title: Comparison optimal pressure between automatic titrating and predicting continuous positive airway pressure.
abstract: BACKGROUND
  Optimal continuous positive airway pressure (CPAP) level reduced excessive daytime sleepiness and improved healthy status compared with subtherapeutic CPAP pressure for patients with obstructive sleep apnea syndromes. To date there have been no studies comparing the differences between the automatic CPAP titrating pressure levels (ACPAPL) and the predicting CPAP pressure levels (PCPAPL). In this study, we compared the differences between these two pressures and investigated the factors effecting ACPAPL and PCPAPL.
  
  
  METHODS
  A retrospective study included 49 patients who were diagnosed with obstructive sleep apnea syndromes and prescribed CPAP therapy by physicians. ACPAPL as determined using automated CPAP was defined as 95th percentiles pressure. The PCPAPL was calculated according to body mass index (BMI), neck circumference (NC), and apnea/hypopnea index (AHI) formula. The paired t-test was used to compare ACPAPL and PCPAPL. The correlation analysis was used to determine the relationship between ACPAPL with maximum leak values, median leak values, 95th percentile leak value, BMI, NC, and AHI.
  
  
  RESULTS
  The mean ACPAPL (10.4 +/- 1.8 cmH2O) was significantly higher than the mean PCPAPL (7.82 +/- 1.51 cmH2O). The differences in the results were statistically significant (p < 0.001). There were 98% of patients had air leaks. The ACPAPL had good correlation with maximum leaks (r = 0.44, 95% CI 0.18 to 0.64), median leak values (r = 0.46, 95% CI 0.20 to 0.66), and 95th percentile leak values (r = 0.30, 95% CI 0.02 to 0.54), however, the correlations with BMI (r = 0.05, 95% CI -0.23 to 0.33), NC (r = -0.18, 95% CI -0.44 to 0.10), and AHI (r = 0.23, 95% CI -0.06 to 0.48) were poor.
  
  
  CONCLUSIONS
  The ACPAPL were higher than PCPAPL. The pressure differences between ACPAPL and PCPAPL were wide. Air leaks were common during the automatic CPAP titration. Leak value was one of the important factors that effected ACPAPL.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Sleep Center, Chang Gung Memorial Hospital, Keelung Taiwan, R.O.C. ycc@cgmh.org.tw
authors.forename: Chung-Chieh
authors.initials: CC
authors.lastname: Yu
authors.forename: Chung-Ching
authors.initials: CC
authors.lastname: Hua
authors.forename: Jo-Chi
authors.initials: JC
authors.lastname: Tseng
authors.forename: Yu-Chi
authors.initials: YC
authors.lastname: Liu
mesh_terms: D000328:Adult; D000368:Aged; D015992:Body Mass Index; D045422:Continuous Positive Airway Pressure; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011312:Pressure; D012189:Retrospective Studies