REVISTA
BRASILEIRA
DE
ANESTESIOLOGIA
PublicaçãoOficialdaSociedadeBrasileiradeAnestesiologiawww.sba.com.br
SCIENTIFIC
ARTICLE
Perioperative
warming
with
a
thermal
gown
prevents
maternal
temperature
loss
during
elective
cesarean
section.
A
randomized
clinical
trial
Ricardo
Caio
Gracco
de
Bernardis
a,
Monica
Maria
Siaulys
a,
Joaquim
Edson
Vieira
b,∗,
Lígia
Andrade
Silva
Telles
Mathias
caHospitalCentraldaIrmandadedaSantaCasadeMisericórdiadeSaoPaulo,SãoPaulo,SP,Brazil bDepartamentodeCirurgia,FaculdadedeMedicina,UniversidadedeSãoPaulo,SãoPaulo,SP,Brazil cDepartamentodeCirurgia,FaculdadedeCiênciasMédicasdaSantaCasadeSãoPaulo,SãoPaulo,SP,Brazil
Received27October2014;accepted30December2014 Availableonline19November2015
KEYWORDS
Bodytemperature;
Perioperativecare; Anesthesia; Spinal;
Cesareansection; Intraoperative complications/
preventionand
control
Abstract
Backgroundandobjectives: Decrease in body temperature is common during general and
regionalanesthesia.Forced-airwarmingintraoperative duringcesareansectionunderspinal anesthesiaseemsnotabletopreventit.Thehypothesisconsidersthatactivewarmingbefore theintraoperativeperiodavoidstemperaturelossduringcesarean.
Methods:Forty healthypregnant patients undergoing electivecesarean sectionwith spinal
anesthesiareceivedactivewarmingfromathermalgowninthepreoperativecareunit30min beforespinalanesthesiaandduringsurgery(Go,n=20),ornoactivewarmingatanytime(Ct,
n=20).Afterinduction ofspinal anesthesia,thethermalgownwasreplacedoverthechest andupperlimbsandmaintainedthroughoutstudy.Roomtemperature,hemoglobinsaturation, heart rate,arterialpressure,andtympanicbodytemperaturewereregistered30minbefore (baseline)spinalanesthesia,rightafterit(timezero)andevery15minthereafter.
Results:There was no difference for temperature at baseline, but they were significant
throughout thestudy (p<0.0001;repeatedmeasure ANCOVA).Tympanic temperature base-linewas36.6±0.3◦C,measured36.5±0.3◦Cattimezeroandreached36.1±0.2◦Cforgown
group,whilecontrolgrouphadbaselinetemperatureof36.4±0.4◦C,measured36.3±0.3◦C
attimezeroandreached35.4±0.4◦C(F=32.53;95%CI0.45---0.86;p<0.001).Hemodynamics
didnotdifferthroughoutthestudyforbothgroupsofpatients.
∗Correspondingauthor.
E-mail:joaquimev@usp.br(J.E.Vieira).
http://dx.doi.org/10.1016/j.bjane.2014.12.007
Conclusion:Activewarming30minbeforespinalanesthesiaandduringsurgerypreventedafall inbodytemperatureinfull-termpregnantwomenduringelectivecesareandelivery.
©2015SociedadeBrasileiradeAnestesiologia.PublishedbyElsevierEditoraLtda.Thisisan openaccessarticleundertheCCBY-NC-NDlicense( http://creativecommons.org/licenses/by-nc-nd/4.0/).
PALAVRAS-CHAVE Temperatura corporal;
Cuidadosno
perioperatório; Anestesia; Espinhal; Cesariana; Complicac¸õesno intraoperatório/ prevenc¸ãoecontrole
Oaquecimentonoperioperatóriocomaventalcirúrgicotérmicoimpedeaperda
detemperaturamaternaduranteacesarianaeletiva.Estudoclínicorandômico
Resumo
Justificativaeobjetivos: A reduc¸ãoda temperaturacorporal é comum durantea anestesia
tantogeralquanto regional.Osistemadearforc¸adoaquecidonointraoperatóriodurantea cesarianasobanestesiaperiduralnãoparececonseguirimpedi-la.Ahipóteseconsideraqueo aquecimentoativo antesdoperíodointraoperatórioevitaaperdadetemperaturadurantea cesariana.
