The role of gas transfer on responses to exercise training in patients with pulmonary hypertension

<bold>Introduction:</bold> Pulmonary hypertension (PH) is a debilitating and life shortening condition. Diffusing capacity of the lung for carbon monoxide (DLCO) measures the ability of the lungs to transfer gas from inspired air to the bloodstream. Due to potential increased thickness of the alveolar capillary membrane and/or reduced capillary blood volume, PH patients often have reduced DLCO, correlating with mortality risk. Exercise training is now recommended for stable PH patients. <bold>Aim:</bold> The aim of this study was to explore the efficacy of baseline DLCO as a predictor of response to exercise training in patients with PH. <bold>Methods:</bold> Post-hoc exploratory analysis evaluated data from the 10-week exercise intervention in patients with PH. Patients were stratified into two groups based on the group median DLCO value of 61%. Changes in activity levels, exercise capacity and workload were compared between groups following participation in the intervention. <bold>Results:</bold> Nineteen patients (79% female; mean±SD: age 48 ± 15 y) completed the intervention. Eight patients had DLCO of > 61% and eleven had ≤ 61%. Patients with higher DLCO had a significantly greater improvement in step count (p=0.032), 6-min walk distance (p=0.001), and resistance training workload (p=0.009) than patients with lower DLCO following the exercise intervention. <bold>Conclusion:</bold> Improvements in activity levels, exercise capacity and workload in response to a 10-week exercise intervention are significantly greater in patients with a baseline DLCO value > 61% compared to those with ≤ 61%. Considering baseline DLCO in the design of exercise programmes may enhance the precision, safety, and efficacy of exercise programmes for PH patients.