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META-ANALYSIS

The Effect of Perioperative Music on Medication Requirement and Hospital Length of Stay

A Meta-analysis

Fu, Victor X. MD∗,†; Oomens, Pim MD∗,†; Klimek, Markus MD, PhD; Verhofstad, Michiel H. J. MD, PhD; Jeekel, Johannes MD, PhD

Author Information
doi: 10.1097/SLA.0000000000003506

Abstract

A majority of patients continues to experience moderate to severe postoperative pain,1 which is a risk factor for delayed hospital discharge2 and the occurrence of postoperative complications,3,4 persisting chronic pain and the predominant factor for the immediate postsurgical quality of life.5 Opioid analgesics are the primary treatment modality for acute postoperative pain, which is the second most common reason to prescribe opioids.6 However, opioid-related side effects are common.7,8 Opioid use is considered a risk factor for pruritus, nausea, vomiting, drowsiness, urinary retention and the development of delirium.9 Higher opioid doses also increase the incidence of postoperative ileus and respiratory depression.10,11 Moreover, persistent opioid use in surgical patients is quite prevalent. Earlier studies reported that 5.9% of patients still filled an opioid prescription 3 to 6 months after minor surgical procedures,12 whereas over half of the patients receiving 90 days of continuous opioid medication still use opioid analgetics 1 year later.13 Both opioid prescription dosage and duration of use are important predictors for chronic opioid use.6 The concomitant use of benzodiazepines can potentially increase the risk of adverse effects, delirium, and prolonged opioid misuse even more.11

Despite these common adverse events and an increase in opioid-related deaths, opioid prescription rates have currently reached epidemic proportions.6 Therefore, there is an increasing interest in nonpharmacological interventions to reduce both postoperative pain and opioid consumption. Recently, several studies have reported beneficial effects of perioperative music.14–16 The purpose of this systematic review and meta-analysis is to assess and quantify the effect of perioperative music as a nonpharmacological intervention on medication requirement before, during and after invasive, surgical procedures. Secondary outcomes are the effect of perioperative music on length of stay and cost reduction.

METHODS

This systematic review and meta-analysis adheres to the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines and has been registered with PROSPERO (CRD42018093140).

Literature Search Strategy

A literature search using the exhaustive literature search method was performed with a biomedical information specialist.17 The databases Embase, Medline Ovid, Web-of-science, Scopus, Cochrane central, Cinahl, PsychINFO Ovid, and Google Scholar were searched from date of inception until January 7th, 2019. The full search terms and number of search results of each database are detailed in Appendix A, http://links.lww.com/SLA/C758. Also, manual cross-referencing of the included studies was performed.

Study Screening and Selection

Three reviewers (V.F., P.O., and V.E.) independently identified eligible studies using a 2-stage approach. First, title and abstract of all identified papers screened, followed by reading of the full text if eligibility criteria were matched. Inclusion criteria for this systematic review were all available, peer-reviewed, full-text articles of randomized controlled trials in the English language, containing adult patients ≥18 years old undergoing an inhospital or outpatient invasive, surgical procedure, investigating the use of recorded music before, during and/or after surgery with either medication requirement, hospital length of stay or direct medical costs as outcome measures. As these predefined outcome measures were often secondary outcomes and therefore not always mentioned in titles or abstracts, the 3 reviewers screened all studies full text for potential review inclusion if during the title and abstract screening process music as a perioperative intervention in adult patients was investigated. The music intervention was predefined as vocal sound, instrumental sound or both, containing the elements melody, harmony, and rhythm. Therefore, studies investigating solely nature sounds were excluded. Studies investigating live music with a music therapist were also excluded, because of the possibility that the effect is caused by the presence of the musical therapist and the irreproducibility of the study. Finally, studies investigating music with an additional, concomitant intervention were excluded, except if this additional intervention was used in both the intervention and control group (for example, the music intervention occurred during bed rest, and the control group received only bed rest). Disagreements between the investigators were resolved by referring to the supervisor (J.J.).

Data Extraction

Study data were independently extracted by the 3 reviewers (V.F., P.O., and V.E.) using a custom, predesigned Microsoft Excel 2010 document. Risk of bias was also independently assessed using the Cochrane Collaboration's tool for assessing risk of bias in randomized trials.18 Authors of included studies were contacted for additional information if necessary. All data was mutually discussed and disagreements between the investigators were resolved by referring to the supervisor (J.J.).

