A method for measuring oxygen consumption and cardiac output in intensive care units

A simplified measurement of oxygen consumption was investigated in 15 spontaneously ventilating and 11 apnoeic patients in the intensive care unit following open-heart surgery, using a Godart Pulmonet type 11e. Three consecutive measurements were performed on each patient to define the reproducibility of the method. The coefficient of variation of VO2 was plus or minus 3.16 per cent and plus or minus 3.42 per cent in spontaneously breathing and apnoeic patients respectively. Arterio-mixed venous oxygen difference (CaO2-CVO2) was also measured and cardiac output (CO) calculated using the Fick principle, in the spontaneously ventilating patients. Coefficient of variation of CaO2-CVO2 and CO values were plus or minus 4.63 per cent and plus or minus 4.70 per cent respectively.