Effect of nature-based sounds’ intervention on agitation, anxiety, and stress in patients under mechanical ventilator support: A randomised controlled trial
Vahid Saadatmand
a, Nahid Rejeh
b,*, Majideh Heravi-Karimooi
a, Sayed Davood Tadrisi
c, Farid Zayeri
d, Mojtaba Vaismoradi
e, Melanie Jasper
f,1aDepartmentofNursing,FacultyofNursingandMidwifery,ShahedUniversity,Tehran,Iran
bDepartmentofNursing,FacultyofNursingandMidwifery,ShahedUniversity,IranianPainSociety,IASP,Tehran,Iran
cFacultyofNursing,BaqiyatallahUniversityofMedicalScience,Tehran,Iran
dDepartmentofBiostatistics,FacultyofParamedicalSciences,ShahidBeheshtiUniversityofMedicalSciences,Tehran,Iran
eCollegeofHumanandHealthSciences,SwanseaUniversity,UnitedKingdom
fCollegeofHumanandHealthSciences,SwanseaUniversity,Room142VivianTower,SwanseaSA28PP,UnitedKingdom
ARTICLE INFO Articlehistory:
Received21July2012
Receivedinrevisedform25November2012 Accepted25November2012
Keywords:
Anxiety
Mechanicalventilation Nature-basedsounds Nursing
Stress Therapy
ABSTRACT
Background:Few studies have been conducted to investigate the effect of nature- basedsounds (N-BS)on agitation,anxietylevel andphysiologicalsignsof stressin patients under mechanical ventilator support. Non-pharmacological nursing inter- ventionssuchasN-BScanbelessexpensiveandefficientwaystoalleviateanxietyand adverse effects of sedative medications in patients under mechanical ventilator support.
Objectives:Thisstudywasconductedtoidentifytheeffectofthenature-basedsounds’
interventiononagitation,anxiety leveland physiologicalstressresponsesin patients undermechanicalventilationsupport.
Methods:Arandomizedplacebo-controlledtrialdesignwasusedtoconductthisstudy.A totalof60patientsaged18–65yearsundermechanicalventilationsupportinanintensive careunitwererandomlyassignedtothecontrolandexperimentalgroups.Thepatientsin theinterventiongroupreceived90minofN-BS.Pleasantnaturesoundswereplayedtothe patientsusingmediaplayersandheadphones.Patients’physiologicalsignsweretaken immediatelybeforetheinterventionandatthe30th,60th,90thminutesand30minafter theprocedurehadfinished.Thephysiologicalsignsofstressassessedwereheartrate, respiratoryrate,andbloodpressure.DatawerecollectedovereightmonthsfromOct2011 toJune2012.AnxietylevelsandagitationwereassessedusingtheFacesAnxietyScaleand RichmondAgitationSedationScale,respectively.
Results:Theexperimentalgrouphadsignificantlylowersystolicbloodpressure,diastolic bloodpressure,anxiety andagitationlevels thanthecontrolgroup.Thesereductions increasedprogressivelyinthe30th,60th,90thminutes,and30minaftertheprocedure hadfinishedindicatingacumulativedoseeffect.
Conclusions: N-BS canprovide aneffective methodof decreasingpotentially harmful physiologicalresponsesarisingfromanxietyinmechanicallyventilatedpatients.Nurses
* Correspondingauthorat:FacultyofNursingandMidwifery,ShahedUniversity(OppositeHolyShrineofImamKhomeini-KhalijFarsExpressway), Tehran,Iran.
E-mailaddresses:[email protected],[email protected](N.Rejeh),[email protected](M.Vaismoradi),[email protected] (M.Jasper).
1Tel.:+4401792295086;fax:+4401792518640.
ContentslistsavailableatSciVerseScienceDirect
International Journal of Nursing Studies
journalhomepage:www.elsevier.com/ijns
0020-7489/$–seefrontmatterß2012ElsevierLtd.Allrightsreserved.
http://dx.doi.org/10.1016/j.ijnurstu.2012.11.018
Whatisalreadyknownaboutthetopic?
While mechanical ventilation in itself is a life-saving treatment,itinducesavarietyofexperiences,whichare physiologicallyandpsychologicallystressfulforpatients.
To relieve anxiety and promote relaxation, nurses frequently administer a varietyof sedative non-phar- macologic interventions topatients under mechanical ventilation.
Whatthispaperadds
N-BSinterventionscanbeconsideredtobeaneffective method of reducing potentially harmful physiological responsesarisingfromanxiety.
This study supports the effectiveness of the N-BS intervention as a complementary therapy to thecare ofpatientsundermechanicalventilation.
