Shock Dr. Afsar Saeed Shaikh M.B.B.S, M.Phil. Assistant Professor of Chemical Pathology Pathology Department, KEMU, Lahore. What is haemodynamics?

INTRODUCTION Cardiovascular Collapse Final common pathway Definition: ‘A clinical entity characterized by systemic hypoperfusion caused by reduction either in cardiac output OR in the effective circulatory blood volume’

INTRODUCTION Clinical Effects of Shock: Hypotension Impaired tissue perfusion Cellular hypoxia

Shock ETIOLOGICAL CLASSIFICATION: Cardiogenic Shock Hypovolemic Shock Septic Shock (Endotoxin Shock) Neurogenic Shock Anaphylactic Shock

Stages of Shock FIRST stage; Non-progressive Stage: are activated Reflex compensatory mechanisms are activated Profusion of vital organ is maintained

Stages of Shock 2nd Stage; Progressive Stage: Tissue hypoperfusion Circulatory & metabolic imbalances leading to Acidosis

Stages of Shock 3rd Stage; Irreversible Stage: Cellular & tissue injury Even with correction of hemodynamic defects, survival is not possible

Mechanism of different Stages of Shock 1. Non-progressive Stage : Neurohumoral Mechanisms maintain cardiac output and blood pressure: Baroreceptors reflexes Release of catecholamine Activation of renin-angoitensin axis ADH release Generalized sympathetic stimulation

Mechanism of different Stages of shock 1. Non-progressive Stage : Different Clinical Outcome of these compensatory mechanisms: Tachycardia Peripheral vasoconstriction (cool & pale skin) Renal conservation of fluid

Mechanism of different Stages of shock 2. Progressive Stage : Widespread hypoxia: Anaerobic glycolysis Production of lactic acidosis pH lead to blunting of vasomotor response leading to vasodilatation Peripheral pooling of blood cardiac output

Mechanism of different Stages of shock 2. Progressive Stage : Different Clinical Outcome of these failing mechanisms: Feeble, failing pulse Mental confusion urine output

Mechanism of different Stages of shock 3. Irreversible Stage : Widespread Cellular injury: Damage to the organelle of cells Leakage of lysosomal enzymes Production of nitric oxide by cells Worsened myocardial contractility

Mechanism of different Stages of shock 3. Irreversible Stage : Different Clinical Outcome of cellular injury: Septic shock (entry of intestinal flora into circulation) Complete renal shutdown (acute tubular necrosis) Downward clinical spiral

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