The invention relates to a method for determining a cardiovascular performance reserve for each individual patient, comprising the steps of: a) receiving input physiological data from the patient for obtaining a parameter Z which is or approximates the product of the Stroke Volume (SV) by the Systemic Vascular Resistance (SVR); b) providing a value representing the Respiratory Rate (RR) of said patient, wherein the Respiratory Rate (RR) value is provided by measurements using dedicated device(s), calculations from the input physiological data or manually by using best estimate; c) providing anthropometric data of said patient for calculating the Body Surface Area (BSA) of said individual, wherein the anthropometric data includes at least body dimensions (such as height and weight) of said patient; d) calculating the Cardiovascular Reserve (CVR) by using said Z parameter and said RR according to following formula: CVR=(Z/RR); e) calculating a Cardiovascular Reserve Index (CVRI) by standardizing said CVR (by said BSA) and normalizing it to a scale of 1 according to the following formula: CVRI=CVR/(BSA*4); and outputting said Cardiovascular Reserve Index.