Importance of the PaCO(2) from 3 to 6 months after initiation of long-term non-invasive ventilation.
BACKGROUND
The level at which arterial carbon dioxide tension (PaCO(2)) a few months after introduction of long-term non-invasive positive pressure ventilation (NPPV) is associated with a favorable prognosis remains uncertain.


METHODS
Data on 184 post-tuberculosis patients with chronic restrictive ventilatory failure who were receiving long-term domiciliary NPPV were examined retrospectively. Average PaCO(2) 3-6 months after NPPV (3- to 6-mo PaCO(2)) and potential confounders were analyzed with discontinuation of long-term NPPV as the primary outcome. The effects of 3- to 6-mo PaCO(2) on annual hospitalization rates due to respiratory deterioration from 1 year before to 3 years after the initiation of NPPV were examined. The effect of the difference between the PaCO(2) value at the start of NPPV (0-mo PaCO(2)) and the PaCO(2) value 3- to 6-mo later (d-PaCO(2)) on continuation rates for NPPV was also assessed in patients who initiated NPPV while in a chronic state.


RESULTS
Patients with relatively low 3- to 6-mo PaCO(2) values maintained a relatively low PaCO(2) 6-36 months after NPPV (p < 0.0001) and had significantly better continuation rates (p < 0.03) and lower hospitalization rates from the 1st to 3rd year of NPPV (p = 0.008, 0.049, 0.009, respectively) than those with higher levels. The 0-mo PaCO(2) (p = 0.26) or d-PaCO(2) (p = 0.86) had no predictive value.


CONCLUSIONS
A relatively low 3- to 6-mo PaCO(2) value was predictive of long-term use of NPPV. The target values for 3- to 6-mo PaCO(2) may, therefore, be less than 60 mmHg in post-tuberculosis patients, although more studies are needed.
Department of Respiratory Care and Sleep Control Medicine, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto, Japan. tomomasa@kuhp.kyoto-u.ac.jp
Tomomasa
T
Tsuboi
Motoharu
M
Ohi
Toru
T
Oga
Kazuko
K
Machida
Yuichi
Y
Chihara
Yuka
Y
Harada
Kenichi
K
Takahashi
Kensuke
K
Sumi
Tomohiro
T
Handa
Akio
A
Niimi
Michiaki
M
Mishima
Kazuo
K
Chin
D000368:Aged; D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000097:blood*; D002908:Chronic Disease; D005260:Female; D018575:Home Care Services, Hospital-Based / Q000592:standards; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D011175:Positive-Pressure Respiration / Q000379:methods*; D011379:Prognosis; D012129:Respiratory Function Tests; D012131:Respiratory Insufficiency / Q000097:blood* / Q000503:physiopathology / Q000628:therapy; D012189:Retrospective Studies; D013997:Time Factors; D014397:Tuberculosis, Pulmonary / Q000097:blood* / Q000503:physiopathology / Q000628:therapy
D002245:Carbon Dioxide