AIM:To investigate factors predicting failure of percutaneous endoscopic gastrostomy(PEG)to eliminate gastroesophageal reflux(GER). METHODS:Twenty-nine consecutive mechanically ventilated patients were investigated.Patients were evaluated for GER by pH-metry pre-PEG and on the 7th post-PEG day.Endoscopic and histologic evidence of reflux esophagitis was also carried out.A beneficial response to PEG was considered when pH-metry on the 7th post-PEG day showed that GER was below 4%. RESULTS:Seventeen patients responded(RESP group)and 12 did not respond(N-RESP)to PEG.The mean age,sex,weight and APACHEⅡscore were similar in both groups.GER(%)values were similar in both groups at baseline,but were significantly reduced in the RESP group compared with the N-RESP group on the 7th post-PEG day[2.5(0.6-3.8)vs 8.1(7.4-9.2, P<0.001)].Reflux esophagitis and the gastroesophageal flap valve(GEFV)grading differed significantly between the two groups(P=0.031 and P=0.020, respectively).Histology revealed no significant differences between the two groups.CONCLUSION:Endoscopic grading of GEFV and the presence of severe reflux esophagitis are predisposing factors for failure of PEG to reduce GER in mechanically ventilated patients. AIM: To investigate factors predicting failure of percutaneous endoscopic gastrostomy (PEG) to eliminate gastroesophageal reflux (GER). METHODS: Twenty-nine consecutive nursing ventilated patients were investigated. Patients were evaluated for GER by pH-metry pre-PEG and on the 7th Post-PEG day. Endoscopic and histologic evidence of reflux esophagitis was also carried out. A beneficial response to PEG was considered when pH-metry on the 7th post-PEG day showed that GER was below 4%. RESULTS: Seventeen patients responded (RESP group) and 12 did not respond (N-RESP) to PEG. The mean age, sex, weight and APACHE II score were similar in both groups. GER (%) values ​​were similar in both groups at baseline, but were significantly reduced in the RESP group compared with the N-RESP group on the 7th post-PEG day [2.5 (0.6-3.8) vs 8.1 (7.4-9.2, P <0.001)]. Reflux esophagitis and the gastroesophageal flap valve (GEFV) grading differed significantly between the two groups (P = 0.031 and P = 0.020, respectively) .Histology revea led no significant differences between the two groups. CONCLUSION: Endoscopic grading of GEFV and the presence of severe reflux esophagitis are predisposing factors for failure of PEG to reduce GER in mechanically ventilated patients.