Music listening for anxiety relief in children in the preoperative period: a randomized clinical trial

ABSTRACT Objective: to investigate the effects of music listening, for 15 minutes, on the preoperative anxiety levels in children undergoing elective surgery in comparison with conventional pediatric surgical care. Method: randomized controlled clinical trial pilot study with 52 children in the preoperative period, aged 3 to 12 years, undergoing elective surgery and randomly allocated in the experimental group (n = 26) and control group (n = 26). Anxiety was assessed in both groups by the application of the modified Yale Preoperative Anxiety Scale and measurement of the physiological variables, upon arrival and 15 minutes after the first measurement. Results: there was a statistically significant difference in preoperative anxiety between the two groups only in relation to the physiological variable, since the respiratory rate of preschool children in the experimental group reduced in the second measurement compared to the control group (p = 0.0453). The experimental group showed a statistically significant reduction in anxiety levels after 15 minutes of music listening (p = 0.0441), specifically with regard to the behavioral domains of activity, vocalization, emotional expression and apparent awakening state. Conclusion: music listening emerges as a potential nursing intervention for relief of preoperative anxiety in children undergoing surgical procedures. RBR-7mcr59.


Introduction
Pediatric hospitalization is a significant event in the lives of children and their families and usually tends to be a traumatic and stressful event, as it implies deprivation in the affective, cognitive and leisure spheres, and it is even more intense when associated with surgical procedure or if it is the child's first hospital experience (1) . It is estimated that between 40% and 75% of children undergoing surgery experience anxiety and fear in the preoperative period (2) , which are manifested by psychological and physiological changes.
In addition to the need of physio-biological care, it is important that nurses are attentive of the psychological, emotional, social and cultural needs of children, issues often ignored by the health team, which focuses mainly on restoring the organ weakened by the surgical procedure than on providing humanized, atraumatic and holistic care (3) .
Musical intervention is a therapeutic resource that has been increasingly used in nursing care as a complementary therapy to promote relaxation, emotional and spiritual comfort, distraction, wellness sensation (4) and relief of pain in hospitalized patients (5) .
Despite the use of musical intervention by nursing, the therapeutic effectiveness of music has not yet been clearly established (6) . Specifically in relation to the use of musical intervention applied to children undergoing surgical procedures, there are few national studies (6)(7) , with highlight to a clinical trial that evaluated the therapeutic effect of music on pain in the postoperative period in children undergoing cardiac surgery (7) . Therefore, considering the issue of children   (8) .
Pre-school children (3-6 years) and schoolchildren (6-12 years), of both genders, undergoing elective surgery were included. The rationale for selection of children at these ages was based on prior knowledge of the age profile of the surgical unit demand, which was very variable. Therefore, it was necessary to consider such age range in order to enable data collection, in addition to the limitation of the validated tools used to evaluate preoperative anxiety in children, mainly limited to the Yale Preoperative Anxiety Scale, which covers precisely these age groups.
Children undergoing emergency surgery; who received pre-anesthetic medications before or during music listening; and/or those with hearing or cognitive problems reported by the parents/guardians of the child were excluded. It is noteworthy that all participating children were hospitalized on the same day of surgery and subject to general anesthesia.
For sample size calculation, given the scarcity of published data regarding the variables of interest, it was used the Central Limit Theorem, which ensures that the distribution of sample means derived from samples larger or equal to 30 approximates the normal distribution for any population (9) .  The conventional care of the Pediatric Surgical Unit consisted in providing some toys and a TV, as well as the presence of the family and other children who were also awaiting surgery. All children participating in this study, both in the CG and EG were exposed to conventional care and these distracting factors were not controlled in this study, except in the EG, in which the participating children were also exposed to music listening for a specific period of 15 minutes. Sony NWZ-B172F MP3 player with disposable Bright 0025 in-ear headphones or Acorde SH-S1 multimedia MP3 headphones, used mainly for children with small outer ear. After each use, the headphones were cleaned with 70% alcohol, according to standard precautions in audiology (11) .
The choice of the 15 minutes duration period for the music listening was based on the average duration indicated by studies carried out in adult populations, varying from 15 to 30 minutes (10) or from 20 to 30 minutes (12) , since there was no strong evidence indicating the minimum time needed.
Anxiety, the dependent variable of this study, was assessed using indicators of physiological and behavioral variables. The indicators of physiological variables were heart rate (HR), respiratory rate (RR), blood pressure (BP) and oxygen saturation (SpO2). BP and HR were measured using the automatic Omron HEM-710INT blood pressure monitor and the Omron H003DS small adult blood pressure cuff; and, in the cases of children with arm circumference higher than 23 cm, it was used the Omron HEM-CR24 cuff. A pediatric fingertip oximeter, PM100D New Tech, was used to measure the SpO 2 . The RR, in turn, was measured by observing the number of breaths/min.
In order to assess the behavioral variables of anxiety, it was used the modified Yale Preoperative Anxiety Scale (m-YPAS), an instrument validated and translated in Brazil, which has been widely used in international (13)(14) and national (2,15)  of anxiety (2) .
As for the blinding, children were masked in relation to the musical intervention by adapting the strategy used in an Australian study (16) , in which the participants in the control group also listened to music, but only after the completion of data collection. As in that study, children were not told which group they belonged, but they knew they would listen to music. Although the research team was not masked and knew who belonged to the CG and EG, the children did not know how distinguish because all listened to music. In the case of CG, the researcher provided MP3 Players for children to listen to the music at the time that the measurements had been completed, that is, after the two measurements of physiological and behavioral variables of anxiety.
The research team was composed of the lead researcher and two undergraduate Nursing students.
The students received prior training for the application and completion of the m-YPAS and the proper handling Rev. Latino-Am. Enfermagem 2016;24:e2841 of the equipment used for measuring the physiological variables, but no interobserver reliability analysis was carried out during training and data collection.
In addition to the participants, the statistical staff was also masked, since before the data be available, the groups CG and EG were coded as G1 and G2 to prevent the statisticians from distinguishing the group receiving the intervention. Thus, although the research team was not blinded, yet this study is characterized as double-blind, as the participants and statistical staff were blinded.

