Abstract
BACKGROUND:
The significance of changes in PaCO2 during long-term noninvasive ventilation (NIV) on prognosis remains unclear. We aimed to clarify whether stabilizing PaCO2 during NIV had a favorable prognostic effect.
METHODS:
Data from 190 subjects with restrictive thoracic disease and who received long-term NIV were studied retrospectively. The annual change in PaCO2 during NIV was determined using a simple linear regression method for each subject who had at least 4 6-month intervals of PaCO2 data. Annual changes in PaCO2 during long-term NIV and possible confounders were analyzed with discontinuation of long-term NIV as the main outcome.
RESULTS:
One hundred and twenty-five subjects who had > 4 6-month intervals of PaCO2 data were included in the study. PaCO2 during long-term NIV decreased in 41 subjects (group 1; < 0 mm Hg/y), increased slightly in 42 subjects (group 2; between 0 and 1.85 mm Hg/y), and increased significantly in 42 subjects (group 3; > 1.85 mm Hg/y). Smaller annual changes in PaCO2 (P < .001) and a control ventilator mode (P = .008) were associated with a significantly higher probability of continuing NIV, compared with decreased PaCO2 3–6 months after the start of long-term NIV (P = .11). The 10-y probability of continuing NIV was 69% in group 1, 39% in group 2, and 12% in group 3.
CONCLUSIONS:
A decrease in the annual change of PaCO2 during long-term NIV was shown to be a significantly prognostically favorable factor. Efforts to reduce PaCO2 should be made if PaCO2 increases at a greater rate during long-term NIV.
Keywords
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