phenomenon · claim-type · cross-domain-transfer · mechanism · claim-relation · replication-status · limitation — grounded in the full text| phenomenon | auditory evoked potentials as a measure of anaesthetic depth— “Auditory evoked potentials (AEPs) are changes of the electrical activity of the brain (i.e. the electroencephalogram—EEG), produced by auditory stimuli.” | |
| claim-type | method— “With regard to the monitoring of consciousness, both the AMLR and 40 Hz ASSR provide a reliable indication of the presence or absence of consciousness in subjects receiving a general anesthetic agent.” | |
| method — evidence | — “We will review their physiological basis, the recording methodology, the effects of general anesthetics, their ability to track changes in level of consciousness and their clinical applications.” | |
| mechanism | 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— “With stimulus rates near 40/second, the next stimulus occurs during wave Pa of the AMLR evoked by the preceding stimuli, thus allowing progressive build-up of the 40 Hz ASSR by superimposition of the individual AMLR.” | mechanisms[0] |
| mechanism | 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— “This therefore suggests that the 40 Hz ASSR partly arises from synchronization of naturally occurring neuronal rhythms63 (that are affected by general anesthetics64) or that general anesthetics interfere with the superimposition process (possibly by not uniformly affecting the refractory period of the AMLR components).” | mechanisms[1] |
| mechanism | general anesthetics abolish consciousness by interfering with thalamocortical 40 Hz rhythms, which is why the 40 Hz response and consciousness disappear together— “An example is the hypothesis66 that general anesthetics impair consciousness by interfering with thalamocortical 40 Hz rhythms.” | mechanisms[2] |
| contradicts | Pockett et al.3— “Presence of PAMR led Pockett et al3 to conclude erroneously4 that the 40 Hz ASSR is not a suitable monitor of anesthesia.” | claim_relations[0] |
| contradicts | Galambos et al.42 (the 40 Hz ASSR as superimposition of the AMLR)— “We have examined the effect of enflurane/N2O anesthesia on the AMLR and 40 Hz ASSR and found that attenuation of the 40 Hz ASSR was much more pronounced that predicted by alterations of the AMLR.52” | claim_relations[1] |
| sense | 40 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— “The above evidence collectively suggests that the 40 Hz ASSR provides a fairly reliable measure of the level of consciousness.” | senses[0] |
| sense | 40 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— “Physostigmine restored consciousness in 10 of 11 volunteers who had been rendered unconscious by propofol. In the 10 subjects who regained consciousness, there was a concomitant increase of the 40 Hz ASSR to awake baseline values.” | senses[1] |
| edge | level of consciousness —operationalised-as→ 40 Hz ASSR— “The above evidence collectively suggests that the 40 Hz ASSR provides a fairly reliable measure of the level of consciousness.” | concept_edges[0] |
| for which use | limitation — the scope of the review: BECAUSE OF SPACE CONSTRAINTS, THIS REVIEW WILL BE LIMITED TO HUMAN STUDIES | limitations[0] |
| for which use | limitation — 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] |
| for which use | limitation — clinical application specifically: APPLICABILITY [to the] MULTI-DRUG REGIMEN COMMONLY SEEN IN CLINICAL PRACTICE REMAINS TO BE ASSESSED Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | limitations[2] |
| for which use | limitation — the amplitude measure only: whether ASSR parameters other than amplitude could support titration has not been examined Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | limitations[3] |
| for which use | limitation — 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 Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | limitations[4] |
| for which use | limitation — 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 Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | limitations[5] |
| for which use | limitation — the auditory evoked potentials used in anaesthetic monitoring: slow and late responses are excluded as too sensitive to anaesthetic effect for routine clinical monitoring Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | limitations[6] |
| replication | untested | |
| limitation | Scope restricted to human studies for reasons of space Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | limitations[0] |
| limitation | The association between ASSR attenuation and loss of consciousness is correlational, not demonstrated to be functional Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | limitations[1] |
| limitation | Applicability to real-world multi-drug anaesthetic regimens is untested Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | limitations[2] |
| limitation | Whether ASSR parameters other than amplitude could support titration has not been examined Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | limitations[3] |
| limitation | The 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. Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | limitations[4] |
| limitation | The supporting evidence is explicitly said to fall short of proof. Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | limitations[5] |
| limitation | Whole 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. Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | limitations[6] |
finding · quantity · variable · definition · key-term — grounded in the full text| finding | Most 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. Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.findings[0] |
| finding | Nitrous oxide and ketamine leave the main AMLR components unchanged even at concentrations that produce unconsciousness. Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.findings[1] |
| finding | Unlike other anesthetics, ketamine increased the amplitude of the 40 Hz steady-state response. Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.findings[2] |
| finding | Reversing anesthetic hypnosis with physostigmine raises the 40 Hz ASSR in proportion to the behavioural reversal, so ASSR attenuation seems to reflect impaired consciousness. Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.findings[3] |
| finding | Under enflurane/N2O the 40 Hz ASSR was attenuated far more than the accompanying AMLR changes predicted. Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.findings[4] |
| finding | The 40 Hz ASSR amplitude does not appear useful for titrating anesthetic dose, because it is already markedly reduced at loss of consciousness. Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.findings[5] |
| finding | The AMLR is suggested to reflect the balance between anesthetic suppression and brain activation caused by noxious stimulation. Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.findings[6] |
| quantity | 2.1 ng/ml — sufentanil concentration producing half-maximal suppression of the 40 Hz ASSR Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.quantities[0] |
| quantity | more than 70% — reduction in 40 Hz ASSR amplitude when sevoflurane was titrated to unconsciousness (mean 0.85% end-tidal) Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.quantities[1] |
| quantity | about 33 Hz / 15 Hz — coherent frequency of the steady-state response when awake versus when unconscious Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.quantities[2] |
| quantity | z20% — 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) Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.quantities[3] |
| quantity | 10 of 11 — propofol-anesthetized volunteers in whom physostigmine restored consciousness Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.quantities[4] |
| quantity | two of eight — sevoflurane-anesthetized subjects who regained consciousness after physostigmine (three more regained wakefulness only) Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.quantities[5] |
| variable | concentration of the anesthetic (control) Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.variables[1] |
| variable | 40 Hz ASSR amplitude (dependent) Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.variables[3] |
| variable | level of consciousness (dependent) Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.variables[4] |
| definition | auditory evoked potential Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.definitions[0] |
| definition | transient AEP Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.definitions[1] |
| definition | steady-state AEP Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.definitions[2] |
| definition | 40 Hz auditory steady-state response (40 Hz ASSR) Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.definitions[3] |
| definition | auditory middle latency response (AMLR) Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.definitions[4] |
| definition | coherent frequency (CF) Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.definitions[5] |
| definition | unintentional awareness Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.definitions[6] |
| definition | AAI Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.definitions[7] |
| concept | 40 Hz ASSR Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | concepts[0] |
| concept | level of consciousness Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | concepts[1] |
| concept | auditory middle latency response Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | concepts[2] |
| statistical significance test | as written: statistically significant Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.statistics[0] |
| mean (signal averaging across trials) | as written: the average of 1000 responses Quotation withheld — this paper is not ours to reproduce, and the page has already quoted as much of it as the rights layer allows. The tag, its field and its confidence stand; the sentence is at the publisher. | content_tags.statistics[1] |
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