Abstract
Anesthetics such as isoflurane act in the spinal cord to suppress movement in response to noxious stimulation. Spinal anesthesia decreases hypnotic/sedative requirements, possibly by decreasing afferent transmission of stimuli. We hypothesized that isoflurane action in the spinal cord would similarly depress the ascending transmission of noxious input to the thalamus and cerebral cortex. In six isoflurane-anesthetized goats, we measured electroencephalographic (EEG) and thalamic single-unit responses to a clamp applied to the forelimb. Cranial bypass permitted differential isoflurane delivery to the torso and cranial circulations. When the cranial-torso isoflurane combination was 1.3% ± 0.2%-1.0% ± 0.4% the noxious stimulus did not evoke significant changes in the EEG or thalamic activity: 389 (153-544) to 581 (172-726) impulses/min, (median, 25th-75th percentile range, P > 0.05). When the cranial-torso isoflurane combination was 1.3% ± 0.2%-0.3% ± 0.2%, noxious stimulation increased thalamic activity: 804 (366-1162) to 1124 (766-1865) impulses/min (P < 0.05), and the EEG 'desynchronized': total EEG power decreased from 25 ± 20 μV2 to 12 ± 8 μV2 (P < 0.05). When the cranial-torso isoflurane was 1.7% ± 0.1%-0.3% ± 0.2%, the noxious stimulus did not significantly affect thalamic: 576 (187-738) to 1031 (340-1442) impulses/min (P > 0.05), or EEG activity. The indirect torso effect of isoflurane on evoked EEG total power (12.6 ± 2.7 μV2/vol%, mean ± SE) was quantitatively similar to the direct cranial effect (17.7 ± 3.0 μV2/vol%; P > 0.05). These data suggest that isoflurane acts in the spinal cord to blunt the transmission of noxious inputs to the thalamus and cerebral cortex, and thus might indirectly contribute to anesthetic endpoints such as amnesia and unconsciousness.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1282-1288 |
| Number of pages | 7 |
| Journal | Anesthesia and Analgesia |
| Volume | 91 |
| Issue number | 5 |
| State | Published - 2000 |
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ASJC Scopus subject areas
- Anesthesiology and Pain Medicine
Cite this
Isoflurane depresses electroencephalographic and medial thalamic responses to noxious stimulation via an indirect spinal action. / Antognini, Joseph F.; Carstens, Earl; Sudo, Makoto; Sudo, Satoko.
In: Anesthesia and Analgesia, Vol. 91, No. 5, 2000, p. 1282-1288.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Isoflurane depresses electroencephalographic and medial thalamic responses to noxious stimulation via an indirect spinal action
AU - Antognini, Joseph F.
AU - Carstens, Earl
AU - Sudo, Makoto
AU - Sudo, Satoko
PY - 2000
Y1 - 2000
N2 - Anesthetics such as isoflurane act in the spinal cord to suppress movement in response to noxious stimulation. Spinal anesthesia decreases hypnotic/sedative requirements, possibly by decreasing afferent transmission of stimuli. We hypothesized that isoflurane action in the spinal cord would similarly depress the ascending transmission of noxious input to the thalamus and cerebral cortex. In six isoflurane-anesthetized goats, we measured electroencephalographic (EEG) and thalamic single-unit responses to a clamp applied to the forelimb. Cranial bypass permitted differential isoflurane delivery to the torso and cranial circulations. When the cranial-torso isoflurane combination was 1.3% ± 0.2%-1.0% ± 0.4% the noxious stimulus did not evoke significant changes in the EEG or thalamic activity: 389 (153-544) to 581 (172-726) impulses/min, (median, 25th-75th percentile range, P > 0.05). When the cranial-torso isoflurane combination was 1.3% ± 0.2%-0.3% ± 0.2%, noxious stimulation increased thalamic activity: 804 (366-1162) to 1124 (766-1865) impulses/min (P < 0.05), and the EEG 'desynchronized': total EEG power decreased from 25 ± 20 μV2 to 12 ± 8 μV2 (P < 0.05). When the cranial-torso isoflurane was 1.7% ± 0.1%-0.3% ± 0.2%, the noxious stimulus did not significantly affect thalamic: 576 (187-738) to 1031 (340-1442) impulses/min (P > 0.05), or EEG activity. The indirect torso effect of isoflurane on evoked EEG total power (12.6 ± 2.7 μV2/vol%, mean ± SE) was quantitatively similar to the direct cranial effect (17.7 ± 3.0 μV2/vol%; P > 0.05). These data suggest that isoflurane acts in the spinal cord to blunt the transmission of noxious inputs to the thalamus and cerebral cortex, and thus might indirectly contribute to anesthetic endpoints such as amnesia and unconsciousness.
AB - Anesthetics such as isoflurane act in the spinal cord to suppress movement in response to noxious stimulation. Spinal anesthesia decreases hypnotic/sedative requirements, possibly by decreasing afferent transmission of stimuli. We hypothesized that isoflurane action in the spinal cord would similarly depress the ascending transmission of noxious input to the thalamus and cerebral cortex. In six isoflurane-anesthetized goats, we measured electroencephalographic (EEG) and thalamic single-unit responses to a clamp applied to the forelimb. Cranial bypass permitted differential isoflurane delivery to the torso and cranial circulations. When the cranial-torso isoflurane combination was 1.3% ± 0.2%-1.0% ± 0.4% the noxious stimulus did not evoke significant changes in the EEG or thalamic activity: 389 (153-544) to 581 (172-726) impulses/min, (median, 25th-75th percentile range, P > 0.05). When the cranial-torso isoflurane combination was 1.3% ± 0.2%-0.3% ± 0.2%, noxious stimulation increased thalamic activity: 804 (366-1162) to 1124 (766-1865) impulses/min (P < 0.05), and the EEG 'desynchronized': total EEG power decreased from 25 ± 20 μV2 to 12 ± 8 μV2 (P < 0.05). When the cranial-torso isoflurane was 1.7% ± 0.1%-0.3% ± 0.2%, the noxious stimulus did not significantly affect thalamic: 576 (187-738) to 1031 (340-1442) impulses/min (P > 0.05), or EEG activity. The indirect torso effect of isoflurane on evoked EEG total power (12.6 ± 2.7 μV2/vol%, mean ± SE) was quantitatively similar to the direct cranial effect (17.7 ± 3.0 μV2/vol%; P > 0.05). These data suggest that isoflurane acts in the spinal cord to blunt the transmission of noxious inputs to the thalamus and cerebral cortex, and thus might indirectly contribute to anesthetic endpoints such as amnesia and unconsciousness.
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M3 - Article
C2 - 11049923
AN - SCOPUS:0033756646
VL - 91
SP - 1282
EP - 1288
JO - Anesthesia and Analgesia
JF - Anesthesia and Analgesia
SN - 0003-2999
IS - 5
ER -