JPediatr(RioJ).2016;92(5):528---531
www.jped.com.br
ORIGINAL
ARTICLE
Interference
of
heart
and
transcutaneous
oxygen
monitoring
in
the
measurement
of
bioelectrical
impedance
analysis
in
preterm
newborns
夽
,
夽夽
Viviane
C.
Comym
a,∗,
Yuri
S.
Macedu
a,
Eduardo
K.P.B.
Neves
a,
Arnaldo
C.
Bueno
b,
Herminia
C.
Fernandez
a,
Maria
E.L.
Moreira
c,
Alan
A.
Vieira
baUniversidadeFederalFluminense(UFF),Niterói,RJ,Brazil
bUniversidadeFederalFluminense(UFF),DepartamentoMaternoInfantil,Niterói,RJ,Brazil
cFundac¸ãoOswaldoCruz(Fiocruz),InstitutoFernandesFigueira(IFF),RiodeJaneiro,RJ,Brazil
Received3October2015;accepted13January2016 Availableonline26May2016
KEYWORDS
Electricalimpedance;
Neonate;
Bodycomposition
Abstract
Objective: Toverifyiftheconnectionofelectrodesforheartandtranscutaneousoxygen
mon-itoringinterferewiththemeasurementofelectricalbioimpedanceinpretermnewborns.
Methods: Thiswas a prospective,blinded, controlled, cross-sectional,crossover study that
assessedandcomparedpairedmeasuresofresistance(R)andreactance(Xc)byBIA,obtained
withandwithoutmonitoringwiresattachedtothepretermnewborn.Themeasurementswere
performedinimmediatesequence,afterrandomizationtothepresenceorabsenceof
elec-trodes.Thesamplesizecalculatedwas114measurementsortestswithmonitoringwiresand
114withoutmonitoringwires,consideringforadifferencebetweentheaveragesof0.1ohms,
withanalphaerrorof10%andbetaerrorof20%,withsignificance<0.05.
Results: Nodifferenceswere observedbetweenthe R(677.37±196.07vs.677.46±194.86)
and Xc (31.15±9.36 vs. 31.01±9.56) values obtained with and without monitoringwires,
respectively,withgoodcorrelationbetweenthem(R:0.997andXc:0.968).
夽
Please citethisarticle as:Comym VC,Macedu YS, Neves EK,Bueno AC,FernandezHC, Moreira ME, et al. Interference ofheart andtranscutaneousoxygenmonitoringinthemeasurementofbioelectricalimpedanceanalysisinpretermnewborns.JPediatr(RioJ). 2016;92:528---31.
夽夽
StudycarriedoutatUniversidadeFederalFluminense,Niterói,RJ,Brazil. ∗Correspondingauthor.
E-mail:[email protected](V.C.Comym).
http://dx.doi.org/10.1016/j.jped.2016.01.009
0021-7557/©2016PublishedbyElsevierEditoraLtda.onbehalfofSociedadeBrasileiradePediatria.Thisisanopenaccessarticleunder
InterferenceofmonitoringinBIAinpreterminfants 529
Conclusion: Thepresenceofheartand/ortranscutaneousoxygenmonitoringwiresconnected
tothepretermnewborndidnotaffectthevaluesofRorXcmeasuredbyBIA,allowingthemto
becarriedoutinthispopulationwithoutrisks.
©2016PublishedbyElsevierEditoraLtda.onbehalfofSociedadeBrasileiradePediatria.Thisis
anopenaccessarticleundertheCCBY-NC-NDlicense(http://creativecommons.org/licenses/
by-nc-nd/4.0/).
PALAVRAS-CHAVE
Impedânciaelétrica;
Recém-nascido; Composic¸ãocorporal
Interferênciadamonitorac¸ãocardíacaetranscutâneadeoxigênionaaferic¸ão dabioimpedânciaelétricaemrecém-nascidospré-termo
Resumo
Objetivo: Verificar seaconexãodeeletrodosefiosdemonitorac¸ãocardíacaetranscutânea
deoxigênio interferem naaferic¸ãodabioimpedânciaelétricaemrecém-nascidospré-termo
(RNPT).
