1. Lecture - 13 DR ZAHOOR ALI SHAIKH
SHOCK
Lecture - 13
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. Signs of Hypovolemic shock Patient is
pale
Cold clamy skin
Hypotension
Increased pulse rate
Increased respiratory rate
(Vasoconstriction due to increased sympathetic stimulation )

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 CAUSES:
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 Parameter I II III IV
Blood loss (ml)
<750
750–1500
1500–2000
>2000
Blood loss (%)
<15%
15–30%
30–40%
>40%
Pulse rate (beats/min)
<100
>100
>120
>140
Blood pressure
Normal
Decreased
Respiratory rate (bpm)
14–20
20–30
30–40
>35
Urine output (ml/hour)
>30
5–15
Negligible
CNS symptoms
Anxious
Confused
Lethargic
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 Carotid sinus 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