Mean ± standard error for intra-abdominal pressure during 1 week of PAL-treatment. IAP increases significantly in control patients and remains stable in PAL-treated patients. According to PAL-treatment protocol, PEEP level was titrated to IAP (best PEEP equals IAP) resulting in a mean PEEP of 11.0 ± 2.8 cmH2O. PAL-treated patients are depicted by a full line and control patients by a dotted line. *p < 0.05, day-by-day pairwise compared between the PAL group and the control group (one-way ANOVA).