Metodologia: Estudoprospectivo,cego, randomizado,transversal,crossover,emque foram
mensuradasecomparadasmedidaspareadasderesistência(R)ereatância(Xc)pormeioda
BIA,obtidascomesemosfiosdemonitorac¸ãoacopladosaosRNPT.Asmedidasforamfeitasem
sequênciaimediata,apósaleatorizac¸ãoparaapresenc¸aouausênciadoseletrodos.Otamanho
amostralcalculadofoide114aferic¸õesouexamescomfiosdemonitorac¸ãoe114semfiosde
monitorac¸ão,considerandoparaumadiferenc¸aentreasmédiasde0,1ohms,comerroalfade
10%eerrobetade20%,comsignificância<0,05.
Resultados: Nãoforamobservadasdiferenc¸asentreosvaloresderesistência(677,37±196,07
vs 677,46±194,86) e reatância (31,15±9,36 vs 31,01±9,56) obtidos com e sem fios de
monitorac¸ãorespectivamente,comboacorrelac¸ãoentreambos (resistência:0,997e
reatân-cia:0,968).
Conclusão: A presenc¸a defios de monitorac¸ão cardíacae/ou transcutânea de oxigênio não
interferiunosvaloresdaresistênciaoudareatânciaaferidospelaBIAemRNPT.Recomenda-se,
então,esseexame,semriscos,paraessapopulac¸ão.
©2016PublicadoporElsevierEditoraLtda.emnomedeSociedadeBrasileiradePediatria.Este
´
eumartigoOpenAccesssobumalicenc¸aCCBY-NC-ND(http://creativecommons.org/licenses/
by-nc-nd/4.0/).
Introduction
Among the methods used for assessing body composition,
bioelectricalimpedanceanalysis(BIA)hasbeenwidelyused, especiallyforbeingnon-invasive,painless,practical,safe, low-cost,andeasilyperformedatthebedside.Another rea-sonfor itsuseisthe factthatitestimates, inadditionto bodycomponents,thedistributionoffluidsintheintra-and extracellularspaces,aswellasthequality,sizeandintegrity ofcellmembranes.1,2Itcanberepeatedasoftenas
neces-sary,thusallowingforthefollow-upofpatientsofdifferent ages,bodyweight,andhealthstatus.
It istherefore apromisingtooltobeincorporated into clinical research and routine evaluation of patients from differentmedicalspecialties,includingneonatology.3
Currently,inadditiontothelimiteddataavailableonBIA in newborns, mainly preterm ones, thereis no consensus onthemethodologicalstandardizationofthisexamforthis population.4Forinstance,ithasbeensuggestedthatbeing
attachedtoa monitoringwire precludes the performance oftheBIA. However,the continuousmonitoringof several physiologicalparametersisrequiredtomaintainthesafety ofnewbornsinintensivecare.
Theobjectiveofthisstudywastoverifywhether,infact, thepresenceofelectrodesandwiresforheartand transcu-taneousoxygen monitoringattachedtopretermnewborns
interferewith the values of resistance (R)and reactance (Xc)measuredbyBIA.
Methods
This was a prospective, blinded, randomized, crossover
study that compared measurements made by BIA for the
evaluationofRandXcinpreterminfantswithandwithout
heartandtranscutaneousoxygenmonitoringwires.
Thetestwasstandardizedasfollows:theinternal elec-trode(detector---redcolor)ofthearm wasplacedonthe dorsalsurfaceoftherightwristbetweentheulnarandradius bones,whereastheouterelectrode(emitter---blackcolor) wasplacedonthethirdmetacarpal;theinternalleg elec-trodewasplacedontheanteriorsurfaceoftherightankle,
betweentheprominentportionsofthebones,whereasthe
externalwasplacedonthesurfaceofthethirdmetatarsus.5
Duringtheexaminations,boththeexaminerandthe par-ents/guardianswereaskednottotouchthenewborn,who was placed on the dorsal position, with the limbs sepa-rated,withouttouchingmetal,toavoidreduction/random dispersion of electric current. The examination lasted approximately5min.
530 ComymVCetal.
digestion.The pretermnewborns werecarefully observed bytheresearcherthroughouttheexaminationperiod.
