Hence, the present meta-analysis investigates the efficacy of therapeutic suggestions under general anesthesia on surgically relevant postoperative outcomes, i.e., pain intensity, mental distress, recovery, or the use of medication, and intraoperative outcomes, i.e., length of procedure and physiological parameters, by including randomized controlled trials only.Įligible studies were randomized controlled trials that investigated therapeutic suggestions presented during general anesthesia to adult patients undergoing surgery or medical procedures. However, these results must be interpreted with caution since a) the inclusion of non-randomized trials threatens the validity of meta-analytic results and b) the effects on patient-controlled analgesia are based on four studies only. Even though the effect on postoperative hospitalization was not statistically significant, the small positive effect of suggestions on patient-controlled analgesia reached statistical significance. One meta-analysis so far investigated the efficacy of therapeutic suggestions presented during general anesthesia to encourage well-being and recovery of surgical patients and has found mixed results.
Moreover, strong impact of negative intraoperative remarks on prognosis has been reported. In addition, the occurrence of implicit memory has been proven much more frequently. In some cases, intraoperative awareness occurs under general anesthesia with explicit memory of the situation and of conversations. Even further processing of words in the central nervous system including development of memory and appropriate responses has been demonstrated by postoperative recognition of intraoperatively presented words, and postoperative nonverbal responses to instructions given during anesthesia. Intraoperative measurement of auditory evoked potentials has shown that the central auditory pathway remains intact during general anesthesia. This approach is based on the consideration that anesthesia does not interrupt perception of sounds and words by the brain. In this context, suggestions are defined “as verbal or nonverbal messages that the receiver involuntarily accepts and follows” and that might affect emotions, behavior and autonomous body functions. Some of the studies included suggestions presented during general anesthesia to the unconscious patient. Several meta-analyses show small to large effect sizes of therapeutic suggestions given pre- or postoperatively with or without hypnosis induction on various outcomes. Other challenges such as anxiety, hopelessness and negative expectations further impair recovery and outcome, or lead to nocebo effects which usually cannot be treated with drugs and call for non-pharmacological approaches.Īmong psychological interventions to improve recovery and well-being hypnotherapeutic approaches are most effective. Pain and PONV are usually prevented and treated by medications that carry their own side effects. Recovery from anesthesia and surgery is often hampered by side effects such as pain or postoperative nausea and vomiting (PONV), by disturbances of well-being and even complications.