Increase in edema (NI %) in the left-sided ROI, reflecting free fluid in the abdomen (ascites) during 2.5 hours of either (1) spontaneous breathing with a CPAP of 5 cm H
O (■), (2) mechanical ventilation with PEEP 5 cm H
O (▲) or (3) mechanical ventilation with PEEP 15 cm H
O (◆) in endotoxemic piglets. All piglets had been on mechanical ventilation with PEEP 5 cm H2O for 2.5 hours before the allocation to one of the three groups. Note the 2- to 2.5-fold increase in edema over 150 minutes in the mechanically ventilated piglets, whereas the increase was only about 50% in the piglets on CPAP. The difference between CPAP and the two MV modes was significant during the latter part of the observation time (*P < 0.01 between either CPAP 5 and PEEP 5 or CPAP 5 and PEEP 15). No significant difference was seen between PEEP 5 and PEEP 15.