N-BS intervention as a non-pharmacologic nursing interventionalleviatedpatients’anxietyandagitation.
1. Introduction
Mechanicalventilation(MV)isacommon,lifesavingand frequentlyemployedtreatmentmodalityfora varietyof medicaldiagnosesinintensivecareunits(ICU)(Besel,2006).
While this intervention itself is a life saving treatment, patients who are mechanically ventilated often face a variety of distressing situations including anxiety and agitationduetoemotionaldistress,fearofpainordying, fearraisedfromfamilymembers’previousexperiencesof thosewhohavediedinsimilarsituations,discomfort,thirst, immobility, dyspnoea, confusion, and inability to relax (Dijkstraetal.,2010),pain,lackofsleep,tenseness,lackof controlandloneliness,whicharetypicallycommonstress and anxious reactions even when patients are sedated (Yaganetal.,2000;Rotondietal.,2002;Thomas,2003).
PatientsundergoingMVrequireendotrachealintuba- tion and often have either intermittent or sustained periods of agitation because of the endotracheal tube itself.Intubatedpatientswho arerelativelyalertmostly become frustrated by their inability to communicate verballyandthenfallintoacycleofcontinuedagitation.
Finally,theICU environment,withitshighnoise levels, lights, and continual other stimuli can significantly contribute to increasing distress and agitation (Hei- derscheitetal.,2011;Khalailaetal.,2011).
Having a dependency on MV to breathe can result insleep disturbances, increasedmyocardial oxygencon- sumption and increased sympathetic output (Tracy and Chlan, 2011). Poorly managed stress can result in the patient’sinabilitytoadjusttothediseaseandtheuseof
medical assistance or anti-anxiety agents (Wong et al., 2001).Thus,MVmaybeadistressingexperienceforthe patient,andmayresultinanincreaseinanxietyandreduced comfortevenwhenthepatientissedated(Besel,2006).
Nurses in the ICU frequently administer sedative medication to ventilated patients to counteract the negativeeffectsoftreatment.However,sedativeagents have a number of undesirablesideeffects, which may result in complications such as nausea and vomiting, decreasedgutmotility,urinaryretention,mentalstatus instability,respiratorydepression,pruritus,venousstasis, hypotension,softtissuedamage,respiratoryandextrem- ity muscle weakness or atrophia, increased risk of infection,centralnervoussystemchangesandevendeath, anddelayedweaningfromMV(Chlan,2002).These,in turn,prolongthelengthofdependencyontheventilator (Lee et al., 2005; Lindgren and Ames, 2005), increase lengthofstayintheICU,increasetheneedformedication, andcosts of hospitalcare (Seneffet al., 2000;Arroliga etal.,2005).
Drugs may be prescribed to preserve patient safety duringperiodsofsevereagitationandanxiety.However, use of complementary therapies in conjunction with sedative agentsmaypotentiatetheeffectsofbothtypes of therapiesand decreasetheamountofsedative drugs neededtogetthesameoutcome.Complementarythera- pies,ifusedon aroutinebasis, canhelpreduceanxiety (Punand Dunn,2007). Therefore,sedative drugsdo not havetobethefirstchoiceinattemptstomitigatepatients’
distressassociatedwithMVsupport(Chlan,2002).
There is a need for additional research examining alternativenon-pharmacologicalinterventionsforpatients requiringMV.Non-pharmacologicalapproachesconsistofa varietyofenvironmentaladjustmentsthatarefrequently underutilized(Summer,2002).Althoughmusictherapyhas beenshowntobeaneffectiveinterventioninthecareof patientsunderMV,notallpatientswelcomethisinterven- tion.NursescaringforpatientsunderMVsupportmusthave several non-pharmacological adjuncts, which can be implemented in order to provide a humanistic caring environmentinwhichhealingcanoccur(Chlan,2002).In thisrespect,soundtherapycanactasanon-pharmacologi- calnursinginterventiontoallaythesignsofanxietyinsuch patients.Soundtherapyhasbeenusedtoreduceanxietyand distressandimprovephysiologicalfunctioninginmedical patients;howeveritseffectonpatientsundermechanical ventilationsupportneedstobeinvestigated.
1.1. Background
Ulrich (1984) demonstrated that patients whose windows faced a park recovered faster compared to canincorporateN-BSinterventionasanon-pharmacologicinterventionintothedailycare ofpatientsundermechanical ventilationsupportinorderto reducetheirstressand anxiety.
ß2012ElsevierLtd.Allrightsreserved.
patients whose windowsfaced a brickwall.Since then, several studies havedemonstrated restorativeeffects of naturalenvironmentsincomparisonwithurbanenviron- ments. These effects include increased well-being and decreasedphysiologicalstressresponses(GrindeandPatil, 2009;Malleretal.,2006).
