After study enrollment, 15 days before the performance of the experimental protocol, patients performed neurocognitive tests (Digit Span Test, Digit Symbol-Coding, Corsi Block-tapping, Trail Making Test A and B and Stroop Test) and NIV adaptation. Pulmonary function (spirometry) was measured in all subjects after a thorough medical history and physical examination. Before initiating the protocol, patients were asked about discomfort related to NIV or any aspect of the experiment. CBF, capnometry, arterial blood gases (ABG) and neurocognitive tests were performed before, during and after NIV.