Indirect calorimetry in nutritional therapy. A position paper by the ICALIC study group

12 Pages·2016·0.81 MB·English

by  Taku Oshima

ClinicalNutritionxxx(2016)1e12
ContentslistsavailableatScienceDirect
Clinical Nutrition
journal homepage: http://www.elsevier.com/locate/clnu
Review
Indirect calorimetry in nutritional therapy. A position paper by the
ICALIC study group
Taku Oshima a, Mette M. Berger b, Elisabeth De Waele c, Anne Berit Guttormsen d,e,f,
Claudia-Paula Heidegger g, Michael Hiesmayrh, Pierre Singer i, Jan Wernerman j,
Claude Pichardk,*
aDepartmentofEmergencyandCriticalCareMedicine,ChibaUniversityGraduateSchoolofMedicine,1-8-1InohanaChuou-ku,ChibaCity,Chiba260-
8677,Japan
bAdultIntensiveCare,LausanneUniversityHospital,1011Lausanne,Switzerland
cDepartmentofIntensiveCare,VrijeUniversiteitBrussel,Brussels,Belgium
dDepartmentofAnaesthesiologyandIntensiveCare,HaukelandUniversityHospital,JonasLiesvei65,5021Bergen,Norway
eDepartmentofClinicalMedicineUniversityofBergen,Bergen,Norway
fHaukelandUniversitetssykehusLaboratoriebygget,7.etg.Heisøst,Norway
gServiceofIntensiveCare,GenevaUniversityHospital,RueGabrielle-Perret-Gentil4,1211Geneva14,Switzerland
hDivisionofCardiacThoracicVascularAnesthesiaandIntensiveCareMedicine,UniversityHospitalofVienna,WaehrihgerGuertel18-20,1090Vienna,
Austria
iCriticalCareMedicine,InstituteforNutritionResearch,RabinMedicalCenter,BeilisonHospital,PetahTikva49100,Israel
jDepartmentofAnesthesiologyandIntensiveCareMedicine,KarolinskaUniversityHospitalHuddinge,Sweden
kNutritionUnit,GenevaUniversityHospital,RueGabrielle-Perret-Gentil4,1211Geneva14,Switzerland
a r t i c l e i n f o s u m m a r y
Articlehistory: Background&aims: Thisreviewaimstoclarifytheuseofindirectcalorimetry(IC)innutritionaltherapy
Received21February2016 for critically ill and other patient populations. It features a comprehensive overview of the technical
Accepted15June2016 concepts,thepracticalapplicationandcurrentdevelopmentsofIC.
Methods: Pubmed-referenced publications were analyzed to generate an overview about the basic
Keywords: knowledgeofIC,todescribeadvantagesanddisadvantagesofthecurrenttechnology,toclarifytechnical
Indirectcalorimetry issues and providepragmatic solutions for clinical practice and metabolic research.The International
Energyexpenditure(EE)
MulticentricStudyGroupforIndirectCalorimetry(ICALIC)hasgeneratedthispositionpaper.
Respiratoryquotient(RQ)
Results: IC can be performed in in- and out-patients, including those in the intensive care unit, to
OCaxrybgoenndcioonxsiudmepprtioodnuc(VtiOon2)(VCO2) measureenergyexpenditure(EE).Optimalnutritionaltherapy,definedasenergyprescriptionbasedon
Restingenergyexpenditure(REE) measured EE by IC has been associated with better clinical outcome. Equations based on simple
anthropometric measurements to predict EE are inaccurate when applied to individual patients. An
ongoing international academic initiative to develop a new indirect calorimeter aims at providing
innovativeandaffordabletechnicalsolutionsformanyofthecurrentlimitationsofIC.
Conclusion: Indirectcalorimetryisatoolofparamountimportance,necessarytooptimizethenutrition
therapy of patients with various pathologies and conditions. Recent technical developments allow
broaderuseofICforin-andout-patients.
©2016ElsevierLtdandEuropeanSocietyforClinicalNutritionandMetabolism.Allrightsreserved.
1. Introduction
* Corresponding author. Geneva University Hospital, 1211 Geneva 14, Indirectcalorimetry(IC)measurestheoxygenconsumptionand
Switzerland.Tel.:þ41223729345;fax:þ41223729363. the carbon dioxide production, which correspond to the cellular
E-mail addresses: [email protected] (T. Oshima), [email protected]
respirationandallowstocalculatetheenergyexpenditure(EE)of
(M.M.Berger),[email protected](E.DeWaele),anne.guttormsen@
helse-bergen.no (A.B. Guttormsen), [email protected] thewholebody[1].Thestudyofthebasicprinciplesstartedmore
(C.-P. Heidegger), [email protected] (M. Hiesmayr), psinger@ than 100 years ago mainly by physicists and chemists, from the
clalit.org.il (P. Singer), [email protected] (J. Wernerman), claude. discovery of gas and its components to the establishment of the
[email protected](C.Pichard).
http://dx.doi.org/10.1016/j.clnu.2016.06.010
0261-5614/©2016ElsevierLtdandEuropeanSocietyforClinicalNutritionandMetabolism.Allrightsreserved.
Pleasecitethisarticleinpressas:OshimaT,etal.,Indirectcalorimetryinnutritionaltherapy.ApositionpaperbytheICALICstudygroup,Clinical
Nutrition(2016),http://dx.doi.org/10.1016/j.clnu.2016.06.010
2 T.Oshimaetal./ClinicalNutritionxxx(2016)1e12
conceptofgasexchangerelatedtocombustion[1].Technicalpro- An ongoing initiativesupported by two majoracademic orga-
gresses have enabled measurements of oxygen (O2) and carbon nizations (i.e. The European Society for Clinical Nutrition and
dioxide(CO2)concentrations,aswellasthevolumeofrespiratory Metabolism(ESPEN)andTheEuropeanSocietyforIntensiveCare
gasses and heat production of living organisms. In 1949, Weir Medicine (ESICM)) was launched todevelop a newindirect calo-
derived an equation to calculate EE based on the heat produced rimeter.Thegoalsweredefinedbyabottom-upapproachwiththe
whenagivensubstratewasburnedandthevolumeofO2neededto aimofdevelopinganaccurate,easy-to-useandaffordableindirect
burnthissubstrateandontheproteinoxidationderivedfromurea calorimeterfortheuseofthescientificandmedicalcommunity.
excretion via the kidney. The EE can be derived from O2 con- This review aims at summarizing the scientific background
sumption, CO2 production and urea excretion[Table 1] [2]. Many supportingICinordertooptimizenutritiontherapyforcriticallyill
proposedformulaedeviateminimallyfromtheWeirformula,and patientsandotherpatientpopulations.Itfeaturesacomprehensive
are not valid if other substrates such as ketones or pyruvate are overview of the technical concepts, the practical application and
oxidizedinsubstantialamounts[5].Theprinciplethatnitrogenis currentdevelopmentsofIC.
neither utilized nor produced during respiration has enabled
calculation of EE without measuring inhaled air volume [4]. This 2. Technicalconcepts
principle, known as the Haldane transformation, has contributed
greatlytosimplifyingthemeasurementsystemsasonlyexpiratory 2.1. Calorimetry:thebasics
gasvolumeneededtobemeasured.