Ulrich suggested that natural environments have restorativeeffectsbyinducingpositiveemotionalstates, decreasedphysiological activity,and sustainedattention (Ulrich,1984).ThisisconcurrentwithKaplanandKaplan’s theory (1995) that a natural environment facilitates recovery of directed attention capacity and thereby reduces mental fatigue (Kaplan, 1995). Ithasalsobeen found that positive emotion improves physiological recoveryafterstress(Fredricksonetal.,2000).Soundscape research has shown that natural sounds are typically perceivedtobepleasant(LavandierandDefre´ville,2006;
NilssonandBerglund,2006).
Naturesoundshaveapositiveemotionaleffectonall people(Malleretal.,2006),andareusedinstudiesasthey have the most relaxing effect in comparison to other interventions(LavandierandDefre´ville,2006;Nilssonand Berglund, 2006). Nature sounds are limited only by geographicalboundariesandhavethecapacitytoappeal to all cultures. Nature-based sounds (NB-S) in thepre- operative area can be considered culturally neutral (Cullum,1997).
Investigators atJohns HopkinsMedicalCentre (2003) havestrongevidencethatdistractingpatientsduringand afterbronchoscopywithacolourfulmuralofameadowand thegurgleofababblingbrooksignificantlyenhancesefforts toreducepain(Anon.,2003).TheHopkinsgrouptestedthe naturalsightsandsoundson41menandwomenduring their 25-min bronchoscopies and three-hour recovery periods. They listened to nature sounds through head- phones and a tape player. Thirty-nine similar patients underwenttheprocedureswithoutdistractiontherapy,but withcomparablelevelsofcareandpaincontrol.Bothgroups completedquestionnairesratingtheirpainonafive-point scale, along with their anxiety, perceptions of privacy, difficultyinbreathing,willingnesstohavethe procedure doneagainandsafety.Patientswholistenedtothenature soundsandlookedatthemuralduringbronchoscopywere 43% more likely to report pain control as very good or excellent, evenafter controllingfor such factors aspain medication,health,raceandeducation(Anon.,2003).
No studies have focused on the effect of NB-S on physiologicalstressresponses,agitationandanxietylevel in patients receiving MV support. This study was conductedtoidentifytheeffectofnature-basedsounds’
interventiononagitation,anxietylevelandphysiological stressresponsesinpatientsundermechanicalventilation support.
2. Methods
2.1. Studydesign
A randomized placebo-controlled trial was used to conductthisstudy(Fig.1)fromOct2011toJune2012.To
determinethesamplesize,a pilotstudywasconducted withfivepatients.Theleastamountofdifferenceineach endpointwasrelatedtoagitation30and60minafterthe interventionintheexperimentgroup(0.00.707)andin thecontrolgroup(0.60.548).Usingthestatisticalparam- etersof
a
=0.5andb
=0.5,thesamplesizewasdeterminedto be30patientsinboththeinterventionandcontrolgroups.60 patients under mechanical ventilation support were ran- domlyassignedtoeithertheinterventionorcontrolgroups whereboth theinvestigatorandpatientswereblindedto treatmentallocation.Randomisationnumberswere gener- atedfromtheRandmiserwebsiteoftheSocialPsychology Network.2.2. Settingandparticipants
The intensive care unit of a university teaching hospital in Tehran, Iran was the study’s setting. A convenience sample of patients who met the study criteria and who were under mechanical ventilation supportinanICUwaschosen,withnopatientdeclining toparticipate.Thepatients wereaged between18and 65years;wereonpressuresupportventilationmodeand SIMV/CPAP;wereabletohear;hadGlasgowComaScale Point9orabove;werementallycompetentandableto communicate by holding up fingers responsive to researcher’s questions at the time of data collection;
were haemodynamically stable; had no psychiatric or neurological illnesses; were not receiving inotropic support; were not taking any neuromuscular blocker agent and antihypertensive drug; had no previous experience of the N-BS intervention; were not drug- addicted,andhadnofacialsignsof beingscared.
2.3. Measures
2.3.1. Clinicalanddemographicalcharacteristicsofthe patients
DatawascollectedovereightmonthsfromOct2011 to June 2012 by one investigator. Baseline data was collected using patients’ medical records to compare patients in the experimental and control groups with respecttoage,gender,educationallevel,maritalstatus, primarymedicaldiagnosis,drugtherapyinthepast24h, ventilatorsettings,lengthofstay,lengthofstayintheICU beforethebeginningoftheintervention,numberofdays receivingMV andalso theirGlasgowComaScale(GCS) score.
