Tracheal Dosage of Amylase : a New Surrogate for Microaspirations in Ventilated ICU Patients

Microaspirations of the oropharyngeal ± gastric contents through the endotracheal tube cuff contribute to the constitution of VAP. The pepsin has been recently proved effective as a surrogate of gastric content and was assessed in tracheal secretions. However, the pepsin dosage is fastidious, expensive and only characterizes aspirations from gastric origin. The aim of our study is to asses whether the value of amylase, which is mostly secreted by salivary glands, may turn out to be a new and simpler surrogate for microaspirations in ventilated ICU patients. Thirty patients ventilated for an anticipated length > 48h whose endotracheal tube includes a subglottic secretion device and producing sufficient endotracheal aspirations will be included. From H48, 4 sets of 3 aspirations each (oral, subglottic, tracheal) will be performed during one ventilation day for amylase dosage purpose. In ten of these patients, a comparison between pepsin and amylase will be assessed. In addition, 10 non intubated patients with an indication to bronchoscopy and necessitating a tracheal aspiration during the procedure will be included as a control group. The primary assessment criteria will be the oral/tracheal amylase ratio.