To investigate if a time-dependent effect of heliox could be found, the change in relative Δ EELV was correlated with the change in R rs for T = 30 to T = 0 (R 2 0.068, P = NS), T = 60 to T = 30 (R 2 0.110, P = NS) and T = 90 to T = 60 (R 2 0.498, P = 0.01).