It has been established that music affects moods and emotions (1). The role of music as a therapeutic modality for the treatment of preoperative anxiety in adult patients has been evaluated (2). These investigators concluded that there are anxiolytic effects of music when used before surgery. Additionally, music was reported to decrease sedative requirements during regional anesthesia (3). However, there is debate concerning whether the decrease in sedative requirements was caused by music itself or the prevention of distracting noises in the operating room (OR) (4). It has been alleged that noise in the OR may interfere with the ability of anesthesia providers to achieve a stable level of sedation for patients undergoing surgical procedures with local anesthesia as part of a monitored anesthesia care technique (5).
Bispectral index (BIS) monitoring is used for measuring the hypnotic effects of anesthetics. Although more often used for this purpose in general anesthesia, BIS has also been used to evaluate depth of sedation with midazolam (6). It has been reported that BIS is affected by noise at lighter levels of propofol sedation, and noise increased BIS values of patients at an equal depth of sedation (5).
The aim of this study was to use the BIS monitor to assess the effect of music on the level of sedation after midazolam premedication in noiseless conditions.
After approval from the Institutional Ethics Committee and written informed consent, this randomized controlled study included 54 ASA physical status I–II patients aged 18–60 yr, scheduled to undergo septo-rhinoplastic surgery. The patients were scheduled for surgery between 08.00–10.00 am.
At the preoperative evaluation, the day before surgery, habitual music listening scores for all patients were recorded (4-point scale: 1 = once a week, 2 = a couple of times per week, 3 = no more than once a day, and 4 = few times a day). All the participants were asked to bring their favorite tape recorder cassette or CD to the hospital on the morning of surgery in case they were assigned to the music group.
On the morning of the surgery, after completion of the preoperative admission process by a nurse, a baseline modified Observer Assessment of Alertness/Sedation Scales (OAAS) score, with 0 = fully awake to 5 = unconscious, and measurements of routine monitoring were obtained. Midazolam 0.08 mg/kg was administered IM to all patients 50 min before surgery. The subjects were then tested for their OAAS, and other variables were recorded at 10-min intervals over the subsequent 50-min study period (7). In the preoperative room, routine monitors were used, as well as the BIS® monitor (A-2000, Aspect Medical Systems Inc, Natick, MA). The BIS values were stored electronically on a computer, and the average of the BIS measurements was calculated at 10-min intervals.
Before their group assignments, patients were informed that they may or may not have an opportunity to listen to their music. Suitable headphones (Philips stereo headphone SBC HPI50) were worn by all patients, and they were assigned, using a table of random numbers, to receive either music (music group) or no music (control group) after midazolam injection. A suitable substitution was provided for those patients in the music group who did not bring a CD or cassette. The nurse placed the cassette or CD in the player according to the group assignment. Patients in the control group listened to a blank cassette or CD both for establishing blinding and for preventing environmental noise contamination. Throughout the duration of the experimental session, no hospital personnel were allowed to communicate with the patient. However, patients could control the sound level with a wheel switch. Once the experimental session was started, OAAS scores were measured of 10-min intervals by a blinded observer. To test observer blinding, the observer was asked whether he recognized the patient’s group at any stage during the study period.
The induction of anesthesia was provided with a propofol IV injection via an infusion pump (LC 5000, Abbott Laboratories Inc, Park, IL) at a constant rate of 1000 mL · kg−1 · h−1. Propofol injection was stopped when the eyelash reflex disappeared or a total dose rate of 2 mg/kg was administered. The time to reach 60 values of BIS was recorded to determine the hypnotic end-point of anesthesia during the induction.
A priori power assessment was performed to detect a difference of 15% in the BIS values, suggesting a sample size 26 per group (α = 0.05; d = 1.5; power, 0.95; two-tailed). Data were analyzed with the use of SPSS for Windows Release 9.0 (SPSS Inc, Chicago, IL). Normality was assessed with the Kolmogorov-Smirnov test, and depending on the results, either parametric or nonparametric analysis was performed. Nonrepeated parametric data were analyzed with independent samples t-test. Repeated parametric measurements were compared with the two-way repeated-measures analysis of variance followed by an adjustment with Bonferroni post hoc test. Nonparametric data, such as OAAS and musical background scores, were analyzed with χ2 and Mann-Whitney U-test. P values <0.05 were considered statistically significant.
