Auditory evoked potentials

Plourde · Best Practice & Research Clinical Anaesthesiology · 2006 · anaesthesiology · 10.1016/j.bpa.2005.07.012 · record Plourde2006-auditory-evoked-potentials
tag layer · index · concepts · authors · עברית
Where this record's text came from. faceted 2026-08 by reading the locally held text (pdftext); every evidence string verified as an exact substring of that text before merging. Extracted from PDF text, so a few sentences in the source are garbled by column interleaving (e.g. the 'Applicability multi-drug regimen' sentence and 'Transient responses fast (6-10 millisecond)...are classified according to their latency'); the limitation quote is copied exactly as the source renders it, including the trailing reference number. Claim type is method because the chapter's payload is the case for AEP monitoring as a way of assessing level of consciousness, not a new empirical result; the author does report his own physostigmine experiments as supporting evidence but they are described, not newly analysed here. 2026-08-14 schema-0.3 pass: every quote verified as an exact substring of the staged text and anchored at merge time; concept terms verified present; every edge endpoint an existing node.
This record’s own method is review, and the tags below follow from that. A review’s findings, quantities and statistics are things stated IN this paper, and some of them report results obtained elsewhere. No tag on this page names a different author. Measured across every review in this corpus, 81% of a review’s tags carry no citation at all — most of them are the review speaking. The corpus does not adjudicate the rest: read an unmarked tag as a claim this paper makes, not necessarily one it made first.
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Tags on this paper

Every tag the record carries, each linking to every other paper in the corpus that carries it. A tag appears here whether or not its words occur in the article — the spans below are only the ones a sentence in this paper licenses. Of the 3 concept tags on this paper, all 3 are grounded in a quoted sentence.
40 Hz ASSR level of consciousness auditory middle latency response at ~40 stimuli per second each new stimulus arrives during wave Pa of the preceding response, so successive middle-latency responses overlap and progressively build up into the steady-state response the 40 Hz ASSR is generated partly by anesthetic-sensitive synchronization of naturally occurring neuronal rhythms, and/or anesthetics disrupt the superimposition process by non-uniformly changing the refractory periods of AMLR components general anesthetics abolish consciousness by interfering with thalamocortical 40 Hz rhythms, which is why the 40 Hz response and consciousness disappear together auditory evoked potential transient AEP steady-state AEP 40 Hz auditory steady-state response (40 Hz ASSR) auditory middle latency response (AMLR) coherent frequency (CF) unintentional awareness AAI concentration of the anesthetic 40 Hz ASSR amplitude statistical significance test statistically significant mean (signal averaging across trials) review

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relation to other workclaim_relationshow this paper stands to another: agrees, contradicts, extends, qualifies
claim typeclaim_typethe shape of the claim: existence, mechanism, method, critique, prediction, null
concept edgeconcept_edgesan asserted relation between two concepts, with the sentence asserting it
conceptconceptsan idea the paper works with, quoted where the paper uses it
content tagcontent_tagsa finding, definition, quantity, statistic or variable named in the paper
limitationlimitationswhat the paper says its evidence cannot support
mechanismmechanismshow the reported effect is said to come about
methodmethodhow the paper produced its evidence
phenomenonphenomenonthe effect or regularity under study
sensesensesa distinct use of a term, quoted where the paper fixes it

The paper

The full text is not reproduced here. This article is not cleared for redistribution, so the page carries the tag layer only. Its evidence sentences are withheld; the grounding status remains with each tag, and the article itself is at https://doi.org/10.1016/j.bpa.2005.07.012. The reading view exists for the papers whose licence permits it.

Every tag on this page

claim_relations 2 · claim_type 1 · concept_edges 1 · concepts 3 · content_tags 26 · limitations 7 · mechanisms 3 · method 1 · phenomenon 1 · senses 2

Relations on this page carry a quotation for the claim. Where a relation was separately evidenced — and so tested against the vocabulary for its type — the row says so; none of 1 relation here carry that mark. The rest are the tagger’s reading of the sentence quoted beside them.

This record holds no controls. A layer is empty when the tagger recorded nothing in it — which is not the same as the paper having nothing to record.

