Table 4. MAC-awake of Xenon and N²O Administered in Combination with the 0.5-MAC-awake Concentrations of Isoflurane or Sevoflurane

The values predicted assuming additivity were calculated by multiplying the minimum alveolar concentration (MAC)-awake of xenon and nitrous oxide (N²O) presented in table 3by 0.5 because the assumption of additivity between xenon or N²O and isoflurane or sevoflurane predicts that the addition of the 0.5 MAC-awake concentrations of these volatile anesthetics would halve the MAC-awake of xenon and N²O. These predicted values were then compared to those determined in the presence of isoflurane or sevoflurane.

*P < 0.01 versus  the value predicted assuming additivity, analysis of variance and Dunnett test, indicating infraadditivity between N²O and isoflurane or sevoflurane.