Invasive catheters, fiber-optic

Figure 17-13. Fiber-optic invasive catheter for measuring oxygen in vivo [114].

Invasive continuous hepatic function monitoring by the fluorescence procedure was also evaluated in rabbits [148]. In this study, a commercial catheter equipped with fiber optic technology for mixed venous oxygen saturation measurements (SVO2) was modified to emit light at 780 nm and detect fluorescence at 840 nm. The catheter was placed into the right jugular vein and advanced... 

Thus, in critically ill patients where catheters are conventionally inserted for diagnostic or therapeutic interventions, incorporation of the appropriate fiber optics to commercial catheters would enable the monitoring of hepatic function continuously and simultaneously with other medical interventions. Previous studies by the absorption method also found a close correlation between invasive and noninvasive ICG plasma elimination kinetics [157,160]. 

Figure 18- Fiber-optic catheter for invasive absorbance measurement and associated instrumentation. From [50].

Since the original discovery of this phenomenon over 50 years ago, there has been progressive development in instrumentation to measure oxygen saturation along three different paths bench-top oximeters for clinical laboratories, fiber optic catheters for invasive intravascular monitoring, and transcutaneous sensors, which are noninvasive devices placed against the skin. 

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