Results
Of the 113 participants assessed for eligibility, 17 refused to participate and 96 were randomly allocated to the EG or the CG, and only 52 children were included in the final sample, as detailed in Figure 1.  (Table 1).   In the analysis of physiological variables, the preschool and school ages were considered separately, since each age group has a different average for the physiological variables. It was found, by analysis of variance (ANOVA), that there was a statistically significant difference of triple interaction among the variables age group, group and time on the heart and respiratory rates (Table 3).

Discussion
In this study there was a predominance of males and genitourinary surgeries, which is justified in that they comprise 60% of the pediatric surgeries demand (17) , followed by phimosis, hypospadias, hydrocele and cryptorchism because they are surgical conditions performed only in male. The mother was the child's main accompanying person in both groups, fact widely described in the pediatric literature (2) .
A sample loss rate was 54%, which contrasts with the average dropout rate in studies related to musical intervention in adults (12) , comprising 0-13% of the total sample. One of the main causes of sample losses, particularly in the EG, was the interruption of the music listening due to the musical style and duration of the intervention.
Refusals to participate because of the musical style were also found in a study using classical music to children in the postoperative period (7) . Some studies point out that the musical preferences of participants must be met, considering that there is a greater impact and a Franzoi MAH, Goulart CB, Lara EO, Martins G.
higher correlation with the degree of relaxation (12,18) , and songs considered stimulating may also be used (18) . In this way, these studies question the music considered as sedating and attribute the effects of music not only to the structural characteristics of the musical work, but also to the extramusical aspects such as preference The other losses were related to the service routine, as routing to the surgical center before completing the intervention and administration of sedatives, reasons that are similar to those described in Cochrane's systematic review (12) . This indicates the need to develop more clinical trials with hybrid research designs, which simultaneously assess the effect of the intervention under study and the implementation of this strategy in clinical practice (19) , since the healthcare services are dynamic and "difficult-to-monitor" scenarios.
On analyzing the mean of the m-YPAS scores, it was noted that it was lower in the EG in the two times (p = 0.0132), which did not occur in the CG. The reduction of almost 31% in the m-YPAS scores, from 40.77 at the basal time to 28.26 in the post-intervention time, is related to the music listening, since this was the only intervention performed in the EG during this time interval, thus corroborating the studies that also found statistical significance for the group-time interaction (13)(14) . the two groups, corroborating other studies (7,13) . It is worth mentioning that this research is one of the few that considered the specificity of age range in the analysis of physiological variables, as in most studies, the analysis included participants of different ages, without considering physiological values, according to pediatric age groups (7,13) .
Among the limitations of this research, it is mentioned the reduced size of the sample and the absence of an inter-observer reliability analysis in the application of the m-YPAS, aspects that may cause selection bias and external validity bias. In addition, the selected musical genre, combined with the expanded age range of participants, which ranged from 3 to 12 years, and the duration of the intervention contributed to the high dropout rate among participants allocated in the EG. It is suggested that future studies include narrower age groups, considering that the musical preferences may change with age, compare the selection of sedative songs with the musical preferences of children, and investigate the effects of music listening with a duration of less than 15 minutes.
Furthermore, for being a research that uses music, it is important that the children's hearing conditions are assessed more accurately, based not only on the reports of the child's parents/guardians, but also in simple tests used in nursing to assess hearing acuity, such as the whisper test, which would require more time for data collection.
It is worth mentioning that this pilot study was conducted with high methodological rigour, based on the CONSORT guidelines, which enables the replication of this study and the use of its findings in future systematic reviews. In addition, it subsidizes new studies that allow the incorporation of music listening as an evidence-based nursing intervention in the care of children undergoing surgical procedures.

Conclusion
There was a statistically significant difference between the groups regarding preoperative anxiety only