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Summary: Background: The level at which arterial carbon dioxide tension (PaCO2) 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 PaCO2 3–6 months after NPPV (3- to 6-mo PaCO2) and potential confounders were analyzed with discontinuation of long-term NPPV as the primary outcome. The effects of 3- to 6-mo PaCO2 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 PaCO2 value at the start of NPPV (0-mo PaCO2) and the PaCO2 value 3- to 6-mo later (d-PaCO2) 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 PaCO2 values maintained a relatively low PaCO2 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 PaCO2 (p = 0.26) or d-PaCO2 (p = 0.86) had no predictive value. Conclusion: A relatively low 3- to 6-mo PaCO2 value was predictive of long-term use of NPPV. The target values for 3- to 6-mo PaCO2 may, therefore, be less than 60 mmHg in post-tuberculosis patients, although more studies are needed. [Copyright &y& Elsevier]

Summary: Background: Long-term noninvasive positive pressure ventilation (NPPV) is associated with an excellent survival rate, especially in post-tuberculosis patients. Nothing is currently known on which method of ventilatory support is associated with a better continuation of long-term NPPV, which itself might lead to longer survival. Methods: One hundred and eighty four post-tuberculosis patients, who started NPPV at the Kyoto University Hospital group and the National Tokyo Hospital from June 1990 to August 2007, were examined retrospectively. Ventilator mode (an assisted mode or a pure controlled mode) and potential confounders were examined with the discontinuation of NPPV as the primary outcome. Results: Patients treated with a pure controlled mode had significantly better continuation rates (hazard ratio, 3.09; 95% confidential interval, 1.75–5.47; p =0.0001) and better survival rates (Log-rank test; p =0.0031) than those treated with an assisted mode. Female gender and no pulmonary lesions were also associated with a significantly better probability of continuing NPPV. The five- and ten-year probabilities of continuing NPPV for 106 patients with a pure controlled mode were 68.3% and 41.4%, respectively, while those for 76 patients with an assisted mode were 46.7% and 12.7%, respectively. Conclusions: Patients treated with pure controlled ventilation had significantly better continuation rates and survival rates than those treated with assisted ventilation. Prospective randomized controlled trials are needed to verify the effectiveness of a pure controlled mode in patients with not only restrictive thoracic disease but also other diseases including chronic obstructive pulmonary disease. [Copyright &y& Elsevier]