  We use the flow equations to determine the different hierarchy Hubble
parameters as a function of the number of e-folds for intermediate models in
single-field inflation. The obtained expressions allow us to determine at
second order in the hierarchy Hubble parameters different observational
parameters. We distinguish the scalar spectral index, its running and the
tensor-to-scalar ratio, among others. Recently, it has been noticed that
measurements released by Planck, combined with the WMAP large-angle
polarization are in tension with this sort of model. Here, we show in detail
why this occur. The conclusions do not change even when the recent BICEP2 data
are included.
