1. Accuracy of feedback-controlled oxygen delivery into a closed anaesthesia circuit for measurement of oxygen consumption† 
A.W. Schindler, T.W.L. Scheeren, O. Picker, M. Doehn, J. Tarnow 
British Journal of Anaesthesia 
Volume 90, Issue 3, Pages (March 2003)
DOI: /bja/aeg072
Copyright © 2003 British Journal of Anaesthesia Terms and Conditions

2. Fig 1
A typical record of a lung model experiment. Simulated oxygen consumption ( V ˙ o2-Model) was estimated by the closed anaesthesia circuit ( V ˙ o2-PF). Simulated V ˙ o2 (continuous line) was set randomly to different values, each maintained for 20 min. Control periods of no oxygen consumption ( V ˙ o2-Model 0 ml min−1) separated each of the other V ˙ o2 levels. Single values of V ˙ o2-PF (circles) showed substantial scatter. V ˙ o2-PF tracked increases of V ˙ o2-Model faster than decreases.
British Journal of Anaesthesia  , DOI: ( /bja/aeg072)
Copyright © 2003 British Journal of Anaesthesia Terms and Conditions

3. Fig 2
Bland–Altman comparisons of V ˙ o2 measured with a closed circuit ( V ˙ o2-PF, values averaged over 10 min) and Fick-derived V ˙ o2 ( V ˙ o2-FickDOG) measured simultaneously in six anaesthetized healthy dogs. Each symbol represents values obtained from the same dog at different levels of FIO2: 0.21–0.3 (upper panel), 0.5–0.85 (middle panel), 0.9–1.0 (lower panel). At lower FIO2 values the methods agreed well, but they differed significantly by about 40 ml min−1 when FIO2 exceeded Note that variation within subject was less than variation between subjects.
British Journal of Anaesthesia  , DOI: ( /bja/aeg072)
Copyright © 2003 British Journal of Anaesthesia Terms and Conditions

4. Fig 3
Linear correlations of V ˙ o2 measured with PhysioFlex ( V ˙ o2-PF, values were averaged over 10 min) and using the Fick method ( V ˙ o2-FickDOG) measured simultaneously in three anaesthetized dogs. V ˙ o2 was reduced by increasing the depth of anaesthesia from 1.5 to 2.5 MAC sevoflurane and increased by epinephrine infusion 0.8 μg kg−1 min−1. Each panel represents the results from one dog at 30% (open symbols) and 75% (filled symbols) of inspired oxygen. The broken line in each panel represents the line of identity (slope=1).
British Journal of Anaesthesia  , DOI: ( /bja/aeg072)
Copyright © 2003 British Journal of Anaesthesia Terms and Conditions

5. Fig 4
Difference between V ˙ o2 measured with a closed circuit ( V ˙ o2-PF, data averaged over 10 min) and calculated using the Fick method ( V ˙ o2-FickPAT) in patients ventilated mechanically (FIO2 0.3–0.5) during anaesthesia alone (open circles, n=21) and during anaesthesia plus major surgery (filled circles, n=17). Data values from the same individual are connected. The grey area indicates the estimated maximum error of the Fick method, calculated from our own data on reproducibility of cardiac output (thermodilution) and arteriovenous oxygen content difference (calculated from blood gas analysis). V ˙ o2-PF exceeded V ˙ o2-FickPAT significantly by 52 (sd 40) ml min−1 (P<0.05), and surgery did not systemically affect V ˙ o2 or the difference between the two methods.
British Journal of Anaesthesia  , DOI: ( /bja/aeg072)
Copyright © 2003 British Journal of Anaesthesia Terms and Conditions