Measuring EE was labor-intensive and reserved for laboratory ICmeasuresinspiredandexpiredgasexchangestocalculateEE.
research. It is only in the 1980's, that indirect calorimeters were Thisispossiblebecauseheatproductionistightlycorrelatedwith
commercialized for medical use. Their complexity and high cost O2consumption(VO2)andCO2production(VCO2)accordingtothe
havelimitedtheiruseforclinicalroutineduringthelast4decades. typeofenergysubstrate[20,25].
ICwasmostlyusedformetabolicresearch.Nevertheless,inclinical TheconditionsofthesubjectsduringICmustbedefinedasthey
practiceithasbeentakinghold,andbecameindispensableinpe- deeplyinfluencetheresults.Forhealthyindividuals,basalenergy
diatricintensivecareunits(ICU)[6].Incriticallyilladults,halfof expenditure (BEE) is measured in a resting state that is free of
patientsinamixedmedical-surgicalICUhadindicationsforIC[7,8], physicalandpsychologicalstress,athermallyneutralenvironment,
butwererarelymeasured. i.e. at temperature ranges where energy used for the body tem-
The assessment of EE requires IC and cannot be predicted by perature maintenance is minimal, and a fasting state, i.e. no oral
equations[9,10]:anumberofpredictiveequationsbasedonsimple intakeformorethan10hpriortothemeasurement,toavoidtheEE
anthropometric measures and some including gender, age and related to physical activityand diet-induced thermogenesis (DIT)
minuteventilationhavebeenproposedforclinicaluseasasurro- [Table2].DITisdefinedastheproductionofheatrelatedtosub-
gateofmeasuringEE[11].Unfortunately,manyreportshaveshown strateoxidationduringenergyuptake.Restingenergyexpenditure
thatpredictiveequationsarenotaccurateenough,becausepatients (REE) is defined as the sum of BEE and DIT, and total energy
withacuteorchronicconditionshavedifferentmetaboliccharac- expenditure(TEE)asthesumofREEandactivityinducedenergy
teristics,reflectedbyhighlyvariableEE.Bodycompositionisalsoan expenditure(AEE)[1,25].Bydefinition,BEEmeasurementsmustbe
importantmodifierofEEbecausefatfreemassaccountsformostof conductedinconditionsthatareunfeasiblefordiseasedindividuals
EE[12]. [Table3].Inclinicalpractice,REEorTEEreflectsthepatientenergy
Recently, it became clear that both overfeeding and under- needs.ForpatientsintheICU,measuredEEshouldbeconsideredas
feeding can be harmful [13e18] and that optimizing nutrition TEE.IfphysicalactivitybecomesastandardroutineICUcareinthe
support to the patients specific needs is an urgent task. IC is the future,thenthisstatementmustberevised.
onlypracticalclinicalmethodtomeasureEEofin-andout-patients
[3,19,20]inordertotailornutritiontherapy/supporttotheirspe- 2.2. HowisEEmeasured?
cific needs; assuming that the energy target should match EE.
However,thecalorimeterscurrentlyavailableonthemarketarenot IC requires the measurement of inspired and expired O2 and
sufficientlyaccurate[9,21e24],difficulttouse,andtooexpensiveto expired CO2concentrations,aswellasthevolumeofexpiredgas
bereadilyaccesibleingeneralhospitals. perminutetocalculatetheVO2(L/min)andVCO2(L/min)[28].Then
VO2 and VCO2 are used to calculate the EE(kcal/day) using the
Weir'sequation[Table1][2,20,28,29].
In a mechanically ventilated patient, the gas sampling is ob-
Table1
Equationsusedforthecalculationsrelatedtoindirectcalorimetry[2e4]. tained from the circuit connecting the endotracheal tube to the
ventilator, and measured by using either the breath-by-breath
CalculationsofO2consumption analysis [Fig.1 a] or the analysis using a mixing chamber [Fig.1
VVCOaO2n2¼d¼(CV(OVi2(cid:2)ep(cid:2)FroiOFde2uC)cOtei2o)(nVee((cid:2)ViF(cid:2)eOF2i)CO2) cba]n[oTpayblheoo4d].oIrnafispttoendtafanceeomusalsykbisreuastehdintogcsoullbejcetctths,eiansvpeinretidlaatnedd
Haldanetransformation expired gas [Fig.1c] [28]. Air leaks of respiratory gases alter the
AssumptionbasedontheconceptthatN2 accuracyofthemeasurementsandshouldbeavoided.
isconstantininspiredandexpiredgas
VFeiN¼2[¼Fe(N12(cid:3)/FFiNeO2]2(cid:2)(cid:3)FVeeCO2) VO2FoarndmeVaCsOu2recmanenbtseucasilncuglattheedcaasnoapdyifwfeirtehnocuetbOe2tweenernichthmeenOt2,
FiN2¼(1(cid:3)FiO2(cid:3)FiCO2) concentration in ambient air and the measured O2 and CO2 con-
IfFiCO2of0.03e0.05%isignored, centration in the expired gas, collected by the canopy. For mea-
VO2¼[(1(cid:3)FeO2(cid:3)FeCO2)(cid:2)(FiO2(cid:3)FeO2)(cid:2)Ve]/(1(cid:3)FiO2) surements in mechanically ventilated conditions or using the
Weir'sequation
EE¼[(VO2(cid:2)3.941)þ(VCO2(cid:2)1.11)þ(uN2(cid:2)2.17)](cid:2)1.44 canopywithO2enrichment,themeasurementsaremorecomplex.
