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SHOCK Dr Begashaw M (MD) Introduction • is a life-threatening condition • occurs when the circulatory system fails to deliver oxygen and nutrients to the body tissues & becomes unable to remove waste products • may rapidly progress to an irreversible state with subsequent multi-organ failure and death DEFINITION • a pathological state causing inadequate oxygen delivery to the peripheral tissues and resulting in lactic acidosis, cellular hypoxia & disruption of normal metabolic condition CLASSIFICATION 1. Hypovolemic 2. Cardiogenic 3. Obstructive 4. Distributive - Septic shock - Neurogenic shock - Anaphylactic shock Shock • Hypovolemic – Hemorrhage – Anemia – Fluid loss • Obstructive – Aortic valve stenosis • Distributive – Sepsis – Thyrotoxicosis – Anaphylaxis • Cardiogenic – – – – Decompensated CHF Acute coronary syndrome Dysrhythmia Myocarditis Hypovolemic •Hemorrhage •Anemia Cardiogenic •CHF •ACS •Dysrhythmia Distributive •Sepsis •Thyrotoxicosis Obstructive •Aortic valve stenosis Preload Inotropy Shock MAP = (SV x HR) x SVR Afterload Cardiac Performance Preload Left ventricular size Peripheral resistance Stroke volume Contractility Myocardial fiber shortening Cardiac output Heart rate Afterload Arterial pressure Cardiovascular & metabolic characteristics of shock Hypovolemic shock • inadequate vascular volume • results from loss of fluid from circulation, either directly or indirectly E.g ▪ Hemorrhage • Loss of plasma due to burn • Loss of water & electrolytes in diarrhea • Third space loss Where do pt bleed enough to die? • Remember, there are only 5 places into which a person can bleed enough to cause hemodynamic instability – – – – – Chest Peritoneum Retroperitoneum Thighs World Not the mediastinum Cardiogenic shock • impaired cardiac function • myocardial infarction • pericardial tamponade Obstructive Shock • Resistance to cardiac outflow – ↑ afterload – Aortic stenosis – Tension pneumothorax Septic Shock (vasogenic shock) • as a result of the systemic effect of infection • result of a septicemia with endotoxin and exotoxin release by gram-negative and gram-positive bacteria • impaired extraction as a result of impaired metabolism Neurogenic shock • disruption of the sympathetic nervous system - to pain - loss of sympathetic tone, as in spinal cord injuries PATHOPHYSIOLOGY OF SHOCK • stimulates a physiologic response - conserve perfusion to the vital organs (heart and brain) - vasoconstriction of skin, splanchnic & renal vessels leads to renal cortical necrosis and acute renal failure Hypovolemic shock: physiology • Reduced blood volume • Reduced preload • Reduced stroke volume • Reduced cardiac output Response to shock - physiology – Cathecholamines , ADH – Vasoconstriction, tachycardia – Improve venous return and CO CLINICAL FEATURES • • • • • • • Tachycardia Feeble pulse Narrow pulse pressure Cold extremities (except septic shock) Sweating, anxiety Breathlessness / Hyperventilation Confusion leading to unconscious state Classification of Hemorrhage Class Parameter I II III IV Blood loss (ml) Blood loss (%) Pulse rate (beats/min) <750 <15% <100 1500– 750–1500 2000 15–30% 30–40% >100 >120 Blood pressure Normal Decreased Decreased Decreased >2000 >40% >140 Respiratory rate (breaths/min) 14–20 20–30 30–40 >35 Urine output (ml/hour) >30 5–15 Negligible Mental status Normal Anxious 20–30 Confused Lethargic MANAGEMENT OF SHOCK • restoring oxygen delivery to the cells of vital organs General Management Priority-ABC • Stop bleeding • Fluid resuscitation-crystalloids • Head down position-flat • Transfusion • Oxygen , inotropic • Monitoring -determine hourly urine output, BP, pulse rate Specific Management Hypovolemic Shock • Restore vascular volume • Fluid and blood replacement • Oxygen support Specific Management Septic Shock • antibiotics • Inotropic –adrenaline,dopamine • Surgical eradication of the infection focus Cardiogenic shock • Inotropes Neurogenic shock • Pain relief • Treat the causes, give supportive measures inotropic support COMPLICATIONS OF SHOCK 1. Shock lung (ARDS) 2. Acute renal failure 3. Gastrointestinal ulceration 4. Disseminated intravascular coagulation 5. Multiorgan failure 6. Death Questions?