Statistical Analysis

Data were analyzed with the open-source, meta-analysis software OpenMeta-Analyst, which uses R as the underlying statistical engine.19 Random effect models were used, because heterogeneity between the included studies was assumed to be present. Standardized mean differences (SMD) and absolute mean differences were calculated with 95% confidence interval (CI). Studies were included for meta-analysis if mean values and standard deviations (SDs) of the outcome measures were reported. Opioid doses were converted to milligrams (mg) of morphine equianalgesic (ME), with 1 mg ME being equivalent to 1 mg parenteral morphine. If interquartile ranges or ranges were reported, an approximation of the SD was calculated by dividing the interquartile range by 1.35 and the range by 4. When the standard error of mean was reported, SDs were calculated by multiplying the standard error of mean with the square root of the number of patients.18 Publication bias was visually assessed using funnel plots, if more than ten studies were included in the meta-analysis. Heterogeneity was analyzed using the I2-test. Statistical significance was inferred at P-value <0.05.

If studies included several music groups, the means and SDs of the music groups were pooled to an approximated mean and SD of the entire group.18 If this was not appropriate, the music group that offered patients the choice to select from a preselected music list was preferred for meta-analysis. Choosing music from a preselected playlist has been observed to have a more beneficial effect on postoperative pain, compared to the own favorite music of the patient or preselected music without offering any choice.16 If studies included several control groups, only the group which resembled standard perioperative patient care the most was included for meta-analysis.

RESULTS

The literature search yielded 2414 results. A total of 1524 titles and abstracts were screened after removal of duplicates and 154 articles were assessed full text. Fifty-five studies (4968 patients) were included in the qualitative synthesis and 33 studies (2390 patients)20–53 in the meta-analysis (Fig. 1). There was a high agreement rate of over 85% between the 3 reviewers on study inclusion, risk of bias assessment, and data extraction, and all disagreements could be resolved through mutual discussion.

FIGURE 1
FIGURE 1:
PRISMA Flow diagram. N indicates number of studies.

Study Characteristics

A detailed overview of the study characteristics is presented in Table 1. The music intervention was assessed in a wide range of different surgical procedures. General anesthesia was the most commonly used anesthesia method during surgery in 36 studies (65%), whereas locoregional anesthesia was used in 8 studies (15%). Eight studies (15%) did not report the anesthesia method used and 3 studies (5.5%) contained different surgical procedures with different anesthesia methods. The moment of music intervention varied. Music was played solely preoperatively in 3 (5.5%), intraoperatively in 10 (18%), postoperatively in 25 (45%), and on multiple moments in 15 studies (27%). Two studies by the same author contained both an intraoperative music intervention group and a second music intervention group in which the intervention was solely applied postoperatively.