Métodos: Quarentapacientesgrávidas,saudáveis,submetidasàcesarianaeletivacom
aneste-sia espinal receberam aquecimento ativo de um avental térmico na unidade de cuidados pré-operatórios30minutosantesdaanestesiaeduranteacirurgia(Go,n=20)ounenhum aque-cimentoativoaqualquermomento(Ct,n=20).Apósainduc¸ãodaanestesiaespinhal,oavental térmicofoicolocadosobreotóraxemembrossuperioresemantidoduranteoestudo. Temper-aturaambiente,saturac¸ãodehemoglobina,frequênciacardíaca,pressãoarterialetemperatura corporaltimpânicaforamregistradas30minutosantes(fasebasal)daanestesiaespinhal,logo apósaanestesia(tempozero)eacada15minutossubsequentemente.
Resultados: Nãohouvediferenc¸adetemperaturanafasebasal,masasdiferenc¸asforam
signi-ficativasaolongodoestudo(p<0,0001;ANCOVAdemedidarepetida).Atemperaturatimpânica nafasebasalfoide36,6±0,3◦C,mediu36,5±0,3◦Cnotempozeroeatingiu36,1±0,2◦C
nogrupoavental,enquantoatemperaturabasaldogrupocontrolefoide36,4±0,4◦C,mediu
36,3±0,3◦Cnotempozeroeatingiu35,4±0,4◦C(F=32,53;ICde95%0,45-0,86,p<0,001).
Ahemodinâmicanãodiferiuaolongodoestudoemambososgruposdepacientes.
Conclusão:Oaquecimentoativo30minutosantesdaanestesiaespinhaleduranteacirurgia
evitouaquedadatemperaturacorporalem mulheresgrávidasatermo duranteacesariana eletiva.
©2015SociedadeBrasileiradeAnestesiologia.PublicadoporElsevierEditoraLtda.Este ´eum artigoOpen Accesssobumalicenc¸aCCBY-NC-ND( http://creativecommons.org/licenses/by-nc-nd/4.0/).
Introduction
The reduction in body temperature is a common occur-rence following the induction of anesthesia even when activewarming measuresaretakenduringthe intraopera-tiveperiod.1,2However,whensuchmeasuresareestablished
immediatelypriortoanesthesia,theonsetofhypothermia is slower, and its intensity is milder due to increases in peripheralandcoretemperatureswithoutanymodification tometabolicrates.3---6
Body temperature decreasing withgeneral or regional anesthesiaiscaused byacore-to-peripheralredistribution of heat, as demonstrated by several previous studies.7---12
Perioperativehypothermiaanditscomplicationshavebeen widely studied in patients subjected to non-obstetric surgery.Thereisnoguidelinesfortheobstetricpopulation, buttheNICEprovidesaframeworkwithwhichtoimprove perioperativethermalmanagementthatcouldbe transfer-abletoobstetrics.13 The incidenceof shiveringcan be as
high as 60% in these patients.14---16 Previous studies based
ontheuseofforced-airwarmingunitduringintraoperative periodsduringcesareandeliveryreachedconflictingresults for hypothermia and shivering in patients given epidural (reducing)orspinalanesthesia(notchanging).17,18
Severalmethodshavebeen developedtohelpmaintain normothermia during surgery, including warming patients beforeinducinganesthesia.Theforced-airsystemisbyfar themostcommonlyusedintraoperativewarmingapproach. However,blanket-forcedairwarming,circulating-water gar-ments,orwatermattressesdonoteasilyallowthechanging ofpositiononthebed,especiallywhenthepatientis ina sittingposition.
Methods
This study is registered with clinicaltrials.gov (http://www.clinicaltrials.gov/ct2/home) (NCT02091466). After obtaining Institutional Review Board approval from theEthicsResearchCommitteeofHospitalCentral, Irman-dade de Misericórdiada Santa Casa deSão Paulo, city of São Paulo, and written informed consent from patients, 40 healthy ASA physical status I or II pregnant women presenting for scheduled cesarean delivery under spinal anesthesia were enrolled in this prospective, randomized study.Theinvitationoccurredduringtheiradmissiontothe hospitalwhenarandomcomputer-generatedcodethatwas maintained in sequentially numbered opaque envelopes wasopened.
Eligible participants were pregnant women between 18 and 40 years of age, with singleton pregnancy and gestation longer than 37 weeks, scheduled for elective cesarean section, between March 18, 2010 and July 17, 2010.Patientswithfever(peripheraltemperature>37.8◦C)
and/or infectious conditions, familial history of poten-tialmalignanthyperthermia,bodymassindex(BMI)values below 18.5kgm−2 or above 36kgm−2, thyroid disorders, dysautonomia,Raynaud’ssyndrome,andthoseinlaborwere excluded.
