Oxygen consumption and carbon dioxide production during liquid ventilation

Area of Science:

• Neonatal Physiology
• Respiratory Medicine
• Biomedical Engineering

Background:

• Liquid ventilation with perfluorocarbon (PFCV) offers potential benefits for premature and lung-injured newborns.
• Indirect calorimetric measurements of gas exchange (VO2 and VCO2) during PFCV have not been previously reported.
• Comparative data between PFCV and conventional gas ventilation (GV) using indirect calorimetry is lacking.

Purpose of the Study:

• To perform indirect calorimetric measurements of oxygen consumption (VO2) and carbon dioxide production (VCO2) during PFCV.
• To compare VO2 and VCO2 measurements during PFCV with those obtained during GV.
• To evaluate the respiratory quotient (RQ) in normal cats under both ventilation methods.

Main Methods:

• Ten normal cats underwent tracheostomy after anesthesia.
• Gas exchange (VO2, VCO2) was measured using indirect calorimetry during both GV and PFCV.
• VO2 was measured via a closed-circuit volumetric technique, and VCO2 via capnographic analysis.

Main Results:

• No significant differences were observed in VO2 between PFCV and GV (5.6 +/- 0.5 vs. 5.7 +/- 0.3 mL/kg/min, P=NS).
• No significant differences were observed in VCO2 between PFCV and GV (4.8 +/- 0.9 vs. 4.9 +/- 1.1 mL/kg/min, P=NS).
• The respiratory quotient (RQ) remained unchanged between PFCV and GV (0.86 +/- 0.21 vs. 0.85 +/- 0.21, P=NS).

Conclusions:

• Indirect calorimetric measurement of gas exchange is feasible during PFCV.
• PFCV does not alter resting metabolic rate (VO2, VCO2) compared to GV in normal cats.
• Further research is needed to explore PFCV's efficacy in lung-injured models.