title: PaCO2 six months after the initiation of long-term noninvasive ventilation in patients with COPD.
abstract: OBJECTIVE
  The appropriate target level for PaCO(2) after the introduction of long-term noninvasive positive pressure ventilation (NPPV) in patients with COPD remains uncertain, and therefore must be tested.
  
  
  METHODS
  Data on 54 patients with COPD receiving long-term domiciliary NPPV were examined retrospectively. PaCO(2) a few months after NPPV and potential confounders were analyzed with discontinuation of long-term NPPV as the primary outcome. The differences in annual hospitalization rates due to respiratory deterioration between those from 1 year before to 2 years after initiation of NPPV were compared according to the PaCO(2) measured at 6 months after NPPV (6-mo PaCO(2)).
  
  
  RESULTS
  6-mo PaCO(2) seemed to be most related to continuation of NPPV (p=0.019). Patients with 6-mo PaCO(2) of less than 60 mmHg had maintained a significantly lower PaCO(2) value 6 to 24 months after NPPV (p=0.04) and had a significantly higher continuation rate of NPPV (p=0.03) than those with a 6-mo PaCO(2) of 60 mmHg or more. Annual hospitalization rates due to respiratory deterioration were not associated with the 6-mo PaCO(2) level, but fatal hospitalization rates during the first year of NPPV were significantly correlated with relatively high 6-mo PaCO(2) (p=0.008).
  
  
  CONCLUSIONS
  A relatively low 6-mo PaCO(2) value was predictive of long-term use of NPPV. The target values of 6-mo PaCO(2) may, therefore, be less than 60 mmHg in COPD patients with extremely severe hypercapnia, although more prospective studies are needed.
authors.affiliation: Department of Respiratory Care and Sleep Control Medicine, Kyoto University Graduate School of Medicine, Japan. tsuboit@skyoto.hosp.go.jp
authors.forename: Tomomasa
authors.initials: T
authors.lastname: Tsuboi
authors.forename: Toru
authors.initials: T
authors.lastname: Oga
authors.forename: Kazuko
authors.initials: K
authors.lastname: Machida
authors.forename: Kensuke
authors.initials: K
authors.lastname: Sumi
authors.forename: Susumu
authors.initials: S
authors.lastname: Oguri
authors.forename: Atsuo
authors.initials: A
authors.lastname: Sato
authors.forename: Takuya
authors.initials: T
authors.lastname: Kurasawa
authors.forename: Motoharu
authors.initials: M
authors.lastname: Ohi
authors.forename: Michiaki
authors.initials: M
authors.lastname: Mishima
authors.forename: Kazuo
authors.initials: K
authors.lastname: Chin
mesh_terms: D000368:Aged; D001784:Blood Gas Analysis / Q000379:methods; D002245:Carbon Dioxide / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011175:Positive-Pressure Respiration / Q000639:trends; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood* / Q000628:therapy*; D011659:Pulmonary Gas Exchange / Q000502:physiology; D012189:Retrospective Studies; D013997:Time Factors
chemical_list: D002245:Carbon Dioxide