Non Invasive Ventilation in Abdominal Postoperative Period

The Non-Invasive Ventilation After Surgery (NIVAS) is an investigator-initiated, multi-center, stratified, two-arm parallel-group trial with a computer-generated allocation sequence and electronic system based randomization. The study protocol and statistical analysis plan were approved for all centers by a central Ethics Committee (France) according to French law.The NIVAS study is conducted in accordance with the declaration of Helsinki and was registered on August 2013.All centers have a long experience with NIV (more than 10 years of NIV use for ARF, and more than 5 years of NIV use for ARF following abdominal surgery). Randomization will stratified by department, age (less or more 60 years), site of surgery (upper or lower abdominal) and according to the presence or absence of postoperative epidural analgesia as this may influence outcomes. Treatment assignments will concealed from patients, research staff, the statistician, and the data monitoring and safety committee.