Fig. (6) Chest expansion in anterior-posterior (AP) and lateral directions for 5 patients. The measurements are made according to Fig. (5). The average changes are 2 mm in AP direction and -1.6 mm in lateral direction, corresponding to average air volume change from FRC+TV of 2.81 liters to FRC of 2.27 liters, with a TV of 0.54 liters.