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Background: This study is aimed to evaluate the effect of inspiratory muscle training (IMT) added to rehabilitation in patients with chronic obstructive pulmonary disease (COPD) who remain hypercapnic and use non-invasive ventilation after successful weaning., Methods: Patients received rehabilitation and were randomized to inspiratory muscle or sham training for 4 weeks. The primary outcome was distance walked within 6 min. Secondary outcomes were inspiratory muscle strength, endurance, lung function, and blood gas levels., Results: Twenty-nine patients participated in this study. Walking distance of the sham group increased from 93 ± 52 m at baseline to 196 ± 85 m at week 4 (p = 0.019, 95% CI: 11-196 m). Patients in the IMT group significantly improved their walking distance from 94 ± 32 to 290 ± 75 m (p < 0.0001 [107-286 m]; p = 0.04 [3-186 m] for between-group comparison). Patients in the IMT group increased their maximal inspiratory pressure from -35 ± 8 to -55 ± 11 cmH 2 O (p = 0.001; -6 to -33 cmH 2 O), while the increase in the sham group failed to reach significance (-29 ± 10 to -37 ± 13 cmH 2 O [-22 to 6 cmH 2 O]). Inspiratory power increased from 9.6 ± 5.4 to 20.7 ± 9.7 joules/min (2.6-19.5 joules/min, p = 0.003) in the IMT group, while no significant change occurred in the sham group (7.6 ± 4.2 joules/min at study entry and 11.1 ± 6.9 joules/min [-5.2-12.3 joules/min] at study end)., Conclusions: Rehabilitation of successfully weaned patients with COPD and persistent hypercapnia significantly improves functional exercise capacity. Additional IMT significantly enhances functional exercise capacity and increases respiratory muscle strength and power., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Background: Although the endurance shuttle walk test (ESWT) has proven to be responsive to change in exercise capacity after pulmonary rehabilitation (PR) for COPD, the minimally important difference (MID) has not yet been established. We aimed to establish the MID of the ESWT in patients with severe COPD and chronic hypercapnic respiratory failure following PR., Methods: Data were derived from a randomized controlled trial, investigating the value of noninvasive positive pressure ventilation added to PR. Fifty-five patients with stable COPD, GOLD stage IV, with chronic respiratory failure were included (mean (SD) FEV1 31.1 (12.0) % pred, age 62 (9) y). MID estimates of the ESWT in seconds, percentage and meters change were calculated with anchor based and distribution based methods. Six minute walking distance (6MWD), peak work rate on bicycle ergometry (Wpeak) and Chronic Respiratory Questionnaire (CRQ) were used as anchors and Cohen's effect size was used as distribution based method., Results: The estimated MID of the ESWT with the different anchors ranged from 186-199 s, 76-82% and 154-164 m. Using the distribution based method the MID was 144 s, 61% and 137 m., Conclusions: Estimates of the MID for the ESWT after PR showed only small differences using different anchors in patients with COPD and chronic respiratory failure. Therefore we recommend using a range of 186-199 s, 76-82% or 154-164 m as MID of the ESWT in COPD patients with chronic respiratory failure. Further research in larger populations should elucidate whether this cut-off value is also valid in other COPD populations and with other interventions., Trial Registration: ClinicalTrials.Gov (ID NCT00135538).

Background: COPD patients who remain hypercapnic after acute respiratory failure requiring mechanical ventilation have a poor prognosis. Long-term nocturnal non-invasive ventilation (NIV) may be beneficial for these patients. We hypothesized that stable patients on long-term NIV would experience clinical worsening after withdrawal of NIV., Methods: We included 26 consecutive COPD patients (63 ± 6 years, 58% male, FEV(1) 31 ± 14% predicted) who remained hypercapnic after acute respiratory failure requiring mechanical ventilation. After a six month run-in period, during which all patients received NIV, they were randomised to either continue (ventilation group, n = 13) or to stop NIV (withdrawal group, n = 13). The primary endpoint was time to clinical worsening defined as an escalation of mechanical ventilation., Results: All patients remained stable during the run-in period. After randomisation the withdrawal group had a higher probability of clinical worsening compared to the ventilation group (p = 0.0018). After 12 months, ten patients (77%) in the withdrawal group, but only two patients (15%) in the ventilation group, experienced clinical worsening (p = 0.0048). Six-minute walking distance increased in the ventilation group., Conclusion: COPD patients who remain hypercapnic after acute respiratory failure requiring mechanical ventilation may benefit from long-term NIV., (Copyright © 2010. Published by Elsevier Ltd.)

To determine the immediate effects of bilevel non-invasive ventilation plus oxygen (NIV+O(2)) during exercise compared to exercise with O(2) alone in people recovering from acute on chronic hypercapnic respiratory failure (HRF), a randomised crossover study with repeated measures was performed. Eighteen participants performed six minute walk tests (6MWT) and 16 participants performed unsupported arm exercise (UAE) tests with NIV+O(2) and with O(2) alone in random order. Distance walked increased by a mean of 43.4m (95% CI 14.1 to 72.8, p=0.006) with NIV+O(2) compared to exercise with O(2) alone. In addition, isotime oxygen saturation increased by a mean of 5% (95% CI 2-7, p=0.001) and isotime dyspnoea was reduced [median 2 (interquartile range (IQR) 1-4) versus 4 (3-5), p=0.028] with NIV+O(2). A statistically significant increase was also observed in UAE endurance time with NIV+O(2) [median 201s (IQR 93-414) versus 157 (90-342), p=0.033], and isotime perceived exertion (arm muscle fatigue) was reduced by a mean of 1.0 on the Borg scale (95% CI -1.9 to -0.1, p=0.037) compared with O(2) alone. Non-invasive ventilation plus O(2) during walking resulted in an immediate improvement in distance walked and oxygen saturation, and a reduction in dyspnoea compared to exercise with O(2) alone in people recovering from acute on chronic HRF. The reduction of dyspnoea during walking and arm muscle fatigue during UAE observed with NIV+O(2) may allow patients to better tolerate exercise early in the recovery period.

We measured the ventilatory responses and subjective sensations during arm exercise in patients with lower cervical and upper thoracic spinal cord injuries in order to evaluate the effects of chest wall deafferentation on these responses. Visual analog scales with verbal descriptors were used to quantify respiratory sensations of different affectional qualities. Patients as well as normal subjects reported stronger respiratory sensations upon CO2 rebreathing as compared to during arm exercise with an equivalent minute ventilation (p<0.05). There were no qualitative nor quantitative differences in the respiratory sensations during CO2 rebreathing between the patients and normal subjects. However, patients with spinal cord injuries showed a higher minute ventilation and a lower end-tidal PCO2 during incremental arm exercises (p<0.01), and thus tended to hyperventilate. We conclude that chest wall afferent denervation does not contribute significantly to the perception of breathlessness in patients with spinal cord injuries.