Hypovolemic shock is a pathological condition caused by a rapid decrease in the volume of circulating blood. It is manifested by a decrease in blood pressure, tachycardia, thirst, nausea, dizziness, pre-fainting states, loss of consciousness and pallor of the skin. With the loss of a large volume of fluid, disorders worsen, irreversible damage to internal organs and death become a consequence of hypovolemic shock. The diagnosis is made on the basis of clinical signs, test results and instrumental research data. Treatment – urgent correction of disorders (intravenous infusions, glucocorticoids) and elimination of the cause of hypovolemic shock.
ICD 10
R57.1 Hypovolemic shock
Meaning
Hypovolemic shock is a condition that occurs due to a rapid decrease in the volume of circulating blood. It is accompanied by changes in the cardiovascular system and acute metabolic disorders: a decrease in the shock volume and filling of the ventricles of the heart, deterioration of tissue perfusion, tissue hypoxia and metabolic acidosis. It is a compensatory mechanism designed to ensure normal blood supply to internal organs in conditions of insufficient blood volume. With the loss of a large volume of blood, compensation is ineffective, hypovolemic shock begins to play a destructive role, pathological changes worsen and lead to the death of the patient.
Resuscitators are engaged in the treatment of hypovolemic shock. Treatment of the underlying pathology, which is the cause of the development of this pathological condition, can be carried out by orthopedic traumatologists, surgeons, gastroenterologists, infectious disease specialists and doctors of other specialties.
Causes
There are four main causes of hypovolemic shock: irreversible loss of blood during bleeding; irreversible loss of plasma and plasma-like fluid during injuries and pathological conditions; deposition (accumulation) of a large amount of blood in capillaries; loss of a large amount of isotonic fluid during vomiting and diarrhea. The cause of irreversible blood loss can be external or internal bleeding as a result of trauma or surgery, gastrointestinal bleeding, as well as sequestration of blood in damaged soft tissues or in the fracture area.
The loss of a large amount of plasma is characteristic of extensive burns. The reason for the loss of plasma-like fluid is its accumulation in the lumen of the intestine and abdominal cavity with peritonitis, pancreatitis and intestinal obstruction. The deposition of a large amount of blood in the capillaries is observed in injuries (traumatic shock) and some infectious diseases. Massive loss of isotonic fluid as a result of vomiting and /or diarrhea occurs in acute intestinal infections: cholera, gastroenteritis of various etiologies, staphylococcal intoxication, gastrointestinal forms of salmonellosis, etc.
Pathogenesis
Blood in the human body is in two functional “states”. The first is circulating blood (80-90% of the total volume), delivering oxygen and nutrients to the tissues. The second is a kind of reserve that does not participate in the general blood flow. This part of the blood is found in the bones, liver and spleen. Its function is to maintain the necessary volume of blood in extreme situations associated with the sudden loss of a significant part of the CBV. With a decrease in blood volume, irritation of the baroreceptors occurs, and the deposited blood is “ejected” into the general bloodstream. If this is not enough, a mechanism is triggered designed to protect and preserve the brain, heart and lungs. Peripheral vessels (vessels supplying blood to limbs and “less important” organs) narrow, and blood continues to actively circulate only in vital organs.
If the lack of blood circulation cannot be compensated, centralization increases even more, spasm of peripheral vessels increases. Subsequently, due to the depletion of this mechanism, the spasm is replaced by paralysis of the vascular wall and sharp dilation (dilation) of the vessels. As a result, a significant part of the circulating blood moves to the peripheral parts, which leads to an aggravation of the insufficiency of blood supply to vital organs. These processes are accompanied by gross violations of all types of tissue metabolism.
There are three phases of hypovolemic shock development: deficiency of circulating blood volume, stimulation of the sympathoadrenal system and shock itself.
- Phase 1 – deficiency of CBV. Due to the lack of blood volume, the venous flow to the heart decreases, the central venous pressure and the stroke volume of the heart decrease. The fluid that was previously in the tissues moves compensatorily into the capillaries.
