Non-attendance or non-invitation?

Some patients were given volume loading to improve cardiac output after the application of positive end expiratory pressure.Without measurements of wedge pressure the volume of fluid required is difficult to assess, and clinical indicators of volume state in this type of patient are not accurate.In addition, to maintain optimal oxygen delivery and cardiac output in the face of a high positive end expiratory pressure it mav be necessary to utilise vasoactive drugs.These drugs have unpredictable and sometimes deleterious effects on oxygen transport and respiratory func- tion (particularly pulmonary venous admixture).Unless mixed venous oxygen saturation and oxygen consumption are monitored these effects, which may make tissue hypoxia worse, will be missed.We agree that the study of Drs Singer and Bennett confirms the need for haemodynamic monitoring.Measurements should also be made to ensure that optimal global oxygen transport has been achieved, which, with our present under- standing and technical skill, will necessitate pulmonary artery catheterisation.