Australian Journal of Physiotherapy 2003Vol. 49 99Berney and Denehy: Effect of physiotherapy treatment on oxygen consumption and haemodynamics in critically ill patientsIntroductionPhysiotherapytreatmentisoftenusedinpatientsinintensivecare(ICU)forthepreventionandtreatmentofpulmonarycomplicationssuchassputumretentionandatelectasis(Mackenzieetal1980,Pontpiddan1985).Ntoumenopoulos et al (2002) demonstrated in critically illpatients that physiotherapy treatment was associated with areductioninnosocomialpneumonia.Inaddition,variouscomponentshavebeenshowntoimprovelungandthoraxcompliance,reducethevolumeofretainedsecretionsandimprove intrapulmonary shunt (Hodgson et al 2000, Jonesetal1992,Mackenzieetal1980,MackenzieandShin1985,NtoumenopoulosandGreenwood1996).Inparticular,theshorttermeffectsofmanualhyperinflation(MHI)usingamanualresuscitationbagonpulmonarycompliance,resolutionofatelectasisandsputumproductionhavebeenwelldocumented(Hodgsonetal2000, Jones et al 1992, Rothen et al 1993, Stiller et al 1990,1996and2000).Arecentstudydemonstratedthathyperinflation can be performed with equal benefit using amanualresuscitationbagoraventilator(BerneyandDenehy 2002).AswithmanyotherroutineICUinterventions,however,thistreatmenthasbeenassociatedwithanincreaseinmetabolicandcardiovasculardemand(Cohenetal1996,Gormezano and Branthwaite 1972, Harding et al 1993 and1994,Kleinetal1988,MathewsandWeissman1990,Swinamer et al 1987, Weissman et al 1984, Weissman andKemper1993).Incriticallyillpatients,cellularoxygenconsumption(VO2)isalreadyincreasedandperipheraloxygen(O2)extractioncapabilitiesmaybeimpaired(Clarke 1997, Silance et al 1994). Therefore any reductionindeliveryorincreaseinO2demand,asmayoccurwithphysiotherapytreatment,maypredisposethepatienttoadverse events (Treacher and Leach 1994).Previousstudiesexaminingtheeffectofphysiotherapytreatment on VO2have failed to differentiate the effects ofthistreatmentfrompatientpositioningalone,aprocedurethatreportedlyincreasesVO2 by31%(Swinameretal1987).Inaddition,theaimofthesestudieswastoinvestigatetheadministrationofmedicationtosupresscardiovascularandmetabolicresponsesusingphysiotherapy treatment as a physiological stress. There is,however, no supporting evidence from controlled trials thatphysiotherapytreatmentisphysiologicallystressful.ThepurposeofthisstudywastodeterminetheeffectofphysiotherapytreatmentonVO2mean,MAPandCIinstable,intubatedandventilatedpatientscomparedwithturning the same patient into the side lying position. The effect of physiotherapy treatment on oxygenconsumption and haemodynamics in patients who are critically illSusan Berney1and Linda Denehy21The Austin Hospital, Melbourne2The University of MelbourneThe purpose of this study was to determine metabolic and haemodynamic changes with and without physiotherapy treatmentinhaemodynamicallystable,intubatedandventilatedpatients. Thiswasaprospective,randomisedcross-overstudy. Tenintubated, ventilated and haemodynamically stable patients underwent a 20 min physiotherapy treatment and a 20 min periodofundisturbedsidelying. Meanoxygenconsumption(VO2mean)wasmeasuredonaminute-to-minutebasisbyindirectcalorimetry. Mean arterial pressure (MAP) was recorded minutely from the indwelling arterial line and cardiac index (CI) wascalculated from the indwelling pulmonary artery catheter. Time to recovery to within 5% of resting VO2was also recorded. Theresults showed no significant increase in VO2mean with either positioning the patient in side lying or physiotherapy treatment(p=0.17). Timetorecoverytowithin5%ofbaseline VO2occurredwithinsevenminutesforallpatientsandtherewasnosignificant difference between either physiotherapy treatment or positioning in side lying (p = 0.63). There were no significantdifferencesinCI(p =0.44)orMAP(p =0.95)duringphysiotherapytreatmentcomparedwithundisturbedsidelying. Itisconcluded that physiotherapy treatment does not significantly alter VO2mean or MAP and CI in stable intubated and ventilatedpatients. [BerneySandDenehyL(2003): Theeffectofphysiotherapytreatmentonoxygenconsumptionandhaemodynamics in patients who are critically ill. Australian Journal of Physiotherapy 49: 99-105]Key words: Intensive Care; Oxygen Consumption; Pulmonary