The Effect of Intraoperative Music Listening on Sevoflurane Consumption and Recovery Parameters

* The perioperative period can be a significant source of psychological burden, anxiety and fear for patients
* Both pharmacological and non-pharmacological methods have been proposed in order to alleviate perioperative stress
* Music is one of the non-pharmacological methods which have been used in this context, with favorable effects both preoperatively and postoperatively
* The attenuation of perioperative stress through music listening is probably due to the activation of emotional and cognitive processes that evoke feeling of pleasure and can distract patients' attention from fear and unpleasant thoughts related to the surgical procedure
* Little information is available regarding the effect of intraoperative music listening on anesthetized, unconscious patients
* There is a notion that general anesthesia does not completely abolish auditory perception and that some processing of intraoperative events can occur in unconscious patients, even in the absence of postoperative recall
* The investigators hypothesis is that intraoperative music listening can decrease anesthetic requirements and reduce sevoflurane consumption in female patients subjected to abdominal hysterectomy for benign disease.

* The perioperative period can be a significant source of psychological burden, anxiety and fear for patients
* Both pharmacological and non-pharmacological methods have been proposed in order to alleviate perioperative stress
* Music is one of the non-pharmacological methods which have been used in this context, with favorable effects both preoperatively and postoperatively
* Listening to music during the preoperative period has proved useful as an adjunct to premedication and can even be used instead of premedication. Additionally, listening to music postoperatively can also be useful, since it has been related to a more favorable recovery profile and possible attenuation of postoperative pain. In this context, music has also been used in Intensive Care Units, with measurable effects on anxiety scales and hemodynamic parameters. There are also studies investigating the use of music during operations under regional anesthesia, which have shown that music listening substantially decreases the need for anxiolytic administration throughout the operation
* The attenuation of perioperative stress through music listening is probably due to the activation of emotional and cognitive processes that evoke feelings of pleasure and can distract patients' attention from fear and unpleasant thoughts related to the surgical procedure
* Although the favorable effects of music listening during regional anesthesia for the attenuation of intraoperative stress in conscious patients are more or less expected and easily interpreted, less is known regarding the effect of intraoperative music listening on anesthetized, unconscious patients
* Generally, there is a notion that general anesthesia does not completely abolish auditory perception and that some processing of intraoperative events can occur in unconscious patients, even in the absence of postoperative recall
* The preservation of some form of auditory processing during general anesthesia is not necessarily undesirable and can be used to the patient's benefit, since it has been shown that subjecting patients to therapeutic suggestions during general anesthesia can improve recovery parameters or decrease hospital stay
* The investigators hypothesis is that intraoperative music listening can decrease anesthetic requirements. Therefore, the investigators will investigate sevoflurane consumption necessary to achieve a depth of anesthesia corresponding to bispectral index values of 45-55. Female patients subjected to abdominal hysterectomy for benign disease will be randomized to one of two groups: in the first group, audiotapes playing relaxing soothing orchestral music will be placed on the patients' ears after induction of general anesthesia while in the other group the same set of audiotapes will be used without however playing any music
* Sevoflurane consumption will be estimated by weighing the sevoflurane vaporizer in a high-precision scale before induction and after completion of the surgical procedure. Patients will also be queried regarding recall of any sounds or intraoperative events, dreaming while anesthetized and they will be asked to rate their satisfaction from anesthesia. Recovery parameters will also be investigated, such as postoperative nausea and vomiting and the intensity of postoperative pain. To ensure homogeneity, standardized analgesia will be administered in the two groups
* Since prolactin is related to the neuroendocrine response to stress, blood will also be sampled at predetermined timepoints during anesthesia, to detect potential differences between the two groups
* The clinical interest of this study lies in the fact that if a non-costly intervention such as music listening during anesthesia can lead to reduced requirements of anesthetic agents or to reduced need for postoperative analgesia, this theoretically can be translated to a reduction in anesthetic cost. In addition, improvement in recovery profile parameters could lead to a quicker discharge from the post-anesthesia care unit with reduction in turnaround times and overall time optimization.

Eligibility Criteria:
Inclusion Criteria:

* adult patients, American Society of Anesthesiologists (ASA) distribution I-III, scheduled for elective hysterectomy for benign disease

Exclusion Criteria:

* hearing impairment
* psychiatric disease (depression, dementia)
* mental disability
* concurrent treatment with medication known to affect anesthetic requirement, such as benzodiazepines, anticonvulsants, opioids, psychotropic drugs or alcohol