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ORIGINAL ARTICLE
Soothing music can increase oxytocin levels during bed rest after
open-heart surgery: a randomised control trial
Ulrica Nilsson
Aim. To evaluate the effect of bed rest with music on relaxation for patients who have undergone heart surgery on postoperative
day one.
Background. Music intervention has been evaluated as an appropriate nursing intervention to reduce patients ‘pain, stress and
anxiety levels in several clinical settings, but its effectiveness in increasing patients’ subjective and objective relaxation levels has
not been examined.
Design. A randomised controlled trial.
Method. Forty patients undergoing open coronary artery bypass grafting and/or aortic valve replacement surgery were ran-
domly allocated to either music listening during bed rest (n= 20) or bed rest only (n= 20). Relaxation was assessed during bed
rest the day after surgery by determining the plasma oxytocin, heart rate, mean arterial blood pressure, PaO
2,
SaO
2
and
subjective relaxation levels.
Results. In the music group, levels of oxytocin increased significantly in contrast to the control group for which the trend over
time was negative i.e., decreasing values. Subjective relaxation levels increased significantly more and there were also a sig-
nificant higher levels of PaO
2
in the music group compared to the control group. There was no difference in mean arterial blood
pressure, heart rate and SaO
2
between the groups.
Conclusion. Listening to music during bed rest after open-heart surgery has some effects on the relaxation system as regards
s-oxytocin and subjective relaxations levels. This effect seems to have a causal relation from the psychological (music makes
patients relaxed) to the physical (oxytocin release).
Relevance to clinical practice. Music intervention should be offered as an integral part of the multimodal regime administered to
the patients that have undergone cardiovascular surgery. It is a supportive source that increases relaxation.
Key words: coronary artery bypass, music, nursing, oxytocin, postoperative care, relaxation
Accepted for publication: 30 September 2008
Introduction
Patients undergoing surgical treatment for coronary artery
disease and valvular heart disease begin to experience
anxiety when the decision to undergo surgery is made and
they remain anxious for up to three months after surgery
(Burg et al. 2003, Twiss et al. 2006). Studies indicate that
there is a correlation between high preoperative anxiety
levels and acute pain following breast surgery (Katz et al.
2005). In addition, patients with higher anxiety and depres-
sion levels preoperatively have higher postoperative pain and
analgesic requirements (Ozalp et al. 2003). Postoperative
anxiety can cause increased sensitivity to noise, which results
in increased autonomic response, sensory overload and sleep
deprivation leading to physiological problems that can
increase the duration of hospital stay (Caumo & Ferreira
Author:Ulrica Nilsson, PhD, RNA, Assistant Professor, Department
of Cardiothoracic Surgery and Centre for Health Care Sciences,
O
¨rebro University Hospital and School of Health, O
¨rebro University,
O
¨rebro, Sweden
Correspondence: Ulrica Nilsson, Assistant Professor, Centre for
Health Care Sciences, P.O. Box 1324, SE 70113 O
¨rebro, Sweden.
Telephone: +4619602844.
E-mail: ulrica.nilsson@orebroll.se
2009 The Author. Journal compilation 2009 Blackwell Publishing Ltd, Journal of Clinical Nursing,18, 2153–2161 2153
doi: 10.1111/j.1365-2702.2008.02718.x
2003). There is a need for interventions to reduce stress, pain
and anxiety by providing an environment that is more
conducive to healing and can be used as an integral part of
the multimodal regime administered to the patients under-
going surgery. One possible treatment could be music
intervention, used as an ‘audioanalgesia’, ‘audioanxiolytic’
and/or ‘audio relaxation’ defined as ‘ a supportive source of
environmental sound that stimulates and maintains relaxa-
tion as well reduces or controls distress by a self-manage-
ment technique’ (Nilsson 2008, p. 708). Music intervention
should not be mistaken for music therapy, which is an
expressive therapy that focuses on means of contact and
communication to achieve therapeutic relationships (Batt-
Rawden 2007).
