Do we feel pain during anesthesia? A critical review on surgery-evoked circulatory changes and pain perception

Abstract

The difficulty of defining the three so-called components of « an-esthesia » is emphasized: hypnosis, absence of movement, and adequacy of anti-nociception (intraoperative « analgesia »). Data obtained from anesthetized animals or humans delineate the activation of cardiac and vasomotor sympathetic reflex (somato-sympathetic reflex) and the cardiac parasympathetic deactivation observed following somatic stimuli. Sympathetic activation and parasympathetic deactivation are used as monitors to address the adequacy of intraoperative anti-nociception. Finally, intraoperative nociception through the administration of nonopioid analgesics vs. opioid analgesics is considered to achieve minimal postoperative side effects.

Keywords: ANI; CARDEAN; OFA; RVLM; SPI; SSI; alpha-2 agonist; analgesia; analgesics; anesthesia; anti-nociception; cardiac baroreflex; cardiac vagal motoneurons; hyperalgesia; movement; nociception; nonopioid analgesics; nucleus ambiguus; opioid; opioid-free anesthesia; pain; presympathetic neurons; respiratory genesis; somato-sympathetic reflex; surgery; vasomotor baroreflex; vasomotor center; ventilatory depression.