MONITORING OF MIXED VENOUS OXYGEN-SATURATION AND PRESSURE FROM BIOSENSORS IN THE RIGHT VENTRICLE - A 24-HOUR STUDY IN PATIENTS WITH HEART-FAILURE

Right ventricle venous oxygen saturation was studied in 10 heart failu re patients over 24 h using a lead equipped with an oxygen biosensor i nserted temporarily. At the same time a pressure sensor, incorporated in the same lend to measure right ventricular pulse pressure and maxim um positive and negative rate of pressure development (RV dP/dt), was tested to see whether it would interfere with the oxygen sensor. Data from the biosensor lend were continuously compared with mixed venous o xygen saturation obtained from a fibreoptic Swan-Ganz catheter with th e tip in the pulmonary artery. For reference, blood samples were drawn at regular intervals from this catheter. A provocative protocol was u sed to cause haemodynamic changes. There was good correlation between oxygen saturation in the right ventricle (biosensor-derived) and mixed venous oxygen saturation in the pulmonary artery (fibreoptic-derived) (r = 0.86) and between sensor-obtained right ventricular oxygen satur ation and oxygen saturation in the blood samples from the pulmonary ar tery (r = 0.90). Changes in central ro haemodynamics were also well re flected by changes in pulse pressure and dP/dt derived from the pressu re sensor. As it was not possible to obtain absolute pressures no atte mpt was made to compare the pressure changes with conventional haemody namics. These 24 h haemodynamic measurements suggest that a biosensor- equipped lead placed in the right ventricle could be a valuable tool f or long-term monitoring of mixed venous oxygen saturation and pressure in patients with congestive heart failure.