Breath-by-breathsystemsmeasuretheexhaledgasvolumeandthe
V(LO),2:VOe:2ecoxpnisruemdpvtoiolunm(Le/m(Li)n,)F,iVOC2O:2f:raCcOti2onproodfuinctsipoinre(dL/moxiyng),enV,i:FienOsp2:irefrdacvtoiolunmoef Oin2staanndtaCnOe2oucosnceexnptirraetdiongatsrancsointicoennst,raantidoninstewgriathtetihnestpanrotadnuecotuosf
expiredoxygen,FeN2:fractionofexpirednitrogen,FiN2:fractionofinspiredni-
trogen,EE:energyexpenditure(kcal/d),uN2:urinarynitrogen(g/d). expiratoryflowovertime.Amixingchambersystemmeasuresthe
Pleasecitethisarticleinpressas:OshimaT,etal.,Indirectcalorimetryinnutritionaltherapy.ApositionpaperbytheICALICstudygroup,Clinical
Nutrition(2016),http://dx.doi.org/10.1016/j.clnu.2016.06.010
T.Oshimaetal./ClinicalNutritionxxx(2016)1e12 3
®
Table2 Monitor (Datex,Finland)produced35yearsagoisoftenviewedas
Componentsoftheenergyexpenditureinhealthysubjectsanddiseasedindividuals thereferencedevice[9,22e24,33].Thisdevicefeaturesbothcanopy
[1].
and ventilator measurements [30]. When on ventilator mode, it
Componentsof Definition uses the mixing chamber technique with a unique constant flow
energyexpenditure chamber to dilute the exhaled gas to enable calculations of VO2,
Basalenergy Energyexpendedinfastingstate, VCO2 and EE without directly measuring the expired gas volume
expenditure(BEE) restinginlyingpositionatneutral [30]. The device has been repeatedly validated, including a com-
ambienttemperature,freeofphysical parison against mass spectrometry [30,34,35]. However, existing
andpsychologicalstress.
units are progressively disappearing and the manufacturer no
Note:Onlyapplicableinhealthysubjects.
Diet-induced Oxidationofenergysubstratesduringoral, longeroffersanysupport.
thermogenesis(DIT) enteralorintravenousenergyintake
Activityenergy Energyexpendituretosupport
2.4. Technologyofmodernindirectcalorimeters
expenditure(AEE) physicalactivity
Restingenergy BEEþDIT
expenditure(REE) Calorimetersaredesignedtomeasurespontaneouslybreathing
Totalenergy REEþAEE patients or mechanically ventilated patients [28]. The different
expenditure(TEE) techniques predetermine the limitations of their performances
[Table4].
Deviceswithbreath-by-breathtechnologycanbemadesmaller
inhaledandexhaledgassesseparately,todetecttheglobalchange astheydonotrequireabulkymixingchamber.Theygeneraterapid
intheinhaledandexhaledgas[30].Theexpiredvolumeisusually readings by measuring short intervals of gas samples, a valuable
measuredbyaseparateflowmeter,orbyadilutiontechniqueusing feature in case of exercise physiology or rapid shift in substrates
aconstantflowchambertocalculatethevolume[30].Bothsystems oxidation.
use the Haldane transformation, i.e. the method to calculate Devices with a mixing chamber generate more stable mea-
inspired gas volume by the ratio of the inspired and expired ni- surementsbecausethegasesarephysically“averaged”beforebeing
trogen concentrations, to calculate the inspired gas volume thus analyzed, allowing the gas analyzers to generate very accurate
simplifyingthefloworvolumemeasurements[Table1][4,20,28]. analysis. The mixing chamber typically occupies 3e5 L of space,
Some commercially available simplified devices only measures precluding the making of a small device. The capacity to make
eitherVO2ortheVCO2tocalculateEEbyassumingthattheRQisa reliable measurements in a short duration (e.g. 3e5 min) is also
fixedvalue(i.e.0.8e0.85)[28,31,32].Whilethistypeofassumption limited,asittakesjustasmuchtimeforthegasconcentrationsin
maybeacceptableinhealthysubjectsonbalancednutrition[28],itis themixingchambertostabilize.
notrecommendedforpatientsbecausetheirsubstrateoxidationmay
changesignificantlyaccordingtothetypeofdiseaseandnutrition.
2.5. Accuracyandreproducibility
AssumingafixedRQinpatientsgiveinaccurateEE,inturnleadingto
suboptimalenergyprescription.UsingtheVCO2andRQofprescribed Threecomponentsofthehardwareplayamajorrole:theO2and
nutritionformulas(foodquotient)tocalculateEEhasbeenproposed CO2 analyzers, and the flowmeter. Their accuracy, precision and
asawaytoimprovetheaccuracyofthecalculationforICUpatients reproducibilityarecriticalforICandareinfluencedbymanyfactors
[32].Theanalysiswasconductedonstabilizedpatientswhotolerated
[Table5].Forbreath-by-breathsystems,thereactiontimeofthegas
morethantwo-thirdsoftheprescribednutritionallowingthemean
analyzersisimportant.Thereliabilityofthesoftwaretosynchro-
EE bias of 7.7% (¼þ141 kcal/d) while improving the precision nize the signals from the gas analyzers and the expiratory flow-
comparedtopredictiveequations.However,theaccuracylevelofthis
meter to allow continuous calculations is a challenging demand.
methodforindividualpatientscanonlybevalidatedbyconductingIC.
Smallerrorsinthealignmentoftheacquireddatacanleadtogreat
Thus,thismethodcanbeconsideredasanalternativeforpredictive
differences in the results. Mixing chamber devices are not as
equations,butshouldnotbeconsideredasavalidalternativeforICin
technically demanding. However, the use of the Haldane trans-
thegeneralICUpopulation.
formationformulaintroducesamathematicallimitation,especially
incaseofO2enrichmenthigherthan60%astheinaccuracyofthe
2.3. Thereferencedeviceofthe20thcentury analyzerswillbeenhancedbythecalculation[28,30,34].
Outside the calorimeter itself, the collection of inspired and
Numerous indirect calorimeters have been in and out of the expiredgasesbyanappropriateandairtightsystemismandatory
market in the past decades. However, the Deltatrac Metabolic [Fig.2].Avoidingleaks ofinspiredandexpired gasiscrucial, and
Table3
Requiredconditionsforaccuratemeasurementofenergyexpenditureinhealthysubjectsordiseasedindividuals[1,26,27].