2.3.2. Physiologicalparameters
Physiologicalsignsofanxietymeasuredweresystolic blood pressure,diastolic bloodpressure, heartrate, and respiratoryrateobtained bymeansofbedsidemonitors, whichwerecalibratedcarefullybeforedatagathering.
2.3.3. Anxietylevel
DuringtheN-BSinterventionorrestperiods, dataon thelevelofanxietywasrecordedusingtheFacesAnxiety Scale (FAS). This scale was chosenbecause it has been demonstratedtobeeasierforICUpatientstorespondtoin comparisontootheranxietyscales(Chlan,2004).Unlike
most studies, the FAS was used for assessing anxiety because critically ill ICU patients are often nonverbal, many of whom cannot respond to existing validated parametersofanxiety,thereforeuseofcurrentlyavailable anxiety measures is difficult. The FAS appears to be a promisingmeansofobtainingself-reportsonthestatusof anxiety from ventilator-dependent patients for routine clinical purposes as well as for researchpurposes. The relationship between FAS and patients’ nonverbal responses to short questions from the Profile of Mood States Anxiety Subscale has been reported to be 0.64 (p<.001),withintherangeof0.4–0.8forcriterionvalidity, indicatingtheFacesAnxiety Scaleis a validmeasureof anxiety(McKinleyetal.,2004). TheFASisasingle-item scalewith5possibleresponses,rangingfromaneutralface toafaceshowingextremefear,andisscoredfrom1to5.It isbelievedthatmostICUpatientsareabletorespondto this scale in comparison toa 6-item anxietyscale or a numericanalogue anxiety scale,and it hasordinal and intervalpropertiesofcontinuousmeasurement(McKinley etal.,2003).
2.3.4. Agitationlevel
TheRichmond AgitationSedationScale(RASS)score wasalreadyapartofroutinemonitoringofpatientsinthe ICUsinthishospital.RASSisa10-pointscale,withfour levelsofanxietyoragitation(+1to+4[combative]),one leveltodenoteacalmandalertstate(0),and5levelsof sedation( 1to 5)culminatinginunarousable( 5).The validityofRASSafterimplementationinamedicalICUhas beendemonstratedbystrongcorrelationsbetweenRASS and the Sedation–Agitation Scale score (r=0.78, p<0.0001), Ramsay sedation scale score (r= 0.78, p<0.0001), and Glasgow Coma Scale score (r=0.79, p<0.0001).Excellentinter-raterreliabilityisalsodem- onstratedforRASSamongtheentireadultICUpopulation (intraclass correlation=0.956 [0.948]) (
k
=0.73 [0.71, 0.75]).CorrelationsbetweenRASS,andRamsaySedation Scale(r= 0.78)andtheSedationAgitationScale(r=0.78) confirm its validity (Sessler et al., 2002). The Persian versionofRASShasbeenshowntobeavalidandreliable for measuring patients’ agitation in ICUunits (Tadrisi etal.,2009).Fig.1.Theprocessofstudydesign.
2.4. Intervention
Patients were randomised to a control group who receivedonlystandardcareandaninterventiongroupwho received the N-BS intervention consisting of 90min of listeningtotheN-BSandstandardcareusingsequentially numbered containers as the allocation concealment mechanism.
To accommodate nursing activities and the unit’s routine, the intervention was conducted during the afternoon orearlyevening. UnlikeKorhanet al.’sstudy (2011),ourstudywasconductedintheafternoon,because anxietymightbeaffectedbythetimeofthedayatwhich the data were collected. Moreover, patients’ family members were asked not to visit the patients in the afternoontopreventinterferencewiththeintervention’s effectandtheycooperatedwell.
Thepatientswereonlyinformedaboutthetruepurpose ofthestudyaftertheexperiment(i.e.,ourinterestinthe effectofnature-basedsounds).Theywereaskedtoselecta CD(pleasantnaturesounds)tolistentoaccordingtotheir preferencefromacollectionofN-BSconsistingof:birds’
song,soothingrainsounds,riverstreams,waterfallsounds, or a walk through the forest; using media player and headphones.Thevolumeofthesoundwasadjustedtothe patients’ preference; when the patient wasnot able to expressapreference,thevolumewasdeterminedbythe attendingnurse.
Itisnotedthat,inmusic therapy,patientsmayneed timetoaccustomthemselvestothemusic(Leeetal.,2005), unlikewiththeN-BSintervention;andtheirchoicesmight differbecauseofculturaldiversitybetweenpatients.