Participants remained seated in the preoperative care unit and were allocated into one of two groups. Control group(Ct,n=20)receivednoactivewarminginthe preop-erativesettingandreceivedpassivethermalinsulationfrom regularblanketsduringsurgery;thegowngroup(Go,n=20) received activewarming from athermal gown (BairPaws Standard Warming Gown model 810, Bair Hugger® model 850 warming unit, Arizant Healthcare Inc., Eden Prairie, MN,USA)withforced-airflowat 40◦C.Patientswithgown
remained covered entirely in the pre-operative care unit 30minbeforetheinductionofspinalanesthesia.Oncethey transferredtotheoperativeroom,thesystemswitchedto coverthe chestandupperlimbsandmaintained untilthe endofsurgery.
Allthepatientsreceivedavenouscatheterinsertedinto the forearm and an infusion of Ringer’s lactate solution fluidsat 37◦Cwasinitiated. Spinalanesthesiawas
admin-istered using 10mg of hyperbaric bupivacaine, combined with 10g of fentanyl and 80g of morphine. Puncture
was performed at level L2---L3 or L3---L4 of the lumbar vertebra, and surgery began when the sensory blockage reachedalevelbetween theT4andT6thoracicvertebra, as established by the loss of sensitivity toneedle pricks. Intraoperative hydration was maintained using 500mL of 37◦CRinger’slactate solutionbeforefetalextraction and
800gmetaraminolwasprovidedviaslowinfusionor400g
wasdeliveredasanIVboluswheneverthearterialpressure decreasedbymorethan25%ofthebaselinevalue. Follow-ingfetalextractionbutbeforetheendofsurgery,1000mL of heated Ringer’s lactatesolution with 20IU of oxytocin wasinfused---aserviceprotocol.Obstetriciansdidnotapply anyfluidirrigationtothesurgicalfieldafteruterinesuture ligation.
Demographicvariablesincludedage,weight,heightand BMI.Patients weremonitored withhemoglobinperipheral saturation(SpO2),heartrate(HR),noninvasivesystolic arte-rial pressure (SAP) and diastolic arterial pressure (DAP).
The tympanic temperature was measured by means of a digital thermometer (Techline Model TS 201, Sao Paulo, SP, Brazil). Ambient temperature wasmaintained approx-imately at 22◦C according to wall thermostat(ABNT NBR
7256---BrazilianregulatoryandnormalizationAgency). Alldatawereassessedatbaseline,30minbefore induc-tionof spinalanesthesia;T0 (immediatelyafterthespinal anesthesia);andT15,T30,T45,andT60(15,30,45,and60min followingtheonsetofspinalanesthesia,respectively).
Inaddition,postoperativedatawereassessedduringthe admissionto the post-anesthesiacare unit(PACU). Shive-ringwasevaluatedaccordingtoWrench’s scalethat uses: 0--- no shivering;1 --- oneor moresymptoms of piloerec-tion,peripheral vasoconstriction, and peripheral cyanosis withoutanyothercauseandwithoutvisiblemuscular activ-ity; 2 --- visible muscular activity confined to one muscle group;3---visiblemuscularactivityinmorethanone mus-cle group; and 4 --- gross muscular activity involving the entirebody.19ThermaldiscomfortaccordingtoHorn’s
ver-bal numerical scale: 0 --- worst imaginable cold, 100 ---insufferablyhot17 and adverse effectsduring the
immedi-ate postoperative period were also registered. Moreover, patients received 12.5---25mg meperidine whenever their shiveringscoreswereequaltoorgreaterthanthree.
Sample size was calculated to be 20 subjects in each grouptoensurethatadifferenceof0.5◦Cat60mincouldbe
detectedatsignificancelevelof5%withastatisticalpower of90%, assuming thestandard deviation ofdifferences to be0.5◦C,consideringatemperaturebelow36.0◦Ccouldbe
consideredhypothermia.13
Data are presented as mean and standard deviation or median andinterquartileinterval (25---75) according to testeddistribution(Shapiro---Wilktest). Analysisof covari-anceforrepeatedmeasures(ANCOVA),adjustedforbaseline values, compared tympanic temperatures between the groups.Statistical significancewasestablished atp<0.05, andthestatisticalanalysiswasperformedusingSPSS (Sta-tisticalPackagefortheSocialSciences)softwareversion20.
