Fig. 4. Comparison of the effect of different volatile anesthetics at equivalent concentrations on total pulmonary resistance. At 1 minimum alveolar concentration (MAC), only desflurane significantly increased pulmonary resistance compared with isoflurane and sevoflurane (  P < 0.001 for both comparisons). The difference between isoflurane and sevoflurane was not statistically significant (  P = 0.15). At 1.5 MAC, sevoflurane significantly increased (  P = 0.015) total pulmonary resistance compared with isoflurane, whereas desflurane caused a more pronounced increase compared with isoflurane and sevoflurane (  P < 0.001 for all comparisons). The same findings apply at 2 MAC. Sevoflurane significantly increased pulmonary resistance compared with isoflurane (  P < 0.001) and desflurane caused a significant increase compared with the other two volatile agents (  P < 0.001 for both comparisons). * Increased pulmonary resistance compared with seroflurane and isoflurane; ** increased pulmonary resistance compared with isoflurane.