Fig. 4. Distribution of tidal volumes after cardiac surgery. The number (percentage) of patients with tidal volumes less than 10, 10–12, and more than 12 ml/kg were 724 (21.1%), 1,567 (45.6%), and 1,143 (33.3%), respectively, when predicted body weight was used. The number (percentage) of patients with tidal volumes less than 10, 10–12, and more than 12 ml/kg were 1,956 (57.0%), 1,429 (41.6%), and 49 (1.4%), respectively, when actual body weight was used.