Figure 2. Concentration-effect relations for desflurane (filled circles) and halothane (open circles). Maximum pressure increases in the pulmonary artery (Delta PAP) of the individual lungs were determined during hypoxia (fraction of inspired oxygen 0.03) for increasing concentrations of the anesthetics. Pulmonary arterial pressure (PAP) under baseline conditions was 19.6 plus/minus 2.5 cmH2O for all lungs. With increasing concentrations of desflurane and halothane Delta PAP decreased.