High Frequency Jet Ventilation during stereotactic ablation of liver tumours: an observational study on blood gas analysis as a measure of lung function during general anaesthesia

Abstract

Background: Stereotactic ablation of tumours in solid organs is a promising curative procedure in clinical oncology. The technique demands minimal target organ movements to optimise tumour destruction and prevent injury to surrounding tissues. High frequency jet ventilation (HFJV) is a novel option during these procedures, reducing the respiratory-associated movements of the liver. The effects of HFJV via endotracheal catheter on gas exchange during liver tumour ablation is not well studied. Methods: The aim of this explorative study was to assess lung function and the effects on blood gas and lactate during HFJV in patients undergoing stereotactic liver ablation. Blood gases were analysed in 25 patients scheduled for stereotactic liver ablation under general anaesthesia pre-induction, every 15 minutes during HFJV and following extubation in the recovery room. The HFJV was set at fixed settings. Results: None of the patients developed hypoxia or signs of increased lactate production but a great variation in PaO 2/FiO 2 ratio was found; from 13.1 to 71.3. An increase in mean PaCO 2 was observed, from a baseline of 5.0 to a peak of 7.1 at 30 minutes (p <0.001) and a decrease was found in median pH, from a baseline of 7.44 to 7.31 at 15 minutes (p=0.03). We could not see any clear association between a decrease in PaO 2/FiO 2 ratio and PaCO 2 elevation. Conclusions: HFJV during general anaesthesia in patients undergoing stereotactic liver ablation is feasible and it did not cause hypoxemia or signs of increased lactate production. A reversible mild to moderate impairment of gas exchange was found during HFJV.

Keywords: Anesthesia; Blood Gas Analysis; Computer-Assisted/methods; General; High-Frequency Jet Ventilation; Liver Neoplasms; Stereotaxic Techniques; Surgery.

Conflict of interest statement

No competing interests were disclosed.

Copyright: © 2019 Galmén K et al.

Figures

Figure 1.. PaO 2/FiO 2 ratio.

PaO 2/FiO 2 ratio at baseline, during high frequency jet ventilation and after extubation in the recovery room. An inter-individual variation was seen in oxygenation during HFJV and the PaO 2/FiO 2 ratio significantly decreased but was restored at recovery.

Figure 2.. PaCO 2.

PaCO 2 at baseline, during high frequency jet ventilation and after extubation in the recovery room. A significant raise was seen in mean PaCO 2 from baseline to 1 st CT. Five out of 23 patients had a PaCO 2 value >6 kPa at recovery, the highest value being 8.03 kPa.

Figure 3.. pH.

pH at baseline, during high frequency jet ventilation and after extubation in the recovery room. There was a significant drop in pH from baseline during HFJV. Four out of 23 patients had a pH

Figure 4.. PaO 2/FiO 2 ration vs PaCO 2.

Plotted blood gas pairs of PaO 2/FiO 2 ration vs PaCO 2 in the 25 patients studied. No clear correlation could be seen.