Monitoring of mixed venous oxygen saturation and pressure from biosensors in the right ventricle. A 24 hour study in patients with heart failure.

Abstract

Right ventricle venous oxygen saturation was studied in 10 heart failure patients over 24 h using a lead equipped with an oxygen biosensor inserted temporarily. At the same time a pressure sensor, incorporated in the same lead to measure right ventricular pulse pressure and maximum 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 lead were continuously compared with mixed venous oxygen saturation obtained from a fibreoptic Swan-Ganz catheter with the tip in the pulmonary artery. For reference, blood samples were drawn at regular intervals from this catheter. A provocative protocol was used 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 saturation and oxygen saturation in the blood samples from the pulmonary artery (r = 0.90). Changes in central haemodynamics were also well reflected by changes in pulse pressure and dP/dt derived from the pressure sensor. As it was not possible to obtain absolute pressures no attempt was made to compare the pressure changes with conventional haemodynamics. These 24 h haemodynamic measurements suggest that a biosensor-equipped lead placed in the right ventricle could be a valuable tool for long-term monitoring of mixed venous oxygen saturation and pressure in patients with congestive heart failure.