title: Oxygen With Cold Bubble Humidification Is No Better Than Dry Oxygen in Preventing Mucus Dehydration, Decreased Mucociliary Clearance, and Decline in Pulmonary Function.
abstract: BACKGROUND
  Little is known about the effects of long-term nasal low-flow oxygen (NLFO) on mucus and symptoms and how this variable is affected by dry or cold humidified gas. The aim of this study was to investigate the effects of dry-NLFO and cold bubble humidified-NLFO on nasal mucociliary clearance (MCC), mucus properties, inflammation, and symptoms in subjects with chronic hypoxemia requiring long-term domiciliary oxygen therapy.
  
  
  METHODS
  Eighteen subjects (mean age, 68 years; 7 male; 66% with COPD) initiating NLFO were randomized to receive dry-NLFO (n = 10) or humidified-NLFO (n = 8). Subjects were assessed at baseline, 12 h, 7 days, 30 days, 12 months, and 24 months by measuring nasal MCC using the saccharin transit test, mucus contact angle (surface tension), inflammation (cells and cytokine concentration in nasal lavage), and symptoms according to the Sino-Nasal Outcome Test-20.
  
  
  RESULTS
  Nasal MCC decreased significantly (40% longer saccharin transit times) and similarly in both groups over the study period. There was a significant association between impaired nasal MCC and decline in lung function. Nasal lavage revealed an increased proportion of macrophages, interleukin-8, and epidermal growth factor concentrations with decreased interleukin-10 during the study. No changes in the proportion of ciliated cells or contact angle were observed. Coughing and sleep symptoms decreased similarly in both groups. There were no outcome differences comparing dry vs cold bubble humidified NLFO.
  
  
  CONCLUSIONS
  In subjects receiving chronic NLFO, cold bubble humidification does not adequately humidify inspired oxygen to prevent deterioration of MCC, mucus hydration, and pulmonary function. The unheated bubble humidification performed no better than no humidification.
  
  
  BACKGROUND
  ClinicalTrials.gov; No.: NCT02515786; URL: www.clinicaltrials.gov.
authors.affiliation: Department of Physiotherapy, Communication Science and Disorders and Occupational Therapy, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Michelle Lisidati
authors.initials: ML
authors.lastname: Franchini
authors.affiliation: Pulmonary Division, Heart Institute (InCor), Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Athanazio
authors.affiliation: Department of Pathology, LIM-5, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Luis Fernando
authors.initials: LF
authors.lastname: Amato-Lourenço
authors.affiliation: Federal University of Santa Catarina, Santa Catarina, Brazil.
authors.forename: Waldir
authors.initials: W
authors.lastname: Carreirão-Neto
authors.affiliation: Department of Pathology, LIM-5, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Paulo Hilario Nascimento
authors.initials: PH
authors.lastname: Saldiva
authors.affiliation: Pulmonary Division, Heart Institute (InCor), Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Geraldo
authors.initials: G
authors.lastname: Lorenzi-Filho
authors.affiliation: Pediatrics Department, Virginia Commonwealth University School of Medicine, Richmond, VA.
authors.forename: Bruce K
authors.initials: BK
authors.lastname: Rubin
authors.affiliation: Department of Physiotherapy, Communication Science and Disorders and Occupational Therapy, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil. Electronic address: naomi.kondo@usp.br.
authors.forename: Naomi Kondo
authors.initials: NK
authors.lastname: Nakagawa
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001987:Bronchiectasis / Q000628:therapy*; D003371:Cough; D016207:Cytokines / Q000276:immunology; D018450:Disease Progression; D004815:Epidermal Growth Factor / Q000378:metabolism; D005260:Female; D006801:Humans; D000068998:Humidifiers; D006813:Humidity; D006976:Hypertension, Pulmonary / Q000628:therapy*; D016753:Interleukin-10 / Q000276:immunology; D016209:Interleukin-8 / Q000276:immunology; D008264:Macrophages / Q000166:cytology / Q000276:immunology; D008297:Male; D008875:Middle Aged; D009079:Mucociliary Clearance; D009093:Mucus / Q000378:metabolism*; D017817:Nasal Lavage Fluid / Q000166:cytology / Q000276:immunology; D010102:Oxygen Inhalation Therapy / Q000379:methods*; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology / Q000628:therapy*; D011658:Pulmonary Fibrosis / Q000628:therapy*; D012129:Respiratory Function Tests; D013500:Surface Tension
chemical_list: C508606:CXCL8 protein, human; D016207:Cytokines; C508609:IL10 protein, human; D016209:Interleukin-8; D016753:Interleukin-10; D004815:Epidermal Growth Factor
keywords: humidity; inflammation; mucociliary transport; oxygen therapy