Gas exchange measurements within a magnetic environment: Validation of a new system

Although simultaneous measurements of pulmonary oxygen uptake (V˙O2p) and Phosphorus-31 magnetic resonance spectroscopy (31P MRS) is attractive to investigate muscular metabolism during exercise, the superconducting magnet requires the design of specific gas exchange analyser (GEA). Thus, this study aimed to assess the validity of a commercial GEA system (ZAN600) compatible with 31P MRS measurements.Using nonmagnetic pneumotachograph and prolonged sampling line (from 2 m, control condition, to 6.5 m) did not alter the proper synchronisation between flow and gas concentration signals. Also, end-expiratory fraction of O2 (FETO2) and CO2 (FETCO2), and finally the values of steady-state ventilation (V˙E), carbon dioxide production (V˙CO2) and V˙O2p kinetics during moderate knee-extension exercise were not significantly different between 2 m and 6.5 m conditions and between 6.5 m condition inside and outside the magnet.These results showed that a prolonged sampling line used inside the superconducting magnet did not affect the accuracy of V˙O2p measurements of a commercial GEA system; the latter appears suitable for simultaneous measurements of V˙O2p and 31P MRS.

► Co-measurement of muscular metabolism and pulmonary V˙O2 at exercise is of interest. ► However, magnetic resonance spectroscopy device impedes V˙O2p measurements. ► Sampling lines were lengthened to put the metabolic cart away from a magnetic field. ► Longer sampling lines do not alter synchronisation between flow and gas fraction. ► Finally, the reliability of gas exchange measurements was also preserved.