title: The Importance of Stabilizing PaCO2 during Long-term Non-invasive Ventilation in Subjects with COPD.
abstract: OBJECTIVE
  In subjects with chronic obstructive pulmonary disease (COPD), the effect of partial pressure of CO2 (PaCO2) alterations during long-term non-invasive ventilation (NIV) on continuance remains uncertain. We herein investigated the utility of PaCO2 stability during long-term NIV as a prognostic outcome.
  
  
  METHODS
  We retrospectively assessed data from 54 subjects with COPD who received long-term NIV. The annual alteration in PaCO2 during NIV was determined using a simple linear regression method for each subject who had at least two 6-month intervals of PaCO2 data. Annual alterations in PaCO2 during long-term NIV and probable confounders were examined, and long-term NIV discontinuation was the major outcome.
  
  
  RESULTS
  Data from 37 subjects who met the criteria were analyzed. PaCO2 during long-term NIV increased slightly in 19 subjects (group 1, <2 mm Hg/y), and increased greatly in 18 subjects (group 2, >2 mmHg/y). In the multivariate modality model, smaller annual alterations in PaCO2 (p=0.009) and lower PaCO2 6 months after the start of long-term NIV (6 m-PaCO2) (p=0.03) were associated with a significantly higher probability of continuing NIV. The 2- and 5-year probabilities of continuing NIV were 89% and 66% for group 1 and 78% and 32% for group 2, respectively.
  
  
  CONCLUSIONS
  A lower 6 m-PaCO2 and a lower annual alteration of PaCO2 during long-term NIV are significant predictive variables for patients with COPD.
authors.affiliation: Department of Respiratory Medicine, National Hospital Organization Minami-Kyoto Hospital, Japan.
authors.forename: Tomomasa
authors.initials: T
authors.lastname: Tsuboi
authors.forename: Toru
authors.initials: T
authors.lastname: Oga
authors.forename: Kensuke
authors.initials: K
authors.lastname: Sumi
authors.forename: Kazuko
authors.initials: K
authors.lastname: Machida
authors.forename: Motoharu
authors.initials: M
authors.lastname: Ohi
authors.forename: Kazuo
authors.initials: K
authors.lastname: Chin
mesh_terms: D000368:Aged; D001784:Blood Gas Analysis; D005260:Female; D006801:Humans; D006935:Hypercapnia / Q000097:blood / Q000209:etiology / Q000503:physiopathology* / Q000628:therapy; D008297:Male; D008991:Monitoring, Physiologic; D063087:Noninvasive Ventilation; D011175:Positive-Pressure Respiration / Q000379:methods; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood / Q000150:complications / Q000503:physiopathology* / Q000628:therapy; D012189:Retrospective Studies