The nature sounds wereplayed using a MP3 media player through disposable foam-lined headphones (the patients had nofurther stimulation).Thevolumeofthe MP3playerwasadjustedtotheparticipants’satisfaction byrespondingtotheirfacialexpression.Participantswere askedtoclosetheir eyes andfollow theflowof sounds duringtheintervention.Theparticipants’hearingthresh- oldsweretested.Theaveragesoundpressurelevelwasset to25–50dB.
Thepatientsassignedtothecontrolgroupwereasked towearthefoam-linedheadphoneandrestinsilencefora similartimeframeastheinterventiongrouptominimize unpleasantenvironmentalnoisesorstimuli.Bothgroups were assessedin the last thirtyminutes withouthead- phonesandsoundsplaying.
The environment for both groups was enhanced to promoterestandtominimizeunnecessarydisturbanceby dimmingthe lights(unless contraindicated),closingcur- tains, partiallyshutting the doorand posting a ‘Patients AreatRest.PleaseDoNotDisturb’sign.Nursingandmedical staffwereinstructednottodisturbthepatientduringtheN- BSinterventionorrestperiodunlessimperative.
The investigator returned to the room to record the physiological parameters of agitation and anxiety score acrossthetwogroupsduringtheprocedure.Hewasunaware of who was assigned to eachgroup to limitbias in the recordingofparametersandsedationscores.Theseparam- eterswerebeingcontinuouslymonitoredforeachpartici- pantperICUprotocol,facilitatinginvestigatorcollectionwith
minimalpatientdisturbance.Patientsinbothgroups had physiologicalsignsrecordedimmediatelybeforetheproce- dure, at 30, 60, and 90min intervals throughout the procedure,and30minaftertheprocedurehadfinished.
Astheprimaryoutcome,agitationwasassessedusing the RASSafter the intervention, at 30, 60, 90min (end intervention),and30minafterfinishingtheintervention.
Asthesecondaryoutcome,anxietywasassessedusingthe FASaftertheintervention,atthesametimeintervals.
2.5. Ethicalconsiderations
TheEthicsCommitteeofShahedUniversityapprovedthe research proposal. After providing patients with brief information on the purpose of the study and before assigningthemintogroups,informedconsentwasobtained fromthepatients.Theywereassuredoftheirconfidentiality and anonymity. Thepatients chosethe typeof pleasant naturesounds intervention.Patients weretoldthatthey couldwithdrawatanytimethroughoutthestudyandthat notparticipatingwouldnothaveanydetrimentaleffectsin termsofthe essentialorregularhospitaltreatmentsand servicesreceived.NorisksassociatedwiththeuseofN-BS interventionasaninterventionwereidentifiedinprevious studies. Measurement of physiological parameters and anxietyandagitationscoreswasonepartofroutineICU careconsequentlyno additional burdenwas put on the patients.Furthermore,thepreviously describedinclusion criteriawerechosensoasnottoplaceanadditionalburden onunstablepatientsandtheirrelatives.
2.6. Dataanalysis
Data were analysed using SPSS (version 16.0; for Windows).Descriptivestatisticswereusedtosummarise demographic dataand clinical characteristicsof partici- pantsinthegroups.
Chi-square testswere used to detect any significant differencebetweenthegroups’baselinedatasuchasage, gender, marital status, educational level, job, insurance, interest in pleasant nature-based sounds, number of ventilator-dependentdays,numberofdaysofhospitaliza- tionintheICU.Mann–WhitneyU-testwasusedtodetect any significant difference in GCS, FAS, RASS scores. An independent t-test was used to detect any significant differencesbetweenthegroups’meanvaluesofphysiologic parameters.TheKolmogorov–Smirnovtestwasusedtotest the normaldistributionofvariables (p>0. 05).Asthere werenovariableswhichdeviatedfromnormaldistribution, different repeated measures of analyses of variance (RANOVA)wereusedforeachvariable.RANOVAwasalso usedtoexaminemeanSBP,DBP,RR, andHR acrossthe interventionperiod,measuredat30-minintervalswithin groupsandbetweengroups.Mauchly’s testofSphericity wasusedtoexaminethedifferencebetweentheintervals withineachgroupandtoexaminetheinteractionbetween thegroupsandintervals.Pairedt-testwascarriedoutinthe periodsbetween 0 andthe 30th, 0and the 60th, 0and the90th,0and30minaftertheprocedurehadfinished;and the30thand60th,the30thand90th,the30thand30min aftertheprocedurehadfinished;andthe60thand90th,the
60thand30minaftertheprocedurehadfinished,andfinally 90thand30minaftertheprocedurehadfinished.RANOVA was used to examine the effects of sociodemographical characteristicson thedifferenceinphysiological signsof stress occurring during the N-BS intervention in the interventiongroup.AMann–WhitneyU-testwasusedon Richmondscorestodetectchangesbetweentheinterven- tionandcontrolgroup.
