1. Cerebral haemodynamic physiology during steep Trendelenburg position and CO2 pneumoperitoneum 
A.F. Kalmar, F. Dewaele, L. Foubert, J.F. Hendrickx, E.H. Heeremans, M.M.R.F. Struys, A. Absalom 
British Journal of Anaesthesia 
Volume 108, Issue 3, Pages (March 2012)
DOI: /bja/aer448
Copyright © 2012 The Author(s) Terms and Conditions

2. Fig 1
Determination of the ZFP by regression analysis of the pressure-flow plot of the flow velocity (FV) and invasive AP (P). Each dot of the flow velocity waveform represents a pressure sample and corresponds to a data point in the regression analysis. The X-intercept of the regression line is the ZFP. An R²>0.91 is used as a cut-off value to select heartbeats with adequate signal quality.
British Journal of Anaesthesia  , DOI: ( /bja/aer448)
Copyright © 2012 The Author(s) Terms and Conditions

3. Fig 2
Formulae to determine the eCPP as described by Belfort and colleagues,15 the ZFP as described by Czosnyka and colleagues6 and Schmidt and colleagues,7 and the RI and PI. All formulae are a function of the mean (m), diastolic (d), or systolic (s) value of the flow velocity (FV) and invasive AP.
British Journal of Anaesthesia  , DOI: ( /bja/aer448)
Copyright © 2012 The Author(s) Terms and Conditions

4. Fig 3
(a) CVP, ZFP calculated by linear regression (ZFP), ZFP as described by Czosnyka and colleagues6 and Schmidt and colleagues,7 and the end-tidal CO2 pressure (PE′CO2). (b) PI, RI, and PE′CO2. (c) The course of the CVP, invasive MAP, CPP determined as (CPP=MAP−CVP), and the eCPP as described by Belfort and colleagues (eCPPBelfort).15 The variables are shown as mean values at 10 min intervals. Pre-values are defined as the average of the 30 s interval at 5 min before steep Trendelenburg repositioning, after induction of anaesthesia. All data are synchronized at the moment of initiating Trendelenburg positioning and resynchronized at resumption of the supine position. The variables are shown as mean values at 10 min intervals from 5 min before to 165 min after institution of the Trendelenburg position. At reassuming the supine position, the curves are resynchronized and values are shown for another 20 min.
British Journal of Anaesthesia  , DOI: ( /bja/aer448)
Copyright © 2012 The Author(s) Terms and Conditions

5. Fig 4
Linear regression analysis of the ZFP as a function of the PE′CO2.
British Journal of Anaesthesia  , DOI: ( /bja/aer448)
Copyright © 2012 The Author(s) Terms and Conditions