RESUMO
AIMS: Gastro-esophageal reflux disease (GERD) is frequent in mechanically ventilated patients, often source of hemorragic or respiratory complications. The aim of this study was to determine promoting factors for acid reflux and to define the role of methods of ventilation and body position on reflux. METHODS: Fifteen patients with no history of GERD were included, following scheduled abdominal surgery. Reflux was measured in the proximal and distal esophagus by pH-metry. Events associated with reflux were detected by a videocamera linked to a videocassette recorder synchronized to the pH data logger. Position of the patients was randomized between supine and recumbent 30 degrees. Patients were first placed on mechanical ventilation then breathed spontaneously, determining 2 periods of equal duration during which provocative maneuvers were carried out. RESULTS: Acid reflux was absent in recumbent 30 degrees posture. Acid contact time and number of reflux in supine posture were 0.5 +/- 0.4% and 0.3 +/- 0.2/h respectively with mechanical ventilation and 4 +/- 2.5% and 1 +/- 0.5/h respectively with spontaneous breathing (P<0.05 vs position 30 degrees ) in distal esophagus. Twenty-five% of reflux episodes were associated with an event, mainly cough. CONCLUSION: Acid reflux is rare immediately following laparotomy. Seventy-five per cent of reflux occurred without any detectable event. Reflux was absent in semi recumbency. Mechanical ventilation did not facilitate reflux.