Shock

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Shock

  1. 1. Shock : Pathophysiology Causes & Management Dr.Anil Haripriya Assistant Professor Surgery NHDC & RC
  2. 2. Introduction <ul><li>“ Rude unhinging of machinery of life’ </li></ul><ul><ul><ul><li>Gross </li></ul></ul></ul><ul><li>Inadequate delivery of oxygen and nutrients to maintain normal tissue and cellular function </li></ul><ul><li>Clinically accompanied by hypotension </li></ul><ul><li>MAP < 60 mmHg in a previously normotensive person </li></ul>
  3. 3. Types of Shock <ul><li>Hypovolemic </li></ul><ul><li>Vasodilatory (Septic) </li></ul><ul><li>Neurogenic </li></ul><ul><li>Cardiogenic </li></ul><ul><li>Obstructive </li></ul><ul><li>Traumatic </li></ul>
  4. 4. Pathophysiology <ul><li>Physiologic response to hypovolemia directed </li></ul><ul><li>at preservation of perfusion to vital organs </li></ul><ul><li>- Increase cardiac contractility & peripheral vascular tone via ANS </li></ul><ul><li>- Hormonal response to preserve salt & water </li></ul><ul><li>- Change in local micro circulation to regulate </li></ul><ul><li>regional blood flow </li></ul>
  5. 5. Neuroendocrine response <ul><li>Mediated via baro & chemo receptors which stimulates ANS & HPA axis </li></ul><ul><li>release of epinephrine & norepinephrine </li></ul>
  6. 6. Hormonal response Hypothalamus Hyperglycemia Lypolysis Gluconeogenesis Glycogenolysis Cortisol ACTH CRH
  7. 7. Hormonal response <ul><li>Stimulation of renin angiotensin system </li></ul><ul><li>Release of ADH to conserve salt & </li></ul><ul><li>water </li></ul>
  8. 8. Cellular response <ul><li>Inadequate delivery of oxygen & substrates </li></ul><ul><li>leads to in oxidative phosphorylation & ATP </li></ul><ul><li>generation </li></ul><ul><li>Anaerobic respiration leads to lactic acidosis </li></ul>
  9. 9. Cellular response <ul><li>Na+,K+ ATP ase activity decrease leading to </li></ul><ul><li>accumulation of Na+ & leak of K+ </li></ul><ul><li>Cellular gene expression for HSP,VEGF,NO </li></ul><ul><li>synthase & cytokines is also increased </li></ul>
  10. 10. Hypovolemic shock <ul><li>M/C form of shock </li></ul><ul><li>Due to loss of blood, plasma, extravascular </li></ul><ul><li>sequestration </li></ul><ul><li>C/f and severity depends upon amount of volume lost </li></ul>
  11. 11. Hypovolemic shock <ul><li>Causes </li></ul><ul><li>- Trauma </li></ul><ul><li>- Severe dehydration </li></ul><ul><li>- Burns </li></ul><ul><li>- Intestinal obstruction </li></ul><ul><li>- Perforation peritonitis </li></ul>
  12. 12. Hypovolemic shock <ul><li>Phases </li></ul><ul><li>- Compenseted </li></ul><ul><li>- Decompenseted </li></ul><ul><li>- Irreversible </li></ul>
  13. 13. Hypovolemic shock Same + Hypotension Mental status deterioration Same + Tachycardia Tachypnoea Oliguria Postural -hypotension Cold extremities CRT Diaphoresis Anxiety Severe(>40%) Moderate(20-40%) Mild (<20%)
  14. 14. Cardiogenic shock <ul><li>Circulatory pump failure in setting of adequate vascular volume </li></ul><ul><li>Sustained hypotension SBP < 90 mm Hg for at least 30 minutes </li></ul><ul><ul><li>CI < 2.2 L/min/m 2 </li></ul></ul><ul><ul><li>PAWP >15mmHg </li></ul></ul><ul><li>Surgical importance in patients with chest trauma for </li></ul><ul><ul><li>Tamponade </li></ul></ul><ul><ul><li>Tension pneumothorax </li></ul></ul>
  15. 15. Cardiogenic shock <ul><li>Chest pain </li></ul><ul><li>Hypotension </li></ul><ul><li>Arrhythmias </li></ul><ul><li>Beck’s triad </li></ul>
