Journal of Clinical Monitoring and Computing

, Volume 29, Issue 5, pp 561–567

Effect of propofol and remifentanil on a somatosensory evoked potential indicator of pain perception intensity in volunteers

  • Ana Castro
  • Pedro Amorim
  • Catarina S. Nunes
  • Fernando Gomes de Almeida
Original Research

DOI: 10.1007/s10877-014-9632-0

Cite this article as:
Castro, A., Amorim, P., Nunes, C.S. et al. J Clin Monit Comput (2015) 29: 561. doi:10.1007/s10877-014-9632-0

Abstract

Somatosensory evoked potentials (SEPs) have been linked to noxious activation and stimulus intensity. In this exploratory study we investigated the impact of anaesthetic drugs on SEPs and pain ratings, to assess their applicability as an objective measure of the nociception/anti-nociception balance. Following institutional approval and written informed consent, 10 healthy adult volunteers were enrolled (29.5 ± 9.1 years, 63.0 ± 8.9 kg and 171.4 ± 7.2). Median nerve electrical stimulation was adjusted according to volunteers’ sensitive, motor and painful thresholds (PT). Baseline SEPs were registered, and remifentanil and propofol administered using a stair scheme TCI. For each drug combination a 1.3×PT stimulus was administered, and volunteers evaluated pain intensity in a numerical rating scale (0–10). SEPs’ amplitudes and latencies were normalized by the baseline values, reducing volunteers’ intervariability. Stimulation currents varied between 6–52 mA (1.3×PT) and pain ratings between 0 and 9. Cortical SEPs latencies were decreased for higher stimulus intensities (P < 0.01), accompanied by increased pain ratings (P < 0.01). An individually adjusted/normalized ratio based on cortical SEPs amplitude and interpeak latency is proposed(\(R_{Norm}\)): \(R_{Norm}\) and NSR were significantly correlated in three out of nine subjects, and \(R_{Norm}\) and remifentanil Ce were significantly correlated in two (low number of evaluation points). \(R_{Norm}\) was shown to decrease with increasing doses of propofol and remifentanil (P < 0.05). The proposed metric was depressed by anaesthetics and reflected pain evaluations. Further research is necessary to increase the number of volunteers and drugs’ combination, to assess its applicability during surgically adequate anesthetic leves.

Keywords

Pain Nociception Monitoring Somatosensory evoked potentials (SEPs) TIVA 

Copyright information

© Springer Science+Business Media New York 2014

Authors and Affiliations

  • Ana Castro
    • 1
    • 2
  • Pedro Amorim
    • 2
  • Catarina S. Nunes
    • 2
    • 3
  • Fernando Gomes de Almeida
    • 1
    • 2
  1. 1.Faculdade de Engenharia da Universidade do PortoPortoPortugal
  2. 2.Centro de Investigação Clínica em Anestesiologia, Serviço de AnestesiologiaHospital de Santo António, Centro Hospitalar do PortoPortoPortugal
  3. 3.DCeT - Departamento de Ciências e Tecnologia, Universidade AbertaDelegação do PortoPortoPortugal

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