Literature review
Studies with music intervention in the perioperative care have
shown evidence that soothing music by inhibiting stress by
reducing anxiety, sedative use (Nilsson 2008) and neurohor-
monal responses to psychological stress (Nilsson et al. 2005),
as well as postoperative pain (Good et al. 2001, Nilsson et al.
2003, 2005, Cepeda et al. 2006, Nilsson 2008). However,
soothing music seems to have minor effect on vital signs as
reduction of heart rate, blood pressure and respiratory rate
(Nilsson 2008). Studies with patients in the cardiac surgery
care, have found that music has some beneficial effects.
Cadigan et al. (2001) reported that patient who listened to
30 minutes of symphonic music with nature sounds during
bed rest because of procedural sheaths or an intra-aortic
balloon pump had reductions in blood pressure, respiratory
rate and psychological distress. Reduction in pain, heart rate
and respiratory rate was found after 45 minutes of self-
selected relaxing music in patients undergoing application of
a C-clamp after percutaneous coronary intervention (PCI)
treatment. However, oxygen saturation was also reduced
when listening to music (Chan 2007). Anxiety in coronary
artery bypass grafting and valvular surgery patients can be
reduced and intubation time can be decreased when listening
to self-selected relaxing music continuously throughout the
surgery and postoperatively in the intensive care area (Twiss
et al. 2006). Subjective anxiety levels can also decrease if
patients, after a brief session of relaxation, listen to 20 min-
utes of relaxing music postoperatively twice a day after open-
heart surgery. However, in this study, the music intervention
did not have any influence on blood pressure and heart rate
(Sendelbach et al. 2006). Voss et al. (2004) have reported
decreased anxiety and pain levels in patients who listen to
30 minutes of self-selected soothing music during chair rest
after open-heart surgery.
If music can reduce anxiety and pain as reported above, a
new challenge is to study if music can influence the relaxation
system, which incorporates oxytocin. Oxytocin is a hormone
synthesised in the hypothalamus and transported down axons
of the posterior pituitary for secretion in the blood (Evans
1997) (Petersson & Uvnas-Moberg 2007). The oxytocin
system operates in parallel with the stress response systems by
inhibiting sympathetic and hypothalamic–pituitary–adrenal
activity during stress (Evans 1997). Oxytocin also takes part
in cardiovascular regulation and its effects are exerted both
within the central nervous system and through peripheral
effects (Petersson & Uvnas-Moberg 2007). Oxytocin is
produced in both male and females, with similar central
oxytocinergic pathways and connections across genders. Low
oxytocin levels are present in children with abdominal pain
and there is a connection between low levels of oxytocin and
pain and anxiousness (Evans 1997). Furthermore, oxytocin
concentrations increase in amateur and professional singers
who have been attending singing lessons (Grape et al. 2003)
and also in males who have undergone tactile massage
(Wikstrom et al. 2003). Oxytocin has been measured during
bed rest in intensive care patients. Two groups were
compared; one with standard care and one intervention
group with tactile touch and standard care. No differences
were reported in oxytocin levels between the groups. How-
ever, both groups included relaxing music (Henricson et al.,
[unpublished]). It is therefore of interest to study if relaxing
music alone can enhance oxytocin release although, at
present, no such data have been presented.
Aim
The aim of the present trial was to compare the effect of bed
rest with or without music on relaxation after coronary
artery bypass grafting and/or aortic valve replacement
surgery on postoperative day one, by measuring changes in
plasma levels of oxytocin, haemodynamic parameters, oxy-
gen saturation and subjective relaxation levels.
Method
Sample and setting
A sample of 40 consecutive open-heart surgery patients on
their first postoperative day following a coronary artery
bypass grafting (CABG) and/or aortic valve replacement
(AVR) under general anaesthesia were considered for the
study. All patients were scored III on the American Society of
Anaesthesiologists (ASA) physical status classification system
i.e., patients with severe systemic disease. The patients were
U Nilsson
2154 2009 The Author. Journal compilation 2009 Blackwell Publishing Ltd, Journal of Clinical Nursing,18, 2153–2161
consecutively and prospectively enrolled between May 2006–
November 2006. Exclusion criteria were: undergoing an
emergency operation; start of surgery after 12 noon; previous
cardiac surgery; being treated with corticosteroids; the need
of an intra-aortic balloon pump or temporary pacemaker; not
extubated in the evening of the day of surgery; participation
in other studies any hearing impairment or difficulties with
cooperating during measurements.