The RandXcmeasurementswereperformed usingthe single-frequencyequipment(BIA101QuantumII---RJL Sys-tems,USA),which appliesa sinusoidalalternatingcurrent of50kHzand800A.1
The measurements were performed in immediate sequence,afterdrawinglotsforrandomizationofthe pres-enceorabsenceofelectrodes(‘‘yes’’or‘‘no’’raffle).When assessing the database, the presence or absenceof mon-itoring wires connected to the newborn was not known by researchers and/or statistician, i.e., the analysis was blinded.
The studyincludedallpreterm infantswithgestational age (GA) between 24 and 36 weeks and six days, who were hemodynamically stableand couldstay for at least 10min without heart andtranscutaneous oxygen monitor-ing.Infants on mechanical ventilation were notassessed, astheauthorsbelieveditwouldbetooriskytokeepthem withoutmonitoring,evenforafewminutes.
All preterm infants with congenital malformations, hemodynamicallyunstable, andthosereceivingvasoactive drugswereexcludedfromthestudy,aswellasthosewhose familiesrefusedtoparticipate.
Thesamplesizeof114measurementsortestswith mon-itoringwires and 114 without wires wascalculated for a differencebetweenthemeansof 0.1ohms, withanalpha errorof10%andbetaerrorof20%.
Thevariableswerepresentedbymeasuresofcentral ten-dencyandanalyzedbypairedt-test.Asignificancelevel≤5% wasusedandthedatawereanalyzedusingSPSS(SPSSInc. Released2007.SPSSforWindows,Version16.0,USA).
The study was approved by the Research Ethics Com-mittee (REC), registered under No. 193/2010, CAAE No. 0153.0.258.000-10.
Results
Atotalof114measureswerecarriedoutinpreterminfants
attached to heart and transcutaneous oxygen monitoring
wires, aswell as 114 measures in preterm newborns not
attached to these wires. Altogether, 90 newborns were
assessed,ofwhom70wereevaluatedonce, 16were
eval-uatedtwice,andfourwereevaluatedthreetimes, witha
minimumintervalofoneweekbetweenmeasurements.
The birth weight(BW) ofthe participants ranged from
630g to 1980g. Of these, 7% had BW between 500g and
750g;10%,between751gand1000g;51%,between1001g
and1500g;and33%,between 1501gand2000g.On
aver-age, the assessments were performed in preterm infants
withchronologicalageof15days(range9---33days).
No differences were observed between the R and Xc
values obtained with and without monitoring wires, with
agoodcorrelationbetweenmeasurements(Fig.1).Means
andstandarddeviationsoftheRmeasuredwithandwithout thepresenceofelectrodesforheartandoxygensaturation monitoringwere677.37±196.07and677.46±194.86ohms (p=0.952),respectively;themeansofXcwere31.15±9.56 and31.01±9.56ohms(p=0.532),respectively.The corre-lations between the paired measures of R and Xc were, respectively,0.997and0.968(p<0.001).
1400.00
1200.00
1000.00
800.00
Resistance (ohm)
Reactance (ohm)
600.00
400.00
200.00
Resistance with wires
Reactance with wires Resistance without wires
Reactance without wires 70.00
60.00
50.00
40.00
30.00
20.00
10.00
Figure 1 Analysis of resistance and reactance by
single-frequencybioelectricalimpedance inpretermnewborns with
andwithoutmonitoringwires.
Discussion
Theresultsofthisstudymakeitclearthatthepresenceof
electrodesfor heartandtranscutaneous oxygensaturation
monitoringattachedtothepreterminfantdoesnotinterfere
withRandXcmeasurementsperformedbysingle-frequency
equipment.
Instudiesconductedintheadultpopulation,Fosterand Lukaskiaffirmedthat,althoughtheelectric fieldsthatare inducedbytheBIAinthebodyaremuchlowerthanthoseof thesusceptibilitylimitsofdevicessuchasimplanted pace-makersanddefibrillators,intheabsenceofadetailedsafety analysis,itiswisetoavoidperformingbodyimpedance mea-surements inindividuals withsuchdevices.6 It isbelieved
that there could be a dispersion of the electric current inducedbyBIA,mainlyofelectrodesforheartmonitoring, astheyaresuitableforsensingtheelectricalvariations pro-ducedbyheartmuscledepolarization.
