shock

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By: princebassam (43 month(s) ago)

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shock : 

shock Dr . Srinivas M.S. Asst. professor Dept. of surgery M.N.R. Medical college

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Most important cause of death - surgical pts. Death may occur rapidly – profound shock delayed – organ ischemia – failure Definition : systemic state of low tissue perfusion , which is inadequate for normal cellular respiration Insufficient Glucose & Oxygen – Aerobic Anaerobic metabolism Perfusion not restored in time - cell death

Pathophysiology : 

Pathophysiology Cellular : lactic acidosis - metabolic acidosis Failure of Na+, K+ pumps of cell – release of auto digestive enzymes

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Micro vascular : Hypoxia & Acidosis – activate Complement & WBC Release Oxygen free radicals & cytokines injury of capillary endothelial cells Leaky endothelial cells – tissue oedema – inc. hypoxia

Pathogenesis of Shock : 

Pathogenesis of Shock Nguyen H et al. Severe Sepsis and Septic-Shock: Review of the Literature and Emergency Department Management Guidelines. Ann Emerg Med. 2006;42:28-54.

systemic : 

systemic Cardiovascular : Decrease in preload & after load Increased sympathetic activity , catecholamines Tachycardia & Vasoconstriction Respiratory : Increased RR & ventilation Renal : Decreased GFR & urine output Renin – angiotensin system – Na. & water retention

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Endocrine : Vasopressin ( ADH) released from the hypothalamus Cortisol , from Adrenal cortex Ischemic – reperfusion syndrome : Acid & K+ load – Myocardial depression , vascular dilatation –hypotension All the cellular & humoral components – circulation – further damage Multi organ failure This can be attenuated by reducing extent & duration of tissue perfusion

Classification of shock : 

Classification of shock Hypovolemic shock : Most common form of shock Haemorrhagic Non – haemorrhagic Cardiogenic shock : Primary failure of the Heart Venous hypertension, pulmonary & systemic edema coexist Obstructive shock : Reduction in preload , mechanical obstruction Cardiac tampanode , tension pneumo thorax , air embolism

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Disributive shock : Includes septic, anaphylaxis & spinal cord injury Endocrine shock : Combination of hypovolaemic, cardiogenic, distributive shock Hypo & hyperthyroidism , Adrenal insufficiency

Severity of shock : 

Severity of shock Compensated shock : Shock progresses , CVS & Endocrine systems compensate Decrease to non essential organs Maintain to main organs De compensation shock : Further loss of circulating volume Progressive renal, respiratory & CVS decompression Blood loss of 30 – 40 % - BP is maintained Mild shock : Tachycardia, tachypnoea, decrease in urine output BP is maintained, decrease in pulse pressure

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Moderate shock : Renal compensatory mechanisms fail , renal perfusion fall Urine output < 0.5 ml /kg/hr Tachycardia BP starts to fall Drowsy & mildly confused Severe shock : Profound tachycardia & hypotension Urine output falls to zero Unconscious with laboured respiration

Consequences : 

Consequences Unresistable shock : Profound shock for a prolonged period Ability of the body to compensate is lost Myocardial depression – loss of response to fluid & inotropes Peripherally loss of ability to maintain systemic vascular resistance Death is the inevitable result Multi organ failure : two or more failed organ systems Timely intervention , period is limited , rapid & uncomplicated recovery

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Prolonged ischemia + reperfusion injury = end organ damage Lung – ARDS Kidney – ARF Liver – Acute liver failure Clotting – Coagulopathy Cardiac – Cardiovascular failure No specific treatment Support organ systems – ventilation, CVS support , dialysis mortality rate is 60%

Resuscitation : 

Resuscitation Immediate resuscitation manoeures : Patent Airway Adequate Oxygenation Ventilation Cardio vascular resuscitation

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Conduct of Resuscitation : Not to be delayed, in diagnosing Safer to assume as Hypovolemia – begin fluid resuscitation Assess the response Actively bleeding – Haemostasis Haemostasis & resuscitation should proceed in parallel

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Fluid therapy : Hypovolemia & inadequate preload – addressed first Inotropic agents to an empty heart – deplete the myocardium First line therapy – IV access & IV fluids administration Short & wide bore useful

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Types of fluids : No ideal resuscitation fluid Crystalloids : NS , Hartmanns solution , RL Colloids : Albumin , Haemocoele No much difference Blood loss – Blood Hypo tonic solutions , 5D are poor volume expanders

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Dynamic fluid response : 250 – 500 ml of fluid is rapidly administered in 5 – 10 min Pts. Are divided into : Responders – improvement Transient responders – improve & revert Non responders – severely volume depleted Vasopressor & inotropic support : Not indicated as first line Vasopressor agents – phenylnephrine , noradrenaline Indicated in distributive shock Inodilator – dobutamine – cardiogenic shock

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Monitoring for pts. in shock : Minimum : ECG Pulse oximetry Blood pressure Urine output Additional modalities : CVP Invasive blood pressure Cardiac output Base deficit & serum lactate

Treatment Algorithm : 

Treatment Algorithm

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End points of resuscitation : Easier to know when to start than when to stop Resuscitated until pulse, BP & urine output are normal GUT & Muscle beds are under perfused Activation of inflammation & reperfusion injury Multi organ failure

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State of Normal vital signs & continued under perfusion – Occult Hypo perfusion Pts. with OH > 12 hrs. – 3 times higher Mortality rates Resuscitated algorithms are based on Base deficit , Lactate, mixed venous oxygen saturation

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Thank you