TABLE 1 - Study Characteristics
Study ID Surgical Procedure Anesthesia Intervention Moment Duration N Control N Outcome Parameters
Allred, 2010 Total knee arthroplasty General or spinal with femoral block Choice of easy listening, nonlyrical music Postoperatively POD 1, 20 min before and after first ambulation 28 Quiet rest period 28 Postoperative opioid requirement
Ames, 2017 Surgical procedures requiring ICU stay General MusiCure Postoperatively POD 1-2, 50 min, 1-8 times 20 50 min quiet rest 21 Postoperative opioid requirement
Ayoub, 2005 Urological procedures Regional Own favorite music Intraoperatively Procedure duration 31 Headphones with operation noise recording 28 Intraoperative propofol requirement
PACU length of stay
Bansal, 2010 Abdominal, urological, or lower extremity surgery Spinal Choice of folk, classical, religious, soothing music Intraoperatively Not specified 50 Occlusive headphones 50 Intraoperative midazolam requirement
Binns-Turner, 2011 Mastectomy General Choice of classical, easy-listening, new age, inspirational music PreoperativelyIntraoperativelyPostoperatively Not specified 15 Blank iPOD with occlusive headphones 15 Intraoperative opioid requirementPostoperative opioid requirementPACU length of stay
Blankfield, 1995 Coronary artery bypass surgery General Dreamflight II by Herb Ernst IntraoperativelyPostoperatively Procedure duration and 2 × 30 min daily postoperatively 32 Blank tape intraoperatively and standard care postoperatively 29 Postoperative opioid requirementICU length of stayHospital length of stay
Chen, 2015 Total knee replacement Not specified Chinese piano and violin music PreoperativelyPostoperatively Total 120 min 15 Standard care 15 Postoperative opioid requirement
Ciğerci and Özbayir, 2016 Coronary artery bypass surgery General Choice of Turkish classical and folk music PreoperativelyPostoperatively 90 min before surgery, after surgery 30 min in ICU and 30 min each day 34 Standard care 34 Postoperative opioid requirement
Cutshall, 2011 Coronary artery bypass graft and/or cardiac valve surgery General Choice of 4 CD's Postoperatively 2 × 20 min on POD 2–4, 120 min in total 49 Standard care with bed rest for 20 min 51 Postoperative opioid requirementHospital length of stay
Dabu-Bondoc, 2010 Outpatient surgery General Own favorite music Preoperatively Intraoperatively Preoperative 30 min, procedure duration 20 Intraoperatively headphones with white noise 20 Intraoperative propofol requirementIntraoperative opioid requirementPostoperative opioid requirementPACU length of stay
Easter, 2010 Elective outpatient surgery procedures Not specified Choice of easy-listening, country, gospel, rock Postoperatively During length of stay in PACU 111 No music 102 Postoperative opioid requirementPACU length of stay
Ebneshahidi and Mohseni, 2008 Elective cesarean section surgery General Own favorite music Postoperatively 30 min in the recovery room 38 Headphones without music 39 Postoperative opioid requirement
Finlay, 2016 Total knee arthroplasty Spinal with nerve block 32 tracks with range of genres Postoperatively 15 min 72 Headphones without music 17 Postoperative opioid requirement
Good, 1995 Elective, open abdominal surgery General Choice of sedative nonlyrical piano, harp, synthesizer orchestral or slow jazz music Postoperatively 60 min during the first 2 d after surgery 21 Standard care 21 Postoperative opioid requirement
Good, 1999 Elective, open, major abdominal surgery General Choice of taped soothing music PreoperativelyPostoperatively First 2 d after surgery 151 Standard care 152 Postoperative opioid requirement
Graversen and Sommer, 2013 Laparoscopic cholecystectomy General Musicure using music pillow PreoperativelyIntraoperativelyPostoperatively Before surgery start until day care discharge 40 Standard care 35 Intraoperative propofol requirementIntraoperative opioid requirementPostoperative opioid requirementDay care unit length of stay
Heitz, 1992 (Para)thyroidectomy or unilateral modified radical mastectomy General Choice of 3 instrumental classical tapes Postoperatively 15 min after PACU arrival until discharge 20 Headphones without music 20 Postoperative opioid requirement
Standard care 20 PACU length of stay
Hook, 2008 Moderate or major elective surgery General Choice of Malay, Western, Chinese, soothing music Preoperatively Postoperatively 60 min before and 180 min after surgery 51 Standard care 51 Postoperative opioid requirement
Iblher, 2011 Open heart surgery (coronary bypass, valvular transplant, or both combined) General Baroque organ, flute, string orchestra music with 60-80 bpm Postoperatively 60 min after ICU admission 25 Standard care 25 Postoperative opioid requirement
60 min after sedation stop 24 Postoperative catecholamine requirement
Ignacio, 2012 Elective spine, hip or knee surgery General Not specified Postoperatively 2 × 30 min 12 No music 9 Postoperative opioid requirement
Ikonomodou, 2004 Laparoscopic sterilization or tubal dyeing General Peaceful pan flute music PreoperativelyPostoperatively 30 min before and after surgery 29 Blank compact disk 26 Postoperative opioid requirement
Johnson, 2012 Gynaecological outpatient surgery Not specified Choice of soft country, classical/new age and inspirational music PreoperativelyIntraoperativelyPostoperatively On average 212 min 43 Headphones without music 35 Postoperative opioid requirement
Standard care 41 PACU length of stay
Kar, 2015 Elective cardiac surgery under cardiopulmonary bypass General Raga therapy (Indian classical music) Preoperatively Intraoperatively 30 min before surgery and procedure duration 17 Headphones without music 17 Intraoperative sedative requirement Intraoperative opioid requirement
Kliempt, 1999 Diverse range of surgical procedures General Classical music Adagio Karajan Intraoperatively Procedure duration 25 Headphones without music 26 Intraoperative opioid requirement
Koch, 1998 Outpatient urological procedures Spinal Own favorite music Intraoperatively Procedure duration 19 Standard care 15 Intraoperative propofol requirementPACU length of stay
Koelsch, 2011 Total hip arthroplasty Spinal Joyful instrumental music Preoperatively Intraoperatively 120 min beforesurgery and procedure duration 20 Headphones with breaking sea waves noise 20 Intraoperative propofol requirement
