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In medicine, shock is a life-threatening medical
emergency characterized by profoundly low blood pressure and tissue hypoperfusion.
It may progress to death unless there is immediate medical intervention.
Shock is decrease SBP < 90 or at least 40 less than
baseline BP + signs of hypoperfusion or organ dysfunction.
Consider as serious: a systolic BP < 90 or a decrease
of >40 than normal readings in a previously hypertensive patient. Another
common but not essential manifestation is metabolic acidosis.
Some common causes of shock are:
hypovolemic shock is caused by loss of blood volume.
It is necessary to immediately control any bleeding. Intravenous fluids
and blood transfusions may be needed to save the person's life.
septic shock is caused by overwhelming infection
and is treated by massive doses of antibiotics, fluid replacement, and
vasoactive drugs. Septic shock is often fatal if untreated.
cardiogenic shock is hypotension caused by the failure
of the heart to pump effectively. This can be due to damage to the heart
muscle, most often from a large myocardial infarction, to mechanical impairment
of the heart's ability to pump blood (cardiac tamponade), cardiac arrhythmia,
or failure of a artificial pacemaker.
anaphylaxis is also sometimes called anaphylactic
shock and is caused by allergens which trigger tissue swelling that can
block the airway and cause suffocation.
Symptoms and signs
The signs and symptoms of shock include pallor, hypotension,
tachycardia, cold and clammy extremities and altered mental state.
Sometimes, in cases of septic or toxic shock, the
patient's hands and feet may initially be warm rather than cold and become
clammy as the toxins cause peripheral vasodilatation.
The proper treatment of shock is vital in the performance
of first aid and comprises an essential part of the duties of the emergency
medical technician, nurse, paramedic and doctor.
Quick diagnosis is of key importance. Resuscitation
should be started immediately, the modality of which depends on the patient's
requirements. Virtually all patients with shock will require some kind
of intravenous access; obtaining venous access quickly is of paramount
importance. Most people in shock require intravenous fluids. However,
under certain circumstances such as in cardiogenic shock, too much fluid
can be fatal, so a knowledgeable professional rather than a lay person
should make these decisions.
Shock is sometimes classified into two stages - reversible
shock and irreversible shock. The distinction between reversible and irreversible
shock is clinical (and sometimes retrospective) - reversible shock is
potentially treatable whereas irreversible shock inevitably leads to death.
Most cases of untreated reversible shock will progress to irreversible
shock within about six hours of onset.
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