 Intestinal permeability IP was measured on day 4 using the lactulosemannitol LM test. For the study purpose, the patients were fasted 6 hours before the test. The test was performed with 5g of mannitol M and 10g of lactulose L mixed in 100ml of water. The mixture was given as a bolus via nasogastric tube. At the same time, 4ml of 20 chlorhexidine was added into an empty urine bag. The urine was collected in this bag for six hours. Then 5ml of urine was sampled from the bag and stored at -20 C until analysis. Two hours after the test enteral feeding via nasogastric tube was started. Urinary L and M were determined simultaneously with thin-layer chromatography14, a new method in our laboratory for lactulose and mannitol determination. The method enabled determination of lactulose and mannitol in urine on the same amino HPTLC plate after densitometric quantification of lactulose by use of fluorescence mode, and mannitol by use of absorption mode after detection with AgNO3 reagent. The new method resulted in shorter analysis time, lower consumption of chemicals and HPTLC plates, increased sensitivity lower limits of detection and fewer problems with interfering compounds at determination of lactulose than the previously used two separate methods for determination of both analytes.14 The separation and quantification using this method are highly reproducible, yielding standard errors of less than 2.5 for retention times and less than 3.5 for quantitation.15,16 The investigators in the laboratory were blinded for the study groups. LM index was calculated from urinary concentrations c of L and M using the following formula: LM c L c M x 2. LM test was not performed at the beginning of the study because unstable trauma and septic patients were also included in the study, and at these patients, urine collection is difficult to perform. 