Kumar, 2014 Hernia, breast, appendix and thyroid surgery Not specified Raga Ananda Bairavi (Indian classical music) Preoperatively Postoperatively At admission and POD 1–3 30 Standard care 30 Postoperative opioid requirement
Laurion and Fetzer, 2003 Gynecological, laparoscopic outpatient day surgery General Piano music PreoperativelyIntraoperativelyPostoperatively 2 times a day before surgery, procedure duration, PACU stay 28 Standard care 28 Postoperative opioid requirementPACU length of stay
Lepage, 2001 Nononcologic, outpatient or short-stay surgery Spinal Choice of pop, jazz, classical, new age PreoperativelyIntraoperativelyPostoperatively Anesthesia induction until recovery 25 Standard care 25 Perioperative midazolam requirement
Liu and Petrini, 2015 Thoracic surgery General Soft, melodious music 60-80 bpm Postoperatively 30 min daily on POD 1–3 56 Standard care 56 Postoperative patient-controlled analgesia requirement
Macdonald, 2003 Total abdominal hysterectomy Not specified Own favorite music Postoperatively 2–6 h on day of surgery 30 Standard care 28 Postoperative patient-controlled analgesia requirement
Masuda, 2005 Orthopedic surgery General and spinal Choice of Noh, Gagaku, classical or Enka music Postoperatively 20 min 22 Standard care 22 Hospital length of stay
McCaffrey and Loscin, 2006 Elective hip or knee surgery Not specified Choice of CD's Postoperatively 60 min 4 times a day 62 Standard care 62 Postoperative patient-controlled analgesia requirement
McRee, 2003 ‘Low risk’ surgery General, spinal, local and regional Soft piano music Preoperatively 30 min 13 Standard care 13 Postoperative opioid requirement
Migneault, 2004 Gynaecological surgery General Choice of jazz, classical, popular new-age or piano music Intraoperatively Procedure duration 15 Headphones without music 15 Intraoperative end-tidal isofluraneIntraoperative fentanyl requirementPostoperative opioid requirement
Miladinia, 2017 Abdominal surgery General Relaxing nonlyrical music with a bpm of 60–80 Postoperatively 3 × 10 min sessions on day of surgery 30 Standard care 30 Postoperative opioid requirement
Nielsen, 2018 Unspecified orthopedic, urological, gynaecological and general surgery Epidural, spinal and local Musicure Intraoperatively Procedure duration 58 Standard care 44 Intraoperative fentanyl requirementIntraoperative propofol requirement
Nilsson, 2001 Elective abdominal hysterectomy General Relaxing, calming music with sea waves sound Intraoperatively Procedure duration 30 Headphones with operation noise recording 28 Postoperative opioid requirement Hospital length of stay
Nilsson, 2003a Daycare surgery: varicose veins, open inguinal hernia repair General Soft, relaxing and calming classical music Postoperatively PACU arrival until patient chose to stop 62 Headphones without music 63 Postoperative opioid requirement
Nilsson, 2003b Daycare surgery: varicose veins, open inguinal hernia repair General Soft instrumental new-age synthesizer music Intraoperatively Procedure duration 51 Headphones without music 49 Postoperative opioid requirement
Postoperatively 1 h after PACU arrival 51
Nilsson, 2005 Open hernia repair (Lichtenstein) General Soft, new-age synthesizer Intraoperatively Procedure duration 25 Headphones without music 25 Postoperative opioid requirement
Postoperatively 1 h after PACU arrival 25
Nilsson, 2009a Coronary artery bypass graft and/or aortic valve replacement General MusiCure using music pillow Postoperatively 30 min on POD1 20 Standard care 20 Postoperative opioid requirement
Nilsson, 2009b Coronary artery bypass graft or aortic valve replacement General Soft, relaxing, new age style music using music pillow Postoperatively 30 min on POD1 28 Standard care 30 Postoperative opioid requirement
Reza, 2007 Elective caesean section General Soft, instrumental, Spanish style guitar music Intraoperatively Procedure duration 50 White music 50 Postoperative opioid requirement
Santhna, 2015 Total knee replacement surgery Not specified Choice of soothing and relaxing nonlyrical piano or violin music Postoperatively 60 min, 4 times a day 20 Standard care 20 Postoperative opioid requirement
Schwartz, 2009 Coronary artery bypass graft surgery General Light piano music Postoperatively Patient's choice in ICU 35 Standard care 32 ICU length of stayHospital costs
Sen, 2009a Local urological procedures Propofol PCS with local infiltration Own favorite music Intraoperatively Procedure duration 30 Earphones without music 30 Intraoperative propofol requirement
Sen, 2009b Elective caesarian section General Own favorite music Preoperatively 60 min 50 Headphones without music 50 Postoperative opioid requirement
Sen, 2010 Elective caesarian section General Own favorite music Postoperatively 60 min 35 No music 35 Postoperative opioid requirement
Szmuk, 2008 Laparoscopic hernia or cholecystectomy General Choice of pop-rock, classical or Israeli music Intraoperatively Procedure duration 20 Headphones without music 20 Intraoperative end-tidal sevoflurane Postoperative opioid requirement
Tse, 2005 Endoscopic sinus surgery or tubinectomy Not specified Choice of Chinese, Western or own favorite music Postoperatively 2 × 30 min after surgery and on POD1 27 Standard care 30 Postoperative analgesic medication requirement
Vaajoki, 2012 Elective major abdominal midline incision surgery General Choice of 2000 popular music songs Postoperatively Total of 7 × 30 min 83 Standard care 85 Postoperative opioid requirementHospital length of stay
Zhang, 2005 Total abdominal hysterectomy General with spinal or epidural Own favorite music Intraoperatively Procedure duration 55 Headphones without music 55 Intraoperative propofol requirement
Zhou, 2011 Radical mastectomy General Choice of 202 songs Postoperatively 2 × 30 min daily 60 Standard care 60 Hospital length of stay
Zimmerman, 1996 Coronary artery bypass graft surgery General Choice of 5 soothing music tapes Postoperatively 30 min daily during POD1-3 32 Scheduled rest of 30 min 32 Postoperative opioid requirement
Hospital length of stay
Denotes study included in meta-analysis.CD indicates compact disk; ICU, intensive care unit; Min, minutes; N, number of patients; PACU, post-anesthesia care unit; PCS, patient-controlled sedation; POD, postoperative day; d, days; h, hours.

