Stimulating and provocative work with fiberoptic technology is reported in this volume. Invasive fiberoptic reflectometry has only been used up to now for monitoring intravascular oxygen saturation. These contributions examine how this technique can be clinically applied to measure other parameters in the critically ill patient. Methodological aspects are discussed, but the main focus is on clinical value and application. The authors look at measurements that can be evaluated using a flowdirected fiberoptic pulmonary artery catheter and an arterial fiberoptic thermodulution catheter. These measurements deal with oxygen saturation, intrathoracic and total blood volume, indocyanine green dye liver function, and extravascular lung water. Considering the advanced state of the technology and the innovative physiologic concepts presented here, this book lays the foundation for a new, integrated monitoring system of cardiopulmonary physiology.