Shock is a life threatening clinical syndrome due to the collapse of the cardiovascular system which is characterised by an acute reduction in the effective circulatory blood volume ( also known as Hypotension) and an inadequate perfusion of cells and tissues (Hypoperfusion)
Types of Shock
Primary shock
They are normally caused due to
- Excitement
- Initial shock
- Vasovagal attack (attack on the nerve that innervates the heart muscles)
Secondary shock
It is also called as circulatory shock. They are caused due to
- Cardiovascular collapse
- Imbalance in oxygen supply and requirements.
Symptoms of shock
- Unconsciousness
- Weakness
- Sinking sensation
- Pale and clammy limbs
- Weak and rapid pulse
- Low blood pressure.
Etiology of shock
Hypovolemic shock
It is characterised by
- Acute haemorrhage
- Dehydration from vomiting and diarrhoea
- Burns
- Excessive use of diuretics
- Acute pancreatitis
Cardiogenic shock
Deficient emptying
- Cardiomyopathies
- Myocardial infarction
- Rupture of the heart, ventricles or papillary muscle
- Cardiac arrhythmias
Deficient filling
- Cardiac tamponade
- Pulmonary embolism
- Mitral valve thrombus
- Tensing pneumothoraces (improper breathing)
- Dissecting aortic aneurysm
Septic shock
They are further classified into two types
Gram positive septicemia
It is known as exotoxic shock. It caused by gram positive organisms like Streptococcus and pneumococcus etc.,
Gram negative septicemia
It is known as endotoxic shock caused by gram negative bacterium such as E.coli, Klebsiella, pseudomonas and proteus etc.,
OTHER TYPES OF SHOCK
Traumatic shock
Can be due to-
- Severe injury
- Surgery with marked blood loss
- Obstetrical trauma
Neurogenic shock
Can be due to-
- High cervical spinal cord injury
- Accidental high spinal anaesthesia
- Severe head injury.
Hypoadrenal shock
Can be due to-
- Administration of high doses of glucocorticoids
- Secondary adrenal insufficiency
- Adrenal haemorrhage idiopathies adrenal atrophy
PATHOPHYSIOLOGY
Compensated shock
During the early stage of shock, an attempt is made to maintain adequate cerebral and coronary blood supply by redistribution of blood so that the vital organs (brain and heart) are adequately perfused and oxygenated. Activation of various neurohormonal mechanisms causing widespread vasoconstriction and fluid conservation by the kidney. If the condition that caused the shock is adequately treated, the compensatory mechanism may be able to bring about recovery and reestablish the normal circulation; this is called compensated or reversible shock.
Progressive decompensated shock
This is a stage when the patient suffers from some other stress or risk factors (e.g. pre-existing cardiovascular and lung disease) besides persistence of the shock so that there is progressive deterioration.
Irreversible decompensated shock
The shock is so severe that in spite of compensatory mechanisms and despite therapy and control of etiologic agent which caused the shock, no recovery takes place, it is called decompensated or irreversible shock.
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