Multifactorial analysis of exchanger efficiency and liquid conservation during perfluorochemical liquid-assisted...

Area of Science:

• Respiratory physiology
• Biomedical engineering
• Pulmonary medicine

Background:

• Liquid-assisted ventilation (LAV) using perfluorochemical (PFC) liquids requires efficient gas exchange and minimal PFC loss.
• Current PFC LAV techniques face challenges with PFC volatility and loss in expired gas.
• Effective CO2 elimination and PFC liquid conservation are critical for LAV efficacy.

Purpose of the Study:

• To evaluate the efficiency of spray bubbler and membrane oxygenator exchangers for CO2 elimination from PFC liquid.
• To assess the capacity of these exchangers to prevent PFC liquid loss during LAV.
• To analyze the impact of flow rates and temperature on exchanger performance and PFC conservation.

Main Methods:

• Countercurrent circulation of gas (100% O2) and PFC liquid through oxygenator and bubbler exchangers.
• Temperature control at 25°C or 37°C in an open circuit.
• Calculation of exchanger efficiency index (EEI) for CO2 elimination using mass-transfer theory.
• Measurement of PFC liquid loss rate from mixed expired gas using a thermal detector analyzer.

Main Results:

• PFC loss rate and CO2 elimination efficiency increased with higher gas:PFC liquid flow ratios.
• The membrane oxygenator demonstrated lower PFC loss and superior CO2 elimination compared to the spray bubbler.
• PFC loss increased with temperature, but CO2 elimination efficiency (EEI) showed minimal temperature dependence.
• Exchanger performance was influenced by the physiocochemical properties of the PFC liquid.

Conclusions:

• Membrane oxygenators are more effective than bubblers for CO2 elimination and PFC liquid conservation in LAV.
• Optimizing gas to PFC liquid flow ratios and controlling temperature are crucial for efficient LAV.
• Further research into bulk-gas-flow-independent methods for PFC liquid reconditioning is warranted to minimize PFC loss.