Intervention
The patients were randomly allocated to two groups, one
music group (n= 20) and one control group (n= 20), using a
computer generated randomisation list drawn up by the
statistician. Three special research nurses allocated the next
available number on entry into the trial and conducted all
interventions and outcome assessments. The code was
revealed to the researcher only after recruitment, data
collection and laboratory analyses were complete.
All participants received scheduled rest in bed at 12 noon
at the first postoperative day. The patients in the music group
were also listening to music distributed through a music
pillow connected to a MP3 player (Wellness Musicpillow)
during the rest (Fig. 1). The music, MusiCure, (Musi Cure)
was soft, relaxing, and included different melodies of 60 to
80 beats per minute (bpm) and was for 30 minutes with a
volume of 50–60 dB. Before rest, all patients were sitting in a
chair and received chest physiotherapy as conventionally used
at the clinic. All patients also received oxygen support. At
11Æ45 a.m., the research nurses assisted the participants to lie
down in the bed and turn over to a relaxing position on their
back, supine position, with the bed head at 20–30 degrees.
During the rest, for all participants, the environment was
enhanced to reduce stimuli and facilitate rest by closing the
door and posting a sign to prevent being disturbed by visitors
and health care personnel. However, no changes of the
environmental light were made.
Outcome assessment
Pre values were obtained at 12 noon and first post values
after 30 minutes of rest with or without music i.e., 12Æ00 and
second post value for another 30 minutes i.e., 13Æ00.
The arterial blood samples for blood gas and s-oxytocin
analysis were drawn in a radial artery cannula that was
inserted into each patient’s left arm on the day of surgery.
Blood gas, i.e., PaO
2
and SaO
2
was measured at 12Æ00 (pre
value) and 13Æ00 (post value) (Radiometer ABL 505; inter
Bio-Lab, Orlando, FL, USA). The concentration of serum
oxytocin was measured at all three time points. It was
determined by blood collected in tubes containing EDTA and
Trasylol
(Bayer AB, Solna, Sweden), which were immedi-
ately centrifuged at 4 C. The plasma was stored at 70 C
prior to analysis. Oxytocin was extracted from plasma using
ethanol, all stages being carried out at 4 C. A total of 0Æ6ml
of sample was mixed with 1Æ2 ml of 95% ethanol and
subsequently centrifuged at 3000 ·g for 15 min. The ethanol
was allowed to evaporate at room temperature overnight and
the residue was reconstituted in the assay buffer. Oxytocin
was determined using an enzyme immunoassay kit from
Assay Designs, Ann Arbor, MI, USA according to the
manufacturers instructions. The mean recovery of oxytocin,
using spiked samples, was 103%. The total CV was 5Æ3% at
215 ng/l.
At all three time points, mean arterial blood pressure
(MAP) and heart rate were measured by the GE Carescape
Datex-Ohmeda monitor (GE Healthcare ANANDIC MED-
ICAL SYSTEMS AG/SA, Basel, Switzerland). The patients
rated their relaxation levels on a numeric rating scale (NRS)
scored from 0 = no relaxation to 10 = complete relaxation.
The NRS for relaxation has not been validated; however,
NRS for pain has been validated and tested for reliability
(Lundeberg et al. 2001).
Ethical considerations
The study followed common ethical principles in clinical
research and was approved by the local Ethics committee in
Uppsala. The research nurse explained the study to potential
participants. All patients gave their informed consent and
were provided with written information notifying them that
any individual was permitted to discontinue participation in
the study after receiving the information. The participants
were also entitled to make individual decisions on how long
Figure 1 Music pillow.