Results
All the patients completed the study. The anthropomet-ric data did not exhibit differences between the groups (Table 1). Demographic, monitored dataand temperature datareachednormaldistributionaccordingtoShapiro---Wilk test.SpO2,HR,SAP,andDAPdidnotexhibitsignificant dif-ferencesbetweengroupsandnodeviationsgreaterthan25% ofthebaselinemeasurements(datanotshown).Intravenous hydration followed a protocol of 1500mL of crystalloid solutionof Ringer’slactate. The vasopressorwas used at
Table1 Patient’scharacteristics.
Control(n=20) Gown(n=20) Age(years) 29.1±5.9 28.4±6.0 Weight(kg) 77.9±13.3 81.4±11.0 Height(cm) 164.8±7.7 164.1±8.4 BMI(kgm−2) 28.6±3.8 30.17±2.6
TotalIVinfusion(mL) 1760±50 1735±49
35.00 35.25 35.50 35.75 36.00 36.25 36.50 36.75 37.00
T60 T45
T30 T15
T0 baseline
Control Gown
Figure 1 Tympanic temperature --- baseline to 60min (mean±SD).Whiskers,SD.
anesthesiologist’s discretion. Baseline tympanic
tempera-ture did not differ between groups (p=0.10; Student’s
t-test).Nopatientexperiencedanydelayfrombaselinetime point to T0. The only interruption in the active warming
groupwastotheinjectionofspinalanesthesiathatdidnot lastmorethan3min,roughly,foreverypatient.
Tympanictemperaturesinthecontrolgroupcomparedto
thegowngroup,adjustedforbaselinevalues,reduced sig-nificantlythroughoutthestudy(F=32.53;95%CI0.45---0.86;
p<0.001;Fig.1).Attimezero,thetemperaturedifference alreadyshowedalowervalueinthecontrolgroup(36.40◦C)
comparedtopatientswithgown(36.55◦C)(0.19±0.08◦C;
95%CI0.30---0.37; p=0.02).Thistrendcontinueduntilthe endofobservationat60min,asthepatientsincontrolgroup reached (35.44◦C) while patientswith gownwarming had
a mean temperature of (36.15◦C) (0.66±0.10◦C; 95% CI
0.45---0.87;p<0.001).
The incidenceof shiveringasmeasured usingWrench’s scalewas10%intheGogroupand40%intheCtgroup dur-ingthetimespentinthePACU(p=0.02;2test)(Table2).
Medianthermal discomfortvalue accordingto Horn’s ver-bal numerical scale was 50 for both groups (p=0.27; Mann---Whitney).
Discussion
Thisstudydemonstratedthattheactivewarmingbymeans ofathermalgownfor 30minbeforespinalanesthesiaand theusethisdeviceasablanketduringelectivecesarean sec-tionpreventedasignificantloweringoftemperatureduring perioperativeperiodinfull-termpregnantwomen.
Table2 Incidenceofshivering inthe PACUaccordingto Wrench’sscale.
Scoreofshivering 0 1 2 3 4 Control 12 8 0 0 0 Gown 18 2 0 0 0
0,noshivering;1,oneormoresymptomsofpiloerection, periph-eralvasoconstriction,andperipheralcyanosiswithoutanyother causeandwithoutvisiblemuscularactivity;2,visiblemuscular activityconfinedtoonemusclegroup;3,visiblemuscular activ-ityinmorethanonemusclegroup;and4,grossmuscularactivity involvingtheentirebody.Valuesare‘‘n’’.
Basedonpreviouslypublishedstudiesregardingthebest method for delivering active perioperative warming,20---23
preoperativeuseofathermalgownfollowedbythe intra-operativecoveringofpatientsusingathermalblanketwere selected for the current study. It should be noted that pregnant women scheduled for elective cesarean section generallywaitinasittingpositioninthepre-operativecare unit,which makestheuse oftraditionalthermal blankets veryunlikely. Theuse ofathermal gownwouldmake this usepossible.
Duringthepreoperativeperiod,peripheraltemperature reducedmoderatebutsignificantlyinthecontrolgroup.The useofapreoperativewarmingdevicefor30minseemed suf-ficienttoavoidfurtherfalloftemperatureaftertheonset ofanesthesia.Thesefindingsareinagreementwithprevious studies.24,25Itisalsointerestingtonoticethatstudiesthat
appliedprewarmingprotocolsobservedareducedincidence oflowertemperatureduringsurgery.3However,itisunclear
howlongpre-anestheticwarmingmustbesetuptopreventa fallinintraoperativetemperatureanddealatthesametime withsurgicalcenter’sroutine.26Althoughtympanic
temper-aturemeasurementsreducedbyasmallmargin,thecontrol groupshowedaconsistentandprogressivereductionin tym-panictemperaturereaching35.4◦C,whiletheperioperative
warming avoided the temperature to reach levels below 36.0◦C.