- Phase 2 – stimulation of the sympathoadrenal system. Irritation of baroreceptors stimulates a sharp increase in the secretion of catecholamines. The content of adrenaline in the blood increases hundreds of times, norepinephrine – dozens of times. Due to the stimulation of beta-adrenergic receptors, vascular tone, myocardial contractility and heart rate increase. The spleen, veins in skeletal muscles, skin and kidneys are contracting. Thus, the body manages to maintain arterial and central venous pressure, ensure blood circulation in the heart and brain due to the deterioration of blood supply to the skin, kidneys, muscular system and organs innervated by the vagus nerve (intestines, pancreas, liver). Within a short period of time, this mechanism is effective, with a rapid recovery of the CBV, recovery follows. If the shortage of blood volume persists, the consequences of prolonged ischemia of organs and tissues come to the fore in the future. Spasm of peripheral vessels is replaced by paralysis, a large volume of fluid from the vessels passes into the tissues, which entails a sharp decrease in CBV in conditions of an initial shortage of blood.
- Phase 3 is actually hypovolemic shock. CBV deficiency progresses, venous return and filling of the heart decrease, blood pressure decreases. All organs, including vital ones, do not receive the necessary amount of oxygen and nutrients, multiple organ failure occurs.
Ischemia of organs and tissues in hypovolemic shock develops in a certain sequence. First the skin suffers, then the skeletal muscles and kidneys, then the abdominal organs, and at the final stage – the lungs, heart and brain.
Classification
To assess the patient’s condition and determine the degree of hypovolemic shock in traumatology and orthopedics, the classification of the American College of Surgeons is widely used.
- Loss of no more than 15% of CBV – if the patient is in a horizontal position, there are no symptoms of blood loss. The only sign of incipient hypovolemic shock may be an increase in heart rate by more than 20 per minute. when the patient moves to an upright position.
- The loss of 20-25% of CBV is a slight decrease in blood pressure and an increase in heart rate. At the same time, the systolic pressure is not lower than 100 mm Hg, the pulse is not more than 100-110 beats / min. In the supine position, the blood pressure may correspond to the norm.
- Loss of 30-40% of CBV – decrease in blood pressure below 100 mm Hg. in the supine position, pulse more than 100 beats / min, pallor and cooling of the skin, oliguria.
- Loss of more than 40% of CBV – the skin is cold, pale, marbling of the skin is noted. Blood pressure is reduced, there is no pulse in the peripheral arteries. Consciousness is disturbed, coma is possible.
Symptoms
The clinical picture of the shock condition depends on the volume and rate of blood loss and compensatory capabilities of the body, which are determined by a number of factors, including the age of the patient, his constitution, as well as the presence of severe somatic pathology, especially lung and heart diseases. The main signs of hypovolemic shock are progressive increased heart rate (tachycardia), decreased blood pressure (arterial hypotension), pallor of the skin, nausea, dizziness and impaired consciousness.
Diagnostics
The diagnosis and degree of hypovolemic shock are determined based on clinical signs. The scope and list of additional studies depends on the underlying pathology. Urine and blood tests are taken without fail, the blood type is determined. If fractures are suspected, radiography of the corresponding segments is performed, if damage to the abdominal organs is suspected, laparoscopy is prescribed, etc. Before coming out of shock, only vital studies are carried out to identify and eliminate the cause of hypovolemic shock, since shifting, manipulations, etc. can negatively affect the patient’s condition.
Treatment
The main task at the initial stage of therapy is to ensure sufficient blood supply to vital organs, eliminate respiratory and circulatory hypoxia. Catheterization of the central vein is performed (with a significant decrease in BCC, catheterization of two or three veins is performed). A patient with hypovolemic shock is injected with dextrose, crystalloid and polyionic solutions. The rate of administration should ensure the fastest possible stabilization of blood pressure and its maintenance at a level not lower than 70 mm Hg. In the absence of the effect of these drugs, an infusion of dextran, gelatin, hydroxyethyl starch and other synthetic plasma substitutes is carried out.
If hemodynamic parameters do not stabilize, intravenous administration of sympathomimetics (norepinephrine, phenylephrine, dopamine) is performed. At the same time, inhalations are performed with an air-oxygen mixture. According to the indications, a ventilator is carried out. After determining the cause of the decrease in BCC, surgical hemostasis and other measures aimed at preventing further decrease in blood volume are performed. Hemic hypoxia is corrected by making infusions of blood components and natural colloidal solutions (protein, albumin).
Literature
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- Gitz Holler J, Jensen HK, Henriksen DP, Rasmussen LM, Mikkelsen S, Pedersen C, Lassen AT. Etiology of Shock in the Emergency Department: A 12-Year Population-Based Cohort Study. Shock. 2019 Jan;51(1):60-67.
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