  16. 16. Vasodilatory shock <ul><li>Characterised by peripheral vasodilatation with hypotension & resistance to T/t with vasopressors </li></ul><ul><li>Causes </li></ul><ul><li>- Septic shock </li></ul><ul><li>- Hypoxic lactic acidosis </li></ul><ul><li>- CO poisoning </li></ul><ul><li>- terminal stage of cardiogenic & hemorrhagic shock </li></ul>
  17. 17. Septic shock <ul><li>Manifestation of excessive & inflammatory response of endogenous immune mechanism </li></ul><ul><li>Sepsis is SIRS with established focus of infection </li></ul><ul><li>Septic shock - severe sepsis unresponsive to continuous fluid infusion and inotropes </li></ul>
  18. 18. Septic shock Gram –ve bacilli LPS+CD14 TNF IL-1 IL-6/IL-8 NO/PAF
  19. 19. Neurogenic shock <ul><li>tissue perfusion as a result of loss of vasomotor tone to peripheral arterial beds </li></ul><ul><li>Secondary to spinal cord injury from vertebral # </li></ul><ul><li>- Hypotension with bradycardia </li></ul><ul><li>Warm extremities </li></ul><ul><li>Motor and sensory deficit </li></ul>
  20. 20. Management <ul><li>Initially empirical </li></ul><ul><li>Air way secured + oxygenation </li></ul><ul><li>Two wide bore lines </li></ul><ul><li>I.V. fluids NS/BSS </li></ul><ul><li>Catheterisation </li></ul><ul><li>Insertion of central venous catheter </li></ul><ul><li>Hb, CBC, Blood sugar, urea, creatinine, electrolytes </li></ul><ul><li>ABG </li></ul>
  21. 21. Hypovolemic shock <ul><li>I.V. fluid NS/RL 2-3 liters over 15-30 min </li></ul><ul><li>If hemodynamic instability persist then start blood transfusion & control on going heamorrhage </li></ul><ul><li>Ionotropic like </li></ul><ul><li>Dopamine 5-10microgms/Kg/min </li></ul><ul><li>Dobutamine 2-20microgms/Kg/min </li></ul>
  22. 22. Cardiogenic shock <ul><li>Conformation of diagnosis by ECG & ECHO </li></ul><ul><li>Intubation & mechanical ventilation often required </li></ul><ul><li>Avoid fluid overload </li></ul><ul><li>Ionotropic support preferably Dobutamine 2-20microgms/Kg/min </li></ul><ul><li>USG guided pericardiocentesis </li></ul>
  23. 23. Neurogenic shock <ul><li>Restoration of intravascular volume by crystalloids </li></ul><ul><li>Vasoconstrictor </li></ul><ul><li>Dopamine > 10microgms/Kg/min </li></ul><ul><li>Phenylephrine 0.2-2.9microgms/Kg/min </li></ul>
  24. 24. Septic shock <ul><li>Culture of body fluids </li></ul><ul><li>Infuse BSS 500 cc/15min monitor SBP/CVP </li></ul><ul><li>Repeat if CVP 8-12mmHg </li></ul><ul><li>Goal to have a MAP of 65 mmHg & P < 120/min </li></ul><ul><li>If hemodynamic instability persists start vasopressor preferrably Norepinephrine 0.02-0.25microgms/Kg/min </li></ul><ul><li>Broad spectrum antibiotic given </li></ul>
  25. 25. Aims of resuscitation <ul><li>CVP of 8-12 mmHg/ PCWP 8-12 mmHg </li></ul><ul><li>MAP of > 65 mmHg </li></ul><ul><li>Urine output of 0.5ml/Kg/hr </li></ul><ul><li>Hb of 7-9 gm% </li></ul><ul><li>CI of > 4.2 L/Kg/m 2 of BSA </li></ul>
  26. 26. End Points of resuscitation <ul><li>Resuscitation complete when oxygen debt repaid,tissue acidosis corrected & aerobic metabolism restored </li></ul><ul><li>Systemic Parameters </li></ul><ul><li>Lactate </li></ul><ul><li>Base deficit </li></ul><ul><li>Tissue Parameters </li></ul><ul><li>Gastric tonometery </li></ul><ul><li>Near infrared spectroscopy </li></ul>
  27. 27. Conclusion <ul><li>Early recognition of warning signs and diagnosis in the reversible phase important for successful management of shock </li></ul><ul><li>Hypovolemia and sepsis account for majority of shock in surgical patients </li></ul><ul><li>Principles of initial resuscitation same irrespective of type of shock </li></ul><ul><li>Ultimate treatment of underlying cause forms cornerstone of management </li></ul>

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