Biomedical Engineering Reference
In-Depth Information
2
9
16
0.25
7.25
14.25
21.25
28.25
f
1
(a)
f
1
f
2
(b)
f
1
f
2
(c)
Figure 9.8
(a) Two-dimensional plot of bispectrum
B
(
f
1
,
f
2
); (b) three-dimensional perspective illus-
tration of bispectrum
B
(
f
1
,
f
2
); and (c) three-dimensional illustration of the bicoherence
BIC
(
f
1
,
f
2
).
cal data to synthesize a combination that, by design, correlates behavioral assess-
ments of sedation and hypnosis yet is insensitive to the specific anesthetic or sedative
agents chosen. Further, devices that implement BIS are the only ones currently
approved by the Food and Drug Administration for marketing claims to reduce the
incidence of unintended postoperative recall.
The particular (proprietary) mixture of subparameters in BIS version 3 was
derived empirically [6, 61] from a prospectively collected database of EEG and
behavioral scales representing approximately 1,500 anesthetic administrations and
5,000 hours of recordings that employed a variety of anesthetic protocols. BIS was
then tested prospectively in other populations and the process iterated. At present,
the commercial device incorporates the fourth major revision of the index.
The calculation of the BIS (Figure 9.9) begins with a sampled EEG that is filtered
to exclude both high- and low-frequency artifacts and divided into epochs of 2-sec-
Search WWH ::
Custom Search