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A Novel Algorithm to Estimate the Pulse Pressure Variation Index MateoAboy*,JamesMcNames,TranThong,CharlesR.Phillips, MilesS.Ellenby,andBrahmGoldstein Abstract—Wedesignedanewmethodologytoestimatethepulsepressure variationindex inarterialbloodpressure(ABP).Themethoduses automaticdetectionalgorithms,kernelsmoothing,andrank-orderfiltersto continuouslyestimate .Thetechniquecanbeusedtoestimate fromABPalone,eliminatingtheneedforsimultaneouslyacquiringairway pressure. Index Terms—Cardiac index (CI), fluid responsiveness, pulse pressure variation ,respiratorychangesinsystolicpressure,volumeexpan- sion (VE). I. INTRODUCTION Inthispaper,wedescribeamethodologytoestimatethepulsepres- sure variation index in arterial blood pressure (ABP) signals. Several studies have shown to have important clinical utility [1]–[3]. In mechanically ventilated patients, has been found to beapotentiallyusefuldynamicindicatoroffluidresponsiveness.Ina studyinvolving40mechanicallyventilatedpatientswithacutecircula- toryfailurerelatedtosepsisitwasconcludedthat wasasensitive andspecificmethodforpredictingandassessingthehemodynamicef- fectsofvolumeexpansion(VE)[4].Areviewstudyoftheindexesused inintensivecaretopredictfluidresponsivenessfound tobeone ofthemostspecificandsensitivepredictorsoffluidresponsivenessin sedatedpatientsreceivingmechanicalventilationwithsepsis[5]. hasalsobeenshowntobeusefulinpredictingandassessingthehemo- dynamiceffectofpositive-end-expiratorypressureandfluidloadingin ventilatedpatientswithacutelunginjury(ALI)[6]. The standard method for calculating requires simultaneous recordingofarterialandairwaypressure.Pulsepressure(PP)iscalcu- latedonabeat-to-beatbasisasthedifferencebetweensystolicanddias- tolicarterialpressure.MaximalPP andminimalPP arecalculatedoverasinglerespiratorycycle,whichisdeterminedfrom the airway pressure signal. Pulse pressure variations are calcu- latedintermsof and andexpressedasapercentage (1) Manuscript received August 27, 2003; revised March 6, 2004. This work was supported in part by the Northwest Health Foundation and in part by the DoernbecherChildren’sHospitalFoundation. Asteriskindicatescorresponding author. *M.AboyiswiththeBiomedicalSignalProcessingLaboratory,Department ofElectricalandComputerEngineeringatPortlandStateUniversity,1900SW 4thAve.,Portland,OR97201USA(e-mail:mateoaboy@ieee.org). J. McNames is with the Biomedical Signal Processing Laboratory, Depart- mentofElectricalandComputerEngineeringatPortlandStateUniversity,Port- land,OR97201USA. T.ThongiswiththeDepartmentofBiomedicalEngineering,OGISchoolof Science and Engineering at Oregon Health and Science University, Portland, OR97206USA. C.R.PhillipsiswiththePulmonaryandCriticalCareMedicineDepartment, OregonHealthandScienceUniversity,Portland,OR97201USA. M.S.EllenbyandB.GoldsteinarewiththeComplexSystemsLaboratoryin theDepartmentofPediatricsatOregonHealthandScienceUniversity,Portland, OR97201USA. DigitalObjectIdentifier10.1109/TBME.2004.834295 0018-9294/04$20.00 © 2004 IEEE