Effects of denitrogenation on bubble formation during decompression in rabbits.

Objective To explore the effect of different degrees of denitrogenation on decompression sickness. Method Twenty-four rabbits were randomly divided into control group, 100% oxygen inhalation 30 min group, 60 min group and 120 min group. The rabbits were anesthetized and ventilated by mechanical ventilator. After 0, 30, 60 and 120 min of denitrogenation by inhalation of 100% oxygen, the rabbits were exposed to 11 000 m for 30 min. The gas bubbles generated in the body of rabbits were detected and monitored by a Doppler ultrasound detector over the precordium. Result Time to bubble appearance increased with time of 100% oxygen inhalation during altitude decompression. As compared with the control group, time to bubble appearance lengthened significantly in 100% oxygen inhalation 60 min and 120 min groups (P0.01). Time to bubble appearance was positively correlated with time of 100% oxygen inhalation (P0.01). Accumulative number of bubbles decreased with the time of 100% oxygen inhalation. As compared with the control group, accumulative number of bubbles decreased significantly in 100% oxygen inhalation 60 min and 120 min groups (P0.01). Accumulative number of bubbles was negatively correlated with time of 100% oxygen inhalation (P0.01). Conclusion Denitrogenation by inhalation of 100% oxygen for 60 min and 120 min may reduce the generation of gas bubbles in rabbits when decompressed to an altitude of 11 000 m.