Since the 1960's, intraoperative administration of opioids is considered a keystone of
anesthesia as well as hypnotics and muscle relaxants. Synthetic opioids were introduced to
achieve hemodynamic stability during anesthesia. They allow an inhibition of the sympathetic
system without cardiovascular collapse and histamine release. Since then, anesthesia has
changed from inhalation to multimodal anesthesia with lower doses of hypnotic. In 2017, the
intraoperative objectives of hypnosis, hemodynamic stability, immobility and anticipation of
postoperative analgesia can be achieved without opioids. Moreover, opioid administration
consequences are neither scarce nor benign for the patient. Perioperative opioids are
associated with nausea and vomiting, sedation, ileus, confusion/delirium, respiratory
depression, increased postoperative pain and morphine consumption, immunodepression,
hyperalgesia and chronic postoperative pain. Among these complications, hypoxemia, ileus and
confusion/delirium are the most frequent.
Efficacious multimodal analgesia and anesthesia are the basis of successful fast-track
surgery. These multidrug regimens aim at decreasing postoperative pain, intra- and
postoperative opioid requirements, and subsequently, opioid-related adverse effects and to
fasten recovery. Opioid-free postoperative analgesia has been recommended for more than 10
years. Opioid-free anesthesia (OFA) is based on the idea that hemodynamic stability can be
achieved without opioids during anesthesia. OFA is multimodal anesthesia associating
hypnotics, N-methyl-D-aspartate (NMDA) antagonists, local anesthetics, anti-inflammatory
drugs and alpha-2 agonists (Dexmedetomidine).
Proofs of the effect of OFA on reducing opioid-related adverse effects after major or
intermediate non-cardiac surgery are still scarce. We hypothesized that the reduced opioid
consumption during and after surgery allowed by OFA compared with standard of care will be
associated with a reduction of postoperative opioid-related adverse events.