Circulatory shock


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Circulatory shock

  1. 1. Circulatory shock<br />It is a syndrome characterized by serious reduction of tissue perfusion with inadequate cardiac output.<br />Shock is a condition characterized by inadequate delivery of oxygen and nutrients to critical organs such as heart, brain, liver, kidney and GIT.<br />Types and causes of shock<br />Depending upon cause of inadequate cardiac output the circulatory shock is divided into 4 types:<br />Hypovolaemic shock<br />Vasogenic shock<br />Cardiogenic shock<br />Obstructive shock<br />
  2. 2. 1. Hypovolaemic shock:<br />It occurs due to low blood volume resulting in decreased cardiac output.<br />Depending on causes this shock is divided into following types:<br />Haemorrhagic shock: result as a internal or external blood loss due to ruptured blood vessels.<br />Dehydration shock: due to dehydration circulatory blood volume reduces.<br />Traumatic shock: trauma or injury which produce severe pain which inhibits vasomotor center in medulla oblongata.<br />
  3. 3. 2. Vasogenic shock:<br />It occurs due to toxic substances released by pathogens which leads to excessive vasodilation within the vessels.<br />Depending upon causes vasogenic shock is divided in to following types:<br />Neurogenic shock: occurs when nerves decreases sympathetic vasomotor tone and increase in vagal tone.<br />Anaphylactic shock: it refers to acute allergic reaction in which large quantities of histamine releases. This histamine causes vasodilation of blood vessels leads to shock.<br />Septicaemic shock: it is a condition in which bacteria circulate and multiply in the blood and form toxic products and cause high fever and vasodilation.<br />
  4. 4. 3. Cardiogenic shock:<br />It occurs due to decreased pumping ability of the heart because of cardiac abnormality.<br />Causes of this shock are:<br />Myocardial Infarction<br />Cardiac arrhythmia<br />Congestive Cardiac Failure<br />
  5. 5. 4. Obstructive shock:<br />It occurs due to impairment of ventricular filling during diastole due to some external pressure on the heart. Due to decreased ventricular filling stroke volume and hence cardiac output decreases.<br />Causes of this shock are:<br />Pericardial cardiac temponade means bleeding into the pericardium with external pressure on the heart.<br />Pulmonary embolism: embolus formation occurs in the pulmonary vein so that no blood reaches to left heart.<br />
  6. 6. Stages and clinical features of the shock:<br />Depending upon severity circulatory shock is divided into 3 categories:<br />First stage or non-progressive shock:it is also known as compensatory shock in which body try to compensate the loss of blood to vital organs with few mechanisms like:<br />Rapid compensatory mechanism – baroreceptor reflex, chemoreceptor reflex, CNS ischemic response.<br />Inter-mediate compensatory mechanism – renin angiotensin system, capillary fluid shift mechanism<br />Long term compensatory mechanism – restoration of plasma volume and proteins, restoration of red cell mass.<br />2.Second stage or progressive shock: here compensatory mechanisms are not able to stop progression of shock and some positive feedback mechanism occurs which can lead to serious damage.<br />3. Third stage or irreversible shock: all treatment becomes ineffective and patient dies due to severe tissue damage to the vital organs of the body.<br />
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  11. 11. Treatment of shock<br />General treatment: <br />Patient should be kept in cold because exposed to warmth can cause sweating which can lead to hypovolemia and aggravate shock.<br />Raising foot end of the patient bed by 6 to 12” which helps in promoting venous return and cardiac output increases.<br />Replacement therapy:<br />In hemorrhagic shock and burns whole blood or plasma or plasma substitute like dextran can be transfused.<br />In hypovolemic shock due to dehydration balanced electrolyte solution (Intravenous Ringer Lactate solution) can be given.<br />Sympathomimetic drugs:<br />Helpful in neurogenic and anaphylactic shock where either sympathetic tone is low or vasodilation is present.<br />Drugs like dopamine should be used if it is not available epinephrine and norepinephrine can also be used. <br />Oxygen therapy:<br />Little bit helpful because it relieves hypoxia<br />