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The association between propofol-induced loss of consciousness and the SNAP index.
Anesth Analg. 2005 Jan; 100(1):141-8.A&A

Abstract

The SNAP is a processed electroencephalogram monitor that uses an algorithm based on low- and high-frequency spectral components to derive a SNAP index. In this study we sought to determine the relationship of the SNAP index with loss of consciousness in subjects receiving a bolus of propofol. Unpremedicated subjects were randomized to receive 1 of 11 doses of IV propofol (0, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, or 2.4 mg/kg; n=20 per group). The SNAP index was recorded when the subject became unconscious (end-point) or at 160 s after the injection. Sixty-five percent of subjects achieved the end-point (defined as the time at which the subject dropped a weighted syringe). The 50% effective dose for propofol was 0.97 mg/kg (95% confidence interval [CI], 0.86-1.07 mg/kg). The median awake SNAP index was 92 (range 78-99) and did not differ between subjects who reached the end-point and those who did not. The end-point SNAP index decreased from baseline in the subjects who dropped the syringe to a median of 76 (range, 57-94) at doses > or =1.0 mg/kg but was not different among doses. The index was not different from baseline at 160 s in subjects who did not reach the end-point. Binary logistic regression models predicted a SNAP index 95% effective dose for loss of consciousness of 71 (95% CI, 63-74) and 19 (95% CI, 16-22) for changes in SNAP index from baseline. The areas under the receiver operator characteristic curves for these models were 0.837 and 0.864. The SNAP index correlated with propofol-induced loss of consciousness. It appears to be a useful indicator of loss of consciousness and should be further investigated as a monitor of anesthesia depth.

Authors+Show Affiliations

Department of Anesthesiology, Northwestern University Feinberg School of Medicine, 251 E. Huron St., F 5-704, Chicago, IL 60611, USA. c-wong2@northwestern.eduNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Clinical Trial
Journal Article
Randomized Controlled Trial
Research Support, Non-U.S. Gov't
Validation Study

Language

eng

PubMed ID

15616068

Citation

Wong, Cynthia A., et al. "The Association Between Propofol-induced Loss of Consciousness and the SNAP Index." Anesthesia and Analgesia, vol. 100, no. 1, 2005, pp. 141-8.
Wong CA, Fragen RJ, Fitzgerald PC, et al. The association between propofol-induced loss of consciousness and the SNAP index. Anesth Analg. 2005;100(1):141-8.
Wong, C. A., Fragen, R. J., Fitzgerald, P. C., & McCarthy, R. J. (2005). The association between propofol-induced loss of consciousness and the SNAP index. Anesthesia and Analgesia, 100(1), 141-8.
Wong CA, et al. The Association Between Propofol-induced Loss of Consciousness and the SNAP Index. Anesth Analg. 2005;100(1):141-8. PubMed PMID: 15616068.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The association between propofol-induced loss of consciousness and the SNAP index. AU - Wong,Cynthia A, AU - Fragen,Robert J, AU - Fitzgerald,Paul C, AU - McCarthy,Robert J, PY - 2004/12/24/pubmed PY - 2005/1/22/medline PY - 2004/12/24/entrez SP - 141 EP - 8 JF - Anesthesia and analgesia JO - Anesth Analg VL - 100 IS - 1 N2 - The SNAP is a processed electroencephalogram monitor that uses an algorithm based on low- and high-frequency spectral components to derive a SNAP index. In this study we sought to determine the relationship of the SNAP index with loss of consciousness in subjects receiving a bolus of propofol. Unpremedicated subjects were randomized to receive 1 of 11 doses of IV propofol (0, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, or 2.4 mg/kg; n=20 per group). The SNAP index was recorded when the subject became unconscious (end-point) or at 160 s after the injection. Sixty-five percent of subjects achieved the end-point (defined as the time at which the subject dropped a weighted syringe). The 50% effective dose for propofol was 0.97 mg/kg (95% confidence interval [CI], 0.86-1.07 mg/kg). The median awake SNAP index was 92 (range 78-99) and did not differ between subjects who reached the end-point and those who did not. The end-point SNAP index decreased from baseline in the subjects who dropped the syringe to a median of 76 (range, 57-94) at doses > or =1.0 mg/kg but was not different among doses. The index was not different from baseline at 160 s in subjects who did not reach the end-point. Binary logistic regression models predicted a SNAP index 95% effective dose for loss of consciousness of 71 (95% CI, 63-74) and 19 (95% CI, 16-22) for changes in SNAP index from baseline. The areas under the receiver operator characteristic curves for these models were 0.837 and 0.864. The SNAP index correlated with propofol-induced loss of consciousness. It appears to be a useful indicator of loss of consciousness and should be further investigated as a monitor of anesthesia depth. SN - 0003-2999 UR - https://www.unboundmedicine.com/medline/citation/15616068/The_association_between_propofol_induced_loss_of_consciousness_and_the_SNAP_index_ L2 - https://doi.org/10.1213/01.ANE.0000138057.61904.FD DB - PRIME DP - Unbound Medicine ER -