The music intervention was commonly described as soothing, relaxing, nonlyrical, instrumental music and was preselected by the research team in most studies (45 studies, 82%): patients could select music from a preselected list in 21 studies (38%), whereas no choice was offered in 24 studies (44%). The preferred music of the patient was used in 9 studies (16%), whereas 1 study (1.8%) did not elaborate on the exact music intervention. In a majority of studies, music delivery was achieved using a music player and headphones (41 studies, 75%). Other reported music delivery methods were a music pillow (3 studies, 5.5%), CD-player (3 studies, 5.5%), personal stereo (1 study, 1.8%), an integrated music system in the patient room (1 study, 1.8%), or not specified (6 studies, 11%). The control group consisted of standard care (26 studies, 47%), headphones without music (16 studies, 29%), headphones with white noise or recorded OR noise intraoperatively (5 studies, 9.1%), no music without further specification (3 studies, 5.5%), or an unspecified rest period (3 studies, 5.5%). Two studies (3.6%) had both a standard care and headphones without music group acting as control.

Risk of Bias Assessment

An overview of the risk of bias assessment is presented in Fig. 2 and a more detailed description in Appendix B, http://links.lww.com/SLA/C758. A potentially high risk of selection bias was present in several studies (8 studies, 15%),24,29,47,54–58 as sequence generation was done using odd and even numbers, days of the week or hospital record number. Several studies provided insufficient details to assess selection bias (14 studies, 25%).20,22,26–28,30,32,36,38,40,59–62 A moderate to high risk of performance bias was present, as blinding of patients for the music intervention is only possible when the intervention is performed solely intraoperatively during general anesthesia. Blinding of personnel can theoretically be achieved by using headphones for all patients, but is more difficult in practice when patients are free to change music tracks or adjust the volume. Five studies (9.3%) employed a study design in which patients, surgical personnel and outcome assessors were all blinded adequately.38,41,46,63,64 The “other risk of bias” category was reported as unclear in more than half of the studies (36 studies, 65%), because one of the baseline characteristics age, sex, weight, or the duration of surgery, which can influence intraoperative and postoperative medication requirement, was not reported. There was a high risk of other bias because of significant difference in either surgery duration or age between the music and control group in 3 studies.25,36,45 A funnel plot to investigate publication bias of studies assessing the effect of perioperative music on postoperative opioid requirement showed a near funnel-shaped plot, lacking a small number of studies in the lower-left corner which could be indicative of studies with relatively small samples sizes and small effect sizes being potentially absent (Appendix C, http://links.lww.com/SLA/C758).

FIGURE 2
FIGURE 2:
Risk of bias summary. Risk of bias summary graph.

Opioid Requirement

The effect of perioperative music on postoperative opioid requirement was assessed in 42 studies, of which 2022–24,26–32,38,39,41–43,45,46,49,50 could be included in the meta-analysis. Thirteen studies presented the postoperative opioid dose requirement as morphine equivalents (ME) or parenteral morphine. In 3 studies, postoperative ketobemidone requirement was evaluated, which are equipotent to parenteral morphine (1 mg parenteral ketobemidone = 1 mg ME65). Postoperative parenteral tramadol requirement (10 mg parenteral tramadol = 1 mg ME66) was assessed in 3 studies and pethidine requirement in 1 study (10 mg pethidine = 1 mg ME67). Length of follow-up differed, as 5 studies assessed opioid requirement during the stay in the post-anesthesia care unit,26,29,30,32,43 3 within the first 2 postoperative hours27,42,44 and 2 within the first 12 postoperative hours.39,46 Ten studies (50%) assessed opioid requirement for minimally 24 hours after surgery or longer.22–24,28,31,38,41,45,49,50 General anesthesia was used during surgery in all of these 20 studies.