TheseresultscorroboratethoseofHornetal.17inwhich
pre-andintraoperativewarmingwasperformedinpregnant womensubjectedtoelectivecesareansectionbycovering theupperlimbswithathermalblanketat 43◦Cfor15min
prior to the onset of epidural anesthesia and found that onlythewarmedgroupmaintainedanormaltemperature. Inaddition,itisworthnotingthatpatientsfromthisstudy received spinal anesthesia with morphine, an association that may intensifythe hypothermiceffect of bupivacaine spinalanesthesia.27,28
Previous results suggest that warming methods do not affectphysiologicalparametersinpregnantwomen.Butwick etal.appliedintraoperativeblanketsandfounda27% inci-denceofshiveringamongwarmedpatientsascomparedto anincidenceof47%inthecontrolgroup.18Moreover,astudy
byHornetal.appliedblanketstopatients15minpriortothe inductionofanesthesiaandfounda13%prevalenceof shiv-eringinthetreatedgroupascomparedtoaprevalenceof 60%inthecontrolgroup.17However,thestudyofWoolnough
etal.showedthattheinfusionofwarmedsolutionsdidnot contributetoanysignificantdifferencesintheprevalence of shiveringbetween groups.29 In thepresent study,there
wasacleardifferenceintheincidenceofshivering,which was10%inthe groupthatreceivedthethermalgown and 40%inthecontrolgroup.
Evaluation of thermal discomfort can be therefore an importantissueduringregionalanesthesia.Indeed, consid-eringresultsfromarecentsurveywhereonlyaminorityof obstetricsunitsinUKmonitoredpatienttemperaturewhile intheoperatingroom(27%)orusedactivewarming(18%), the results of the present investigation may point to the humanenecessityofpromotingactivewarmtothe obstet-ricspopulationduringcesareansection.30
use of blanket that is a reality in many services, even thoughunfortunatelyasasolemeasure.Itwasshownthat high-qualityevidencesupportingtheaccuracyoftympanic thermometry is lacking,31 but this method could provide
an acceptable andcomfortable wayfor this healthy pop-ulation. Another limitation is that the protocol was an openrandomizedcontrolledtrialwithout blinding.Finally, adrenoceptor-mediatedvasoconstrictor,likephenylephrine, wasreportedtoattenuatehypothermiaduringspinal anes-thesiaandthetotalamountofmetaraminolusedwithinboth groupswerenotreported.32
Conclusion
Theresultsofthepresentstudydemonstratedthebeneficial effectsofusingathermalgownat40◦Cfrom30minbefore
andthroughout a60mincesarean sectiontomaintain the patient’sbodytemperature.
Conflicts
of
interest
Theauthorsdeclarenoconflictsofinterest.
References
1.Sessler DI. Temperature monitoring and perioperative ther-moregulation.Anesthesiology.2008;109:318---38.
2.SesslerDI,SladenRN.Mildperioperativehypothermia.NEnglJ Med.1997;336:1730---7.
3.SesslerDI,SchroederM,MerrifieldB,etal.Optimaldurationand temperatureofpre-warming.Anesthesiology.1995;82:674---81.
4.InslerSR,SesslerDI.Perioperativethermoregulationand tem-peraturemonitoring.AnesthesiolClin.2006;24:823---37.
5.CarpenterL,BaysingerCL.Maintainingperioperative normoth-ermia in the patient undergoing cesarean delivery. Obstet GynecolSurv.2012;67:436---46.
6.AndrzejowskiJ,HoyleJ,EapenG, etal.Effect of prewarm-ingonpost-induction coretemperatureandtheincidence of inadvertentperioperativehypothermiainpatientsundergoing generalanaesthesia.BrJAnaesth.2008;101:627---31.
7.SesslerDI. Temperature monitoring and management during neuraxialanesthesia.AnesthAnalg.1999;88:243---5.
8.MacarioA,DexterF.Whatarethemostimportantriskfactors forapatient’sdevelopingintraoperativehypothermia?Anesth Analg.2002;94:215---20.
