Cerebral perfusion pressure - Wikipedia

Cerebral perfusion pressure, or CPP, is the net pressure gradient causing cerebral blood flow to the brain (brain perfusion). It must be maintained within ... Cerebralperfusionpressure FromWikipedia,thefreeencyclopedia Jumptonavigation Jumptosearch Cerebralperfusionpressure,orCPP,isthenetpressuregradientcausingcerebralbloodflowtothebrain(brainperfusion).Itmustbemaintainedwithinnarrowlimitsbecausetoolittlepressurecouldcausebraintissuetobecomeischemic(havinginadequatebloodflow),andtoomuchcouldraiseintracranialpressure(ICP). Contents 1Definitions 1.1Fromresistance 1.2Byintracranialpressure 2Autoregulation 3Footnotes 4References Definitions[edit] Thecraniumenclosesafixed-volumespacethatholdsthreecomponents:blood,cerebrospinalfluid(CSF),andverysofttissue(thebrain).WhileboththebloodandCSFhavepoorcompressioncapacity,thebrainiseasilycompressible. EveryincreaseofICPcancauseachangeintissueperfusionandanincreaseinstrokeevents. Fromresistance[edit] CPPcanbedefinedasthepressuregradientcausingcerebralbloodflow(CBF)suchthat C B F = C P P / C V R {\displaystyleCBF=CPP/CVR} where: CVRiscerebrovascularresistance Byintracranialpressure[edit] AnalternativedefinitionofCPPis:[1] C P P = M A P − I C P {\displaystyleCPP=MAP-ICP} where: MAPismeanarterialpressure ICPisintracranialpressure JVPisjugularvenouspressure ThisdefinitionmaybemoreappropriateifconsideringthecirculatorysysteminthebrainasaStarlingresistor,whereanexternalpressure(inthiscase,theintracranialpressure)causesdecreasedbloodflowthroughthevessels.Inthissense,morespecifically,thecerebralperfusionpressurecanbedefinedaseither: C P P = M A P − I C P {\displaystyleCPP=MAP-ICP} (ifICPishigherthanJVP) or C P P = M A P − J V P {\displaystyleCPP=MAP-JVP} (ifJVPishigherthanICP). Physiologically,increasedintracranialpressure(ICP)causesdecreasedbloodperfusionofbraincellsbymainlytwomechanisms: IncreasedICPconstitutesanincreasedinterstitialhydrostaticpressurethat,inturn,causesadecreaseddrivingforceforcapillaryfiltrationfromintracerebralbloodvessels. IncreasedICPcompressescerebralarteries,causingincreasedcerebrovascularresistance(CVR). FLOW Rangingfrom20ml100g-1min-1inwhitematterto70ml100g-1min-1ingreymatter. Autoregulation[edit] UndernormalcircumstancesaMAPbetween60and160mmHgandICPabout10mmHg(CPPof50-150 mmHg)sufficientbloodflowcanbemaintainedwithautoregulation.[1][2]Althoughtheclassic'autoregulationcurve'suggeststhatCBFisfullystablebetweenthesebloodpressurevalues(knownalsoasthelimitsofautoregulation),inpracticespontaneousfluctuationscanoccur.[3] Outsideofthelimitsofautoregulation,raisingMAPraisesCBFandraisingICPlowersit(thisisonereasonthatincreasingICPintraumaticbraininjuryispotentiallydeadly).IntraumasomerecommendCPPnotgobelow70mmHg.[4][5]Recommendationsinchildrenisatleast60mmHg.[4] Withintheautoregulatoryrange,asCPPfallsthereis,withinseconds,vasodilatationofthecerebralresistancevessels,afallincerebrovascularresistanceandariseincerebral-bloodvolume(CBV),andthereforeCBFwillreturntobaselinevaluewithinseconds(seeasref.Aaslid,Lindegaard,Sorteberg,andNornes1989:http://stroke.ahajournals.org/cgi/reprint/20/1/45.pdf).Theseadaptationstorapidchangesinbloodpressure(incontrastwithchangesthatoccuroverperiodsofhoursordays)areknownasdynamiccerebralautoregulation.[3] Footnotes[edit] ^abSteiner,LA;Andrews,PJ(2006)."Monitoringtheinjuredbrain:ICPandCBF".BritishJournalofAnaesthesia.97(1):26–38.doi:10.1093/bja/ael110.PMID 16698860. ^Duschek,S;Schandry,R(2007)."Reducedbrainperfusionandcognitiveperformanceduetoconstitutionalhypotension".ClinicalAutonomicResearch.17(2):69–76.doi:10.1007/s10286-006-0379-7.PMC 1858602.PMID 17106628. ^abvanBeek,AH;Claassen,JA;Rikkert,MG;Jansen,RW(June2008)."Cerebralautoregulation:Anoverviewofcurrentconceptsandmethodologywithspecialfocusontheelderly".JournalofCerebralBloodFlow&Metabolism.28(6):1071–85.doi:10.1038/jcbfm.2008.13.PMID 18349877. ^abTolias,C;Sgouros,S(2003)."InitialevaluationandmanagementofCNSinjury".Emedicine.com.ArchivedfromtheoriginalonMarch2,2007.Retrieved2007-03-19. ^Czosnyka,M;Pickard,JD(2004)."Monitoringandinterpretationofintracranialpressure".JournalofNeurology,Neurosurgery,andPsychiatry.75(6):813–21.doi:10.1136/jnnp.2003.033126.PMC 1739058.PMID 15145991. References[edit] Sanders,MJ;McKenna,K(2001)."Ch.22:HeadandFacialTrauma".Mosby'sParamedicTextbook(2ndrevised ed.).Mosby. Walters,FJM(1998)."IntracranialPressureandCerebralBloodFlow".Physiology(8,Article4).Archivedfromtheoriginalon2011-05-14.Retrieved2011-02-10. Retrievedfrom"https://en.wikipedia.org/w/index.php?title=Cerebral_perfusion_pressure&oldid=1021974906" Categories:MedicalterminologyNeurologyNeurotraumaPhysiology Navigationmenu Personaltools NotloggedinTalkContributionsCreateaccountLogin Namespaces ArticleTalk Variants expanded collapsed Views ReadEditViewhistory More expanded collapsed Search Navigation MainpageContentsCurrenteventsRandomarticleAboutWikipediaContactusDonate Contribute HelpLearntoeditCommunityportalRecentchangesUploadfile Tools WhatlinkshereRelatedchangesUploadfileSpecialpagesPermanentlinkPageinformationCitethispageWikidataitem Print/export DownloadasPDFPrintableversion Languages العربيةEspañolРусскийTürkçe Editlinks