Perioperative music significantly reduced postoperative opioid requirement (pooled SMD −0.31 [95% CI −0.45 to −0.16], P < 0.001, I2 = 44.3, N = 1398 patients) (Fig. 3). The mean overall absolute reduction in postoperative opioid requirement of the 8 studies which measured postoperative opioid requirement during post-anesthesia care unit stay or within the first 2 postoperative hours was −1.0 mg ME (95% CI −1.6 to −0.49, P < 0.001, I2 = 10.5, N = 698 patients). The mean absolute reduction in postoperative opioid requirement of the 10 studies which measured postoperative opioid requirement for at least 24 hours or more after surgery was −4.4 mg ME (95% CI −8.2 to −0.65, P = 0.022, I2 = 69.6, N = 598 patients). The mean absolute reduction in 5 of these studies which measured opioid requirement for at least 3 postoperative days and involved major surgical procedures was −9.82 mg ME (95% CI −17.9 to −1.70, P = 0.018, I2 = 48.8, N = 298 patients).22–24,31,41 Intraoperative music during general anesthesia in 3 of the 20 studies in which the patients, surgical staff, and outcome assessors were all blinded did not significantly reduce postoperative opioid requirement (pooled SMD −0.16 [95% CI −0.63 to 0.31], P = 0.49, I2 = 57.1, N = 188 patients).38,41,46

FIGURE 3
FIGURE 3:
Effect of perioperative music on postoperative opioid requirement. Forest plot presenting the effect of perioperative music on postoperative opioid requirement (milligrams of morphine equianalgesics). CI indicates confidence interval; Mean, mean milligrams of morphine equianalgesics; N, total number of patients in study; NC, number of patients in the control group; NM, number of patients in the music group; PACU, post-anesthesia care unit; SD, standard deviation in milligrams of morphine equianalgesics; SMD, standardized mean difference.

The effect of preoperative and/or intraoperative music on intraoperative opioid requirement was assessed in 7 studies.23,26,29,33,38,40,63 Meta-analysis was not performed because of insufficient data presented, the broad variation in the types of surgery performed and difference in surgery duration.

Intraoperative Sedative Requirement

The effect of perioperative music on intraoperative sedative medication requirement was assessed in 13 studies (846 patients). Propofol requirement was assessed in 9,20,26,29,33–35,40,48,51 midazolam requirement in 3,21,33,36 and end-tidal inhalation anesthetics concentration in 2 studies.38,64 In one of these aforementioned studies, both propofol and midazolam were administered intraoperatively for sedation.33 Incremental intraoperative sedative medication doses were administered based on sedation depth, which was either assessed using a bispectral index monitor or a validated sedation scale. The infusion rate was patient-controlled in 4 studies.20,34,36,48 The manner of sedation depth assessment and whether or not infusion rate was patient-controlled is specified in Fig. 4.

FIGURE 4
FIGURE 4:
Effect of perioperative music on intraoperative sedative medication requirement. Forest plot presenting the effect of perioperative music on intraoperative propofol (above) and midazolam (below) medication requirement. CI indicates confidence interval; Mean, mean milligrams of propofol or midazolam; N, total number of patients in study; NC, number of patients in the control group; NM, number of patients in the music group; OAA/S, observer assessment of alertness/sedation scale; PACU, post-anesthesia care unit; PCS, patient-controlled sedation; SD, standard deviation in milligrams of propofol or midazolam; SMD, standardized mean difference.

Perioperative music significantly reduced intraoperative propofol requirement (pooled SMD −0.72 [95% CI −1.01 to −0.43], P < 0.00001, I2 = 61.1, N = 554 patients, 9 studies) (Fig. 4). All included studies evaluating the effect of music on propofol requirement, except 229,40 that did not specify the manner of sedation depth assessment, reported that the level of sedation did not differ between the music and control group. This reduction in intraoperative propofol requirement remained present when these 2 studies29,40 were excluded from the analysis (pooled SMD −0.86, [95% CI −1.18 to −0.53], P < 0.00001, I2 = 54.9, N = 377 patients, 7 studies), and when the 3 studies with patient-controlled propofol infusion rate were analyzed as a separate subgroup (pooled SMD −0.82 [95% CI −1.25 to −0.38], P = 0.00025, I2 = 40.1, N = 153 patients). Perioperative music also significantly reduced intraoperative midazolam requirement (pooled SMD −1.07 [95% CI −1.70 to −0.44], P < 0.001, I2 = 73.1, N = 184 patients) (Fig. 4), while achieving the same sedation depth.