Parameter Condition Subject
BEE Atleast10hafterthepreviousmeal Onlyhealthysubjects
Freeofdrugs
Restinginsupinepositionandfreeofphysicalstress
Awakeandfreeofpsychologicalstress
Normalbodytemperature
Ambienttemperatureinzoneofneutrality(27e29(cid:4)C)
REE Atleast5hafterthepreviousmeal,orundercontinuousfeeding Healthysubjectsorpatients
Minimum2hafteralcoholandnicotineingestion,4haftercaffeineingestion
After30minofrestingperiod
Restinginsupinepositionandfreeofphysicalstress
Awakeandfreeofpsychologicalstress
Comfortableenvironmentalcondition
TEE Nospecificconditions Healthysubjectsorpatients
Pleasecitethisarticleinpressas:OshimaT,etal.,Indirectcalorimetryinnutritionaltherapy.ApositionpaperbytheICALICstudygroup,Clinical
Nutrition(2016),http://dx.doi.org/10.1016/j.clnu.2016.06.010
4 T.Oshimaetal./ClinicalNutritionxxx(2016)1e12
Fig.1. Schematicpresentationofindirectcalorimetryusedinpatientsonmechanicalventilationandonthosebreathingspontaneously.a)Breathbybreath:Respiratorygas
compositionandflowaremeasuredcontinuouslybyconnectingthegasanalyzerstotheventilatorcircuit.Thesignalsreceivedbythegasanalyzersandflowmetersaresyn-
chronizedtocalculatetheoxygenconsumption(VO2L/min)andCO2production(VCO2L/min)asthedifferencebetweenthevolumesofinhaledandexhaledO2andCO2perbreath
byintegralcalculations.TheHaldanetransformation[Table1]isusedtocalculatetheinhaledgasvolumefromexhaledgasvolumemeasurement.TheWeir'sequation[Table1]is
usedtocalculateEE(kcal/d)perbreath,andaveragedforthedurationofthemeasurement.ThesystemishighlyresponsivetothedynamicchangesoftheEE,butpronetoerrors
duetotheresponsetimeofthegasanalyzersandsoftware.b)Mixingchamber:TheO2concentrationofinhaledair(FiO2)isfirstmeasured.Exhaledgasiscollectedintothemixing
chamber,whereitisphysicallyaveragedandanalyzedforO2(FeO2)andCO2(FeCO2)concentrations.Thecollectedgasiseliminatedthroughanindependentchamberwherethegas
flow(Q)iskeptconstantat40e45L/min,todilutetheexhaledgasfromthemixingchamberwiththeambientair.CO2inthedilutedgas(FedCO2)ismeasuredtocalculatetheCO2
production(VCO2,L/min)bymultiplyingtheconcentrationbytheflow(VCO2¼FedCO2(cid:2)Q).AnequationusingtheHaldanetransformationallowsthecalculationoftherespiratory
quotient(RQ)fromthemeasuredO2andCO2values(RQ¼(1(cid:3)FiO2)/[(FiO2(cid:3)FeO2)/FeCO2(cid:3)FiO2]),andthusenablesthecalculationoftheoxygenconsumption(VO2,L/min;
VO2¼VCO2/RQ).ThisuniquemethodusedintheDeltatracMetabolicMonitor®(Datex,Finland)enablesVO2andVCO2measurementswithoutmeasuringtheflowoftheexhaled
gas,whichusuallyintroducestechnicaldifficulties.c)Canopy:ThecanopyisusedtomeasureEEinspontaneouslybreathingsubjects.Thesubjectisplacedunderaclearcanopy
withaplasticdrapetoavoidairleakage.Calorimetersfeatureconstantflowgeneratortocreateanoutwardflowthroughthecanopy.Theexhaledbreathbythesubjectisdilutedby
theconstantflowQ(L/min),andcollectedbythecalorimeterforgasanalysis(FedO2,FedCO2),andenablescalculationsofVO2andVCO2[Table1].FiO2andFiCO2areeitherassumed
asambientairvaluesormeasured,dependingonthecalorimeter.ThesevaluesareusedtocalculatetheEEusingtheWeir'sequation.(1:flowanalysis,2:FiO2,3:FiCO2,4:FeO2,
5:FeCO2,6:FedCO2,7:FedO2;smallarrows:respiratorygasflow,solidline:gassampling,dottedline:signalforflowanalysis,smallarrows:respiratorygasflow,boldarrow:
constantflow).
Table4
Technologiesusedincommerciallyavailablecalorimeters.
Patientcondition Patientapplication Technology Practicalcharacteristics(advantages/disadvantages)
SpontaneousBreathing Canopy Constantflowdilution Patientdiscomfortminimum
DifficulttomeasurewithO2supplementation
Facemask Breathbybreathormixingchamber SupportsO2andmaskventilation
Patientdiscomfort,riskofleak
MechanicalVentilation In-circuit Breathbybreath Smalldevice,fastresponse
Pronetoerrorincalculation,deadspace&
resistanceofthemeasurementcomponents
Gascollection Mixingchamber Stablemeasurements,validatedinliterature
Largedevices,difficulttodisinfect
Pleasecitethisarticleinpressas:OshimaT,etal.,Indirectcalorimetryinnutritionaltherapy.ApositionpaperbytheICALICstudygroup,Clinical
Nutrition(2016),http://dx.doi.org/10.1016/j.clnu.2016.06.010
T.Oshimaetal./ClinicalNutritionxxx(2016)1e12 5
becomesevenmorecriticalincaseofO2enrichment.Highquality calculate EE, but the delay to obtain the results limits its use to
ofcalibrationgasforcalibrationandperiodicmaintenanceof the research[3].
calorimetersguaranteethetechnicalperformances[25]. Insummary,thesethreemethodsaretooinvasive,cumbersome
orcostly.ICremainsthemostpracticalmethodthatisapplicablein
patientswithvariouscharacteristics.
2.6. Alternativemethodstomeasureenergyexpenditure
EEcanbemeasuredbyfourdifferentmethods:1)directcalo-
3. Practicalconsiderations
rimetry, 2)indirectcalorimetry, 3)thermodilution(Fickmethod),
and4)2H/1Hand18O/16Odoublylabeledwater.
3.1. Indicationsandlimitations
2.6.1. Directcalorimetry ICisanon-invasivetechnique[25]applicabletomanypatients
Directcalorimetryisthedirectmeasurementofheatproduction in order to individualize their nutrition therapy or for research
in the body. This concept is based on the phenomenon that all purpose. However, IC may require special considerations for the
energysubstrates,uponoxidation,produceheat.Thesubjectneeds interpretation of the results in a number of specific situations
tobeconfinedinaninsulatedchambertomeasuretheheatpro- [Table7].
duction.Thesubjectsalsohavetobeabletomaintainacomplete
restingstateduringthemeasurementinordertoavoidextraheat
productionbyphysicalactivity.Thustheconditionsareunrealistic 3.1.1. Patients
forclinicaluse,andtheavailabilityislimitedtoafewspecialized Bydefinition,themostimportantconditionistheabsenceofair
researchcenters. leak in the respiratory circuit. For example, patients with air-
leakingchestdrainagecannotbestudiedbyIC[27].Mechanically
ventilatedpatientswithhighpressuresettingsontheventilatorare
2.6.2. Fickmethod
pronetoairleakageattheleveloftheendotrachealtube[36].ICin
TheFickmethodrequiresapulmonaryarterycathetertomea-
patients with unstable conditions is less useful, as the measure-
surethecardiacoutput,usingthethermodilutionmethod.Arterial
ment will not represent their true metabolic characteristics. For
andmixedvenousoxygencontentsmustalsobemeasured.After
example, agitated patients or those with seizures or other invol-
measuringtheO2contentinarterialandmixedvenousbloodfrom untary movements are difficult to assess, as measurements will
thepulmonaryartery,VO2canbecalculatedusingtheFickequation
[Table 6]. The EE is calculated by assuming a fixed RQ. Several include the EE related to the body movements, by nature incon-
stant, and therefore will not represent the true daily EE [27]. A
problems limit its use in clinical practice.First, only few patients
patientshouldbeinarestingconditionoratleastbeabletokeep
havepulmonaryarterycathetersandtheinsertionofthecatheter
calmduringmostoftheICduration[26],fortheresultstobeatrue
onlyforEEmeasurementswouldbetooinvasive.Second,theVO2
representativevalueoftherestingEE.Patientswithunstablebody
calculatedbythismethodisonlyasnapshotofthemomentofthe
measurement, while the error of the thermodilution method is temperature,variablepHduetoCO2accumulationorothercauses
are also likely to present unreliable results, and measurements
about15%duetocardiacoutputvariationovertherespiratorycycle.
shouldberepeatedperiodicallyorafterstabilization.