3. Results
3.1. Demographicalandbaselinecharacteristicsofthe patients
Inthisstudy,60patientswererandomlyassignedto thecontrol(n=30)andintervention(n=30) groups.In
thecontrolgroup,20patients(66.7%)weremaleand10 patients (33.3%) female. In the intervention group, 14 patients (46.7%) were male and 16 patients (53.3%) female(p=0.118).ThemeanSDageofthepatientswere 46.6016.76 and 41.2315.31 in the control and intervention groups, respectively (p=0.201). The rate of illiteracywas23.3%(7patients)inthecontrolgroupand 30.0%(9patients)intheinterventiongroup(p=0.559).In addition,30patients(23.3%)inthecontrolgroupand11 patients (36.7%) in the intervention group were single (p=0.260).
Tables 1 and 2 compare the clinical and baseline characteristicsofthepatientsinthecontrolandinterven- tion groups. As shown in these tables, there was no significant difference in the clinical and baseline char- acteristicsbetweenthetwogroups.
Table1
Patients’demographiccharacteristics.
Characteristics Total(n=60) Experimentgroup(n=30) Controlgroup(n=30) Statisticaltest andp-value
MeanSD MeanSD
Age
MeanSD 43.9116.14 41.2315.31 46.6016.76 t=1.295
p=.231 Gender,n(%)
Male 34(%100.00) 14(%41.20) 20(%58.80) f=0.96
Female 26(%100.00) 16(%61.50) 10(%38.50) p=.118
Educationallevel,n(%)
Illiterate 16(%100.00) 9(%56.20) 7(%43.80) x2=2.550
Primary 24(%100.00) 9(%37.50) 15(%62.50) df=2
Secondary 10(%50.00) 6(%30.00) 4(%20.00) p=.279
High/undergraduateschool 10(%50.00) 6(%30.00) 4(%20.00)
Maritalstatus,n(%)
Single 18(%100.00) 11(%61.10) 7(%38.90) f=.199
Married 42(%100.00) 19(%45.20) 23(%54.80) p=.260
Sedativerecipient,n(%)
Yes 26(%100.00) 13(%43.30) 13(%43.30) df=1
No 34(%100.00) 17(%56.70) 17(%56.70) P=.603
Table2
Patientsclinicalandbaselinecharacteristics.
Characteristics Group MeanSD p*
GCS Control 9.930.91 0.884
Intervention 9.970.85
Hospitalizationduration Control 7.577.28 0.937
Intervention 7.705.54
Lengthofmechanicalventilation Control 6.806.24 0.850
Intervention 6.534.47
Baselinesystolicbloodpressure Control 136.3016.23 0.864
Intervention 136.9713.74
Baselinediastolicbloodpressure Control 81.608.87 0.922
Intervention 81.379.39
Baselineheartrate Control 96.2012.91 0.730
Intervention 94.9714.61
Baselinerespiratoryrate Control 19.533.10 0.286
Intervention 18.633.37
p-Valueswereobtainedfromanindependentt-test.
GlasgowComaScale(GCS)thatobjectivelyrecordstheconsciousstateofaperson.ItisamethodforevaluatingtheseverityofCNSinvolvementinhead injury,whichmeasures3parameters–maximumscoreof15fornormalcerebralfunction,0forbraindeath.
3.2. Theeffectsofnature-basedsounds’intervention 3.2.1. Physiologicalparameters
Inthenextstep,therepeatedmeasuresANOVAmodel wasused toassesstheconcurrenteffectof timetrend, intervention (group variable) and interaction between timeandgroupondifferentresponsevariables(physio- logical outcomesincluding systolic anddiastolic blood pressure, heart rate and respiration rate). In these models, the impactof baseline values ofthese physio- logical parametersonresponse variableswasadjusted.
To do this, the baseline values of the physiological parameters asacovariateinallmodelswereincluded.
3.2.1.1. Systolicbloodpressure. TheresultsofRANOVAfor systolicbloodpressureshowednosignificanttimetrend (p=0.612) and interaction between time and group (p=0.223). However, the mean systolic blood pressure wassignificantlylowerintheinterventiongroupatallfour times of measurement (p<0.001). Fig. 2 displays the estimatedtimetrendofmeansystolicbloodpressurein thetwogroups.