facettagfieldconf.whose words
claim_typemethod
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claim_typethe paper's words
phenomenonauditory evoked potentials as a measure of anaesthetic depth
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phenomenonthe paper's words
methodreview
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also in: review
methodthe paper's words
mechanismsmechanisms
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mechanisms[0]the tagger's words
mechanismsmechanisms
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mechanisms[1]the tagger's words
mechanismsmechanisms
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mechanisms[2]the tagger's words
limitationsScope restricted to human studies for reasons of space
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what this limits: the scope of the review: BECAUSE OF SPACE CONSTRAINTS, THIS REVIEW WILL BE LIMITED TO HUMAN STUDIES
limitations[0]the tagger's words
limitationsThe association between ASSR attenuation and loss of consciousness is correlational, not demonstrated to be functional
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what this limits: any use of the 40 Hz ASSR as a consciousness monitor: THESE OBSERVATIONS SUGGEST BUT DO NOT PROVE THAT THERE IS FUNCTIONAL RELATIONSHIP BETWEEN THE ATTENUATION OF THE 40 HZ ASSR AND LOSS OF CONSCIOUSNESS
limitations[1]the tagger's words
limitationsApplicability to real-world multi-drug anaesthetic regimens is untested
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what this limits: clinical application specifically: APPLICABILITY [to the] MULTI-DRUG REGIMEN COMMONLY SEEN IN CLINICAL PRACTICE REMAINS TO BE ASSESSED
limitations[2]the tagger's words
limitationsWhether ASSR parameters other than amplitude could support titration has not been examined
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what this limits: the amplitude measure only: whether ASSR parameters other than amplitude could support titration has not been examined
limitations[3]the tagger's words
limitationsThe monitor and the patient's state may both be effects of the drug rather than related to each other, and the review says so of its own subject.
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what this limits: a 40 Hz ASSR or AMLR reading used to infer that a patient is unconscious: the review states both the response and the loss of consciousness could be effects of the anaesthetic that are otherwise functionally independent
limitations[4]1.0the tagger's words
limitationsThe supporting evidence is explicitly said to fall short of proof.
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what this limits: the claim that attenuation of the 40 Hz ASSR indicates loss of consciousness: the review states the observations suggest but do not prove a functional relationship
limitations[5]1.0the tagger's words
limitationsWhole components of the response are excluded from clinical use for being TOO sensitive, so the monitored signal is selected for stability rather than for sensitivity.
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what this limits: the auditory evoked potentials used in anaesthetic monitoring: slow and late responses are excluded as too sensitive to anaesthetic effect for routine clinical monitoring
limitations[6]1.0the tagger's words
concepts40 Hz ASSR
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also in: 40 Hz ASSR
concepts[0]the paper's words
conceptslevel of consciousness
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concepts[1]the paper's words
conceptsauditory middle latency response
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concepts[2]the paper's words
senses40 Hz ASSR as an index of consciousness - AS CORRELATION: a fairly reliable measure of the level of consciousness, on evidence the review calls suggestive but not probative
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senses[0]1.0the tagger's words
senses40 Hz ASSR as an index of consciousness - AS TESTED BY DISSOCIATION: consciousness was restored with the anaesthetic concentration held constant, and the response returned to awake baseline
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senses[1]1.0the tagger's words
claim_relationscontradicts → Pockett et al.3
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claim_relations[0]the tagger's words
claim_relationscontradicts → Galambos et al.42 (the 40 Hz ASSR as superimposition of the AMLR)
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claim_relations[1]the tagger's words
concept_edgeslevel of consciousness —operationalised-as→ 40 Hz ASSR
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strength of the relation: 1
concept_edges[0]the tagger's words
content_tagsstatistical significance test
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content_tags.statistics[0]the tagger's words
content_tagsmean (signal averaging across trials)
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content_tags.statistics[1]the tagger's words
content_tagsMost volatile and intravenous general anesthetics lengthen the latency and reduce the amplitude of the auditory middle latency response, and do so in proportion to concentration.
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content_tags.findings[0]the tagger's words
content_tagsNitrous oxide and ketamine leave the main AMLR components unchanged even at concentrations that produce unconsciousness.
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content_tags.findings[1]the tagger's words
content_tagsUnlike other anesthetics, ketamine increased the amplitude of the 40 Hz steady-state response.
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content_tags.findings[2]the tagger's words
content_tagsReversing anesthetic hypnosis with physostigmine raises the 40 Hz ASSR in proportion to the behavioural reversal, so ASSR attenuation seems to reflect impaired consciousness.
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content_tags.findings[3]the tagger's words
content_tagsUnder enflurane/N2O the 40 Hz ASSR was attenuated far more than the accompanying AMLR changes predicted.
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content_tags.findings[4]the tagger's words
content_tagsThe 40 Hz ASSR amplitude does not appear useful for titrating anesthetic dose, because it is already markedly reduced at loss of consciousness.
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content_tags.findings[5]the tagger's words
content_tagsThe AMLR is suggested to reflect the balance between anesthetic suppression and brain activation caused by noxious stimulation.
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content_tags.findings[6]the tagger's words
content_tagsauditory evoked potential
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content_tags.definitions[0]the tagger's words
content_tagstransient AEP
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also in: transient AEP
content_tags.definitions[1]the tagger's words
content_tagssteady-state AEP
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content_tags.definitions[2]the tagger's words
content_tags40 Hz auditory steady-state response (40 Hz ASSR)
Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.
content_tags.definitions[3]the tagger's words
content_tagsauditory middle latency response (AMLR)
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content_tags.definitions[4]the tagger's words
content_tagscoherent frequency (CF)
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content_tags.definitions[5]the tagger's words
content_tagsunintentional awareness
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content_tags.definitions[6]the tagger's words
content_tagsAAI
Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.
also in: AAI
content_tags.definitions[7]the tagger's words
content_tagsconcentration of the anesthetic
Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.
content_tags.variables[1]the tagger's words
content_tags40 Hz ASSR amplitude
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content_tags.variables[3]the tagger's words
content_tagslevel of consciousness
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content_tags.variables[4]the tagger's words
content_tags2.1 ng/ml — sufentanil concentration producing half-maximal suppression of the 40 Hz ASSR
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content_tags.quantities[0]the tagger's words
content_tagsmore than 70% — reduction in 40 Hz ASSR amplitude when sevoflurane was titrated to unconsciousness (mean 0.85% end-tidal)
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content_tags.quantities[1]the tagger's words
content_tagsabout 33 Hz / 15 Hz — coherent frequency of the steady-state response when awake versus when unconscious
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content_tags.quantities[2]the tagger's words
content_tagsz20% — reduction of the A-Line ARX index caused by the neuromuscular blocker vecuronium during steady-state anesthesia (i.e. muscle-artefact contribution to the index)
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content_tags.quantities[3]the tagger's words
content_tags10 of 11 — propofol-anesthetized volunteers in whom physostigmine restored consciousness
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content_tags.quantities[4]the tagger's words
content_tagstwo of eight — sevoflurane-anesthetized subjects who regained consciousness after physostigmine (three more regained wakefulness only)
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content_tags.quantities[5]the tagger's words

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