Furthermore, mixed venous oxygen concentration may be over-
estimatedbecauseoftheshuntingofarterialbloodfrombronchial
vessels,thusleadingtounderestimationofVO2andsubsequently 3.1.2. Treatments
theEE. Mechanical ventilation with FiO2 >60% is likely to generate
inaccurate measurements because of the Haldane transformation
2.6.3. Doublylabeledwater [27,30].PatientsonorgansupporttreatmentsthatsupplyO2tothe
Watercontainingnon-radioactiveisotopelabeledhydrogenand bloodorremove CO2 fromtheblood(e.g.ECMO)andtreatments
oxygenatoms(2H/1Hand18O/16O)isgivenorally,afterabaseline that alter acid-base homeostasis (e.g. renal replacement therapy
evaluationofthebodyliquids;urine,saliva,andblood.Theevalu- andliversupporttherapiessuchasMolecularAdsorbentRecircu-
ationofthebodyliquidsisrepeatedafter7e12daystocalculatethe latingSystem(MARS))alsoneedspecialconsideration.
variations of concentrations of the isotopes over time. CO2 pro- CurrentlyavailableICdevicesdonotprovidevalidsolutionsfor
ductioncanbecalculatedbyobservingtheeliminationratesofthe these special conditions. However, the improvements of organ
isotopesfromthebodyliquids.EEcanbecalculatedbyassuminga supporttherapieshaveenabledtheirfrequentapplicationinlonger
givenRQ.Thecalculationsarebasedonseveralassumptionssuch durationsforpatientsunderextremelysevereconditionsorwait-
as steady-state CO2 and H2O turnover, and constant body water ingorgantransplantation. Thus,technicalsolutionstoconductIC
poolsizeduringthemeasurementperiod.Theseassumptionsmay accurately in these patients are mandatory. De Waele et al. sug-
not be applicable for critically ill patients, as fluid volume shifts gestedamethodforconductingIC in ECMOpatients [37].Devel-
together with large changes in CO2 production are frequently opmentofcommercialcalorimetersdesignedforusewithvarious
observed [3]. The costs of the doubly labeled water and of mass treatment conditions will contribute to the improved nutrition
spectrometrymeasurementsareveryhigh.Thismethodallowsto therapyinthesepatients.
Table5
Sourceoferrorsforindirectcalorimetrydependingonthemeasurementtechnology.
Technology Specificfactors Commonfactors
Canopy Leakofthegascollection AccuracyofO2,CO2,andflowanalyzers
Reliabilityoftheconstantflow HaldanetransformationintroduceshighvariabilitywhenFiO2>60%
Breath-by-breath Responsespeedofgasanalyzers Adequatemaintenanceandcalibration
Accuracyofdatasynchronizationbythesoftware
Mixingchamber Leakofthegascollection
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6 T.Oshimaetal./ClinicalNutritionxxx(2016)1e12
Fig.2. Sourcesofairleaksduringindirectcalorimetryinspontaneouslybreathingpatientsandonthoseonmechanicalventilation.Theavoidanceofrespiratorygasleaksiscrucial
totheaccuracyoftheenergyexpendituremeasurement.1:Tubeconnectionswithgascollectiondevicesandcalorimetersmustbe“air-tight”.2:Forpatientsonmechanical
ventilation,leaksfromthecuffoftheendotrachealtubemustbedetected,astheycanbesignificantincasesofhighairwaypressure.3:Pathologies(e.g.bronchialfistula)and
treatments(e.g.chestdrain)causingairleaksfromthelungmustbedetected.4:Canopyanddrapemustbeinspectedforcracksandtears,andfittingtightlytoeachother.The
drapeshouldfullycoverthesurroundingsofthecanopytoavoidleaks.
Table6 theseconditionsarenoteasilymet,practicalrecommendationsare
TheFickmethod(thermodilution)andrelatedequations. proposedbelowaccordingtopatientcharacteristics.Table8sum-
CalculationofO2contentinblood marizestheimportantcheckpointsforasuccessfulroutineuseof
CaO2¼(Hb)(cid:2)1.38#(cid:2)SaO2þ(0.003(cid:2)PaO2) IC.Itcaneasilybeadaptedtocreateprotocolsafteradjustmentfor
CvO2¼(Hb)(cid:2)1.38#(cid:2)SvO2þ(0.003(cid:2)PvO2) thelocalmedicalpractices.
#:O2carryingcapacityofHb(1.34e1.39/gram,
dependingonliterature)
Fickequation 3.3. Calorimetry:importantconsiderations
VO2¼(CaO2(cid:3)CvO2)(cid:2)CO(cid:2)10or
VO2¼1.38(cid:2)(Hb)(cid:2)(CO)(cid:2)(SaO2(cid:3)SvO2)/10 ICistheonlyeasy-to-use,non-invasivemethodtomeasurethe
Ca(v)O2:contentofO2inarterial(venous)blood,Sa(v)O2:O2saturationofarterial EEofhealthyactiveorinactivesubjects,orofpatientswithvarious
(venous)blood,Pa(v)O2:partialpressureofO2inarterial(venous)blood,CO:cardiac levels of metabolic stress in order to obtain immediate results
output(L/min). [3,38]. Nevertheless, the lackof sufficient knowledge to interpret
theresultsgeneratedbyICmayleadtoerroneousprescription.The
3.2. Practicalrecommendationsofclinicaluse conditions of IC measurement are of paramount importance. The
general statement is: the more stable the clinical situation, the
ICissuccessfulwhenanappropriatedeviceisusedinoptimal more reliabletheICresults.Wheneverasituationischanging,IC
conditions, and the results are analyzed by experienced pro- shouldberepeated.Forinstance,ICobtainedduringtheearlyphase
fessionals in order to individualize the nutrition care. Although, ofacriticalillnessshouldberepeatedwithinthenext24e48hto
obtain a result reflecting the dynamic evolution of the disease
[Fig.3].
