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Effects of Different Anesthetics on Pain Processing in an Experimental Human Pain Model
Author(s) -
Nickel Florian T.,
Ott Stephan,
Möhringer Susanne,
Münster Tino,
Rieß Simon,
Filitz Jörg,
Koppert Wolfgang,
Maihöfner Christian
Publication year - 2016
Publication title -
pain practice
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 58
eISSN - 1533-2500
pISSN - 1530-7085
DOI - 10.1111/papr.12326
Subject(s) - medicine , anesthesia , propofol , hyperalgesia , remifentanil , noxious stimulus , analgesic , nociception , threshold of pain , nociceptor , stimulation , habituation , anesthetic , receptor , audiology
Objective After surgical procedures, anesthesia itself may affect pain perception. Particularly, there is increasing evidence that opioids not only have analgesic effects but also provoke pronociceptive changes, that is, opioid‐induced hyperalgesia. We investigated the effect of different anesthetic regimens on pain processing in volunteers using a transdermal electrical pain model. In this model, stimulation of epidermal nerve fibers representing mainly peptidergic C‐nociceptors leads to secondary hyperalgesia and habituation to the stimulus. Methods Forty‐eight healthy volunteers underwent conditioning noxious stimulation ( CS ) over 5 days. On day 2, the volunteers were randomized into 4 groups: control group (no anesthesia) and 3 groups receiving anesthesia before CS in anesthetic doses: propofol (P), propofol/remifentanil ( PR ), and propofol/remifentanil/S‐ketamine ( PRK ). Quantitative sensory testing was performed on days 1 through 5 and on day 22. Results In every group, CS was associated with short‐ and long‐term habituation to the electrical stimulus. Repetitive CS resulted in unmodified short‐term sensitization with stable areas of hyperalgesia. Although the PR group showed a trend toward increased areas of hyperalgesia on day 2, no significant differences were detectable between the groups. In contrast, anesthesia resulted in decreased intensity of the electrically evoked pain on day 2. Finally, the mechanical pain threshold before CS on day 5 was increased in all groups and remained elevated 3 weeks after the first CS , consistent with a long‐term antinociceptive effect after CS . Conclusions The results suggest a short‐term analgesic effect of general anesthesia. Furthermore, the conditioning stimulation over several days induced differential modulation of pro‐ and antinociceptive systems.