9.Frank SM, El-Rahmany HK, Cattaneo CG, et al. Predic-torsofhypothermiaduringspinal anesthesia.Anesthesiology. 2000;92:1330---4.
10.Kurz A, Sessler DI, Schroeder M, et al. Thermoregulatory response thresholds during spinal anesthesia. Anesth Analg. 1993;77:721---6.
11.Doufas AG. Consequences of inadvertent perioperative hypothermia.BestPractResClinAnaesthesiol.2003;17:535---49.
12.FrankSM, Nguyen JM, Garcia CM, et al. Temperature mon-itoring practices during regional anesthesia. Anesth Analg. 1999;88:373---7.
13.NICE Clinical Guideline 65. Inadvertent perioperative hypothermia. The management of inadvertent perioperative
hypothermia in adults. National Institute for Health and ClinicalExcellence;2008http://www.nice.org.uk/nicemedia/ live/11962/40432/40432.pdf[accessed07.04.14].
14.BuggyDJ,CrossleyAW. Thermoregulation,mildperioperative hypothermia and post-anaesthetic shivering. Br J Anaesth. 2000;84:615---28.
15.Eberhart LHJ, Döderlein F, Eisenhardt G, et al. Indepen-dent risk factors for postoperative shivering. Anesth Analg. 2005;101:1849---57.
16.ReynoldsL,BeckmannJ,KurzA.Perioperativecomplicationsof hypothermia.BestPractResClinAnaesthesiol.2008;22:645---57.
17.HornEP,SchroederF,GottschalkA,etal.Activewarmingduring cesareandelivery.AnesthAnalg.2002;94:409---14.
18.Butwick AJ, Lipman SS, Carvalho B. Intraoperative forced air-warming during cesarean delivery under spinal anesthe-sia does not prevent maternal hypothermia. Anesth Analg. 2007;105:1413---9.
19.Wrench IJ, Cavill G, Ward JE, et al. Comparison between alfentanil, pethidine and placebo in the treatmentof post-anaestheticshivering.BrJAnaesth.1997;79:541---2.
20.Taguchi A, Arkilic CF, Ahluwalia A, et al. Negative pressure rewarming vs. forced air warming in hypothermic postanes-theticvolunteers.AnesthAnalg.2001;92:261---6.
21.NgSF,OoCS,LohKH,etal.Acomparativestudyofthree warm-ing interventionstodetermine the mosteffective technique for maintaining perioperative normothermia. Anesth Analg. 2003;96:171---6.
22.SesslerAI.Complicationsandtreatmentofmildhypothermia. Anesthesiology.2001;95:531---43.
23.YokoyamaK,SuzukiM,ShimadaY,etal.Effectofthe admin-istrationofpre-warmedintravenousfluidsonthefrequencyof hypothermiafollowingspinalanesthesiaforcesareandelivery. JClinAnesth.2009;21:242---8.
24.CamusY,DelvaE,SesslerDI,etal.Pre-inductionskin-surface warming minimizes intraoperative core hypothermia. J Clin Anesth.1995;7:384---8.
25.DeBernardisRCG,SilvaMP,GozzaniJL,etal.Useof forced-airtopreventintraoperativehypothermia.RevAssocMedBras. 2009;55:421---6.
26.Shinn H, Lim H, KwakY, et al. Pre-anesthetic active warm-ingreduceshypothermiawithoutdelayinganesthesiaincardiac surgery.AnesthAnalg.2004;98:123---34.
27.RyanKF,PriceJW,WarrinerCB,etal.Persistenthypothermia afterintrathecalmorphine:casereportandliteraturereview. CanJAnaesth.2012;59:384---8.
28.HuiCK, HuangCH, LinCJ, et al.Arandomised double-blind controlled study evaluating the hypothermic effect of 150 microgmorphineduringspinalanaesthesiaforCaesarean sec-tion.Anaesthesia.2006;61:29---31.
29.Woolnough M, Allam J, Hemingway C,et al. Intra-operative fluidwarminginelectivecaesareansection:ablind,randomised controlledtrial.IntJObstetAnesth.2009;18:346---51.
30.AluriS,WrenchIJ.Enhancedrecoveryfromobstetricsurgery: a UK survey of practice. Int J Obstet Anesth. 2013,
http://dx.doi.org/10.1016/j.ijoa.2013.11.006.
31.HooperVD,AndrewsJO.Accuracyofnoninvasivecore tempera-turemeasurementinacutelyilladults:thestateofthescience. BiolResNurs.2006;8:24---34.
