Fig. 3. Comparison of the effects of isoflurane, sevoflurane, and desflurane at 1.0, 1.5, and 2 minimum alveolar concentration (MAC) on total pulmonary resistance. Isoflurane caused a statistically significant ( P = 0.005) increase of the resistance at 2 MAC compared with baseline. Sevoflurane caused significant increase of the resistance at 1.5 and 2 MAC compared with baseline ( P < 0.001 for both comparisons). Desflurane caused significant increase of the resistance from baseline at the three concentrations studied ( P < 0.001 for all comparisons).