Methods and devices for providing a parameter that indicates a higher likelihood of a postoperative delirium occurring
The present disclosure relates to methods and devices for providing parameters that indicate a higher likelihood of a postoperative delirium occurring. According to an aspect of the present disclosure, the following steps are provided: detecting at least one EEG signal at the head of the patient; determining the average amplitude of the “direct current” EEG signal; checking whether an increase in the determined average amplitude when entering anesthetic-induced loss of consciousness is above a predefined amount, and in the event of this, providing a corresponding information in the form of a parameter that shows a higher likelihood of a postoperative delirium occurring.
1. A method for providing a parameter that indicates a heightened likelihood of postoperative delirium occurring, wherein the method comprises:
receiving at least one electroencephalography (EEG) signal from a patient over a period of time;
filtering the at least one EEG signal to produce at least one filtered EEG signal comprising a range of frequencies below a predefined frequency threshold;
determining a plurality of average amplitudes of the at least one filtered EEG signal over the period of time, wherein the plurality of average amplitudes comprises a first average amplitude at a first point in time within the period of time prior to an anesthesia-inducing loss of consciousness of the patient and a second average amplitude at a second point in time within the period of time when the patient enters the anesthesia-inducing loss of consciousness;
determining a difference value between the first average amplitude and the second average amplitude; and
providing the parameter that indicates the heightened likelihood of postoperative delirium occurring based on the difference value being greater than a predefined value.
2. The method of claim 1 , comprising determining a curve of the plurality of average amplitudes of the at least one filtered EEG signal over the period of time, wherein the difference value is determined based on the curve.
3. The method of claim 1 , wherein the predefined value is determined by:
averaging a first plurality of average amplitudes measured from a first plurality of patients who have not developed postoperative delirium at a first point in time when the first plurality of patients enters the anesthesia-inducing loss of consciousness to determine a first reference value,
averaging a second plurality of average amplitudes measured from a second plurality of patient who have developed postoperative delirium at a second point in time when the first plurality of patients enters the anesthesia-inducing loss of consciousness to generate a second reference value, and
determining a relationship between the first reference value and the second reference value.
4. The method of claim 3 , wherein the predefined value is determined based on a difference between the first reference value and the second reference value.
5. The method of claim 1 , wherein the predefined value is dependent on an age bracket of the patient.
6. The method of claim 1 , wherein the at least one EEG signal is received from a sensor in a Cz position of a 10-20 position system on a head of the patient.
7. The method of claim 1 , wherein the parameter is provided when the difference value exceeds a defined percentage deviation from the predefined value or a defined absolute difference between the first average amplitude and the second average amplitude.
8. The method of claim 1 , wherein the at least one filtered EEG signal is filtered through a low-pass filter.
9. The method of claim 8 , wherein the predefined frequency threshold comprises 0.5 Hertz (Hz) or 0.1 Hz.
10. A device for providing a parameter that indicates a heightened likelihood of postoperative delirium occurring, wherein the device comprises:
a sensor to receive at least one electroencephalography (EEG) signal from a patient over a period of time;
a filter to filter the at least one EEG signal to produce at least one filtered EEG signal comprising a range of frequencies below a predefined frequency threshold; and
a processor to:
determine a plurality of average amplitudes of the at least one filtered EEG signal over the period of time, wherein the plurality of average amplitudes comprises a first average amplitude at a first point in time within the period of time prior to an anesthesia-inducing loss of consciousness of the patient and a second average amplitude at a second point in time within the period of time when the patient enters the anesthesia-inducing loss of consciousness;
determine a difference value between the first average amplitude and the second average amplitude; and
provide the parameter that indicates the heightened likelihood of postoperative delirium occurring based on the difference value being greater than a predefined value.
11. The device of claim 10 , wherein the processor determines a curve based on the plurality of average amplitudes of the at least one filtered EEG signal over the period of time, wherein the second average amplitude corresponds with a peak in the curve.
12. The device of claim 10 , wherein the processor determines the predefined value by:
averaging a first plurality of average amplitudes measured from a first plurality of patients who have not developed postoperative delirium at a first point in time when the first plurality of patients enters the anesthesia-inducing loss of consciousness to determine a first reference value,
averaging a second plurality of average amplitudes measured from a second plurality of patient who have developed postoperative delirium at a second point in time when the first plurality of patients enters the anesthesia-inducing loss of consciousness to generate a second reference value, and
determining a difference between the first reference value and the second reference value.
13. The device of claim 10 , comprising a sensor to receive the at least one EEG signal, wherein the sensor is positioned on a head of the patient at a Cz position of a 10-20 position system.
14. The device of claim 13 , wherein the at least one EEG signal comprises a direct current EEG signal.
15. The device of claim 10 , wherein the filter comprises a low-pass filter with a frequency cutoff of 0.5 Hz or 0.1 Hz.