients prior to or during incision and/or intubation and/or anesthesia or sedation.

42-53. -53. (canceled)