Original article Music increases oxytocin
2009 The Author. Journal compilation 2009 Blackwell Publishing Ltd, Journal of Clinical Nursing,18, 2153–2161 2155
they wished to participate and under what conditions. They
were also told that they could withdraw from the study at any
time without adverse consequences on their care.
Statistics
Calculation of sample size was based on the following
assumptions concerning a one-way analysis for the primary
endpoint: s-oxytocin, significance level at 5%, power at 80%,
an estimated medium effect size of 0Æ14. These assumptions
suggested a sample size of 31 patients that resulted in a
sample size of 20 patients in each group for covering
attrition. Statistics are presented as arithmetic means, stan-
dard deviation and range. Student t-test and Kruskal Wallis
tests were used to examine the differences between the groups
on patients’ characteristics, surgical factors, analgesia and
oxygen consumption. A Student t-test was used to determine
whether any statistically significant differences for s-oxytocin,
MAP, heart rate, PaO
2
and SaO
2
between the music and
control group at each time point. Student t-test followed by a
post hoc test with a Bonferroni correction was used to test for
any significant changes in s-oxytocin, MAP and heart rate
over time within groups. Wilcoxons Signed Rank test
followed by a post hoc test with a Bonferroni correction
was used to analyse the change in relaxation score in music
and control group as a between subject factor and time points
as a within subject factor. Mann–Whitney test was used in
the analysis in comparing differences in changes of levels of
s-oxytocin and relaxation scores between two times; between
baseline i.e., 12 noon value vs. values at 12Æ30 and 13Æ00.
Ap-value of <0Æ05 was considered statistically significant.
The computer program SPSS (SPSS Inc., Chicago, IL, USA)
for Windows was used for all statistical analysis.
Results
Among 168 patients undergoing open-heart surgery, 40
fulfilled the inclusion criteria and included in the analysis
(Fig. 2). The two groups were comparable with respect to
age, gender, duration of aortic occlusion (AoO) and extra-
corporeal circulation (ECC) time, O
2
and intra- and postop-
erative analgesia. However, there was a significantly longer
duration of surgery, 241 vs. 190 minutes, in the music group
compared with the control group, which could be explained
by a significant difference in type of surgery between the
groups (Table 1).
Oxytocin
The pre value of s-oxytocin was significantly lower in the
music group compared with the control group; 62Æ2 vs.
73Æ4 pml/l. There were no differences in post values at 12Æ30
and 13Æ00. between the groups (Table 2). There was a
different trend over time with regards to levels of s-oxytocin
(Fig. 3) between the groups. For patients who were listening
to music during rest, levels of oxytocin increased by
3Æ95 pml/l at 12Æ30 and 5Æ90 pml/l at 13Æ00. compared with
levels at 12 noon. For patients in the control group, there was
Open heart surgery = 168
Excluded;
Did not meet inclusion criteria (n = 147)
Refused (n = 1)
Randomised
(n = 40)
Allocated to bed rest
with music (n = 20)
Allocated to bed rest
only i.e. control group
(n = 20)
Analysed (n = 20) Analysed (n = 20)
Figure 2 Study flow chart of the trial.
U Nilsson
2156 2009 The Author. Journal compilation 2009 Blackwell Publishing Ltd, Journal of Clinical Nursing,18, 2153–2161
an opposite trend i.e., decreasing values of oxytocin;
5Æ45 pml/l at 12Æ30 pm and 3Æ90 pml/l at 13 p.m. com-
pared with levels at 12 noon. These changes were statistically
significant between the groups (Table 3), but not over time
within subjects in each group.
