Determinants of DLCO and contribution to exercise capacity and symptoms

Background: The single breath diffusion capacity for carbon monoxide(DLCO) is part of comprehensive pulmonary function testing. Research questions: What are the factors that influence the DLCO, and how does the DCLO influence the intensity of symptoms and the maximum power output achieved during exercise? Methods: Incremental cardio-pulmonary exercise testing included pulmonary function testing, capillary blood gases and muscle strength at McMaster University Medical Center between 1988-2012. This allowed a quantitative analysis of these factors to the symptoms experienced on mBORG scale as power incrementally increased to the MPO achieved. Results: 37,672 subjects had DLCO measured. In the 16,298 with normal spirometry and exercise capacity, the DLCO equation was calculated. In the total population, the effort required to cycle, and breath intensified in a positively accelerating fashion with power and increased as the MPO achieved decreased. Interpretation: The DLCO is predominantly influenced by height, is 15% higher in males, and 6% higher per gram of haemoglobin. A lower DLCO is associated with an increase in symptom intensity, and a lower MPO during exercise