Nociceptive stimuli responses at different levels of general anaesthesia and genetic variability

Background Changes in skin conductance (SC), clinical stress score (CSS), the bispectral index spectroscopy (BIS) index and the variation in the BIS index may be used to monitor responses to nociceptive stimuli. We wanted to examine these methods during noxious stimulation during general anaesthesia and if the responses were associated with variability in genes related to pain. Methods Sixty patients, given propofol to a BIS level of 4050, were stimulated with standardised tetanic electrical stimuli during propofol infusion, plasma level of 3 mu g/ml alone, or together with remifentanil target plasma level of 3?ng/ml or 10?ng/ml. The CSS, SC, BIS index and the variability of the BIS index were registered. The inter-individual variation in nociceptive responses was analysed for co-variation with genotypes of 89 single nucleotide polymorphisms from 23 candidate genes. Results During tetanic stimuli, CSS and SC increased significantly and were attenuated with increasing level of remifentanil, different from the BIS index and the variation in the BIS index. Polymorphisms in the P-glycoprotein (ABCB1), tachykinin 1 receptor (TACR1), dopamine receptor D3 (DRD3) and beta arrestin 2 (ARRB2) genes were associated with the co-variation in SC variables or CSS response or both during standardised nociceptive stimuli (P?