Types of Shock
There are different types of shock which are classified depending on their underline causes. Shock can be defined in simple terms as a syndrome of impaired tissue perfussion, usually it is associated with hypotension but not always.
The most common causes for different types of shock are that result ina reduction of intravascular volume (hypovolemic shock), Myocardial pump failure ( Cardiogenic shock), Increased vascular capacitance (distributive shock).
There are three different types of shock which are as follows:
- Hypovolaemic shock
- Cardiotonic shock
- Distributive shock (Septic shock, Anaphylactic shock, Neurogenic shock)
Hypovolaemic shock is a condition in which there is a sudden decrease in amount of blood volume and it can be further clasifed as:
a) Hemorrhagic – Examples for haemorrhagic are trauma, gastrointestinal bleeding, internal bleedings like aortic aneurysm.
b) Non-Heamorragic – Examples for non-haemorrhagic are dehydration ( vomiting, diarrhea, diabetes insipidus, overuse of diuretics), Cutaneous (severe burns, non replaced perspiration, insensible water loss), Squestration (asities, third space accumulation)
It is a condition resulting due to severe myocardial pump failure. They are of wo types as follows:
a) Non-mechanical causes (Acute myocardial infarction, Low cardiac output syndrome, Right ventricular infraction, End stage Cardiomyopathy)
b) Mechanical causes (Rupture of septum, Mitral or aortic insufficiency, Papillary muscle rupture, Critical cardio stenosis)
Distributive Shock: (Low peripheral arteriolar resistance)
A condition secondary to gram-negative bacteremia (less often due to gram-positive will cause it). Risk factors for Septic shock include extreme of age, Diabetes Mellitus and immunosuppression.
Septic shock is usually associatted with massive vasodilattion which produced by the endotoxin from pathogenic bacteria. hence it is also called as “Warm Shock” to distinguish it from hypovolaemic and Cardiogenic shock. In Cardiogenic shock patient’s extermities are usually cold due to inadequate blood flow.
It is resulting due to severe immediate hypersensitivity reaction and is manifested as excessive vasodilation (Warm Shock), increased capillary permeability, exudation of fluid , angioneurotic oedema and brochoconstriction.
It is caused by traumatic spinal cord injury or as adverse event during epidural / Spinal anaesthesia. This result in a loss in sympathetic tone reflex vagal parasympathetic stimulation producing vasodilation, hypotension, bradycardia and syncope.
Management of Shock:
The volume replacement is a critical in initial management of shock. The different aprroch is needed in different types of shock managements which was discussed as followed.
Blood loss is treated with immediate infusion of blood substitues, such as group specific or type O negative packed red blood cells. If there is severe dehydration, volume replacement is initiated with the rapid infusion of isotonc saline or by ringer lactate solution through large bore intravenous lines.
Followed by fluid relacement therapy, the inotropic support with dopamine infusion is given to maintain adequate ventricular performance. Supplemental O2 should also be provided to support respiratory fuctions is given.
Vasoactive drug therapy with dobutamine /dopamine can be insituted only after adequate fluid recelacement. However, cardiogenic shock require smaller amount of fluid replacement.
Inotropic drug support can be provided with dobutamine (β- adrenoceptor agonist) usual dose range is 2.5 mcg/kg/min as infusion. It will increase contractility and decrease afterload due to reflux reduction in syspathetic tone . Pain Killers need to be used in case of heart failure and cardiomyopathy.
Successful management of shock requires urgent measures to be treat infection and to provide haemodynamic and respiratory support. General measures include correction of acidosis, blood vloume maintanance of BP and appropriate antibiotic in adequate dose.
Empirical antimicrobial therapy with meropenem or ticarcillin with clavulanic acid may be started soon, pending blood-culture report. Treatment of the known pathogen may start later, after culture results. A preparation of recombinant activated protein C drotrecogin alpha, when given as a continuous infusion of 24 mcg/kg/hr for 96 hr, improve mortality in severe septicc shock.
Vasopressin and corticosteroid is used in management of Septic shock and also inotropic agentts to control flow of blood.
In this all clinical feature like hypotension, bronchospasm, and laryngeal oedema neeed to be managed by following:
i) Adrenaline 0.3- 0.5 ml of 1:1000 solution is injected intramuscularly; it promptly reverse the syptoms.
ii) Airways should be maintained. Salbutamol nebulization may be given to relieve bronchospasm.
iii) Foot end of the bed should be elevatede to improve the BP, suitable plasma expander and vasopressor like dopamine may be given.
iv) Hydrocortisone hemisuccinate 100mg may be given intravenously and anti-histamine is needed if required.
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