Ventilation; Mechanical Ventilators MethodsStudypopulation Thisstudywasapprovedby The AustinHospitalEthicsandHumanResearchCommittee,andinformed consent was obtained from next of kin and fromthe treating intensive care physician. Using the results fromHardingetal1993(differenceinthemeansVO2=115mL/min, mean standard deviation = 78 mL/min) with alpha=0.05,twotailedpairedt-test,forapower>0.80thesamplesizerequiredwas10subjects.Tensequentialpatientswhomettheinclusioncriteriawerestudied.Patientswereincludediftheya)wereintubatedandventilated;b)hadapulmonaryarteryandarteriallineinsitu; c) were cardiovascularly stable; and d) would receivephysiotherapyasapartofroutinecare.PatientswereconsideredcardiovascularlystableiftheyhadaMAP>75mmHg,withafluctuationofMAP2.3L/min/m2.Patientswereexcluded from the trial if a) they had a fraction of inspiredoxygen (FiO2) > 0.6; b) a positive end expiratory pressure>10cmH2O;c)pulmonarypathologywherelunghyperinflationwascontra-indicated;ord)weresufferingfromneurologicalconditionswhichnecessitatedarestinghead up position. Metabolic computer Oxygen consumption was measuredusing the Engstrom metabolic computer (EMC) which is amicroprocesser based instrument attached to the EngstromElvira ventilator(a). The EMC consists of a microprocessorandoxygen-sensingfuelcellthatmeasuresboththeinspiredandexpiredfractionsofoxygen(FeO2). The VO2iscalculatedasthedifferencebetweentheproductoftheinspiratory volume and FiO2 and the expiratory volume andFeO2.CalibrationandserviceoftheEMCwasperformedbytheBiomedicalEngineeringDepartmentatthe AustinandRepatriationMedicalCentreaccordingtomanufacturers guidelines for routine service. Prior to eachoccasion of use, the barometric pressure was checked withtheBureauofMeteorologyandprogrammedintotheventilator. Calibration of the oxygen sensors of the EMC toFiO2=1and0.4gasmixturewasalsoperformed.Thecomputerwasconsideredcalibratedwhenthedifferencebetween the O2 sensing fuel cells and the ventilators FiO2waswithin0.3%.ThevalidityandaccuracyofmeasurementofVO2bytheEMChasbeenpreviouslyestablishedinalaboratorysettingagainstasystemdeveloped by Nunn et al (1989) for the absolute calibrationof indirect calorimeters, under the condition of mechanicalventilationandincreasedO2concentrations.ThissamesystemwasutilisedtotestthereliabilityoftheEMCagainsttwoothercommerciallyavailablesystemsanddemonstratedthelowestrelativeerrorinmeasurementof1.4% (Makita et al 1990). Procedure Allsubjectswererandomlyallocatedtoatreatment sequence (Figure 1). The randomisation processinvolved picking a letter from an otherwise sealed envelopedenotingtreatmentsequence.TreatmentAinvolvedphysiotherapytreatmentwhichincludedgravityassisteddrainagewiththefootofthebedelevatedto35to45degrees from the horizontal plane with the patient lying ontheside,ventilatorhyperinflation(VHI),andsuctioning.Theentiredurationofphysiotherapytreatmentwas20minutesandcontainednomorethanthreesuctionpasses.Australian Journal of Physiotherapy 2003Vol. 49 100Berney and Denehy: Effect of physiotherapy treatment on oxygen consumption and haemodynamics in critically ill patientsBaseline 1Physiotherapy 20 minSide lying 20 minBaseline 2Baseline 2Side lying 20 minPhysiotherapy 20 minBaseline 3Baseline 3MABP MABPMABP MABPBaseline 1 = 10 minutes steady state VO2Baseline 2 = within 5% VO2 of Baseline 1Baseline 3 = within 5% VO2 of Baseline 2MABP = Mean arterial blood pressure measured for 20minutes of intervention.= Measure of cardiac indexFigure 1. Flow chart of the experimental procedure.Oxygensaturationwascontinuouslymonitoredduringtreatment using pulse oximetry(b). Ventilator hyperinflationinvolvedreducingtheventilatorsrespiratoryratetosix,decreasing the inspiratory flow to 20 L/min, incorporatingasquarewaveformandincreasingthepatientstidalvolumeby100mLincrementsuntilapeakinspiratorypressureof40cmH2Owasachieved.Sixmechanicalbreaths were delivered to this pressure and the patient wasthenreturnedtotheoriginalventilatoryparametersandallowedtorestforaperiodof30secondswhentheprocedure was repeated. In total, the treatment consisted ofsix sets of six VHI breaths which were all performed by thesameinvestigator.Pre-oxygenationtoFiO2=1wasnotperformed prior