3.2.1.2. Diastolicbloodpressure. TheresultsofRANOVAfor systolicbloodpressureshowednosignificanttimetrend (p=0.825) and interaction between time and group (p=0.110). However, the mean systolic blood pressure wassignificantlylowerintheinterventiongroupatallfour times of measurement (p=0.001). Fig. 3 displays the estimatedtimetrendofmeansystolicblood pressurein twogroups(Table3).
3.2.1.3. Heartrate. TheresultsofRANOVA forheartrate showednosignificanttimetrend(p=0.157).Inaddition, the mean heart rate was not significantly different between the two groups (p=0.292). The interaction between time and group was statistically significant (p<0.001). Fig. 4 displays the estimated time trend of meanheartrateintwogroups(Fig.4).
3.2.1.4. Respirationrate.TheresultsofRANOVAforrespi- ration rateshowedno significanttime trend (p=0.489) andgroupeffect(p=0.558).Theinteractionbetweentime Fig.2.Timetrendofmeansystolicbloodpressureintheinterventionand
controlgroups. Fig.3.Timetrendofmeandiastolicbloodpressureintheinterventionand
controlgroups.
Table3
Baselineanxietyandagitationscoresbetweenthetwogroups.
Parameter Score Control group
Intervention group
p*
Baseline anxiety
1 0(0.0%) 0(0.0%) 0.750
2 0(0.0%) 1(3.3%)
3 20(66.7%) 20(66.7%)
4 6(20.0%) 4(13.3%)
5 4(13.3%) 5(16.7%)
Baseline agitation
0 0(0.0%) 0(0.0%) 0.160
1 5(16.7%) 2(6.7%)
2 21(70.0%) 21(70.0%)
3 4(13.3%) 7(23.3%)
* FromMann–Whitneytest. Fig.4.Timetrendofmeanheartrateintheinterventionandcontrol.
andgroupwasstatisticallysignificant(p<0.001).Fig.5 displaystheestimatedtimetrendofmeanrespirationrate intwogroups(Fig.5).
3.2.2. Anxietyandagitationlevel
Inthefinalstep,becauseoftheordinalnatureofanxiety and agitation scores, the marginal modelling approach (GEEanalysis)wasusedtoassesstheconcurrenteffectof time, intervention (group variable) and interaction be- tween time and group on anxiety and agitation scores (adjustingforbaselinescoresofthesevariables)(Table3).
3.2.2.1. Anxietylevel. Theresultsofmarginalmodellingfor anxiety scores showed no significant effect of time (p=0.466) and interaction between group and time (p=0.055). However, a significantdifference was found betweentheanxietyscoresoftwogroups(p<0.001).The estimatedregressionparameterforthevariablegroupwas 1.496.Thismeansthattheoddsofhavinghigherscoresof anxietyinthecontrolgroupwasexp(1.496)4.5timesof thesameoddsintheinterventiongroup(Fig.6).
3.2.2.2. Agitationlevel. Theresultsofmarginalmodelling for agitationscoresshowedno significanteffectof time (p=0.790) and interaction between group and time (p=0.262). However, a significant difference was found betweentheagitationscoresinthetwogroups(p<0.001).
Theestimatedregressionparameterforthevariablegroup was 2.418. This means that the odds of having higher scores of agitation in the control group was exp (2.418)11.24timesofthesameoddsintheintervention group(Fig.7)
4. Discussion
Thisstudywasconductedtodeterminetheeffectofthe N-BS interventionon thephysiological stressresponses, anxietylevel,andagitationofpatientsundermechanical ventilationsupport.Specifically,theanxietyresponsesof the patients were measured using their physiological parameterswhenprovidedwithN-BSintheintervention group,andnosoundforthecontrolgroup.
In recent years, use of the N-BS intervention as a complementarytherapyhasincreasedand this,tosome extent,mayreflectthegrowinginterestinothercomple- mentarytherapies.ItisknownthattheN-BShasvarious beneficial effects on human health, for instance older people whohavesleepdisturbance(Moritaetal.,2011) and alsoinpatients withmentaldisorders (Pryor etal., 2006). The N-BS intervention provides conditions that foster human and environmental health by reducing anxietyandenablingpsychologicalandphysicalactivity (Hansen-KetchumandHalpenny,2011).
Findings from this study are congruent with other similarstudiessuggestingthatconnectingwithpleasur- able natural environments can facilitate recovery from surgery(Ulrich,1984),positivelyinfluencebloodpressure (Prettyetal.,2005),andincreaseperceptionsofqualityof life(Ogunseitan,2005).
Similartootherstudies,Parsonsetal.(1998)exposed college students to stressors and scenic drives through naturalartefactdominatedurbanandruralsettings.Stress recovery, measured by facial muscle activation, blood Fig.5.Timetrendofmeanrespirationrateintheinterventionandcontrol
groups.
