RESPIMER® Netiflow® vs. Saline Solutions During Nasal Irrigation Following Bilateral Ethmoidectomy (Nasal Polyposis)

Inclusion Criteria: * Males or females between 18 and 65 years of age * Subject in need of sinus surgery as bilateral total ethmoidectomy using an endoscopic endonasal approach whose pathology is the result of a: * Sinonasal polyposis alone * Sinonasal polyposis associated with asthma and / or intolerance to NSAIDs * Free and informed written consent * Member or beneficiary of a social security program Exclusion Criteria: * Oral corticosteroid treatment since less than 2 months * Premenopausal women not using effective contraception (oral or intrauterine device) * Pregnant or nursing women * Uncontrolled diabetes (not treated or stabilized by treatment) * HIV-positive status * Autoimmune diseases affecting the nose and/or sinuses, immune dysfunctions (Wegener's granulomatosis, Churg-Strauss syndrome, Common Variable Immunodeficiency, sarcoidosis...), or malignant diseases (unclear histology) * All contraindication of RESPIMER® NetiFlow® * All diseases resulting in difficulty coughing or swallowing * Ongoing or past radiation treatment to the head and neck * Ongoing or recent chemotherapy (within a three-month period) * Subjects using anticoagulants * Subjects taking part in another study that includes an exclusion period coinciding with that of the run-in period of this study * Subjects placed under judicial protection * Subjects who suffer from severe physical or psychological problems and whose condition can, according to the investigator, affect compliance with the study