Shock

Dr. Afsar Saeed Shaikh

M.B.B.S, M.Phil. Assistant Professor of Chemical PathologyPathology Department, KEMU, Lahore.

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: 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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