METHODS	A total of 160 patients who needed mechanical ventilation were randomized into 4 groups according to the computer-generated random number table : group ( S ) , ( n = 38 ) received sucralfate suspension 60 mg/kg/d in 4 doses via the nasogastric tube that was flushed with 10 mL of sterile water ; group ( R ) , ( n = 42 ) received ranitidine 2 mg/kg/d intravenously in 4 doses ; group ( O ) , ( n = 38 ) received omeprazole 1 mg/kg/d intravenously in 2 doses ; and group ( P ) , ( n = 42 ) did not receive any medication for stress ulcer prophylaxis .\