Forced oscillation technique for the evaluation of severe sleep apnoea/hypopnoea syndrome: a pilot study

• Published in: The European respiratory journal Vol. 11; no. 5; pp. 1128 - 1134
• Main Authors: Badia, , JR, Farre, R, Montserrat, JM, Ballester, E, Hernandez, L, Rotger, M, Rodriguez-Roisin, R, Navajas, D
• Format: Journal Article
• Language: English
• Published: Leeds Eur Respiratory Soc 01.05.1998; Maney
• Subjects: Adult; Airway Obstruction - diagnosis; Biological and medical sciences; Diagnosis, Computer-Assisted; Humans; Male; Medical sciences; Middle Aged; Monitoring, Physiologic - methods; Pilot Projects; Pneumology; Polysomnography; Respiratory system : syndromes and miscellaneous diseases; Sleep Apnea Syndromes - diagnosis; Sleep Apnea Syndromes - physiopathology; Human; Sleep apnea syndrome; Upper respiratory tract; Respiratory disease; Sleep disorder; Exploration; Polysomnography; Obstruction; Electrodiagnosis; Sensitivity; Specificity; Forced oscillation; Non invasive method; Diagnosis; Technique; Comparative study
• ISSN: 0903-1936; 1399-3003
• DOI: 10.1183/09031936.98.11051128

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.