  Within the model of partial chemical equilibrium (PCE) we calculate the
multiplicity ratios of selected unstable resonances to given stable species. We
focus on those ratios that have been measured either in Pb+Pb collisions at the
LHC or in Au+Au collisions at the top RHIC energy. The model provides an
interpretation how in an expanding hadronic fireball with decreasing
temperature the final numbers of stable hadrons after decays of all resonances
remain unchanged. Each stable species acquires its own chemical potential and
the resonances are kept in equilibrium with them. Multiplicities of unstable
resonances provide a test of this scenario. We observe that the ratios of
$K^{*}/K$ and $\rho^0/\pi$ fit reasonably well into the picture of single
kinetic freeze-out of the single-particle spectra, but the $\phi$-meson and
hyperon resonances are not reproduced by this model.
