Unsteady Mass Transport During Liquid Ventilation

• Applicant: Dr.-Ing. Katrin Bauer
• Subject Area: Fluid Mechanics
• Term: from 2014 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 257981040

The method of liquid ventilation is a very promising alternative of life saving, artificial ventilation, especially at severe forms of the Acute Respiratory Distress syndrome (ARDS), where conventional ventilation methods fail. Nevertheless, due to a lack of detailed knowledge about the gas exchange processes and little clinical experience, the method of liquid ventilation has not been used in clinical routine, yet. In order to evaluate the ventilation/perfusion ratio, it is of high importance to gain knowledge about the dissolved gas transport behavior through the perfluorocarbon (PFC) and the bronchial tree, respectively. Only this way, the breathing parameters (frequency, tidal volume) can be set up optimally. Only the gas concentrations before entering the airways as well as the alveolar and blood gas concentrations are known or can be measured.Within the scope of this research project, the transport of dissolved oxygen and carbon dioxide through a model of the upper human airways will be investigated. Here, liquid ventilation with PFC will be applied. For the investigations, novel methods such as the optical measurement of the oxygen concentration by using oxygen sensitive tracer particles in PFC are applied. The particles will be distributed homogeneously in the lung model. Differences in fluorescence intensity due to oxygen quenching of the excited particles are measured optically with the help of a camera system. Besides gathering the oxygen concentration distribution it is necessary to analyze the velocity and mass flow distribution of the , respectively. Only this way the transport of mechanisms of dissolved gas can be evaluated. According to the typical breathing parameters (tidal volume, breathing frequency) during liquid ventilation and the low kinematic viscosity of PCF the upper airways down to the 6th generation are characterized by turbulent flow. This differs from the boundary conditions of conventional ventilation where laminar flow predominates. Consequently, different pathways of mass transport can be expected. This will be investigated by Particle Image Velocimetry (PIV) measurements.

• DFG Programme: Research Grants