Hypoxia-reoxygenation contributes to increased frequency of venous thromboembolism in air travellers

The effect of civil and military flights on coagulation, fibrinolysis and blood flow: insight from a rat model

Background

Air travel thrombosis continues to be a controversial topic. Exposure to hypoxia and hypobaric conditions during air travel is assumed a risk factor. The aim of this study is to explore changes in parameters of coagulation, fibrinolysis and blood flow in a rat model of exposure to hypobaric conditions that imitate commercial and combat flights.

Methods

Sixty Sprague-Dawley male rats, aged 10 weeks, were divided into 5 groups according to the type and duration of exposure to hypobaric conditions. The exposure conditions were 609 m and 7620 m for 2 and 12 h duration. Blood count, thrombin– antithrombin complex, D-dimer, interleukin-1 and interleukin-6 were analyzed. All rats went through flight angiography MRI at day 13-post exposure.

Results

No effect of the various exposure conditions was observed on coagulation, fibrinolytic system, IL-1 or IL-6. MRI angiography showed blood flow reduction in lower limb to less than 30% in 50% of the rats. The reduction in blood flow was more pronounced in the left vessel than in the right vessel (p = 0.006, Wilcoxon signed rank test). The extent of occlusion differed across exposure groups in the right, but not the left vessel (p = 0.002, p = 0.150, respectively, Kruskal-Wallis test). However, these differences did not correlate with the exposure conditions.

Conclusion

In the present rat model, no clear correlation between various hypobaric conditions and activation of coagulation was observed. The reduction in blood flow in the lower limb also occurred in the control group and was not related to the type of exposure.

Progress in understanding effects of positive acceleration on quality of ulcer healing in rats with experimental gastric ulcer

Injuries associated with high-performance fighter aircrafts and spacecrafts are bringing serious challenges to pilots. Exposure to positive acceleration (+Gz) can increase the incidence and recurrence of peptic ulcer. Recurrence of ulcer is closely related to quality of ulcer healing (QOUH), and improving QOUH is considered to be the third leap of understanding of peptic ulcer and has become a hotspot of aerospace medicine research. In this paper, we review the recent advances in understanding the effects of +Gz exposure on QOUH in rats with experimental gastric ulcer in terms of animal model development, QOUH assessment, and influencing factors for QOUH, with an aim to improve the protection against injuries caused by +Gz exposure, strengthen the pilot's overall ability to resist +Gz, and enhance the safety of flight.

Prohibition of artificial hypoxic environments in sports: health risks rather than ethics

There is actual debate on a recent position of the World Anti-Doping Agency (WADA), which has cautiously refrained from banning hypoxic tents and intends to monitor their health risk. Regardless of teleological and deontological concepts, we highlight that the health risks inherent to the widespread use of these artificial performance-enhancing devices would make them as unsafe as other forms of blood doping.