The invention refers to a method of determining an indicator that is representative for a patients volume responsiveness, comprising the following steps: (i) measuring a sequence of pulse signals of a patient (ii) determining an envelope(signal)-curve based on the sequence of measured pulse signals (iii) determining a fit(envelope(signal))-function based on the previously determined envelope(signal)-curve, the fit(envelope(signal))-function representing an idealised curve progression of the envelope(signal)-curve without comprising pulse variations caused by ventilation or respiration induced heart-lung interaction (iv) determining respiratory pulse variation signals corresponding to the pulse variations caused by ventilation or respiration induced heart-lung interaction (v) determining an envelope(respiration)-curve based on the previously determined respiratory pulse variation signals (vi) determining a fit(envelope(respiration))-function based on the previously determined envelope(respiration)-curve, the fit(envelope(respiration))-function representing an idealised curve progression of the envelope(respiration)-curve (vii) determining the indicator that is representative for the patients volume responsiveness based on the fit(envelope(signal))-function and the fit(envelope(respiration))-function. The invention also relates to a logic unit and a system, both for determining an indicator representative for the patients volume responsiveness.Linvention se rapporte à un procédé de détermination dun indicateur qui est représentatif de la réponse au volume dun patient, comprenant les étapes suivantes : (i) mesure dune séquence de signaux de pouls dun patient (ii) détermination dune courbe enveloppe(signal) sur la base de la séquence de signaux de pouls mesurés (iii) détermination dune fonction dajustement(enveloppe(signal)) basée sur la courbe enveloppe(signal) précédemment déterminée, la fonction dajustement(enveloppe(signal)) représentant une progression de courbe id
