Effect of propofol and remifentanil on a somatosen

Authors: Ana Castro Pedro Amorim Catarina S Nunes Fernando Gomes de Almeida

Publish Date: 2014/10/30

Volume: 29, Issue: 5, Pages: 561-567

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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/antinociception balance Following institutional approval and written informed consent 10 healthy adult volunteers were enrolled 295 ± 91 years 630 ± 89 kg and 1714 ± 72 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 13×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 13×PT and pain ratings between 0 and 9 Cortical SEPs latencies were decreased for higher stimulus intensities P  001 accompanied by increased pain ratings P  001 An individually adjusted/normalized ratio based on cortical SEPs amplitude and interpeak latency is proposedR 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  005 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 levesThe authors would like to thank the participation of all volunteers and clinical investigators in this study especially Dr Francisco Lobo Dr Liliana Pinto Dr Diana Afonso Dr Germano Cardoso Dr Helena and Dr Luís Silva Neurinbloc The first author was supported by a scholarship from the Portuguese Foundation for Science and Technology FCT SFRH/BD/35879/2007 The authors would also like to acknowledge the UISPAIDMEC Porto

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