InterferenceofmonitoringinBIAinpreterminfants 531
Studies carried out by Lingwood et al., in adult and neonatal populations, show that single-frequency devices aresusceptibletosignificantinterferenceandthe possibil-ity of errors when used in newborns and adults attached to monitoring equipment necessary in an intensive care scenario.8---10 These studies, in addition to having a small
samplesize,werecarriedoutwithadifferentmethodology thanthecurrentstudy.
Thepresentauthorsbelievethattherewasnodissipation ofelectricalcurrentthroughelectrodesattached/appliedto theskinofthenewborns,oriftherewas,itwassmallenough nottogeneratestatisticallysignificantdifferences.
In thecurrentstudy,whichaimedtoevaluate interfer-enceonBIAmeasurementtechniqueinaspecificpopulation, theuseofpairedmeancomparisonanalysis,i.e.one mea-suretakentwicefromthesamesubject,completelyrefutes the possibilityof interference of the research subjecton theresults. Thatis, itgender, gestationalage,weight,or any other characteristic of the assessed newborns were irrelevant,astheyweretheirowncontrols.Moreover,the calculationofsamplesizegreatlyincreasesthepowerofthe statisticaltestused.
Newborns,ingeneraland,moreprecisely,thosepreterm, aresusceptible,shortlyafterbirth,toaveryseverelossof bodywater.When theyarehealthy,their organscancope well with these losses and generate homeostatic balance rapidly. However, in critically-ill or very premature new-borns,thishomeostaticbalancecanbeseverelydamaged.
Preterminfantsarealsomorelikelytodevelopsome con-ditionsthatcorrelateeitherwithexcessiveadministrationof fluids,suchasbronchopulmonarydysplasiaandpatent duc-tusarteriosus,orhypovolemia,suchasarterialhypotension andmetabolicacidosis.Therefore,astrictcontroloffluid andelectrolytebalanceisessentialintheclinical manage-mentofpreterminfants.11
The possibility of assessing critically-ill newborns in neonatalintensivecareunitswithoutexposingthemtothe risk ofbeingwithout monitoring,evenfor afew minutes, makesit possibletoadd toneonatalcare an easy-to-use, noninvasivetoolwithveryinterestingresearchpossibilities. The measurement of total body water and its varia-tions,theinferenceofvolumesofotherbodycompartments, amongothers, increasesan entire arsenal of data rapidly availableatthebedsidetohelpintheclinicaldecisionsof neonatologists.12 Additionally, thesedata arecrucial in a
population that, up tonow, has many gaps in the under-standingoftheirfluidhomeostasis.
Currently,R andXcmeasurementsobtained byBIA are used for analysis of the bioelectrical impedance vector (BIVA).In thisanalysis,the useof formulas or mathemat-icalmodelsisnotrequired,anditisbelievedthatitisonly affected by a measurement error andthe biological vari-abilityoftheassessedsubjects.Avectorisplottedfromthe measurementsofRandXc,andthisvectoriscomparedwith a knownreferencepopulation. By determining thevector positionandangle,calledphaseangle,onecandetermine, amongothers,the degree of normalityof theindividual’s fluiddistribution,clinicalseverityandevenpredictthe asso-ciatedmortality.2,12---14
Many questions still remain regarding the optimal methodology to analyze R and Xc in the pediatric and
neonatalpopulation.EventheuseofBIAtocalculatetotal bodywaterandofother bodycompartmentsis criticized, astherearenovalidatedliteratureequations forchildren youngerthan6years.1,7However,theauthorshavenotfound
aneasiermethodthanBIAtobeappliedatthebedside. The definition of a single standard for the perfor-manceofBIAmeasuresinpreterminfantsisimportantfor itsvalidity, allowing for comparisonand interpretation of results.
Inconclusion,theuseofsingle-frequencyBIAtomeasure RandXcinpreterminfantsdidnotsufferinterferencefrom the electrodes used for heart and transcutaneous oxygen saturationmonitoringintheassessedpopulation.
Conflicts
of
interest
Theauthorsdeclarenoconflictsofinterest.
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