The collapsed patient, shock and various types of shock

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3. The collapsed patient, shock and various types of shock
4. Treatment of heart attack today
5. Myocarditis, chest pain and feveri
6. Heart failure
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What does shock mean?

Shock is a condition in which a reduced systemic perfusion occurs, that is, it happens, for example, that as a result of massive bleeding, trauma, extensive burns, severe infections or heart pump failure, etc. In shock, a drop in blood pressure occurs.
It follows that, since every tissue and especially the noble ones, requires an adequate supply of oxygen and glucose, if the blood circulation collapses, this eventuality results in a drastic reduction of the blood circulation with a deficit of comburent and fuel and a serious energetic suffering of the tissues (alteration of the metabolism).

Certainly we are talking about conditions at the limits of compatibility with the life of the organism, since every human body, faced with a massive hemorrhage, is in grave danger of life, due to the severe hypotension that follows and for the reasons just mentioned.

But what does the pressure drop depend on?

We also know that blood pressure is a function of:
• the volume of circulating blood
• the diameter of the blood vessels that cause resistance to circulation
• the contractile thrust of the heart pump
Therefore in case of hypotension and/or a shock condition, these factors can be altered.

What does a shock depend on?

A shock, therefore, can depend on the following etiopathogenetic moments:
a) Decrease in cardiac output (cf. chronic heart failure or acute heart failure, as well as in heart attack);

Causes of insufficient heart pump

They depend on:
a) contraction deficit: heart attack, myocarditis, cardiomyopathies;
• volume overload with increased preload: valve insufficiency, shunt defects;
• pressure overload with increased afterload: aortic stenosis, pulmonary embolism;
• obstructed cardiac filling: pericardial tamponade, constrictive pericarditis;
• heart rhythm disturbances.
b) Drop in total peripheral resistances.
Deficit in the regulation of peripheral circulation:
• septic shock (in case of sepsis caused by gram-negative bacteria, often with consumption coagulopathy);
• anaphylactic shock from immediate type allergic reaction (type 1 - triggering allergens: iodinated contrast media, antibiotics, local anesthetics, dextrans and others)
• for drugs, insect poisons, organ extracts, etc.).

c) shock due to the drop in volume
For example. gastrointestinal bleeding, acute loss of blood, plasma, overwhelming vomiting, diarrhea.
Given that arterial pressure (BP) is given by cardiac output (GC) multiplied by the value of total peripheral resistance (RPT) according to the formula: PA = GCxRPT, any condition that alters the flow rate or power of the heart pump or reduces resistance causes a shock.

Causes of shock

Decrease in cardiac output
Cardiogenic shock
Recognizes the following causes
• myopathic due to failure of the heart pump (myocardial infarction, dilated cardiomyopathy)
• mechanical due to problems with cardiac mechanics (severe mitral insufficiency, interventricular septal defects, aortic stenosis, hypertrophic cardiomyopathy)
• arrhythmic
Cardiogenic shock, from left ventricular deficit
It is characterized by arterial hypotension with systolic BP <80-90 mmHg; cardiac index <1.88 I / min / m2;
left ventricular end-diastolic pressure> 20 mmHg. Left Heart Failure Diagnosis

Clinic

The patient has wet rales at the lung bases (see epa), dyspnoea.
Chest X-ray documents signs of pulmonary stasis.
Echocardiography documents possible pericardial tamponade, evaluation of valve and pump function, ventricular kinetics, etc.
Hypovolemic shock due to a decrease in volume, i.e. the volume of liquid in circulation
In fact, it may depend on
• Hypovolemic shock
• post-hemorrhagic
• from dehydration
• secondary to burns
It is divided into 3 stages of hypovolemic shock:
1st cold-moist skin; pale, (almost) normal BP;
2nd pulse> 100 / min., BP <100 mmHg, neck veins collapsed (lying down), thirst, oliguria;
3rd BP <60 mmHg, hardly perceptible pulse, shallow, fast breathing, disturbances of consciousness, mydriasis, anuria.
Shock index rule
Shock Index = Systolic Rate / BP (Index> 1: Threat of Shock)
Acute blood losses <1,000 ml are in most cases well compensated, with higher losses there is a risk of shock!

