Tissue nitrogen elimination in oxygen-breathing pigs is enhanced by fluorocarbon-derived intravascular micro-bubbles

The present study tested the hypothesis that intravascular micro bubbles generated by i.v. infusion of a 2 % dodecafluoropentane (DDFP) emulsion will enhance tissue denitrogenation during oxygen breathing. Eleven spontaneously breathing pentobarbital anesthetized pigs were studied. Six pigs were treated with 0.08 ml/kg of DDFP-emulsion infused over 30 min and five (control) pigs received a matching dose of emulsion vehicle. Circulatory parameters were recorded. The pigs were connected via a tracheal tube to a closed circuit oxygen-primed breathing loop allowing volume measurements and nitrogen analysis by gas chromatography every 7 min. The nitrogen washout was recorded for up to four hrs in each group. The cumulative nitrogen yield during oxygen breathing was considerably larger in treated animals than in controls. Thus, the amount of nitrogen eliminated in the controls in 120 min was achieved already after 65 min in animals treated with the DDFP-emulsion. Blood pressure and cardiac output remained stable and were not different between the two groups during the four hrs of nitrogen washout. The central venous oxygen tension was significantly higher in the treated animals during oxygen breathing than in the controls. This difference was, in all probability due to enhanced oxygen transport by the micro-bubbles. Conclusion: Intravascular micro-bubbles generated by i.v. infusion of a small dose of 2 % DDFP-emulsion very effectively enhanced denitrogenation by oxygen breathing and deserve study as a means to improve prevention and treatment of decompression sickness.