title: Automatic titration and calculation by predictive equations for the determination of therapeutic continuous positive airway pressure for obstructive sleep apnea.
abstract: BACKGROUND
  It is unknown to what extent therapeutic continuous positive airway pressure (CPAP) levels obtained by various methods for the treatment of obstructive sleep apnea syndrome (OSAS) differ. This study aimed to explore the relationships among pressures titrated by an automatic CPAP (APAP) device and those calculated using different predictive equations, and to compare different ranges of calculated pressures with pressure values titrated by APAP.
  
  
  METHODS
  In 140 OSAS patients, the 95th percentile pressure delivered by an APAP device (AutoSet T; ResMed; Sydney, NSW, Australia) during polysomnography, and pressures calculated by three equations (equation 1, Hoffstein and Miljetig [1994]; equation 2, Sériès et al [2000]; and equation 3, Stradling et al [2004]) were compared.
  
  
  RESULTS
  Titrated and calculated pressures were weakly correlated. Significant differences were found between the mean (+/- SD) pressures (11.1 +/- 1.6, 8.3 +/- 1.8, 10.5 +/- 1.6, and 10.3 +/- 1.3 cm H(2)O, respectively) for 95th percentile APAP, and pressures calculated by equations 1, 2, and 3, except between values calculated by equations 2and 3. Differences between the calculated and APAP-derived pressures were negative for the low calculated values, and were progressively attenuated, or became positive, for the high values. The differences were smallest for calculated pressures from 11 to > 13 cm H(2)O, which were represented to a greater extent among the values calculated by equations 2 and 3 than by those calculated by equation 1.
  
  
  CONCLUSIONS
  Considerably different therapeutic CPAP levels may be determined using various methods. The differences between the calculated and APAP-derived pressures are largest for calculated values of < 9 or > 15 cm H(2)O. The clinical consequences of these findings deserve further evaluation. Caution is still required before treating OSAS patients with calculated pressures.
authors.affiliation: Italian National Research Council, Institute of Biomedicine and Molecular Immunology, A. Monroy, Sleep Laboratory, Palermo, Italy. marrone@ibim.cnr.it
authors.forename: Oreste
authors.initials: O
authors.lastname: Marrone
authors.forename: Adriana
authors.initials: A
authors.lastname: Salvaggio
authors.forename: Salvatore
authors.initials: S
authors.lastname: Romano
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Insalaco
mesh_terms: D045422:Continuous Positive Airway Pressure / Q000295:instrumentation*; D004867:Equipment Design; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D000860:Hypoxia / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D011312:Pressure; D012189:Retrospective Studies; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology / Q000628:therapy*; D016896:Treatment Outcome