The paper presents the results of the OES technique to measure local parameters of inhomogeneous fluctuating plasmas using spectral line profiles in the plasma total emission. The technique does not require time-resolved recording of the emission. The plasma time behaviour is accounted for using prior observations at the necessary time resolution. Two cases have been examined: quasi-periodic and stochastic time changes of plasma temperature. Simple equations are found to obtain profile characteristics (half-widths, shifts) of a spectral line for the plasma local (in time and space) emissivity using the line spectral profile in the plasma volume emission during the observation time. The characteristics can be applied for the plasma diagnostics. An extensive numerical simulation is performed for emission spectra of the plasma volumes having different spatial distributions and time behaviour of the parameters. The results have been compared with the analytical approximations. Resulting data have confirmed the technique applicability and allowed to find limits of the technique use and possible errors.