Lecture - 12 DR ZAHOOR ALI SHAIKH 1

We will discuss SHOCK under the following headings - DEFINATION - CLASSIFICATION - CLINICAL PRESENTATION - COMPENSATORY MECHANISM BY BODY - STAGES OF SHOCK - TREATMENT 2

Define Circulatory Shock When Blood Pressure falls so low that there is inadequate tissue perfusion(less blood flow to tissues) therefore decreased oxygen supply with inadequate cardiac output. 3

Types of Shock - Hypovolemic shock - Septic shock - Anaphylactic shock - Neurogenic shock - Cardiogenic shock 4

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GENERAL MECHANISM

HYPOVOLEMIC SHOCK We will discuss in detail HYPOVOLEMIC SHOCK It is also called COLD shock Causes of Hypovolemic shock(Decreased Blood volume) Hemorrhage Surgery Trauma Burns ( loss of plasma ) Fluid loss e.g.: Vomiting, Diarrhea 7

Signs of Hypovolemic shock Patient is pale Cold clamy skin Hypotension Increased pulse rate Increased respiratory rate (Vasoconstriction due to increased sympathetic stimulation ) 8

Sweating Increased thirst Decreased urinary output Metabolic Acidosis Restlessness Signs of Hypovolemic shock--- Continued 9

Clinical Presentation

Hemorrhagic Shock Hemorrhagic Shock is hypovolemic shock due to blood loss There is decreased venous return and decreased cardiac output. Inadequate perfusion of the tissues leads to Anaerobic glycolysis therefore increased production of lactic acid. 11

Compensatory Reactions Compensatory Reactions Activated By Hemorrhage (Blood Loss) Rapid compensatory reaction ---Barorecepreflex—when BP is decreased Increased secretion of norepinephrine and ephinephrine ( vasoconstriction,tachycardia) Increased secretion of vasopressin(ADH) Increased Renin-Angiotensin-Aldosterone mechanism 12

Compensatory Mechanism----cont Increased secretion of Glucocorticoids Extra-cellular Fluid shift from Interstitial fluid to plasma to increase Plasma volume Over a longer period [1 week] there is - Increased secretion of Erythropoietin - Increased synthesis of plasma protein 13

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Stages of Shock 1. Non progessive stage or Compensated stage Here circulatory compensatory mechnism cause Full recovery without help from outside therapy 2. Progressive stage-Decreased BP AND COP. Here without therapy,shock gets worse 3. Refractory shock or Irreversible stage (called before) Here patient does not respond to Treament. 15

Refractory Shock In some patients shock persists for Hours and progresses to a state where there is no response to drugs and COP remains low. Blood pressure continues to drop inspite of therapy. This is called Refractory Shock. CAUSES: 1. Cerebral ischemia therefore depression of Vasomotor center---vasodilatation, decreased BP, decreased HR 2. Myocardial depression due to Acidosis causes decreased COP 16

IMPORTANT NOTE If 10% of Total Blood volume is lost---There is no effect on arterial BP andCOP If more than 10% of Blood volume is lost ---There is decreased arterial BP and COP If 35%-45% of Total Blood volume is lost--- Arterial BP and COP will fall to Zero Therefore depending on Blood loss, some patients Recover, other may die. 17

Hemorrhagic Shock ParameterIIIIIIIV Blood loss (ml)<750750– –2000>2000 Blood loss (%)<15%15–30%30–40%>40% Pulse rate (beats/min)<100>100>120>140 Blood pressureNormalDecreased Respiratory rate (bpm)14–2020–3030–40>35 Urine output (ml/hour)>3020–305–15Negligible CNS symptomsNormalAnxiousConfusedLethargic Crit Care. 2004; 8(5): 373–381. HYPOVOLUMIC SHOCK

SEPTIC SHOCK Usually due to gram-negative bacteria Endotoxins released by gram-negative Bacteria— cause VASODILATATION(Skin is warmTherefore called WARM SHOCK). High fever Increased capillary permeability with loss of plasma in tissues Mortality is 30-50% 19

Causes of Septic shock Bacterial Infection --Trauma– wound infection --Diabetes Mellitus-Gangrene --Abortion- septic 20

GENERAL MECHANISM

ANAPHYLACTIC SHOCK Due to Allergic reaction to Drugs eg pencillin injection, Vaccine, Food allergy There is antigen-antibody reaction,large quantities of Histamine are released causing Vasodilatation therefore decreased BP 22

Anaphylactic Shock Cont…. Decreased venous return(due to increased vascular capacity) Increased capillary permeability,therefore loss of fluid. Sometimes decreased venous return can cause death in minutes 23

Cardiogenic shock Cause---Myocardial Infarction(pump failure) Causes symptoms of shock and congestion in the lungs ( Pulmonary oedema). Note—In Myocardial Infarction, shock occurs in 10% and has mortality of 60-90%. 24

GENERAL MECHANISM

Neurogenic shock In Neurogenic shock, there is decreased sympathetic activity, therefore, increased vascular capacity. Reason—Sudden loss of Vasomoter Tone resulting in massive dilation of veins therefore Venous pooling of blood and decreased venous return to heart. Causes of Neurogenic shock -General Anesthesia, Spinal Anesthesia -Brain damage 26

FAINTING AND SYNCOPE 27

Fainting and Syncope Fainting--Feeling of dizziness due to decreased cerebral perfusion but not sufficient to cause loss of consciousness. Syncope—Temporary impairment of consciousness due to reduction in cerebral blood flow 28

Vasovagal Fainting Vasovagal attacks---Increased Vagal activity,ANS Disturbance -- It causes vasodilatation therefore pooling of blood in extermities and Fainting. --Bradycardia --It is short lived and Benign. Cause---Fear, Pain 29

Other Form of Syncope Postural Syncope - Pooling of blood in legs on standing Carotid sinus syncope - Pressure on carotid sinus due to Tight Collar causes Vasodilatation and Bradycardia, that causes Fainting. Cough syncope - Due to increased Intrathoracic pressure there is decreased venous return 30

Physiology of Treatment in Shock Treat the cause Hemorrhagic shock---Give Blood Transfusion Burn shock----Plasma Transfusion Fluid loss(vomting and Diarrhea)—I/V Fluids (0.9%Saline) 31

Physiology of Treatment in Shock Cont … Anaphylatic shock—Epinephrine,Antihistamine Septic shock– Antibiotics Other Therpy Eg: Vasovagal syncope—Put the patient in supine position,raise the foot end of the bed 32

THANK YOU 33