Patients were recruited consecutively from the ICU of Hospital Nossa Senhora da Penha (São Paulo, Brazil) during a 6-month period. All medical patients admitted to the ICU were considered for inclusion into the study. The criteria for exclusion were disturbance of consciousness, hemodynamic instability, use of vasoactive drugs, airway suctioning, use of invasive or noninvasive mechanical ventilation, presence of tracheal, gastric or enteral tube, inability to taste saccharine, and expected ICU stay < 48 h. Tobacco smoking (number of packs of cigarettes/years), diagnosis at ICU admission, respiratory infection, use of oxygen, and ICU and hospital stay were recorded. In addition, simple markers of disease severity, including heart rate, BP, and respiratory rate, were recorded. Healthy subjects enrolled into the study were members of the ICU staff. Subjects receiving long-term medication, except for contraceptives, who presented inability to taste saccharine and nasal dysfunction, including vasomotor rhinitis, chronic purulent rhinitis, allergic rhinitis (within 4 weeks before the experiments) or previous nasal surgery, were excluded. This study was approved by the local Ethical Committee and by the Ethical Committee of University of São Paulo City, São Paulo, Brazil. The study was performed according to the standards of good clinical practice. The purpose and all procedures of this study were explained to the involved subjects. Each subject gave their informed written consent according to the Declaration of Helsinki of the World Medical Association.