Haemodynamic parameters
There were no differences in pre and post values in MAP and
heart rate between the two groups (Table 2). A decrease over
Table 1 Comparison of patients’ characteristics surgical factors, analgesia consumption and oxygen support
Music group (n= 20)
Mean (±SD)
Control group (n= 20)
Mean (±SD) p-value
Age (year) 64 (10Æ0) 67 (7Æ5) 0Æ297
Gender *
Male 17 15 0Æ435
Female 3 5
Type of surgery*
CABG 17 11 0Æ030
AVR 3 6
CABG & AVR 0 3
Duration of surgery (min) 241 (85Æ8) 190 (55Æ6) 0Æ031
Duration of ECC (min) 97 (66Æ3) 86 (37Æ3) 0Æ529
Intraoperative circulation
ECC 17 17 1Æ000
Off-pump* 3 3
Duration of AoO (min) 68 (53Æ8) 49 (25Æ1) 0Æ162
Intraoperative use of fentanyl (lg) 755Æ0 (187Æ7) 679Æ4 (174Æ1) 0Æ195
Intraoperative use of alfentanil (mg) 1Æ0(1Æ1) 1Æ1(1Æ0) 0Æ882
Postoperative use of ketobemidone the day of surgery (mg) 11Æ7(6Æ5) 13Æ4(6Æ2) 0Æ391
Postoperative use of ketobemidone day one of surgery (mg) 1Æ9(2Æ7) 2Æ4(2Æ9) 0Æ538
O
2
(L/min)
3Æ1(1Æ7) 3Æ1(1Æ2) 0Æ914
CABG, coronary artery grafting; AVR, aortic valve replacement; AoO, aortic occlusion; ECC, extracorporeal circulation.
*Number of patients.
During bed rest the day one of surgery.
Table 2 Comparison of oxytocin, haemodynamic parameters, arte-
rial blood gases and subjective experience of relaxation between
patients listening to music during rest and controls before and after
intervention
Music group
(n= 20)
Mean (±SD)
Control group
(n= 20)
Mean (±SD) p-value
Pre value; 12 noon
s-Oxytocin (pmol/l) 62Æ2 (15Æ8) 73Æ4 (11Æ3) 0Æ013
MAP (mmHg) 79Æ8 (12Æ4) 78Æ3 (13Æ8) 0Æ802
Heart rate (bpm) 77Æ2 (13Æ3) 76Æ6 (10Æ2) 0Æ885
PaO
2
(kPa) 11Æ2(2Æ4) 10Æ5(1Æ5) 0Æ225
SaO
2
(%) 95Æ7(2Æ2) 95Æ1(2Æ0) 0Æ407
Relaxation (0–10) 5Æ2(3Æ4) 8Æ1(2Æ1) 0Æ008
Post value 1; 12Æ30 p.m.
s-Oxytocin (pmol/l) 66Æ2 (18Æ6) 68Æ1 (11Æ8) 0Æ694
MAP (mmHg) 72Æ8 (10Æ4) 73Æ8 (11Æ6) 0Æ795
Heart rate (bpm) 76Æ4 (11Æ7) 76Æ5(8Æ3) 0Æ975
Relaxation (0–10) 8Æ8(2Æ4) 8Æ5(2Æ3) 0Æ662
Post value 2; 13Æ00 p.m.
s-Oxytocin (pmol/l) 68Æ1 (14Æ3) 69Æ7 (10Æ9) 0Æ705
MAP (mmHg) 73Æ2(8Æ7) 75Æ1 (10Æ0) 0Æ595
Heart rate (beats/min) 76Æ4 (12Æ4) 76Æ2(8
Æ4) 0Æ960
PaO
2
(kPa) 12Æ1(2Æ2) 10Æ8(1Æ7) 0Æ036
SaO
2
(%) 96Æ3(1Æ5) 95Æ4(1Æ3) 0Æ580
Relaxation (0–10) 8Æ3(3Æ0) 8Æ2(2Æ5) 0Æ360
MAP, mean arterial pressure; PaO
2
, arterial oxygen tension; SaO
2
,
arterial oxygen saturation.
0
3·95
5·9
0
–5·45
–3·9
–2
–1
0
1
2
3
4
5
6
7
123
Oxytocin changes pml/l
Music
Control
Figure 3 Comparison of oxytocin levels between patients listening to
music and controls during rest. 1 = Pre value at 12 noon. 2 = Post
value at 12Æ30 p.m. after 30 minutes of bed rest. 3 = Post value at
13 p.m. after 60 minutes of bed rest.
