title: Impact of Acute Changes in CPAP Flow Route in Sleep Apnea Treatment.
abstract: BACKGROUND
  CPAP is the gold standard treatment for OSA and was conceived to be applied through a nasal interface. This study was designed to determine the acute effects of changing the nasal CPAP route to oronasal and oral in upper airway patency during sleep in patients with OSA. We hypothesized that the oronasal route may compromise CPAP's effectiveness in treating OSA.
  
  
  METHODS
  Eighteen patients (mean ± SD age, 44 ± 9 years; BMI, 33.8 ± 4.7 kg/m2; apnea-hypopnea index, 49.0 ± 39.1 events/hour) slept with a customized oronasal mask with nasal and oral sealed compartments connected to a multidirectional valve. Sleep was monitored by using full polysomnography and induced by low doses of midazolam. Nasal CPAP was titrated up to holding pressure. Flow route was acutely changed to the oronasal (n = 18) and oral route (n = 16) during sleep. Retroglossal area was continuously observed by using nasoendoscopy.
  
  
  RESULTS
  Nasal CPAP (14.8 ± 4.1 cm H2O) was able to stabilize breathing in all patients. In contrast, CPAP delivered by the oronasal and oral routes promoted obstructive events in 12 (66.7%) and 14 (87.5%) patients, respectively. Compared with stable breathing during the nasal route, there was a significant and progressive reduction in the distance between the epiglottis and tongue base and the retroglossal area when CPAP was delivered by the oronasal and oral routes.
  
  
  CONCLUSIONS
  CPAP delivered through the oronasal route may compromise CPAP's effectiveness in treating OSA.
authors.affiliation: Sleep Laboratory, Pulmonary Division, Heart Institute, University of São Paulo, São Paulo, Brazil.
authors.forename: Rafaela G S
authors.initials: RG
authors.lastname: Andrade
authors.affiliation: Sleep Laboratory, Pulmonary Division, Heart Institute, University of São Paulo, São Paulo, Brazil.
authors.forename: Fernanda
authors.initials: F
authors.lastname: Madeiro
authors.affiliation: Sleep Laboratory, Pulmonary Division, Heart Institute, University of São Paulo, São Paulo, Brazil.
authors.forename: Vivien S
authors.initials: VS
authors.lastname: Piccin
authors.affiliation: Biomedical Engineering Laboratory of Escola Politécnica, University of São Paulo, São Paulo, Brazil.
authors.forename: Henrique T
authors.initials: HT
authors.lastname: Moriya
authors.affiliation: Sleep Laboratory, Pulmonary Division, Heart Institute, University of São Paulo, São Paulo, Brazil.
authors.forename: Fabiola
authors.initials: F
authors.lastname: Schorr
authors.affiliation: Sleep Laboratory, Pulmonary Division, Heart Institute, University of São Paulo, São Paulo, Brazil.
authors.forename: Priscila S
authors.initials: PS
authors.lastname: Sardinha
authors.affiliation: Sleep Laboratory, Pulmonary Division, Heart Institute, University of São Paulo, São Paulo, Brazil.
authors.forename: Marcelo G
authors.initials: MG
authors.lastname: Gregório
authors.affiliation: Sleep Laboratory, Pulmonary Division, Heart Institute, University of São Paulo, São Paulo, Brazil.
authors.forename: Pedro R
authors.initials: PR
authors.lastname: Genta
authors.affiliation: Sleep Laboratory, Pulmonary Division, Heart Institute, University of São Paulo, São Paulo, Brazil. Electronic address: geraldo.lorenzi@incor.usp.br.
authors.forename: Geraldo
authors.initials: G
authors.lastname: Lorenzi-Filho
mesh_terms: D000328:Adult; D045422:Continuous Positive Airway Pressure / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D020181:Sleep Apnea, Obstructive / Q000628:therapy*; D016896:Treatment Outcome
keywords: CPAP; nasal mask; oronasal mask