In order to satisfy a need to obtain the respiratory rate of a post-myocardial infarction patient with high reliability while minimizing the burden for the patient as well as the patients possibility to manipulate the measurement results, the method comprises the following steps:- Generating and/or storing at least two input data series based on recordings of said another biosignal of said patient- Calculating multidimensional vectors on the basis of said input data series- Calculating a variability of at least one parameter attributed to said multidimensional vectors over the time- Producing at least one output data series indicating said variability of said parameter over the time.- Deriving said biosignal substitute from at least one of said input data series and/or at least one of said output data series.