Length of Stay and Medical Costs

The effect of perioperative music on length of stay was assessed in 17 studies, of which 9 studies could be included in the meta-analysis. Total length of hospital stay of surgical inpatients was assessed in 4 studies,22,25,37,52 length of stay in the post-anesthesia or day care unit of patients undergoing outpatient surgery in 4 other studies20,26,29,34 and intensive care unit length of stay in 1 study.47 Perioperative music did not significantly reduce length of stay (pooled SMD −0.18 [95% CI −0.43 to 0.067], P = 0.15, I2 = 56.0, N = 600 patients) (Fig. 5). When analyzing the studies with outpatient surgical patients (pooled SMD −0.053 [95% CI −0.35 to 0.24], P = 0.73, I2 = 13.1, N = 208 patients) and inpatient operations (pooled SMD −0.21 [95% CI −0.66 to 0.25], P = 0.37, I2 = 75.2, N = 325 patients) separately, length of stay was also not reduced.

FIGURE 5
FIGURE 5:
Effect of perioperative music on length of stay. Forest plot presenting the effect of perioperative music on length of stay. CI indicates confidence interval; Mean, mean length of stay; N, total number of patients in study; NC, number of patients in the control group; NM, number of patients in the music group; PACU, post-anesthesia care unit; SD, standard deviation; SMD, standardized mean difference.

Intensive care unit costs tended to be lower in 1 pilot study [3911 (SD 1566) versus 4365 dollars (SD 2632), P = 0.09], as time spent in the intensive care unit was significantly reduced in the music group compared to the control group.47 However, this did not reach statistical significance and overall direct medical costs during hospital length of stay did not differ significantly.

DISCUSSION

This systematic review and meta-analysis of 55 randomized controlled trials evaluates the effect of perioperative music on intraoperative and postoperative medication requirement and length of stay. Because of the current opioid epidemic, which has increased opioid-related deaths and led to a substantial financial burden,6,68 there is an increased interest in nonpharmacological interventions that can reduce both postoperative pain and opioid consumption. Perioperative music reduced opioid consumption by 4.4 mg ME in studies measuring opioid requirement for at least 24 hours or more after surgery. In studies measuring at least 72 hours or more after major surgical procedures, a reduction of 9.82 mg ME was observed. Opioid-related adverse effects have been observed to be dose-dependent and an increased requirement of 3 to 4 mg ME after surgery has been related to the occurrence of 1 additional, clinically meaningful, adverse event.69 A maximum daily dose exceeding 2 mg of parenteral hydromorphone, equivalent to 10 to 14 mg ME,70 were significantly associated with the development of postoperative ileus after colorectal surgery, increasing morbidity, length of hospital stay, and direct medical costs.71 Both a higher daily opioid dose and a prolonged use in opioid-naive patients also increase the risk of chronic opioid use.6 As more elderly patients are nowadays undergoing surgery, this group would be of particular interest to the use of perioperative music, as they have an increased risk of opioid-related adverse effects and chronic abuse because of polypharmacy and comorbidity.72,73

Perioperative music also significantly reduced both intraoperative propofol and midazolam requirement, whilst achieving the same sedation level. Midazolam is often used during locoregional anesthesia or as a preoperative anxiolytic, but is a risk factor for the occurrence of postoperative delirium.74 A higher level of preoperative anxiety has been associated with a higher amount of intravenous sedation requirement to induce and maintain adequate sedation level during surgery.75 Previous studies have reported a beneficial effect of perioperative music on anxiety levels,14–16 which could theoretically explain the reduced sedation dosage needed. Although a dose-dependent relation of sedative medication and intraoperative hemodynamic changes has been observed,76 the predictive outcome capabilities of intraoperative hemodynamics have only been investigated sparingly.77

No effect of perioperative music on length of stay was demonstrated. However, only 4 studies assessed total length of stay and organizational rather than patient factors are the most important predictors of delayed discharge.78 Moreover, almost half of the studies (44%) that assessed length of stay did so in patients undergoing minor surgery in the outpatient setting, making it unlikely to find a clinically relevant difference. Even though opioids are relatively cheap, opioids accounted for 1% of total hospital costs in an observational study of patients undergoing joint replacement surgery.79 As one of the most commonly performed procedures in the developed world, yearly costs in the United States alone amount to more than $20 billion.80 It is therefore likely that the beneficial effects of perioperative music on mediation requirement will also be observed financially, especially when taking into account the costs that come with opioid-related adverse effects.10

