Relating exercise-induced desaturation and gas-exchange in pulmonary artery hypertension

Publication date: Available online 23 July 2018Source: Respiratory Physiology & NeurobiologyAuthor(s): Bryce N. Balmain, Helen Seale, Julie Harris, Kathleen Hall, Aaron C.W. Lin, Surendran Sabapathy, Norman R. MorrisAbstractWe measured pulmonary gas exchange during six minute walk test (6MWT) in patients with idiopathic (IPAH) and congenital heart disease-related pulmonary hypertension (CHDPH), and determined the relationship between the degree of desaturation and changes in minute ventilation to carbon dioxide production V˙EV˙CO2 and end-tidal partial pressure for carbon dioxide (PetCO2) in both groups. Fifty-two patients (IPAH, n = 28; CHDPH, n = 24) completed 6MWT with simultaneous pulmonary gas exchange. Whilst no significant difference in six minute walk distance was observed between groups (IPAH: 529 ± 89; CHDPH: 476 ± 119 m, p = 0.10), oxygen uptake, carbon dioxide production, and minute ventilation were higher in IPAH than CHDPH (p < 0.01). In addition, CHDPH desaturated to a greater extent than IPAH with a lower post-6MWT SPO2 (IPAH: 92.3 ± 7.9; CHDPH: 73.3 ± 14.9%, p < 0.01). The change in SpO2 correlated to the change in V˙E/V˙CO2 (r=-0.44, p = 0.02) and PetCO2 (r = 0.49, p < 0.01) for CHDPH, but not IPAH. The exercise-induced hypoxic stimulus during 6MWT in CHDPH may be associated with an enhanced ventilatory response.
Source: Respiratory Physiology and Neurobiology - Category: Respiratory Medicine Source Type: research