Four patients (three in the music and one in the control group) were excluded from the study because of technical problems related to the music player. There were no significant differences between groups regarding baseline demographics, habitual music listening scores, and surgery times. Times to eyelash reflex abolition and reaching a BIS value of 60 were similar between the groups. The total dose of propofol administered during the induction of anesthesia was also not different between groups (Tables 1 and 2).
In the control group, there were more patients with an OAAS score of 1 (P < 0.05) than in the music group at 30 min after midazolam injection (Fig. 1A). In addition, there were more patients with an OAAS score of 2 (P < 0.05) in the control group than in the music group at 30–50 min (Fig. 1B). However, there were more patients with an OAAS score of 3 in the music group (P < 0.05) than in the control group at 20–50 min (Fig. 2A). One patient had an OAAS score of 4 in the music group.
BIS values in the music group were lower than in the control group at 30 and 40 min (P < 0.05) (F = 4.3). BIS values significantly decreased (P < 0.05) from baseline at 10–50 min in the music group (F = 75), whereas they diminished at 30–50 min in the control group (F = 27.7) (Fig. 2B).
The effect of music on the level of preoperative sedation and anxiety is controversial (8–11). Auditory input is a modulator of the human response to stress (12). Previous studies in the medical and psychological literature have shown that music may play a therapeutic role (13,14). Koch et al. (4) reported that the factors that add to heightened stress, such as an uncomfortable or unfamiliar environment, loss of control, and fear of disfigurement, might all be attenuated by the distracting and calming effects of music (4). In the current study, the calming effect of music was potent enough to increase the sedative effect of midazolam before surgery. The postulated explanation for this, from a psychological perspective, may involve issues of control and distraction (15). Listening to music can modulate the human response to stress (16), and studies have suggested that music can be used as an adjunct during therapeutic interventions (17,18).
Koch et al. (4) described that intraoperative music in awake patients decreased patient-controlled sedative and analgesic requirements. In that study, however, patients in the no-music group did not use a headset during surgery. Thus, the decrease in sedative and analgesic requirements could have been caused by elimination of ambient OR noise and not by the effects of music (4). In our study protocol, control group patients were protected from environmental noise contamination by a headset. Lepage et al. (3) also reported that listening to music throughout the perioperative period was associated with decreased midazolam requirements in patients undergoing ambulatory surgery with spinal anesthesia.
Our study showed that listening to music provided significant patient sedation after 20 minutes. However, the effect of this sedation measured on BIS was limited to two of five time points. This may have resulted from the confounding effect of the midazolam premedication in assessing the effect of music on BIS values. We observed the sedative effect of the music at the same time that the maximal concentration of midazolam may have been achieved. We could not include a music-only group in our study design because in our department, craniofacial surgery septo-rhinoplastic operations are all performed with midazolam premedication. However, we accept that the use of midazolam in all patients was a deficiency in the study design. The other major deficiency of our study design was the lack of patient blinding. Because of the type of intervention studied, these subjects could not be blinded as to the group assignment. Blinding is difficult to achieve in some situations such as comparison of surgical versus medical interventions or of psychological versus no treatment (19). It is noteworthy that four patients were excluded because of a failure in observer blinding after a technical problem. Although the study design was not optimal, this is the first study demonstrating that the sedative effect of listening to music may be a useful adjuvant to premedicant drugs.
Midazolam premedication decreases the dose of propofol required to achieve all the anesthetic end-points. Positive interactions of several sedative drugs with music have been demonstrated (3,4). However, we found no significant difference between the two groups with respect to the total induction dose of propofol on the time to induce anesthesia.
We conclude that in patients receiving midazolam (0.08 mg/kg IM) for premedication, the presence of music during the preoperative period was associated with increased sedation and lower BIS values.
The authors wish to thank Associate Professor Dogan Unal, MD, in the Department of Urology at the Harran University, Sanliurfa, Turkey, for preparing and editing the manuscript.
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© 2005 International Anesthesia Research Society
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