- Shock: pathophysiological division
- Shock: Clinical Division
- Shock: general symptoms
- Shock: Symptom Development
- Shock: treatment
Shock is a medical emergency that leads to the impairment of function and failure of many organs. Any shock, hemorrhagic, hypovolemic, neurogenic, anaphylactic, septic, cardiogenic, requires immediate medical attention. How do I recognize a shock? What are the causes of the shock?
Shockis a generalized form of acute heart failure associated with insufficient oxygen consumption by cells. It is a condition in which there is an imbalance between the demand and the supply of adequate oxygen and nutrients to the body's cells (but the sole or dominant cause of the reduced oxygen supply is not respiratory failure or anemia). As a consequence, anaerobic metabolism is intensified. Shock may have various causes, but in most cases its course is similar and has similar effects - it can lead to unconsciousness, multiple organ failure and even death.
Shock: pathophysiological division
- hypovolemic shock(oligovolemic) - the cause is a decrease in the total blood volume (absolute hypovolemia), which can be caused by: a. whole blood loss - bleeding, haemorrhage - haemorrhagic shockb. decreased plasma volume i. Escape of plasma into crushed tissues or its loss from the skin surface in case of extensive burns ii. states of dehydration
- Distribution shock (vasogenic)- the essence is the expansion of blood vessels with an increase in the volume of the vascular bed, a decrease in vascular resistance and disturbances in the distribution of blood flow, which leads to relative hypovolemia. There is a reduction in the filling of the arterial system with a simultaneous increase in blood volume in the veins and capillaries. The state of hyperkinetic circulation is usually present: cardiac output is increased, peripheral (tissue) blood flow is reduced. Main reasons: a. neurogenic shock b.anaphylactic shockc.septic shockd. hormonal shock - associated with acute adrenal insufficiency, thyroid crisis, hypometabolic coma
- cardiogenic shock- leads to low cardiac output after myocardial infarction, in heart failure, in arrhythmias
- shockobstructive- mechanical obstruction of blood flow. a. Left ventricular filling impairment due to cardiac tamponade b. significant reduction of venous return due to pressure on the venous system from the outside (tension pneumothorax, abdominal tightness syndrome) c. difficulty filling the ventricles by intracardiac causes - heart tumors and blood clots in the heart cavities) d. sudden increase in resistance in the circulatory system (pulmonary embolism, acute pulmonary hypertension in the course of acute respiratory failure)
Shock: Clinical Division
From a clinical point of view, the following types of shock are described:
- hypovolemic shock
- cardiogenic shock
- septic shock - the most common reason is the transfer of Gram (-) and Gram (+) endotoxins into the bloodstream during a generalized infection. There is damage by pro-inflammatory cytokines to many organs, disseminated intravascular coagulation and metabolic disorders caused by it
- anaphylactic shock - an anaphylactic reaction is caused by the reaction of an antigen with circulating antibodies. In this process, mediators such as histamine and serotonin are released or formed, which act on smooth muscle cells and the vascular membrane. The permeability of the capillaries increases, which leads to the formation of puffiness. There is a risk of suffocation from swelling in the lower pharynx and larynx. Through bronchospasm, a life-threatening asthmatic state can develop. Due to the large loss of plasma, there is a decrease in cardiac output and blood pressure. This shock can be considered a special form of decompensated hypovolemic shock.
- neurogenic shock - is extremely rare. It is caused by the disruption of stimulation from the higher levels of the central nervous system to the lower centers of the sympathetic nervous system, which causes the expansion of the vascular bed. Most often due to transverse damage to the spinal cord above Th1 (1 thoracic vertebra).
Shock: general symptoms
Although each type of shock has a separate set of symptoms, common symptoms can be identified:
- tachycardia, the exception is neurogenic shock where bradycardia occurs
- systolic blood pressure<90 mmHg
- elongation of the capillary return>2 s
- rapid and shallow breathing (tachypnoe)
- oliguria
- confusion, anxiety
Shock: Symptom Development
The beginning of each shock, regardless of its origin, is a drop in blood pressure, and thus also in the blood supply to the organs. Compensation reactions are triggeredconstituting a defense mechanism and initially allow, inter alia, maintain normal blood pressure, but it is usually depleted over time, including hypotension. The body's response to persistent tissue hypoxia can be divided into 4 stages depending on the severity of the shock.
- equalized shock - loss of 25% of blood volume. The body activates mechanisms that compensate for hypotension. When the baroreceptors in the arterial walls register a drop in pressure, a burst of adrenaline and noradrenaline ensues, followed by vasoconstriction and an acceleration of the heart rate. There is euphoria and an increase in the pain threshold.
- centralization - circulation shifts towards the protected organs (heart, lungs, brain) at the expense of blood supply to the skin, digestive tract and muscles. There is pale skin, cold and sweating.
- metabolic changes - this is a life-threatening phase. As a result of continuous oxygen deficiency, mitochondria do not synthesize ATP, and respiratory chain dysfunctions will appear, as a result of which the number of released free radicals increases, which damage the cell membrane and other cellular organelles. Hypoxic cells undergo anaerobic metabolism, the product of which is lactic acid, which causes metabolic acidosis. Due to circulatory stagnation, aggregation processes intensify.
- irreversible phase - there is a critical drop in blood pressure, bradycardia, erythrocyte aggregation, platelet aggregation and intravascular coagulation (DIC). There is pulmonary edema and oliguria.
Note that shock is a complex and continuous process with no clear boundaries between the stages. Consequences of organ ischemia:
- acute prerenal renal failure
- consciousness disorders (including coma) and other neurological deficits
- acute respiratory failure
- acute liver failure
- disseminated intravascular coagulation (DIC)
- digestive tract disorders
- bleeding
- paralytic intestinal obstruction
- penetration of microorganisms from the gastrointestinal tract into the blood (may cause sepsis)
Shock: treatment
Each type of shock requires its own treatment. The main thing is to find out the cause and treat it. However, the general procedure is always based on the same basic elements:
- ensuring proper ventilation
- oxygen administration
- protection against heat loss
- fluid administration - colloids, crystalloids
- regulation of the circulatory system in the event of ineffective fluid therapy
- noradrenalina
- dopamine
- patients with low cardiac output are given dobutamine