title: Forced oscillation technique for the evaluation of severe sleep apnoea/hypopnoea syndrome: a pilot study.
abstract: The forced oscillation technique (FOT) is a noninvasive method of potential clinical interest for quantitatively assessing airway mechanics during sleep. We investigated the applicability of FOT as a diagnostic tool for noninvasive assessment of airflow obstruction in patients with sleep apnoea/hypopnoea syndrome (SAHS) during sleep. In seven patients previously diagnosed with severe SAHS (mean+/-SD apnoea/ hypopnoea index (AHI) 67+/-14) we performed a full polysomnography (PSG) together with on-line measurement of respiratory impedance (IZI) using FOT. For each patient we determined: 1) number of respiratory events conventionally detected by full PSG, those obtained by FOT and their degree of concordance; and 2) the characteristics and values of IZI during the respiratory events. FOT was well tolerated and easily applied in conjunction with a conventional sleep setup. The mean number of respiratory events x h(-1) detected by PSG and FOT were 55+/-16 and 58+/-17, respectively, with a strong concordance. IZI increased from a baseline of 11+/-4 to 50+/-20 cmH2O x L(-1) x s during apnoea (mean+/-SD). In all but one patient intermittent increases of IZI occurred immediately before each obstructive apnoea. In four patients, the increases of IZI developed at end-expiration whereas in two others occurred during inspiration. During hypopnoea most of the patients showed decreases of IZI during expiration. In conclusion, forced oscillation technique can be used as a noninvasive and complementary tool for the diagnosis of respiratory events and provides an on-line quantitative approach for continuous monitoring of airflow obstruction during sleep in patients with sleep apnoea/hypopnoea syndrome.
authors.affiliation: Servei de Pneumologia i Al.lèrgia Respiratòria, Departament de Medicina, Hospital Clínic, Barcelona, Spain.
authors.forename: J R
authors.initials: JR
authors.lastname: Badia
authors.forename: R
authors.initials: R
authors.lastname: Farré
authors.forename: J M
authors.initials: JM
authors.lastname: Montserrat
authors.forename: E
authors.initials: E
authors.lastname: Ballester
authors.forename: L
authors.initials: L
authors.lastname: Hernandez
authors.forename: M
authors.initials: M
authors.lastname: Rotger
authors.forename: R
authors.initials: R
authors.lastname: Rodriguez-Roisin
authors.forename: D
authors.initials: D
authors.lastname: Navajas
mesh_terms: D000328:Adult; D000402:Airway Obstruction / Q000175:diagnosis; D003936:Diagnosis, Computer-Assisted; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods*; D010865:Pilot Projects; D017286:Polysomnography; D012891:Sleep Apnea Syndromes / Q000175:diagnosis* / Q000503:physiopathology