1. Cerebrovascular reactivity during hypothermia and rewarming
A. Lavinio, I. Timofeev, J. Nortje, J. Outtrim, P. Smielewski, A. Gupta, P.J. Hutchinson, B.F. Matta, J.D. Pickard, D. Menon, M. Czosnyka 
British Journal of Anaesthesia 
Volume 99, Issue 2, Pages (August 2007)
DOI: /bja/aem118
Copyright © 2007 British Journal of Anaesthesia Terms and Conditions

2. Fig 1
Examples of (a) good pressure reactivity (negative PRx) and (b) disturbed pressure reactivity (positive PRx). PRx was calculated as the moving correlation coefficient between slow waves of ICP and AP from a period of 4 min. Slow waves may be detected by low-pass filtering or simple moving averaging with a period of 5 s.
British Journal of Anaesthesia  , DOI: ( /bja/aem118)
Copyright © 2007 British Journal of Anaesthesia Terms and Conditions

3. Fig 2
Trends in brain temperature, ICP, CPP, and PRx in a 56-yr-old head-injured male monitored for 88 h. Phases in brain temperature include: [B] baseline (from 0 to 4.5 h), ICP > 20 mm Hg, and increasing despite maximal medical treatment, PRx around 0.2; [C] cooling phase (from 4.5 to 9 h), brain temperature decreasing from 37 to 34.5°C during active cooling; [IH] initial hypothermia (from 9 to 12 h), brain temperature 34°C, ICP < 15 mm Hg and PRx < 0.2; [H] hypothermia (from 9 to 46 h), temperature below 35°C, ICP still decreasing and PRx stable at 0.2; [R] rewarming (from 46 to 77 h), brain temperature increasing from 35 to 37°C, ICP and PRx being normal; [P] post-rewarming (from 77 to 88 h), ICP being stable and CPP > 80 mm Hg, but note the dramatic PRx impairment as brain temperature increases from 37 to 38°C.
British Journal of Anaesthesia  , DOI: ( /bja/aem118)
Copyright © 2007 British Journal of Anaesthesia Terms and Conditions

4. Fig 3
Mean values and 95% CI for brain temperature, ICP, CPP, PRx during: [B] baseline, [C] cooling phase, [IH] initial hypothermia, [H] hypothermia, [R] rewarming, and [P] post-rewarming. CPP was stable throughout the cooling and rewarming process. ICP significantly decreased during IH and H, and there was no rewarming-related rebound. PRx significantly increased during P (mean PRx = 0.32, mean brain temperature = 37.8°C). The asterisk indicates repeated measures analysis of variance, Duncan’s post hoc test (n = 17).
British Journal of Anaesthesia  , DOI: ( /bja/aem118)
Copyright © 2007 British Journal of Anaesthesia Terms and Conditions

5. Fig 4
Scatter plot and regression line for PRx and average brain temperature after rewarming from moderate hypothermia (n = 17; P < 0.05; Pearson’s R = 0.53).
British Journal of Anaesthesia  , DOI: ( /bja/aem118)
Copyright © 2007 British Journal of Anaesthesia Terms and Conditions

6. Fig 5
Scatter plot and regression line for PRx and average brain O2 pressure after rewarming (n = 17; P < 0.01; Pearson’s R = 0.66).
British Journal of Anaesthesia  , DOI: ( /bja/aem118)
Copyright © 2007 British Journal of Anaesthesia Terms and Conditions

7. Fig 6
Pooled PRx values, grouped by brain temperature. In patients exposed to moderate hypothermia (n = 24), cerebrovascular reactivity worsened as temperature increased from 35 to 38.8°C, becoming clearly impaired above the 37°C threshold.
British Journal of Anaesthesia  , DOI: ( /bja/aem118)
Copyright © 2007 British Journal of Anaesthesia Terms and Conditions