title: Effects of Prone Position and Positive End-Expiratory Pressure on Noninvasive Estimators of ICP: A Pilot Study.
abstract: BACKGROUND
  Prone positioning and positive end-expiratory pressure can improve pulmonary gas exchange and respiratory mechanics. However, they may be associated with the development of intracranial hypertension. Intracranial pressure (ICP) can be noninvasively estimated from the sonographic measurement of the optic nerve sheath diameter (ONSD) and from the transcranial Doppler analysis of the pulsatility (ICPPI) and the diastolic component (ICPFVd) of the velocity waveform.
  
  
  METHODS
  The effect of the prone positioning and positive end-expiratory pressure on ONSD, ICPFVd, and ICPPI was assessed in a prospective study of 30 patients undergoing spine surgery. One-way repeated measures analysis of variance, fixed-effect multivariate regression models, and receiver operating characteristic analyses were used to analyze numerical data.
  
  
  RESULTS
  The mean values of ONSD, ICPFVd, and ICPPI significantly increased after change from supine to prone position. Receiver operating characteristic analyses demonstrated that, among the noninvasive methods, the mean ONSD measure had the greatest area under the curve signifying it is the most effective in distinguishing a hypothetical change in ICP between supine and prone positioning (0.86±0.034 [0.79 to 0.92]). A cutoff of 0.43 cm was found to be a best separator of ONSD value between supine and prone with a specificity of 75.0 and a sensitivity of 86.7.
  
  
  CONCLUSIONS
  Noninvasive ICP estimation may be useful in patients at risk of developing intracranial hypertension who require prone positioning.
authors.affiliation: *Neurosciences Critical Care Unit, Addenbrooke's Hospital, Cambridge, United Kingdom ∥Brain Physics Laboratory, Department of Clinical Neurosciences, Division of Neurosurgery, Cambridge Biomedical Campus, University of Cambridge, Cambridge §Division of Neurosurgery, Department of Clinical Neurosciences, S.George Hospital, University of London, London, UK Departments of #Neurosurgery †Intensive Care, Galliera Hospital ‡Department of Health Sciences (DISSAL), School of Public Health, University of Genoa, Genoa, Italy ¶Department of Medicine, Division of Critical Care Medicine, Vancouver General Hospital, Vancouver, BC, Canada.
authors.forename: Chiara
authors.initials: C
authors.lastname: Robba
authors.forename: Nicola Luigi
authors.initials: NL
authors.lastname: Bragazzi
authors.forename: Alessandro
authors.initials: A
authors.lastname: Bertuccio
authors.forename: Danilo
authors.initials: D
authors.lastname: Cardim
authors.forename: Joseph
authors.initials: J
authors.lastname: Donnelly
authors.forename: Mypinder
authors.initials: M
authors.lastname: Sekhon
authors.forename: Andrea
authors.initials: A
authors.lastname: Lavinio
authors.forename: Derek
authors.initials: D
authors.lastname: Duane
authors.forename: Rowan
authors.initials: R
authors.lastname: Burnstein
authors.forename: Basil
authors.initials: B
authors.lastname: Matta
authors.forename: Susanna
authors.initials: S
authors.lastname: Bacigaluppi
authors.forename: Marco
authors.initials: M
authors.lastname: Lattuada
authors.forename: Marek
authors.initials: M
authors.lastname: Czosnyka
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D005260:Female; D006801:Humans; D019586:Intracranial Hypertension; D007427:Intracranial Pressure; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D019635:Neurosurgical Procedures; D009900:Optic Nerve / Q000000981:diagnostic imaging; D010865:Pilot Projects; D011175:Positive-Pressure Respiration; D016684:Prone Position; D011446:Prospective Studies; D013131:Spine / Q000601:surgery