Table7
Clinicalsituationsrequiringcarefulinterpretationofenergyexpendituremeasured 4. Developmentsofindirectcalorimetry
byindirectcalorimetry[26,27].
(cid:5) Physicalagitationorunstablesedationand/oranalgesia 4.1. Theglobalinitiativetopromotecalorimetry
(cid:5) Airleaks(>10%ofminutevolume)
(cid:5) Unstablebodytemperature(>±1(cid:4)Cchangeoverlast1h) Commercially available calorimeters are usually of large size
(cid:5) UnstablepH(>±0.1changeoverlast1h)
(cid:5) Oxygenenrichment(FiO2>60%) and heavy weight, need time-consuming warm-up and calibra-
(cid:5) Organ support therapies: renal replacement or liver support therapy (pH tion before measurement, require PCs to record and analyze re-
alterationswhenconductedintermittently),ECMO(directO2supplytothe sults, require cumbersome disinfection of the device and
bloodandCO2removalfromtheblood) repeated-use components after measurements, and are sold at
FiO2:fractionofinspiredoxygen,ECMO:extracorporealmembraneoxygenation. relativelyhighcosts[27,28].ThebestwaytopromoteICistomake
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T.Oshimaetal./ClinicalNutritionxxx(2016)1e12 7
availableaneasy-to-use,accurateandaffordabledevicefordaily
use in in- and out-patients. The requirements of an ideal calo-
rimeterhavebeendefinedusingabottom-upprocess[Table9].As
current calorimeters were unable to meet the requirements
definedbyphysicians,theInternationalMulticentricStudyGroup
forIndirectCalorimetry(ICALIC)wasformedtodevelopandtest
anoptimaldevicewiththefinancialsupportoftwointernational
academic societies (The European Society of Intensive Care
Medicine(ESICM)andTheEuropeanSocietyforClinicalNutrition
andMetabolism(ESPEN)).
Thenewcalorimeterhasbeenvalidatedagainstthegoldstan-
dard technology for gas composition measurements, i.e. mass
spectrometer (MAX300-LG, Extrel, Pittsburgh, USA). The mass
spectrometerwasspeciallytunedforbreathgasanalysis,tobeable
tomeasureO2andCO2withresolutionupto10ppmandaccuracy Fig.3. Evolutionofenergyexpenditureincriticallyillpatients.Theevolutionofenergy
of±0.0025%.TheanalyzersforO2andCO2wereevaluatedfortheir expenditure(EE)ofcriticallyillpatientsisdynamicaccordingtothephaseandthe
accuracyinstaticconcentrationmeasurementsusingprecisiongas severityoftheillness,treatmentandextendedbedrest.Anillustrationofsuchevo-
mixtures to simulate various clinically relevant O2 (16%e21% for lutioninasepticpatientwithrelapsedofthediseaseispresented.Dynamicchangeof
canopymeasurements,andupto70%forventilatormeasurements) EEduringtheearlyphase,andthedifferenceintheevolutionofEEduringthefirst
andCO2(0.3e5.0%)concentrations.Accuracyandresponsetody- opnhsaestesaanrdetimheproeslsaipblseetdoueesttiomfaatcetoacrscusruacthelyasbybepdrerdeiscttiavnedeqimuamtioonbisli[z1a1t]i.o(nCiirncleth:eEElabtye
namicconcentrationchangeswereevaluatedinin-vivoevaluation indirectcalorimetry(kcal/d);triangle:EEbyFaisy'sequation;greyline(kcal/d):pre-
involunteers,bydirectcomparisonofmeasuredO2andCO2con- scribedenergy(kcal/d);dottedline:deliveredenergy).
centrations.Theoverallperformanceof thecalorimeterconsisting
ofthenewlydevelopeddynamicmixingchamberwastestedbythe
Table8
Checkpointsforsuccessfulindirectcalorimetry.
Mechanicallyventilated Spontaneouslybreathing
Planningmeasurement
1. Frequency Conductcalorimetrywithin3e4daysafteradmission
Repeatcalorimetryevery2e3daysduringtheICUstay
Repeatcalorimetryincaseofchangesin
patientordiseaseconditions
Unsuitableconditions
2. Respiration FiO2>60% O2enrichment:
PEEP>10cmH2O Difficultwithcanopy
Peakairwaypressure>30cmH2O Possiblewithleak-tightO2maskusingbreathbybreathdevice
3. Agitation Unstablesedationand/oranalgesia Intoleranceforcanopyand/orfacemask
Uncontrolledseizureand/orinvoluntarymovements
4. Treatments Airleaksfromventilatorcircuitand/or
endotrachealtubecuff
Airleaksfromchestdrains
Specialconsideration:Renalreplacementtherapy,
liversupporttherapy,ECMO
5. Immediatechanges >±1(cid:4)Cchangeofbodytemperature
(<60minbeforeIC) Changeofdrugdose:catecholamine,
sedatives,analgesics,etc.
Invasiveprocedures,mobilization,physicalexercise
Beforemeasurement
6. Device Warmupandcalibration(asrequired)
Secureconnectionsoftubesandcomponents
Searchforanyairleaks
7. Feedingstatus Continuousfeedingpreferred Fastingpreferredforout-patients(>8hbeforeIC)
Iffed,record:energyprescriptionandintake,
duration(hrs)sincelastmeal
8. Environment Record:ventilationsetting AdjustcanopyventilationtomaintainFeCO20.8e1.2%
Maintainroomtemperatureat20e25(cid:4)C
Ensurecomfortablebodyposition
Duringandaftermeasurement
9. QualityofMeasurement Duration:30minoruntilstablestate
(calculatedCVa<5%forVO2andVCO2for>5min,
CVof<10%for25min)
RQ:<0.7and>1.0maysuggestinadequatemeasurement
Record:
- agitationandbodymovements
- anyeventsaffectingbreathingpattern
- changesinvasoactivedrugs
10. Disinfection Disinfectdeviceandcomponentsincontactwithpatients
Discardsingleusecomponents
a Coefficientofvariation.
