Gravity shock

Introduction In order to supply sufficient nutrients and oxygen to the lower limbs that are strenuously exercising during the race, the blood vessels in the legs and feet will relax as much as possible to help the blood flow. If you stop and stand still after the race, due to the gravity of the heart, the blood will be deposited in the lower limbs, causing anemia in the brain, which will lead to pale, purple lips, and even fainting. This phenomenon is called "Gravity shock."

Cause

In the quiet state, the capillaries of the human body in the lower limbs are not all open, only 8% to 16% are open at each moment, and most of them are in the closed state, and this opening and closing are alternated. During the race, the muscles of the lower extremities continue to contract and relax, requiring a lot of oxygen and energy. It has been calculated that when a person is strenuously exercising, the opening of the capillary network is tripled when it is quieter. During the exercise, the veins of the lower extremities expand and the volume of the venous tubes also increases significantly. Because the veins of the lower extremities are far away from the heart, the blood's returning force mainly depends on the compression of the blood vessel wall during muscle contraction and the negative pressure exerted by the chest cavity during inhalation.

After the race, athletes or exercisers, if they stand immediately, cause the capillaries and veins of the lower limbs to lose muscle contraction, and the blood is deposited in the veins and capillaries of the lower feet due to gravity. At the same time, due to the rapid and shallow breathing during exercise, the negative pressure in the chest is reduced, and the venous return is hindered, so that the blood flow to the heart is greatly reduced. In addition, the heart rate is increased during exercise, and the heart's pulsation is reduced every time. At this time, although the blood volume of the whole body has not changed, the effective blood circulation is drastically reduced, resulting in insufficient blood perfusion of the vital organs of the human body, tissue ischemia and hypoxia. Due to the increase of anaerobic metabolism, the body has undergone severe metabolic disorders and dysfunction, and has lost the ability to adapt and resist. Because the blood is deposited by gravity, it is deposited in the blood vessels of the lower extremities, called "gravity shock."

an examination

Related inspection

Blood pressure and urine output

1 has the cause of shock;

2 abnormal consciousness;

3 pulse faster than 100 times / min, fine or can not be touched;

4 limbs wet and cold, sternum skin pressure positive (after refilling time is more than 2 seconds), skin pattern, pale or blemishes, urine volume less than 30ml / h or no urine; 5 systolic pressure less than 10.64kPa (80mmHg); The pulse pressure is less than 2.66 kPa (20 mmHg); 7 the systolic blood pressure of the original hypertension is more than 30% lower than the original level.

A diagnosis can be established if one of 1, 2, 3, 4, and 5, 6, or 7 is met.

Differential diagnosis

Differential diagnosis of gravity shock:

(1) hypovolemic shock: seen in blood loss, fluid loss or burns, blood volume reduction leads to insufficient venous return, decreased cardiac output, decreased blood pressure, inhibition of decompression reflex, sympathetic excitation, peripheral vasoconstriction, tissue The irrigation flow is further reduced.

(2) vasogenic shock: shock, due to long-term tissue ischemia, hypoxia, acidosis and the release of active substances such as histamine and carbon monoxide, resulting in low blood vessel tension, plus white blood cells, platelets adhered at the venule end, resulting in The microcirculatory blood stagnates and the number of capillary opening increases, resulting in a sharp decrease in the effective circulating blood volume.

a, anaphylactic shock: is a type 1 allergic reaction. The pathogenesis combines with IgE and antigen on the surface of mast cells, causing a large amount of histamine and bradykinin to enter the blood, causing dilation of the arterioles, contraction of venules, microcirculation, and increased capillary permeability.

b, septic shock: (often accompanied by sepsis)

1 High-dynamic shock: Because the effect of vasodilator is greater than that of vasoconstrictor, it causes hemodynamic characteristics of high beat and low resistance.

2 low-power shock.

c. Neurogenic shock: due to anesthesia or injury and strong pain inhibiting sympathetic vasoconstriction, causing transient vasodilation and blood pressure drop, the microcirculation is not necessarily significantly reduced, and some people think that it is not true shock.

(3) Cardiogenic shock: The cardiac output decreases rapidly and the blood pressure can drop significantly.

1 low-row high-resistance type: because the blood pressure is reduced, the impulse of the baroreceptor of the aortic arch and carotid sinus is reduced, and the reflex causes the sympathetic nerve to increase the impulse, causing the contraction of the peripheral arterioles, so that the blood pressure can be compensated to a certain extent.

2 low-row and low-resistance type: this type of case is due to the large myocardial infarct area, the cardiac output is significantly reduced, the blood stagnates in the ventricle, the ventricular wall stretch receptor is pulled, the sympathetic center is reflexively inhibited, and the sympathetic nerve is transmitted. Impulse is reduced, peripheral resistance is reduced, and blood pressure is further reduced.

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