Fig.6.Timetrendofmeananxietylevelintheinterventionandcontrol groups.
Fig.7.Timetrendofmeanagitationlevelintheinterventionandcontrol groups.
pressureandelectro-dermalactivitywererecordedbefore andaftertheexposure.Itwasshownthattheparticipants experiencedquickerrecoveryfromstressthroughnature, although participants’ narrative accounts of past and presentexperiencesinsimilarsettingswouldhavehelped interprettheresults.
DataaboutwhatchallengedengagementwiththeN-BS interventioninthisstudywouldhavehelpedunderstand waystostrengthenandsustaintheintervention.Cimprich and Ronis (2003) studiedthe effect of connectingwith nature on attention and mental fatigue in women diagnosedwithbreastcancer.Analysisrevealedasignifi- canteffectofthenaturerestorativeinterventionontotal attentionscoresforthoseintheexperimentalgroup.
Inthisstudy,therewasnostatisticallyandmeaningful relationshipbetweendemographiccharacteristicssuchas educationallevelandreductionofanxietyandagitation.
Also, clinical characteristics such as days of ventilator dependency did not affect the results of the N-BS intervention.
4.1. Limitationsandsuggestionsforfuturestudies
Thestudywaslimited toadultpatients betweenthe ages of 18–65 years who were receiving mechanical ventilation support. This could be a threat to the generalisabilityofthefindingstoothersettingsorsamples.
It is suggested that conducting similarstudies in other settings and in different age groups would test the applicabilityofthefindings.
Itissuggestedthatthisinterventionisrepeatedwith three groups of patients. The added group can usethe interventionwithoutwearingheadphones.Thiscondition would take intoaccount thecalmingeffectof theN-BS intervention associated witha reduction in background noise. Continuous N-BS intervention duringhospitaliza- tionintheICUcouldbedonetoinvestigatethehypothesis concerning patients’ sedation levels, and stress and anxiety.Furthermorethe influenceof backgroundnoise insingleroomsvs.amultiple-beddedroomorwardcanbe addressedwhenroomsizeandroomtypeisconsideredas apotentialconfoundingvariable.
5. Conclusion
This study provides evidence for the use of nature- sound as an anxiolytic intervention. The benefits of preventingphysiologicalreactions toanxietyweredem- onstrated, in patients who were under mechanical ventilator support. Therefore, nature-sound canprovide an easy, simple, safe and effective methodof reducing potentially harmfulphysiological responsesarisingfrom anxiety.
This studyshowed thatchanging surroundingenvi- ronmentalsoundsdecreasesenvironmentalstimulation, whichresultsinreducedanxietyandpromotesrelaxation.
OurresultssuggestthatN-BSinterventioncouldleadto deepersedationlevelsinsedated,mechanicallyventilated patients in the ICU. Physiological parameters were reduced significantly after completion of the N-BS intervention. Nature-based sounds intervention as a
complementary adjunct is safe andcan be applied by clinicalnursestoallayanxietyandagitationinmechanical ventilator-dependentpatientswithoutriskingunwanted sideeffects.Nursescan implementthisinterventionto achieve relaxation for its short-term benefits. The utilizationofthisinterventionenablesnursestoprovide individualized care and helpthe patient manage their anxietyandachieverelaxation.Forthesedated,mechani- callyventilatedpatientsintheICU,thebenefitoftheN-BS may lie in the deeper levelof sedation achieved.This deeper level of sedation may make the patient less susceptibletostressresponses,anxietyandagitation.
TheN-BS asa non-pharmacologicalinterventionis a non-invasive,inexpensiveandnon-timeconsumingnurs- ing intervention in the routine care of patients under mechanical ventilation support. It is a complementary intervention acceptable to patients, is economically feasibletoimplement,andalsoiswithinthecapabilities ofthenursingstaff.
One of the strengths of our study was that patient preferencesofN-BStypewererespected.Inotherwords, throughallowingthepatientstochoosetheirfavouriteN- BS,theneedofthepatientstomaintainasenseofcontrol overtheirsituationwererecognised.
Conflictsofinterest:Noneoftheauthorshaveanyconflictsof interestswithregardstothisresearch.
Funding:Thisresearchwassupportedbygrantsfrom theShahedUniversity(PS-97002).
Ethicalapproval:ShahedUniversityReviewBoard,No.
2011-12-08.
Acknowledgments
ThisresearchwassupportedfinanciallybytheShahed University. The researchers would like to thank the patientsfortheirparticipationinthisstudy.
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