This meta-analysis has several strong points. A comprehensive literature search was performed with a dedicated biomedical information specialist. A predefined definition of music was used and studies with live music, a music therapist and concomitant interventions were excluded. In comparison to earlier performed meta-analyses investigating the effects of perioperative music, our focus was solely on medication requirement and length of stay in adult surgical patients. Vetter et al did observe a significant reduction in pain medication requirement by perioperative music in fourteen studies, but this was not significant for the subgroup of patients who received general anesthesia in 9 studies.15 The meta-analysis by Hole et al contained studies with both surgical and nonsurgical, diagnostic procedures leading to clinical heterogeneity, and did not differentiate between opioid, benzodiazepines, and sedative medication requirement.14 Nevertheless, this meta-analysis has limitations as well. The included studies contained different surgical patients, surgical procedures, and follow-up duration of the outcome assessment. This was reflected in the moderate to high level of heterogeneity observed. Medication requirement can be influenced by factors such as age, body weight, and the duration of surgery. Some of these baseline characteristics were not reported in the included studies, potentially increasing the risk of bias in interpreting results. Therefore, it is not entirely clear whether perioperative music can have the same beneficial effect size on medication requirement for all surgical procedures. Measurement duration of postoperative opioid requirement in 15 of the 20 studies was 24 hours after surgery or less. Consequently, the mean absolute reduction in mg ME in the music group was relatively low and perhaps does not reflect the full beneficial effect of perioperative music on medication requirement. Although a meta-regression analysis could be performed with covariates such as music intervention duration, music exposure moment relative to the surgical procedure (ie, preoperatively, intraoperatively, postoperatively, or multiple moments), operative severity (ie, minor, moderate, or major surgery), and measurement duration, this was not deemed appropriate as at least ten studies for each co-variate are recommended.18 Only postoperative opioids were assessed, as other analgesic medications were often not reported. Some included studies did report that perioperative music also reduced nonopioid analgesic requirement postoperatively.24,49

Our literature search did not include patient-reported outcome measures. However, it should be noted that patients in the included studies were extremely positive towards the use of perioperative music. Almost all patients (88% or higher) found perioperative music to be an enjoyable experience.23,35,55,56,81–83 Likewise, a majority would opt for music again in the future,21,25,28 even pro-actively asking for music in subsequent surgical procedures.21 Patient satisfaction was also markedly increased in the music group,48–51,56 with the only negative comments observed being from those who did not get music or related to the type of available music.25,84 Although side-effects of perioperative music could theoretically occur, none of the included studies reported any adverse effects. Specifically, no cardiorespiratory depressions were observed,34,51 while McCaffrey et al reported that perioperative music had a significant beneficial effect on delirium and confusion.56,85 In some studies, care was taken to restrict music volume and adhere to the noise and hearing loss guidelines to prevent hearing damage,86 whereas others allowed patients the option to adjust the music volume to their liking. The most well-known implemented nonpharmacological, multimodal interventions in surgical patient care are part of the guidelines collectively known as the Enhanced Recovery After Surgery protocols, which focus on reducing the physiological stress response to surgery by optimizing nutritional state, reducing opioid use and early mobilization.87 Originally introduced in colorectal surgical patient care, it has subsequently been implemented in a wide range of different surgical specialties with surgery-specific variations. Likewise, the use of perioperative music should be adapted to fit into the operative procedure, individual clinical setting, and wishes and requirements of the medical team. Although it is difficult to draw a firm clinical recommendation based on the data in our meta-analysis, 75% of studies assessing opioid requirement exposed patients to a total of 120 minutes perioperative music on average or less, delivered either before, during and/or on the first 2 days after surgery. Therefore, it seems that a relatively short exposure to music can already be beneficial, with a majority of the studies using a music player and headphones to avoid disrupting communication of the medical staff. Further research could focus on the effect of perioperative music on postoperative complications, clinical recovery, costs, and implementation.

CONCLUSIONS

Perioperative music can reduce postoperative opioid and intraoperative sedative medication requirement. Therefore, perioperative music may potentially improve patient outcome and reduce medical costs, as a higher opioid dosage is associated with an increased risk of adverse events and chronic opioid use. The use of perioperative music seems to be safe and patient-friendly, given the high patients satisfaction reported whilst no adverse effects were observed.

Acknowledgments

The authors thank W. Bramer, biomedical information specialist of the Medical Library, Erasmus MC University Medical Centre, Rotterdam, for his assistance with the literature search. The authors thank V.P.B. Elbers, BsC, Medical Student, for assistance in the literature screening. The authors thank A. Tomer, MsC, Statistician, for assistance in the statistical analysis.

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Keywords:

analgesia; medication requirement; music; opioids; perioperative patient care; propofol; sedation; surgery

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