Tom Rubin, Theodore von Haimberger, Alexander Helmke, Johan Lock, Martin Stockmann and Karsten Heyne

PHOTONICS 2016, 3, 31; doi:10.3390/photonics3020031

The actual metabolic capacity of the liver is crucial for disease identification, liver therapy, and liver tumor resection. By combining induced drug metabolism and high sensitivity IR spectroscopy of the exhaled air we provide a method for quantitative liver assessment at bedside within 20 to 60 minutes. Fast administration of ¹³C-labelled methacetin induces a fast response of liver metabolism and is tracked in real-time by the increase of ¹³CO₂ in the exhaled air. The ¹³CO₂ concentration increase in the exhaled air allows the determination of the metabolic liver capacity (LiMAx-test). Fluctuations in CO₂ concentration, pressure and temperature are minimized by special gas handling, and tracking of several spectrally resolved CO₂ absorption bands with a quantum cascade laser. Absorption measurement of different ¹²CO₂ and ¹³CO₂ rotation-vibration transitions in the same time window allows for multiple referencing and reduction of the systematic errors. This FLIP (Fast liver investigation package) setup is being successfully used to plan operations and determine the liver status of patients.