to suctioning, as the measurement of VO2becomesunreliablewithvariationinFiO2..Endotrachealsuction was performed using size 12 Baxter catheters(c).Treatment B involved turning the patient onto the side andleavinghimorherundisturbedfor20minutes.Patientswerepositionedontothesamesideforboth Treatment AandTreatmentB.Thepositionwasdecideduponbyconsultationbetweentheradiologist,intensivecarephysician and treating physiotherapist. If bibasal opacitieswere present, patients were turned to the side to which theywerenextdueinaccordancewiththeirpressurecareroutine.Measurement Oncethetreatmentsequencewasdecided,thepatientswerestartedontheElviraventilatorwithventilatoryparametersremainingunchanged.Thepatientwasplacedinthesupinepositionandallowedtostabiliseontheventilatorforaperiodofonehourpriortothecommencement of the data collection. Initial measurementinvolvedrecordingofminute-by-minuteVO2whilstthepatient lay undisturbed for a period of 10 minutes. This wascalledBaseline1.Therewerenorestrictionsregardingadministration of sedative, analgesic or vasoactive drugs ortheprovisionofessentialcarethroughoutthisperiod.MeasuresofCIweremadeusingthepulmonaryarterycatheter(c).Threemeasuresofcardiacoutputweretaken,thefirstwasdiscardedandtheaverageofthesecondandthird measure was divided by the body surface area of thepatient and recorded as the CI. These measures of CI wereperformed immediately on completion of Baseline 1 by theattendingnurse. Thepatientwasthenpositionedintosidelying and another set of CI measures was performed priortothecommencementofthepre-determinedphaseofintervention.Duringtreatment,minute-by-minutemeasurements of VO2and MAP from an indwelling arterialline(d)wererecordedandoncompletionoftreatment,CIwasre-measuredwiththepatientinthesamesidelyingposition. Patients were then returned to the supine positionandlayundisturbeduntiltheyrecoveredtowithin5%ofthe Baseline 1 VO2, which was called Baseline 2. Once thiswas achieved, CI was re-measured and subjects were turnedontothesameside.Measurementfollowedthesamesequenceaspreviouslydescribedandthealternatetreatmentwasperformed.Whenthesecondphaseoftheinterventionwascomplete,patientswerereturnedtotheAustralian Journal of Physiotherapy 2003Vol. 49 101Berney and Denehy: Effect of physiotherapy treatment on oxygen consumption and haemodynamics in critically ill patientsTable 1. Demographic data.Age Condition Gender APACHE II Baseline VO2SedationInotropic support(mL/min) (mg/hr) (g/min)63 MVR M 14 364.1 Nil Noradrenalin 375 Septic shock M 10 261.0 Morphine 1 Noradrenalin 2Dopamine 21*75 AAA rupture M 24 223.6 Morphine 3 Noradrenalin 3171 RespiratoryM 19 479.2 Morphine 2 Noradrenalin 6failure74 Septic shock M 14 678.6 Morphine 1 Noradrenalin 10Midazolam 1 Dopamine 4.9*73 Septic shock F 20 445.2 Morphine 2 Noradrenalin 22Midazolam 254 Septic shock M 16 342.1 Morphine 3 Noradrenalin 14Midazolam 175 Pancreatitis M 19 606.4 Morphine 2 Noradrenalin 8Midazolam 254 PartialM 18 328.0 Morphine 1 nilgastrectomy67 CAGS M 24 387.2 Morphine 5 nilMidazolam 5Haloperidol 3*g/kg/min. APACHE, Acute Physiological Health Evaluation Score. MVR, mitral valve replacement. AAA, aortic abdominalaneurysm. CAGS, coronary artery graft surgery.supinepositionandthelengthoftimerequiredforthepatients to return to within 5% of Baseline 2 was recorded,whichwascalledBaseline3.Thesamephysiotherapistperformedeachtreatmentwhilstanassistantrecordedthedata.Statistical analysis The values for VO2were averaged foreachphaseofthestudytogiveaVO2meanforbothphysiotherapy treatment and side lying. The VO2mean wasusedasitreflectstheaveragemetaboliccostofeachinterventionandhasbeenutilisedextensivelyinpreviousliterature (Cohen et al 1996, Harding et al 1993 and 1994,Kleinetal1988,Swinameretal1987,Weissmanetal1984,WeissmanandKemper1993).PeaksinVO2werealsomeasuredinordertodeterminewhetheranyspecificcomponentsofinterventioninvolvedgreatermetabolicdemandandthesewerepresentedasapercentageriseinVO2comparedwithcorrespondingpreviousbaselinemeasures.ThevariablesVO2mean,MAPandCIwereanalysedusingtwowayanalysisofvariancewithtworepeatedmeasures. Timetorecoveryofbaseline VO2wasanalysed using a one way analysis of variance. The level ofsignificancewassetatp