title: Cerebral haemodynamic physiology during steep Trendelenburg position and CO(2) pneumoperitoneum.
abstract: BACKGROUND
  The steep (40°) Trendelenburg position optimizes surgical exposure during robotic prostatectomy. The goal of the current study was to elucidate the influence of this patient positioning on cerebral blood flow and zero flow pressure (ZFP), and to assess the validity of different methods of evaluating ZFP.
  
  
  METHODS
  In 21 consecutive patients who underwent robotic endoscopic radical prostatectomy under general anaesthesia, transcranial Doppler flow velocity waveforms and invasive arterial and central venous pressure (CVP) waveforms suitable for analysis were recorded throughout the whole operative procedure in 14. The ZFP was determined by regression analysis of the pressure-flow plot and by different simplified formulas. The effective cerebral perfusion pressure (eCPP), pulsatility index (PI), and resistance index (RI) were determined.
  
  
  RESULTS
  While patients were in the Trendelenburg position, the ZFP increased in parallel with the CVP. The PI, RI, gradient between the ZFP and CVP, and the gradient between the CPP and the eCPP did not increase significantly (P<0.05) after 3 h of the steep Trendelenburg position. Using the formula described by Czosnyka and colleagues, the ZFP correlated closely with that calculated by linear regression throughout the course of the operation.
  
  
  CONCLUSIONS
  Prolonged steep Trendelenburg positioning and CO(2) pneumoperitoneum does not compromise cerebral perfusion. ZFP and eCPP are reliable variables for assessing brain perfusion during prolonged steep Trendelenburg positioning.
authors.affiliation: Department of Anesthesiology, University of Groningen, University Medical Center Groningen, Hanzeplein 1, Postbus 30 001, 9700 RB Groningen, The Netherlands. a.kalmar@umcg.nl
authors.forename: A F
authors.initials: AF
authors.lastname: Kalmar
authors.forename: F
authors.initials: F
authors.lastname: Dewaele
authors.forename: L
authors.initials: L
authors.lastname: Foubert
authors.forename: J F
authors.initials: JF
authors.lastname: Hendrickx
authors.forename: E H
authors.initials: EH
authors.lastname: Heeremans
authors.forename: M M R F
authors.initials: MM
authors.lastname: Struys
authors.forename: A
authors.initials: A
authors.lastname: Absalom
mesh_terms: D000368:Aged; D000768:Anesthesia, General; D001783:Blood Flow Velocity / Q000502:physiology; D002245:Carbon Dioxide; D002560:Cerebrovascular Circulation / Q000502:physiology*; D018475:Head-Down Tilt / Q000502:physiology*; D006801:Humans; D007427:Intracranial Pressure / Q000502:physiology; D007430:Intraoperative Care / Q000379:methods*; D008297:Male; D008875:Middle Aged; D056888:Patient Positioning / Q000379:methods; D011028:Pneumoperitoneum, Artificial / Q000379:methods*; D011468:Prostatectomy / Q000379:methods*; D011673:Pulsatile Flow / Q000502:physiology; D012371:Robotics; D014655:Vascular Resistance / Q000502:physiology
chemical_list: D002245:Carbon Dioxide