Original article Music increases oxytocin
2009 The Author. Journal compilation 2009 Blackwell Publishing Ltd, Journal of Clinical Nursing,18, 2153–2161 2157
time compared with the baseline levels was seen in MAP in
the music group (p<0Æ002) i.e., pre values vs. values at
12Æ30, p=0Æ01 and pre values vs. values at 13Æ00, p=0Æ002.
This decrease over time was not seen in the control group.
There were no significant changes over time within subjects in
heart rate.
Oxygen saturation
There were no differences in pre and post values at 12Æ30
between the groups. At 13Æ00, there were significantly
higher PaO
2
levels in the music group compared with the
control group; 12Æ1 kPa vs. 10Æ8 kPa; p=0Æ036. There was
also a trend towards higher SaO
2
in the music group
compared to the control group, 96Æ3% vs. 95Æ4%; p=0Æ058
(Table 2). In comparing pre and post values within subjects,
there was a significant increase in PaO
2
levels in the music
group11Æ2 kPa vs. 12Æ1 kPa; p=0Æ039. This increase was
not seen in the control group or in SaO
2
.
Relaxation
Also pre value levels of relaxation were significantly lower in
the music group; 5Æ2 vs. 8Æ1. There were no differences in post
values at 12Æ30 and 13Æ00 between the groups (Table 2).
There was a different trend over time with regards to
subjective relaxation levels (Fig. 4) between the groups. There
were statistically significant differences in changes over time
between the groups in subjective relaxation levels. This
changes in subjective relaxation levels followed the same
trends as s-oxytocin. In the music group, levels of relaxation
had increased by 3Æ5at12Æ30 and 2Æ6at13Æ00 compared with
levels at 12 p.m (Table 3). In the music group, this increase in
subjective relaxation levels, changed significantly over time
(p<0Æ001) i.e., pre values vs. values at 12Æ30, p=0Æ001
and pre values vs. values at 13Æ00, p=0Æ003. For patients in
the control group, there were no significant changes over time
within subjects.
Discussion
The major finding of this study was that music listening used
as audio-relaxation increased oxytocin levels and relaxation
in patients undergoing CABG or AVR surgery. However,
there were significant differences in oxytocin and relaxation
levels at the pre test. One possible explanation to these
different pre levels could be that the type of surgery and the
duration of surgery were significantly longer in the music
group. On the other hand, it cannot be explained why this
different time of duration in spite of the group allocation by a
computer generate randomisation list. All other pre values
including analgesic use did not differ. When taking this
discrepancy of pre values of s-oxytocin and subjective
relaxation levels into account, the results show that music
listening during bed rest increases oxytocin secretion while
bed rest only decreases oxytocin levels. It is also interesting to
notice that the participants in the music group valued their
Table 3 Mean differences between pre value and post value in serum oxytocin and subjective relaxation levels between participants in the music
group vs. control groups
Pre value vs. post
value 1 mean (range) p-value
Pre value vs. post
value 2 mean (range) p-value
s-Oxytocin (pmol/l)
Music (n= 20) +3Æ95 (10–28) 0Æ004 +5Æ90 (22–22) 0Æ024
Control (n= 20) 5Æ45 (29–8) 3Æ90 (43–19)
Relaxation (0–10)
Music (n= 20) +3Æ5(4–10) 0Æ003 +2Æ6(8–10) 0Æ009
Control (n= 20) +0Æ4(6–7) 0Æ0(6–2)
Pre value = before intervention.
Post value 1 = after 30 minutes bed rest with or without music.
Post value 2 = 30 minutes after posts value 1, no intervention.
0
3·5
2·6
0
0·4
0
0
0·5
1
1·5
2
2·5
3
3·5
4
123
Changes in relaxation (NRS)
Music
Control
Figure 4 Comparison of subjective relaxation levels between patients
listening to music and controls during rest. 1 = Pre value at 12 noon.
