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Shock

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This presentation is made by Dr Ashok Jaisingani for study purpose, if any one like this than please give comment.

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Shock

  1. 1. Dr Ashok Jaisingani
  2. 2.  Shock is the most common and important cause of the death among the surgical patients Death occurs rapidly as result of the 1- Profound state of the shock 2- Consequence of the organ ischemia 3- Reperfusion injury
  3. 3.  Shock is the systemic state of the low tissue perfusion, which is inadequate for the normal cellular respiration. With insufficient delivery of the oxygen and glucose cells switch from aerobic to inaerobic metabolism.
  4. 4.  Pathophysiology of the shock is divided in to three categories 1- Cellular 2- Microvascular 3- Systemic
  5. 5.  Reduced tissues perfusion  dec. cellular O2  switch from aerobic to anaerobic metabolism  accumulation of the lactic acid in the blood  “Systemic Metabolic Acidosis”. As glucose within cells exhausted  stop respiration  failure of Na+/K+ pump of cellular membranes  lysosomal enzymes become released  lyses of the cells Potassium released into the blood stream.
  6. 6.  As tissues ischemia progress  change in the internal environment of the body  activation of the immune and coagulation systems. Hypoxia and acidosis activate compliment and the prime neutrophils  generation of the O2 free radicals and release of the cytokines. Above two mechanism leads to injury to endothelials cells of the capillaries  damage endothelial cells become leaky  tissues edema  exacerbating tissues hypoxia
  7. 7.  Systemic pathophysiology involves 1- Cardiovascular system 2- Respiratory system 3- Renal System 4- Endocrine System
  8. 8.  Due to tissues edema  pre-load & after – load decrease  Compensatory baro receptor response  increase sympathetic activity  release of the catecholamine  tachycardia and systemic vasoconstriction Above mechanism not associated with the shock result from the sepsis.
  9. 9.  Metabolic acidosis and increase sympathetic response  increase respiratory rate and minuet ventilation  increase the excretion of the CO2  Compensatory respiratory alkalosis.
  10. 10.  Due to dec. preload and afterload  dec. perfusion pressure in the kidneys  reduce filtration at glomerulus  dec. urine output  activation of renin – angiotensin – aldosterone system  further vasoconstri – -on  increase water and sodium reabsorbtion from kidneys  further edema  exacerbating further ischemia.
  11. 11.  In addition to adrenal and renin-angiotensin system, vasopressin release from the hypothalamus in response to decrease preload  vasoconstriction and reabsorbtion of the sodium and water
  12. 12.  During period of the systemic hypoperfusion  cellular and organ damage progress just because of the direct effects of tissues hypoxia and local activation of the inflammation. Further injury is also occurs once restoration of the normal circulation  acid and K+ load that has build up  myocardial depression, vascular dilatation and hypotension. The cellular and humoral elements activated by the hypoxia flushed back into circulation  further endothelial injury  Acute lung injury, acute renal injury, multiple organs failure and death. Reperfusion injury only attenuated by reducing extent and duration of the tissue hypoxia.
  13. 13.  Clinically shock is divided on the basis of the initiating mechanism 1- Hypovolemic Shock 2- Cardiogenic Shock 3- Obstructive Shock 4- Distributive Shock 5- Endocrine Shock
  14. 14.  Hypovolemic shock is caused by the reduce circulating volume. It may be due to following causes 1- Hemorrhage 2- Non – Hemorrhagic Non-hemorrhagic causes includes following 1- Poor Fluid intake (dehydration) 2- Excessive loss of fluid in vomiting, diarrhea, urinary loss as in diabetes and “third spacing” in which fluid loss in GIT & interstitial space E.g. bowl obstruction and pancreatitis. Hopovolaemia is most common cause of the shock and in some degree also component of the all other shock.
  15. 15.  Cardiogenic shock result from primary failure of the heart to pump the blood to the tissues and causes of that shock include followings 1- Myocardial Infarction 2- Cardiac Dysrhthemia 3- Valvular Heart Disease 4- Blunt myocardial Injury 5- Cardiomyopathy Cardiac insufficiency may also be caused by myocardial depression resulting from 1- Endogenous factors (Bacterial and humoral agents as in sepsis) 2- Exogenous factors (pharmaceutical and drug abuse) Evidence of the systemic hypertension with pulmonary or systemic edema may co – exist with the classic signs of the shock.
  16. 16.  There is reduction in preload because of the mechanical obstruction of the cardiac filling. Common causes of the obstructive causes are followings 1- Cardiac Temponade 2- Tension Pneumothorax 3- Massive Pulmonary Embolus In each of the above situation there is dec. filling of the left or right ventricles leading to reduce preload  Fall In Cardiac Output.
  17. 17.  That describe the cardiovascular response in variety of the conditions such as 1- Septic Shock 2- Anaphylaxis 3- Spinal Cord Injury Inadequate organs perfusion accompanied by the 1- Vascular dilatation 2- Hypotension 3- Low systemic vascular resistance 4- Inadequate afterload
  18. 18.  There is vasodilatation is caused by the release of the histamine in the systemic circulation. That occurs mostly in allergic reaction.
  19. 19.  In high spinal cord injury there is failure of the sympathetic outflow and that leads to inadequate vascular tone.
  20. 20.  There is release of the bacterial products such as endotoxin and activation of the cellular and humoral components of immune system. There is maldistribution of blood flow at microvascular level with arteriovenous shunting and dysfunction of cellular utilization of the oxygen. Mostly in the late phase of the septic shock hypovolaemia result from fluid loss into interstitial space and there may be myocardial depression which complicate the clinical picture.
  21. 21.  Endocrine shock may present as complication of 1- Hypovolemic Shock 2- Cardiogenic Shock 3- Distributive Shock Causes Of Endocrine Shock 1- Hypo or Hyperthyroidism 2- Adrenal Insufficiency

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