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8 T.Oshimaetal./ClinicalNutritionxxx(2016)1e12
conventionalmixingchambermethod,usingthemassspectrom- 5.2. IsmeasuredEEalwaysreflectingtheenergyneeds?
eterasthegasanalyzer.Thepracticalcharacteristicswillbeeval-
uated in a multicenter study which will start during the 1st This critical question has been asked many times and is
semesterof2016,toensurethatthedeviceiseasytouseandfitsthe frequently investigated, but the answer remains controversial. In
conditionsfoundinvariousclinicalsettings. general, the measured EE defines the energy target for the pre-
Market release of the device is anticipated for 2017. Training scriptionofnutrition.However,duringtheearlyphaseofanacute
coursesareorganizedbyESPENaspartof theLifeLongLearning illness,endogenousenergysupplycoversmostoftheenergyneeds,
(LLL)CoursesandwillbemultipliedtoallowoptimaluseofIC. a condition that is marginallyaffected byexogenous energysup-
plementation [Fig. 4] [49,50]. The energyadministered may then
massively exceed the requirements and generate relative over-
feeding[3],aconditionassociatedwithdeleteriousconsequences
[Table11]andpooroutcome.Thistransitoryperiodgenerallyends
5. Whyyoushoulduseindirectcalorimetry
as soon the patient's overall condition improves. However, the
valueofICmeasurementstoevaluatetheevolutionofendogenous
5.1. Rationaleformeasuringenergyexpenditurebyindirect
energy production needs further investigation. Therefore, careful
calorimetry
interpretationofEEbyICinthisphaseisnecessaryfortheadequate
prescription of energy to avoid overfeeding. However, excessive
Energy expenditure of a patient is massively influenced by a
restriction of energy will result in underfeeding, which has been
number of intrinsic and extrinsic factors [Table 10] [19]. These
associatedwithprogressivelossofleanbodymass[51],leadingto
factorshavesynergicorantagonistimpactontheEElevelandthe
poor outcomes. It should also be noted that predictive equations
estimationoftheEEusingapredictiveequationbasedonanthro-
willnotbeabletotakeintoaccountthistype ofmetabolicalter-
pometriccharacteristics(i.e.bodyweight,height,gender,andage)
ation, and the degree of error in the estimation of EE will be
isfrequentlyinaccurate[3,20,39].Theuseofmultiplicativefactor
unpredictable.
usuallycalled“stressfactor”hasbeenproventofurtherdeteriorate
the estimation of EE based on equations. Forexample, obese pa-
5.3. Respiratoryquotient:anotheradvantageofindirect
tientspresentsignificantEEvariationsduetotheirunderlyingill-
calorimetry
nesses,variablebodycompositionanddegreeofmalnutrition[40].
Patientswithchronicobstructivepulmonarydiseaseorthosewith
ICallowsfornon-invasivemeasurementofEEinspontaneously
cancerhaveanelevatedEE,whichcanbeeasilyunderestimatedby
breathing patients or those on mechanical ventilation, with or
predictive formula [41e43]. Critically ill patients with trauma or
sepsis have dynamic changes of their EE during the successive withoutO2enrichment[9,22,25,28].AnadvantageofICoverother
methods to measure EE is the capacity to derive the respiratory
phasesoftheircriticalillness[3,44e47].Althoughmuchefforthas
quotient (RQ) from direct measurements. The RQ corresponds to
been made to create predictive equations adapted to the clinical
evolution of acute illness [48], IC remains the gold standard to thequotientofVCO2andVO2(RQ¼VCO2/VO2)[25,28],whichen-
ables the calculations of the substrate oxidation ratesfor glucose
measure EE [3,19]. The full benefits of nutrition support may be
and lipids. This would especially allow detecting net lipogenesis.
expectedonlyifthepatientspecificEEisreflectedinthenutrition
For patients with chronic illnesses, EE reflects the energy needs
prescription,accordingtothechangesthatoccurduringthecourse
while the RQ reflects the composition of oxidized substrates [5].
oftheillness.
Thisinformationishelpfultotailortheprescriptionofthenutrition
regimen [28] byobserving the match betweenthe energy intake
andthefoodquotient,i.e.theRQoftheenergysubstratesaccording
Table9 totheirfoodcomposition.
Characteristicsofthenewindirectcalorimeterdefinedbyabottom-upprocessof
Forcriticallyillpatients,itallowstovisualizethemetabolical-
development.
terations, especially during the early phase. IC measurements
Characteristics Description shouldberepeatedtomonitorthedynamicchanges,andtoopti-
Accuracy mizetheprescriptionofenergy[3].
Gasanalyzers ±0.02%forO2andCO2(aftercalibration)
Flowanalyzer ±2%(aftercalibration)
5.4. Routineuseofindirectcalorimetry
Ease-of-use
Portable <2kg,maximumfootprint:15e30cm
Interface Intuitivesoftware,usermanualnotrequired IC is rarely routinely used in medical institutions across the
Calibration (cid:5) Gasanalyzer:Automaticperiodiccalibration world[7,25]inspiteofitsvalueforawiderangeofpatients.Sucha
againstroomair(nocalibrationgasrequired) limiteduseofICismainlyduetotheunavailabilityofcalorimeters,
(cid:5) Flowanalyzer:Automatic the insufficient awareness about the impact of optimal nutrition
Measurement
Duration <10minforstandardmeasurement support on the patients outcome [20], the lack of expertise for
Recording (cid:5) Localmemorybuffer interpretation of results, costs of device and related-manpower.
(cid:5) Variousexportationformats(Excel,CSV,etc) Thissectionaimsatclarifyingtheseissues.
Connectivity WirelessorUSB
Batteryoperated Upto10measurements(duration20min),
5.5. Criticalillness
4hrs(continuousmeasurement)
Safety
Approval ECcertification PatientsintheICUfor>4daysorthoseaftermajorsurgeryare
Disinfection (cid:5) Devicecoveredbyeasytocleanmaterial good candidates for IC as they undergo severe stress related to
(cid:5) Singleusecomponentsforpatientcontact
(samplingtube,flowmeter) variable metabolic needs [52]. Indeed, these patients are at high
Compatible Hospitaldevices nutritionalrisk,astheyareunabletoresumesufficientoralintake
Availability instantlyandoftenrequireenteralorparenteralnutrition[7,53,54].
Cost <10’000US$ Studiesincriticallyillpatientshaverepeatedlyreportedgrossun-
Market Worldwide
derfeeding during the ICU stay [55]. Various factors such as gut
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T.Oshimaetal./ClinicalNutritionxxx(2016)1e12 9
Table10 The course of EE of severely ill patients features dynamic
Factorsinfluencingenergyexpenditure. changesasaconsequenceofstress,prolongedbedrest,atrophyof
(cid:5) Age,sex,bodyheight,bodymass, themetabolicallyactiveleantissuemass(i.e.300e600goftissue/
bodytemperatureBrainactivity,endocrineprofile, day), medications (catecholamine, sedatives, neuromuscular
systemicinflammation blockingagents,etc)[44,65e68],andmodifiedbymechanicalor-
(cid:5) Musclecontractionsorparalysis,physicalactivity
gan support therapies such as mechanical ventilation, renal
(cid:5) Fastingorpost-absorptivestate
(cid:5) Environmentaltemperature replacement and liver support therapies. Thus, IC should be
(cid:5) Drugs (e.g. alpha adrenergic stimulant, beta-blockers, sedatives, muscle repeatedastheclinicalconditionchangestoaccuratelydefinethe
relaxants) energytarget[16,63].