2 = Post value at 12Æ30 p.m. after 30 minutes of bed rest. 3 = Post
value at 13 p.m. after 60 minutes of bed rest.
U Nilsson
2158 2009 The Author. Journal compilation 2009 Blackwell Publishing Ltd, Journal of Clinical Nursing,18, 2153–2161
pre level of subjective relaxation significantly lower than the
control group, which is in line with their objective measure-
ment of relaxation, i.e., oxytocin levels. It has been noticed
that administration of oxytocin decreases anger, fatigue,
anxiety and pain and that there is a connection between
physiology (pain) and behaviour (anxiousness) interpreted as
a low levels of oxytocin (Evans 1997). This would mean that
the previous belief that the causal relation is from the
physiological (oxytocin) to the psychological (less anxious-
ness) should be reconsidered. If music listening increases
oxytocin secretion, then the causal relation is from the
psychological (music makes patients feel good) to the
physical (oxytocin release). It is hard to find any studies that
confirm these results as the majority of studies on music
intervention use subjective stress and pain indicators (Cepeda
et al. 2006, Nilsson 2008). However, Henricson et al.
(accepted 2008) reported no differences in s-oxytocin levels
between ICU patients with bed rest, tactile touch and relaxing
music in comparison with bed rest and relaxing music only.
The study was performed over a period of six days. The
researchers reported that there was a trend of increased
oxytocin levels after every event of bed rest in both groups.
Could this increase be because of the relaxing music? Further
studies are needed to test if relaxing music can enhance
oxytocin release.
The results from the present study also found higher PaO
2
levels and a trend towards higher SaO
2
in the music group
compared with the control group. These results are in line
with an earlier study involving patients who had undergone
minor day care surgery who were listening to music during
their first postoperative hour after surgery (Nilsson et al.
2003). The explanation for these results is unknown. Perhaps
the patients in the music group took deeper breaths although
there were no differences in respiratory rate between the
groups. Further research is needed.
There was a decrease over time compared with the baseline
levels seen in MAP in the music group, but not in the control
group. However, there were no statistically significant effects
of music intervention on MAP and heart rate. This is in line
with a systematic review on music in perioperative care
(Nilsson 2008), which concludes that music has a minor
effect on vital signs. In a study by Bernardi et al. (2006), it
was discovered that respiratory rate, heart rate and blood
pressure were increased by musical inputs and that these
increases were proportional to the tempo of the music.
However, more interestingl was that random intervals of
silence (two minutes) between the different styles and tempo
of music lead to a decrease in respiratory rate, heart rate and
blood pressure below the baseline level. It seems that music
acts more like a ‘driving input’ and therefore, the effect is
minor of music with slow tempo on vital signs. In the present
study, the baseline of the heart rate was 75–76 bpm, which is
the same as the beats of the music i.e., 60–80 bpm, which can
be an explanation for the non-effect.
It is of great importance that the music listening equipment
is of good quality, easy to use and hygienic. Health care
associated infections, such as Methicillin-resistant Staphylo-
coccus aureus (MRSA) can be transmitted indirectly by
sharing items that contain the organism (Romero et al. 2006).
Therefore, allowing patients to use equipment such as
headphones can increase the risk of cross infection. In the
present study, the pillow and the MP3 player connected to it
were covered with a pillowcase that was changed between the
patients. In the majority of earlier studies with music
intervention, headphones connected to a CD, MP3 or cassette
player have been used and no discussion of new equipment
have been made (Cadigan et al. 2001, Voss et al. 2004,
Sendelbach et al. 2006, Twiss et al. 2006, Chan 2007,
Nilsson 2008). The music pillow (Wellness Musicpillow)
offers an adjustable patient focused sound environment
without ‘shutting off the external world’ as well as it enables
the patient to rest in any position without the inconvenience
induced by some types of headphones. The implementation of
music during bed rest in the present study was smooth and
did not cause any disturbance for the other patients and staff
in the recovery room of the cardiothoracic ward. However,
the quality of the sound in the music pillow could be better as
well as the maximum volume limitation of 60 dB. This
volume is acceptable in a silent environment, such as in the
present study, but in a noisier environment, for example in a
Cardiac Radiology Department, there is a need of higher
volume. Another aspect of the equipment is the user
friendliness. To change volume of the music pillow during
music listening, the nurse had to help the patient as the
cord between the pillow and the MP3 player was too short
so the patient had to lift the pillow to reach the MP3
player. Therefore, more innovations from the industry to
handle these requirements; hygiene, quality of sound,
volume, user-friendliness etc., are needed and here should
the industry, music researchers and the Health Care staff
work together.
