1. Novel method for intraoperative assessment of cerebral autoregulation by paced breathing 
N.H. Sperna Weiland, J. Hermanides, M W Hollmann, B. Preckel, W J Stok, J.J. van Lieshout, R V Immink 
British Journal of Anaesthesia 
Volume 119, Issue 6, Pages (December 2017)
DOI: /bja/aex333
Copyright © 2017 The Author(s) Terms and Conditions

2. Fig 1
Exemplary data from one patient. Upper panels are blood pressure (BP), with mean arterial pressure (MAP) in bold; lower panels are MAP power spectra. Preoperative blood pressure variability (A) as the input signal for cerebral autoregulation (CA) shows high variability as a consequence of combined low-frequency (LF) oscillations attributable to sympathetic nervous system activity around 0.1 Hz (↓; B) and high-frequency (HF) oscillations attributable to respiration around 0.25 Hz (*; B). (C–E) During surgery, suppression of the sympathetic nervous system results in loss of LF BP oscillations (↓; D). The only blood pressure variability remaining can be attributed to intrathoracic pressure effects of mechanical ventilation (MV). During MV at 15 bpm (C and D), BP oscillates around 0.25 Hz (*; D), and during MV at 6 bpm BP oscillates around 0.1 Hz (*; F).
British Journal of Anaesthesia  , DOI: ( /bja/aex333)
Copyright © 2017 The Author(s) Terms and Conditions

3. Fig 2
Exemplary data of one patient. (A–C) Frequency domain analysis of spontaneous low (black) and high (grey) frequency variations variations in mean arterial pressure (MAP) and mean cerebral blood flow velocity (CBFVmean) preoperative (A), with high coherence (b) and decreasing phase lead (c). (d–f) Intraoperative, low power in the LF domain was observed, and only MAP variability surrounding the frequency of the mechanical ventilator remained (d and e). Phase lead calculation was therefore impossible (?) in the LF domain (f). (g–l) During paced breathing before and during surgery, high power and coherence were observed for each breathing frequency (g, h, j and k; 6 bpm in black, 10 bpm in dark grey, and 15 bpm in grey, respectively) Phase lead calculation in each frequency band yielded similar results before and during surgery (compare i and l). Group averaged data of i and l are in Fig. 3.
British Journal of Anaesthesia  , DOI: ( /bja/aex333)
Copyright © 2017 The Author(s) Terms and Conditions

4. Fig 3
Group-averaged data (n=14) mean (sd) for phase lead during paced breathing interventions before (blue circles) and during surgery (red circles). We observed a decreasing blood pressure (BP) to cerebral blood flow velocity (CBFV) phase lead with increasing frequency until no autoregulation at zero phase lead (dashed line) during fast oscillations. Cerebral autoregulation indices were similar before and during surgery.
British Journal of Anaesthesia  , DOI: ( /bja/aex333)
Copyright © 2017 The Author(s) Terms and Conditions