RESULTS: The nitrogen concentration and nitrogen output decreased sharply (approximately 93%) in the first 5 min of denitrogenation, then decreased gradually with the prolonged denitrogenation time.

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.

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.

Clinicians can test for an interfering gas such as ethanol before induction by checking the reading in the halothane setting during preoxygenation.

No further change of CO concentration was detected after 10 minutes of preoxygenation (16.4 ± 9.0 vs.

Induction of anaesthesia and endotracheal intubation further increases endtidal CO concentrations beyond the effects attributable to preoxygenation alone.

After preoxygenation, anesthesia was induced with propofoll80 mg and fentanyllO0 pg in a right lateral tilt position.

After preoxygenation and administration of trial drug over 30 seconds, propofol was administered until the loss of eyelash reflex.

Objective To study the probability or risk of decompression sickness in high altitude flight and to establish a probability model. Method Survival analysis technique was used in the analysis of the information about altitude decompression sickness. Result It was found that the risk of decompression sickness initially increases up to a certain time point,and then decreases because of denitrogenation.The hazard function may describe the characteristics of this pattern in changes of risk.The parameters of probability...

Objective To study the probability or risk of decompression sickness in high altitude flight and to establish a probability model. Method Survival analysis technique was used in the analysis of the information about altitude decompression sickness. Result It was found that the risk of decompression sickness initially increases up to a certain time point,and then decreases because of denitrogenation.The hazard function may describe the characteristics of this pattern in changes of risk.The parameters of probability models for altitude decompression sickness can be estimated by using the maximum likelihood method. Conclusion Prediction with the survival models based on the logistic distribution is good.

AIM: To analyse quantitatively the efficiency of nitrogen elimination at different denitrogenation time. METHODS: Twenty four rabbits were randomly divided into control group, denitrogenation 30, 60 and 120 min groups. The rabbits were anesthetized and ventilated by mechanical ventilator. After 0, 30, 60 and 120 min of denitrogenation, the rabbits were exposed to 11000 m for 30 min. The nitrogen output was analysed by chromatography and the gas bubbles generated in the body of rabbits were monitored by Doppler...

AIM: To analyse quantitatively the efficiency of nitrogen elimination at different denitrogenation time. METHODS: Twenty four rabbits were randomly divided into control group, denitrogenation 30, 60 and 120 min groups. The rabbits were anesthetized and ventilated by mechanical ventilator. After 0, 30, 60 and 120 min of denitrogenation, the rabbits were exposed to 11000 m for 30 min. The nitrogen output was analysed by chromatography and the gas bubbles generated in the body of rabbits were monitored by Doppler ultrasound method. RESULTS: The nitrogen concentration and nitrogen output decreased sharply (approximately 93%) in the first 5 min of denitrogenation, then decreased gradually with the prolonged denitrogenation time. Accumulative number of bubbles decreased with the elapse of denitrogenation time. Accumulative number of bubbles was negatively correlated with denitrogenation time ( P < 0.01). As compared with the control group, accumulative number of bubbles decreased significantly in denitrogenation 60 and 120 min groups. CONCLUSION: The nitrogen output decreases sharply at first and then gradually. Denitrogenation for 60 and 120 min may reduce gas babbles 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...

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 (P<0.01). Time to bubble appearance was positively correlated with time of 100% oxygen inhalation (P<0.01). 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 (P<0.01). Accumulative number of bubbles was negatively correlated with time of 100% oxygen inhalation (P<0.01). 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.