In recent years, developments in the measuring of cardiac output and other haemodynamic variables are focused on the so-called 158 minimally invasive methods.The aim of these methods is to simplify the management of high-risk and haemodynamically unstable patients.Due to the need of invasive approach and the possibility of serious complications the use of pulmonary artery catheter has Respirators decreased.This article describes the methods for measuring cardiac output, which are based on volume measurement (Fick method, indicator dilution method), pulse wave analysis, Doppler effect, and electrical bioimpedance.