SHOCK

1. SHOCK Lecture - 12 DR ZAHOOR ALI SHAIKH

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

3. 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.

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

6. GENERAL MECHANISM

7. 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

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

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

10. Clinical Presentation

11. 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.

12. 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

13. 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

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

16. Refractory Shock • 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: • Cerebral ischemia therefore depression of Vasomotor center---vasodilatation , decreased BP, decreased HR • Myocardial depression due to Acidosis causes decreased COP

17. 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.

18. HYPOVOLUMIC SHOCK • Hemorrhagic Shock Crit Care. 2004; 8(5): 373–381.

19. 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%

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

21. GENERAL MECHANISM

22. 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

23. 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

24. 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%.

25. GENERAL MECHANISM

26. 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

27. FAINTING AND SYNCOPE

28. 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

29. 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

30. 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

31. 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)

32. 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

33. THANK YOU