Fig. 4. Single-slice computerized tomography (CT). Percentage of atelectasis 1 cm above the diaphragm. The application of RM + PEEP (n = 10) reduced atelectasis, and this effect was sustained for 20 min. RM + ZEEP (n = 10) caused a reduction of atelectasis, but this effect could not be seen after 20 min. PEEP (n = 10) had no effect on the amount of atelectasis. * P < 0.05 versus anesthesia, † P < 0.05 versus PEEP and RM+ZEEP. PEEP = positive end-expiratory pressure; RM = recruitment maneuver; ZEEP = zero end-expiratory pressure.