Obstructive shock, from circulatory obstruction
• pericardial tamponade
• massive pulmonary embolism
• atrial myxoma, ball thrombus
• tension pneumothorax

Distributive shock, from a decrease in total peripheral resistance
• Septic shock
• Fever (not compulsory), restlessness, confusion;
• hyperventilation, with respiratory alkalosis (later disguised as metabolic acidosis)
• any septic skin manifestations (pustules, necrosis, vesicles), skin bleeding in case of meningococcal sepsis.

There are 2 hemodynamic forms of septic shock:
- Hyperdynamic form (early stage):
• decreased peripheral resistance
• arteriovenous difference in the content of 02 increased
• dry, hot, pink-looking skin
• BP and central venous pressure normal or slightly reduced
- Hypodynamic form:
• increased peripheral resistances
• pale, clammy and cold skin as in hypovolemic shock
• arteriovenous difference in the content of 0, increased
• BP, central venous pressure and decreased diuresis, tachycardia.
Complications of septic shock: "capillary leak syndrome", vasodilation refractory to therapy.

• Anaphylactic shock
It is divided into 4 degrees of severity of anaphylactic shock:
Or it consists of simple limited local skin reactions, without clinical significance
a) general symptoms (dizziness, headache, anxiety, etc.) + skin reactions (flush, itching, hives, etc.)
b) in addition: drop in blood pressure and tachycardia as well as gastrointestinal symptoms (nausea, vomiting, etc.) and mild dyspnoea
c) in addition: bronchospasm (asthmatic attack) and shock, rarely also edema of the larynx with inspiratory stridor
d) circulatory and respiratory arrest.

• Neurogenic shock

Pathophysiology and development of shock

In shock, the drop in blood pressure leads to the release of catecholamines with an increase in heart rate and vasoconstriction of the arterioles and venous capacity vessels.
Through this regulatory mechanism, blood pressure may initially still be normal.
As a function of the different distribution of alpha and beta receptors, a redistribution of the circulating blood mass occurs to ensure the vascularization of the heart and brain.
While initially there is a passage of liquids from the interstitium to the vessel lumen, of compensatory significance, as tissue hypoxia and the accumulation of acid metabolites increase, an increase in capillary permeability occurs, with the passage of liquids from the vessels to the interstitium and worsening of hypovolemia.
The precapillary vascular tracts are more sensitive to acidosis than the postcapillaries: the result is therefore a loss of tone of the precapillary vascular sections with a constriction of the postcapillary sections; local blood sequestration and increased erythrocyte sludge occurs as well as the formation of microthrombi (in extreme cases the formation of multiple microthrombi leads to consumption coagulopathy).

Phases of shock

1. initial phase: formation of a slight depression of the cardiovascular activities
2. compensatory phase: cardiovascular depression worsens and compensatory mechanisms are put in place
3. progression phase: the compensation becomes ineffective and the lack of blood supply to the vital organs causes serious pathophysiological imbalances
4. phase of irreversibility: the shock leads to death.

Shock patient symptoms

The patient presents with hypotension, tachycardia, oliguria-anuria, hypothermia, pallor, weakness, metabolic acidosis, mental confusion, fever-chills (septic shock).
Metabolism in shock: due to the 02 deficiency, aerobic glycolysis worsens and the final products of anaerobic glycolysis accumulate, in particular lactic acid.
This leads to metabolic acidosis.

Effects of shock on individual organs
What happens to the various organs in case of hypoperfusion and shock?
- On the kidneys: oliguria, anuria.
- On the heart: decreased coronary perfusion associated with heart failure.
- In the pulmonary circulation: microembolias, interstitial edema, decrease in the surfactant factor with microatelectasis, formation of hyaline membranes, platelet aggregation, ARDS (Adult Respiratory Distress Syndrome = shock lung). The shock lung is accompanied by intrapulmonary shunts, decreased compliance and diffusion disorders of 02: danger of respiratory failure (high lethality!).
- reticulohistiocytic system: very compromised function with predisposition to infections
- coagulation system: possible disseminated intravascular coagulation (DIC).

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