The obese patients constitute an increasing proportion of the
ICUpatientpopulation.Theirenergyrequirementsareparticularly
intoleranceandtreatmentinterventionsdelayfullenteralfeeding, poorlyaddressedbypredictiveequations[19].ICistheonlywayto
resulting in insufficient energy provision. Underfeeding is closely determinetheirmetabolicrequirementsaccurately.
associated with higher complication rates and poor outcomes In summary, it is recommended to perform IC on days 3 or 4
[13,17,56e59]. Overfeeding has also been repeatedly associated after ICU admission, major surgery or trauma in order to set the
with poor outcome and results often from the use of predictive energytarget[Fig.5].
equations [60]. Recent evidence points out the importance of
optimal nutrition starting within 3e4 days after ICU admission
[16,18,20,61e63],atatimewhenpredictiveequationsareexceed- 5.6. Inpatientsandoutpatientswithchronicconditions
inglyunreliableduetothevariableresponsesofindividualpatients
tothecriticalillness[8].Inotherwords,optimalnutritionpromotes Patients with chronic conditions are good candidates for IC,
betterclinicaloutcomeandICisnecessarytotailortheprescription althoughtheirchangesofEEarenotasdynamicasinICUorsurgical
totherealneedsofthepatient[62e64]. patients.Indeed,chronicdiseasesortreatmentsmodifythemeta-
bolicallyactiveleanbodymassandthelevelofdailyphysicalac-
tivity, which in turn significantly alter the energy needs and
challenge the estimation of EE by predictive equations. Typically,
importantmodificationsofthebodycompositionorofthephysical
activity deeply influence EE. Table 12 shows the most common
pathologieswithimportantEEalterations.
ICisnecessarytoconfirmtheenergyexpenditureandoptimize
therecommendationforfoodintakeortheprescriptionofnutrition
support. Repetition of IC should be considered according to the
appearanceofsubstantialmodificationofthepatientstatus.Con-
ductingICtogetherwiththemeasurementofthebodyweightand
the body composition is useful to further optimize the nutrition
prescriptionbyobservingtheeffectofenergyintakeonthesepa-
rameters[25,74].
Fig. 4. Conceptual presentation of the relative overfeeding frequently related to
parenteralnutritionduringtheearlyphaseofcriticalillness.Duringtheacutephaseof
thecriticalillness,thereleaseofendogenousenergysubstratesisincreasedandmeets
total energy expenditure (TEE), and administering energy does not immediately
terminatethisresponse.Introducingfullfeedinginthisearlyphaseusuallyresultsin
overfeeding, as the endogenous energy production is not attenuated by energy
administrationthuscreatesanexcessiveenergysourceaboveTEE.(Solidboldline:
Total energy expenditure; grey bold line: adapted endogenous energy production;
dottedboldline:earlyenergyadministration;thinline:combinedendogenousand
exogenousenergyadministration).
Table11
Effectsofoverfeedingandunderfeeding.
Insufficientenergyintake Excessiveenergyintake Fig.5. Conceptualpresentationofoptimalfeedingstrategytoavoidbothoverfeeding
andunderfeedingincriticalillness:Introducingtheadequateamountoffeedingin
Earlysigns Hypoglycemia Hyperglycemia
proportiontothebody'scapacitytodown-regulateendogenoussubstrateproduction
Hypothermia Hyperlipidemia(triglycerides)
avoidsbothearlyoverfeedingandlateunderfeeding.Repeatedcalorimetryisneeded
Hypercapnea
to monitor the dynamic changes of energy expenditure, however, providing the
Delayedsigns Infectiouscomplications Infectiouscomplications
optimalamountofenergystillrequiresspecialattentiontoavoidbothunderfeeding
Impairedimmunity Impairedimmunity
andoverfeeding.(Solidboldline:Totalenergyexpenditure;greyboldline:adapted
Impairedhealing Liversteatosis
endogenousenergyproduction;dottedboldline:energyadministrationbyEN;grey
Lossofleanandfatbodymass Increasedfatmass
dottedboldline:energyadministrationbyPN;thinline:combinedendogenousand
Impairedmusclefunction
exogenousenergyadministration).
Pleasecitethisarticleinpressas:OshimaT,etal.,Indirectcalorimetryinnutritionaltherapy.ApositionpaperbytheICALICstudygroup,Clinical
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10 T.Oshimaetal./ClinicalNutritionxxx(2016)1e12
Table12
Commonchronicpathologiesandtreatmentswithimportantalterationsofenergyexpenditure.
Conditions Effectsonenergyexpenditure
Respiratorydiseases
COPD [ Increasedrespiratoryefforts[69]
Cysticfibrosis [ [70]
Metabolicdiseases
Adrenalglanddisease [or[Y Increasedreleaseofcatecholamine[71]
Unpredictablechangeaftersurgicaltreatment
Thyroiddiseases [orY Alteredreleaseofthyroxine[72]
Muscletonealteration
Neuromusculardegenerativediseases Y Degenerationanddisuseofmuscletissue
Paralysis Y Disuseandatrophyofparalyzedbodyarea
Seizure,involuntarymovements [ Increasedmuscleactivity[73]
Cachexicconditions
Cancer [orY Cancergrowthandinflammation
Progressivereductionofleanbodymass
AIDS [orY Chronicinfectionandinflammation
Progressivecachexia
Cardiomyopathy Y Progressivereductionofleanbodymass
Malnutrition
Obesity [orY Increasedleanbodymass,unlessobesityis
associatedwithsarcopenia
Anorexia Y Lowenergyintakeandreducedleanbodymass
Organsupporttherapies
Hemodialysis/peritonealdialysis [orY Chronicinflammation
Progressivereductionofleanbodymass
Continuouspositiveairwaypressure(CPAP) [orY Increasedrespiratoryefforts,modifiedbymechanicalsupport
5.7. ImpactofIConpatientcareandhospitaleconomy Fundingsources,andacknowledgments
Malnutrition is associated with increased morbidity, length of Financial support came from the European Society of Clinical
stay and costs [75]. Oral nutritive supplements, and enteral and Nutrition and Metabolism (ESPEN) and the European Society of
parenteralnutritionarerelatedwithimprovedoutcome,butboth Intensive Care Medicine (ESCIM), APSI-ICU quality funds of the
underfeeding and overfeeding have been shown to mitigate the GenevaUniversityHospital,PublicFoundationNutrition2000Plus.
impactofnutritionsupport[63,76,77].Theprescriptionofnutrition
therapyaimsatmatchingtheenergytargetasdefinedbypredictive
formulas. Unfortunately, these formulas are often inaccurate.
Therefore,wehypothesizethatpromotingalarge-scaleuseofICto References
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