The importance of the genre of music has been discussed in
the literature. Some authors have allowed patients to select
the genre of music from a list covering around five different
types, whereas others used the same type of music, often new
age or classical, for all participants. The results of these
studies are not strictly comparable, as different methods of
investigation have been used such as the length of the
intervention, volume, time period and choice of sound source
(Nilsson 2008). In the present study, only one type of
Original article Music increases oxytocin
2009 The Author. Journal compilation 2009 Blackwell Publishing Ltd, Journal of Clinical Nursing,18, 2153–2161 2159
music MusiCure
(MusiCure, Gefion Records, Copenhagen,
Denmark), a specially composed music designed for
perioperative settings (MusiCure). Descriptions used to
describe music perceived as relaxing; ‘quiet’, ‘peaceful’, ‘soft’,
‘dreamy’, ‘soothing’, ‘serene’, ‘un-dramatic’, ‘slow speed’,
‘regular rhythm’, ‘pleasant combination of instruments’ and
‘low volume’ (Wolfe et al. 2002) are in line with the type of
music (MusiCure) and volume, 50–60 dB, used in the present
study. In the present study, the duration of the intervention
lasted in 30 minutes and was only performed once. Perhaps
the positive effect is greater if the music interventions are
repeated and the duration is longer. More studies with the
aim of comparing duration and repeated interventions of the
music as well as the effect of different genre of relaxing music
are needed.
Limitation of the study
There are some limitations of the present study. First of all, in
the present study, the research nurse remained in the room
during the 60 min for all participants to unobtrusively obtain
data on interruptions and the reliability of music intervention
use. This may have affected patient responses through a
Hawthorne effect (Mayo 1933). The research nurses and the
participants were aware of the interventions and this may
have also affected the result. It has been shown, that studies,
which are un-blinded can overestimate the treatment effects
by about 17% (Nilsson 2008). Furthermore, the NRS scale
has not been psychometric tested for measuring relaxation.
However, in the present study, pre values and changes over
time in levels of subjective relaxation (NRS) and levels of
objective relaxation (oxytocin) followed each other. This can
be used as an indication of agreement between the two
measurements of relaxation.
Although there was a small size in the present study, it was
based on a calculation of the sample size, which is a method
to maximise the chance of detecting a statistically and
clinically significant difference between the interventions
when a difference really exists. The Consolidated Standard
of Reporting Trials (CONSORT), which this manuscript
follows, documents a set of recommendations for reporting of
clinical trials also identifies that the method for determining
sample size should be identified in publications (Moher et al.
2001).
Conclusion
In conclusion, listening to music during bed rest after open-
heart surgery has some effects on the relaxation system as
regard s-oxytocin, subjective relaxations levels and PaO
2
.
This effect seems to have a causal relation from the
psychological (music makes patients feel good) to the
physical (oxytocin release). From a practical point of view,
these positive effects are sufficiently evident to suggest the
proposed regimen of music listening after open-heart surgery
in clinical practice.
Acknowledgements
The investigator’s thanks to Professor A
˚ke Gro
¨nlund, O
¨rebro
University for assistance with the manuscript, Jonas Anders-
son, Anders Franzon and Johan Lindkvist, research nurses at
the cardiothoracic ward and the patients who volunteered for
the study.
Funding
This study was supported by grants from the Research
Committee of O
¨rebro County Council, Sweden.
Contributions
Study design: UN; data collection and analysis: UN and
manuscript preparation: UN.
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