Pressed breathing
The Press breathing is a variant of human respiration , in which strong Ausatmungsbewegungen at deliberately frustrated exhalation through closing of the airways in the larynx are performed.
General
Due to the increase in pressure in the chest cavity, no blood flows to the heart during the pressing process (externally visible due to congestion-related swelling of the veins in the head and reddening of the face). There is a deteriorated respiratory and circulatory situation. Damage possibilities are given on this basis. If the arm is used vigorously when performing sporty movements, compression is unavoidable, as this is the only way to fix the shoulder girdle.
During press breathing, the diaphragm is fixed in the inhalation position in order to create an abutment. The lowering of the diaphragm increases the pressure in the abdomen and thus the pressure on the abdominal wall and the pelvic floor. This can spontaneously lead to hernias and, in the long term, to problems with sagging of the genitals. The increased pressure in the abdominal cavity increases the venous and lymphatic return to the heart, which in turn is supported by the reduced pressure in the thoracic cavity .
Due to the increased return flow to the heart, the contraction force of the heart ( Frank Starling mechanism ) increases and the stroke volume is increased. This increases blood pressure.
This is particularly dangerous for patients with decompensated heart failure, where the increased venous return can no longer be processed. In patients with an (undetected) brain aneurysm , the rise in blood pressure can cause the vessel to burst and thus lead to a stroke .
aviation
During extreme flight maneuvers, high accelerations along the longitudinal axis of the body can cause the blood to be pressed out of the head into the expandable blood vessels in the lower half of the body. As a result, the blood pressure in the upper half of the body and especially in the head drops sharply and the supply of oxygen to the brain is no longer sufficient. In turn, contact between 5 g and 6 g First the loss of Farbsehfähigkeit ( greyout ), an extreme restriction of the field of view, and then the complete loss of vision ( blackout ) a. Finally, the pilot completely loses consciousness ( g-LOC ), a condition from which he only recovers after around half a minute.
When the load increases slowly, the pilot's cardiovascular system can react to the increased load and effect a corresponding compensation of up to about 5 g through an increased pulse rate and a narrowing of the blood vessels . In the event of a rapid rise, however, this is no longer possible and the pilot immediately loses consciousness without warning.
As a countermeasure, u. a. developed the technique of press breathing . After rapid exhalation and inhalation, the muscles in the chest area are tensed and the air in the lungs is pressurized. Simultaneously tensing the muscles in the legs, buttocks and abdomen is intended to delay or prevent the blood from sinking. This approach is exhausting and creates communication problems. In addition, concentration and freedom of movement are restricted. This is why technical aids such as the anti-g-suit are used in military aircraft.
see: flicker test
