| 摘要 |
<p>In a method of determining the quality of AEP signals, which are indicative of the level of consciousness of a patient, a signal to noise ratio SNR is calculated on the basis of calculation of a ratio of a signal AAIs to a signal AAIu, where the signal AAIs is calculated by averaging a number of N synchronised measured successive segments of samples in response to N audio stimulus, and where the signal AAIu is calculated by averaging a number of N unsynchronised measured successive segments of samples in response to the same N audio stimulus. In this way the quality of a measured AEP signal is provided. If the calculated value of the SNR is 1, or even lower, then the quality of the AEP is low. However, if the calculated value of the SNR is high, then a good quality of the AEP is obtained. In order to limit the amount of calculations necessary to obtain a high SNR and thereby a good AEP, a use of a circuit for carrying out the method is provided, said circuit having a controlled loop, inter alia comprising a PID regulator which, on the basis of a given calculated SNR value and a desired SNR value, can estimate to what degree calculations are needed in order to obtain a sufficiently high SNR and thereby a good quality of the AEP.</p> |
