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BackgroundNon-invasive ventilation (NIV) can increase exercise tolerance, reduce exercise induced desaturation and improve the outcome of pulmonary rehabilitation in patients with chronic respiratory disease. It is not known whether it can be applied to increase exercise capacity in patients admitted with non-hypercapnic acute exacerbations of COPD (AECOPD). We investigated the acceptability and feasibility of using NIV for this purpose.MethodsOn a single occasion, patients admitted with an acute exacerbation of chronic respiratory disease who were unable to cycle for five minutes at 20 watts attempted to cycle using NIV and their endurance time (Tlim) was recorded. To determine feasibility of this approach in clinical practice patients admitted with AECOPD were screened for participation in a trial of regular NIV assisted rehabilitation during their hospital admission.ResultsIn 12 patients tested on a single occasion NIV increased Tlim from 184(65) seconds to 331(229) seconds (p = 0.04) and patients desaturated less (median difference = 3.5%, p = 0.029). In the second study, 60 patients were admitted to hospital during a three month period of whom only 18(30)% were eligible to participate and of these patients, only four (7%) consented to participate.ConclusionNIV improves exercise tolerance in patients with acute exacerbations of chronic respiratory disease but the applicability of this approach in routine clinical practice may be limited.Trial registrationhttp://www.controlled-trials.com/ISRCTN35692743

attended a screening visit; 58/129 screen failed (eg, due to deterioration in peak flow, unable to wean off regular asthma medications) leaving 71 randomised (2.5%) of total patients invited. Trial 2: similar picture, completed July 2011, extended by 6 months due to slow recruitment. Target to randomise ¼80, target to complete ¼68. Actual completed: 71/8398 (<1%) of those invited. Conclusion Achieving the completion target in randomised controlled trials requires significant administrative support, and the capacity to increase support should difficulties in recruitment be encountered. Closer partnership with primary care practitioners, better access to primary care patient databases and direct contact with potential recruits can overcome this. Loss of potential recruits during the run-in phase needs exploration, and is of significant importance to improve the efficiency of screening to randomisation. Addressing these issues will mean fewer trials are underpowered and hence provide better return for grant awarding bodies.