The harm of space motion sickness not only affects the health of astronauts, but also reduces their working ability and enthusiasm, which leads to the failure of space missions as planned, especially short-term missions with only a few days. Severe space motion sickness will lead to the failure of the whole mission.
Because space motion sickness has a great influence on the health and working ability of astronauts in the early stage of flight, space doctors attach great importance to the study of its protective measures. Although there is no effective way to prevent the occurrence of space motion sickness so far, at least for now, taking protective measures will play a certain role in reducing the occurrence of motion sickness and alleviating the discomfort of astronauts when they are sick. The main protective measures for space motion sickness include the following aspects:
Selection of vestibular function
It is now believed that motion sickness on the ground or in space is related to the high sensitivity of the otolith and semicircular canal in vestibular organs of human inner ear. It should be an effective and good way to reduce the occurrence of space motion sickness to eliminate people with high sensitivity when selecting astronauts. However, space medical research has proved that the causes of space motion sickness and ground motion sickness are not exactly the same, and it is often impossible to predict whether the subject will get motion sickness in space by examining the vestibular function on the ground. Therefore, some people think that the selection of astronaut vestibular function is of little significance. However, to be on the safe side, the United States, Russia and other countries still keep the vestibular function selection items in the medical selection of astronauts, thinking that these selection methods can at least prevent people with poor vestibular adjustment function from entering space. In addition, the further selection of the vestibular function during astronaut training can help us understand the trainability of the vestibular function of astronauts and prepare for the final selection of astronauts. Some experimental results show that improving the selection method of vestibular function may improve the prediction rate of vestibular function in aerospace.
Swivel chair inspection
The swivel chair inspection mainly uses the angular acceleration generated when the swivel chair suddenly stops to stimulate the ampullary crest in the semicircular canal and check the sensitivity of the semicircular canal. During the examination, the examinee sits on the swivel chair and leans forward 30 degrees, so that the external semicircular canal is in the plane of rotation. When the swivel chair rotates at equal intervals from small to large, it stops suddenly, records the nystagmus after rotation, and calculates the sensitive threshold of ampulla crista in semicircular canal through the curve of speed-nystagmus reactivity. At the same time, the symptoms of autonomic nervous system and sense of rotation were recorded.
Evaluate the sensitivity of semicircular canal according to the above two aspects.
Otolith function test method
Its principle is to use different methods to generate linear acceleration to stimulate otolith organs and induce vestibular response.
Four-column swing method
Candidates sit on a four-poster swing, with their heads leaning forward 30 degrees and their bodies fixed in their seats. When the swing swings, the bottom plate of the swing basket keeps horizontal, and makes reciprocating linear acceleration movement to stimulate the hair cells of the otolith organ of the subject. The swing time of the swing is generally set to 15 minutes, and the experiment will be suspended if the subjects have obvious autonomic nervous reaction during the experiment. The patient's tolerance time and autonomic nervous response were recorded to evaluate the sensitivity of vestibular function. The intensity of stimulation to otolith organs depends on the swing length, swing angle and swing frequency of the swing.
Vestibular function training
The purpose of training is to improve the adaptability of trainees by gradually increasing the stimulation of vestibular organs. The former Soviet Union attached great importance to the vestibular function training of astronauts before flight. Training methods include active and passive. The former includes physical training such as gymnastics, net jumping, springboard, running, skating and swimming (swimming-sauna-swimming-sauna, repeated 2-3 times). The purpose of active training is to consolidate passive training. Passive training includes swivel chair, swing, rotation on centrifuge, head-down 6-body fluid inversion training, biofeedback training, inverted prism walking plus head movement training, aerobatic training and parabolic flight training. It is generally believed that these trainings have certain effects, especially parabolic flight can produce short-term weightlessness and the effect is good. The application of biofeedback training in aerospace field has also achieved certain results.
Learning point
Biofeedback training
Biofeedback method is to control the activity of autonomic nervous system through human consciousness. Its basic principle and method is to let the subjects pay attention to one of their own physiological indexes, such as heart rate and blood pressure, and then adjust their emotional or psychological state to change it, so that it will rise or fall; The changed results are fed back to the subjects through the instrument. After a period of practice, the physiological state can be controlled in a better state. China's Qigong is actually a biofeedback method. Experiments show that it has a certain effect on preventing adverse reactions caused by weightlessness, such as motion sickness symptoms, decreased orthostatic tolerance, subjective and objective reactions when lying in bed, etc.