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dc.contributor.authorLiu, Xiuyun
dc.contributor.authorCzosnyka, Marek
dc.contributor.authorDonnelly, Joseph
dc.contributor.authorCardim, Danilo
dc.contributor.authorCabeleira, Manuel
dc.contributor.authorHutchinson, Peter
dc.contributor.authorHu, Xiao
dc.contributor.authorSmielewski, Peter
dc.contributor.authorBrady, Ken
dc.date.accessioned2018-11-22T00:32:17Z
dc.date.available2018-11-22T00:32:17Z
dc.date.issued2018-07
dc.identifier.issn0022-3751
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/285654
dc.description.abstractKEY POINTS: The brain is vulnerable to damage from too little or too much blood flow. A physiological mechanism termed cerebral autoregulation (CA) exists to maintain stable blood flow even if cerebral perfusion pressure (CPP) is changing. A robust method for assessing CA is not yet available. There are still some problems with the traditional measure, the pressure reactivity index (PRx). We introduce a new method, the wavelet transform method (wPRx), to assess CA using data from two sets of controlled hypotension experiments in piglets: one set had artificially manipulated arterial blood pressure (ABP) oscillations; the other group were spontaneous ABP waves. A significant linear relationship was found between wPRx and PRx in both groups, with wPRx providing a more stable result for the spontaneous waves. Although both methods showed similar accuracy in distinguishing intact and impaired CA, it seems that wPRx tends to perform better than PRx, although not significantly so. ABSTRACT: We present a novel method to monitor cerebral autoregulation (CA) using the wavelet transform (WT). The new method is validated against the pressure reactivity index (PRx) in two piglet experiments with controlled hypotension. The first experiment (n = 12) had controlled haemorrhage with artificial stationary arterial blood pressure (ABP) and intracranial pressure (ICP) oscillations induced by sinusoidal slow changes in positive end-expiratory pressure ('PEEP group'). The second experiment (n = 17) had venous balloon inflation during spontaneous, non-stationary ABP and ICP oscillations ('non-PEEP group'). The wavelet transform phase shift (WTP) between ABP and ICP was calculated in the frequency range 0.0067-0.05 Hz. Wavelet semblance, the cosine of WTP, was used to make the values comparable to PRx, and the new index was termed wavelet pressure reactivity index (wPRx). The traditional PRx, the running correlation coefficient between ABP and ICP, was calculated. The result showed a significant linear relationship between wPRx and PRx in the PEEP group (R = 0.88) and non-PEEP group (R = 0.56). In the non-PEEP group, wPRx showed better performance than PRx in distinguishing cerebral perfusion pressure (CPP) above and below the lower limit of autoregulation (LLA). When CPP was decreased below LLA, wPRx increased from 0.43 ± 0.28 to 0.69 ± 0.12 (P = 0.003) while PRx increased from 0.07 ± 0.21 to 0.27 ± 0.37 (P = 0.04). Moreover, wPRx provided a more stable result than PRx (SD of PRx was 0.40 ± 0.07, and SD of wPRx was 0.28 ± 0.11, P = 0.001). Assessment of CA using wavelet-derived phase shift between ABP and ICP is feasible.
dc.format.mediumPrint-Electronic
dc.languageeng
dc.publisherWiley
dc.subjectBrain
dc.subjectAnimals
dc.subjectSwine
dc.subjectMonitoring, Physiologic
dc.subjectHomeostasis
dc.subjectCerebrovascular Circulation
dc.subjectIntracranial Pressure
dc.subjectWavelet Analysis
dc.subjectArterial Pressure
dc.titleWavelet pressure reactivity index: a validation study.
dc.typeArticle
prism.endingPage2809
prism.issueIdentifier14
prism.publicationDate2018
prism.publicationNameJ Physiol
prism.startingPage2797
prism.volume596
dc.identifier.doi10.17863/CAM.33006
dcterms.dateAccepted2018-04-09
rioxxterms.versionofrecord10.1113/JP274708
rioxxterms.licenseref.urihttp://www.rioxx.net/licenses/all-rights-reserved
rioxxterms.licenseref.startdate2018-07
dc.contributor.orcidLiu, Xiuyun [0000-0001-9540-4865]
dc.contributor.orcidCzosnyka, Marek [0000-0003-2446-8006]
dc.contributor.orcidDonnelly, Joseph [0000-0002-6502-8069]
dc.contributor.orcidHutchinson, Peter [0000-0002-2796-1835]
dc.contributor.orcidSmielewski, Peter [0000-0001-5096-3938]
dc.identifier.eissn1469-7793
rioxxterms.typeJournal Article/Review
pubs.funder-project-idMedical Research Council (G0601025)
pubs.funder-project-idMedical Research Council (G1002277)
pubs.funder-project-idMedical Research Council (G0600986)
pubs.funder-project-idMedical Research Council (G9439390)
pubs.funder-project-idNETSCC (None)
pubs.funder-project-idNETSCC (None)
pubs.funder-project-idTCC (None)
cam.issuedOnline2018-06-13
rioxxterms.freetoread.startdate2019-07-31


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