Physical training and non-invasive ventilation in stable chronic obstructive pulmonary disease patients : a meta-analysis and meta-regression

BACKGROUND: Exercise training improves both exercise tolerance and quality of life in patients with COPD. The intensity of exercise training is crucial to achieve a true physiologic effect. However, in COPD patients, exertional dyspnea and leg fatigue mean that the patient cannot maintain intensity of training for enough time to yield a physiologic training effect. The use of noninvasive ventilation (NIV) support has been proposed as an alternative strategy to improve exercise tolerance and respiratory and cardiovascular performances. The first aim of our meta-analysis was to evaluate exercise training with NIV in terms of physiologic effects after the completion of a pulmonary rehabilitation program. The second aim was to investigate the dose-response relationship between physical improvement and training intensity. METHODS: Literature research was performed using MEDLINE, Embase, and CINAHL. Meta-analysis and meta-regressions were performed using random effects models. RESULTS: Eight studies provided a proper description of a training schedule in stable COPD patients. A similar effect between NIV and placebo was observed for the outcomes considered despite differences between studies. However, subjects experienced a relevant and statistically significant improvement after rehabilitation for almost all of the outcomes considered. Heart rate (6 beats/min [95% CI 0.94-11.01], P.02), work load (9.73 W [95% CI 3.78-15.67], P <.001), and oxygen consumption (242.11 mL/min [95% CI 154.93-329.9], P <.001) significantly improved after training. Improvements in heart rate and work load were significantly correlated to training intensity. CONCLUSIONS: Given the small number of available studies, the small sample sizes, and the complete absence of power calculation, we think that this topic deserves a more in-depth investigation. Randomized clinical trials with larger sample sizes based on statistical power calculations and designed to investigate the effect of training duration and intensity on rehabilitation are needed to confirm results in this important field.