Fig. 1.  Relative change in arterial sevoflurane and nitrous oxide partial pressures versus  time. A comparison of arterial sevoflurane partial pressure (Pa) with baseline (Pa⁰-S) is shown for both study groups versus  time (curve 1: control group, curve 2: nitrous oxide group). Data represent measures from baseline to 30 min after cessation of sevoflurane and nitrous oxide administration. Error bars (1 standard error) at the 2, 5, and 30 min sampling points are shown with a line of best fit. A best fit line for measured nitrous oxide partial pressures in the nitrous oxide group is also shown for comparison with the volatile agent (curve 3).