title: Self-adjusting nasal continuous positive airway pressure therapy based on measurement of impedance: A comparison of two different maximum pressure levels.
abstract: OBJECTIVE
  Automatic titration using the forced oscillation technique (FOT) has recently been developed for the treatment of obstructive sleep apnea syndrome (OSAS). So far, it is not known if therapy with automatic nasal continuous positive airway pressure (nCPAP) using a preset upper pressure limitation or a free range (which might lead to higher mean pressure) is preferable with regard to obstructive events, sleep stages, and pressure characteristics.
  
  
  METHODS
  After diagnostic polysomnography, patients were randomly assigned to two settings with the self-adjusting nCPAP (APAP) device based on the FOT. In mode 1, the pressure variation ranged from 4 to 15.5 cm H(2)O, and in mode 2, the pressure variation ranged from 4 cm H(2)O to an individual upper pressure limit.
  
  
  METHODS
  Eleven men, aged 53.0 +/- 6.8 years with a body mass index of 32.4 +/- 5.1 kg/m(2) and an apnea-hypopnea index (AHI) of 31.6 +/- 26.6/h.
  
  
  RESULTS
  Manually titrated pressure was at 9.3 +/- 2.1 cm H(2)O, the mean pressure in mode 1 was 5.4 +/- 1.0 cm H(2)O (p < 0.01), and the mean pressure in mode 2 was 5.1 +/- 0.7 cm H(2)O (p < 0.01). A reduction of respiratory events (baseline AHI, 31.6 +/- 26.6/h; AHI in mode 1, 3.4 +/- 4.5; AHI in mode 2, 5.0 +/- 7.2; each with p < 0.001) and an increase in the "rapid eye movement" stage of sleep (baseline, 13.0 +/- 5.5%; mode 1, 22.0 +/- 7.7 [p < 0. 05]; mode 2, 23.0 +/- 7.9 [p < 0.01]) were achieved. In mode 1, the mean pressure was below the manual pressure 91.7 +/- 9.3% of the time, and in mode 2, the mean pressure was below the manual pressure 90.4 +/- 6.3% of the time. The manual pressure was exceeded by 5.5 +/- 7.4% (mode 1) and by 5.2 +/- 3.1% (mode 2).
  
  
  CONCLUSIONS
  We conclude that nCPAP therapy based on the FOT permits the adequate treatment of OSAS with significantly lower pressure than manually titrated nCPAP therapy does. A presetting of an upper pressure limit has no advantage compared to free range.
authors.affiliation: Clinic Ambrock, Clinic for Pneumology, Allergology and Sleep Medicine , Hagen, Germany.
authors.forename: W J
authors.initials: WJ
authors.lastname: Randerath
authors.forename: K
authors.initials: K
authors.lastname: Parys
authors.forename: F
authors.initials: F
authors.lastname: Feldmeyer
authors.forename: B
authors.initials: B
authors.lastname: Sanner
authors.forename: K H
authors.initials: KH
authors.lastname: Rühle
mesh_terms: D000328:Adult; D000368:Aged; D000403:Airway Resistance / Q000502:physiology; D004867:Equipment Design; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D006874:Hydrostatic Pressure; D008297:Male; D008875:Middle Aged; D009991:Oscillometry / Q000295:instrumentation*; D017286:Polysomnography / Q000295:instrumentation*; D011175:Positive-Pressure Respiration / Q000295:instrumentation*; D012891:Sleep Apnea Syndromes / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D013813:Therapy, Computer-Assisted / Q000295:instrumentation*; D014797:Vital Capacity / Q000502:physiology