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Shock 1 Pathophysiology of Shock • • Shock = Hypoperfusion Inadequate oxygenation or perfusion causes: – Inadequate cellular oxygenation – Shift from aerobic to anaerobic metabolism • Anaerobic metabolism – Without O2 • Aerobic metabolism – With O2 2 Pathophysiology of Shock Ultimate Effects of Anaerobic Metabolism Inadequate Cellular Oxygen Delivery Inadequate Energy Production Anaerobic Metabolism Lactic Acid Production Metabolic Failure CELL DEATH! Metabolic Acidosis 3 Pathophysiology of Shock • Fick principle – Adequate ventilation – O2 binds with hemoglobin – O2 transported via circulatory system – O2 off-loaded in capillaries Air’s gotta go in and out. Blood’s gotta go round and round. Any variation of the above is not a good thing! 4 Pathophysiology of Shock • Maintaining Perfusion Requires: – – – – • Volume Pump Vessels Failure of one or more of these causes shock Shock occurs through three primary mechanisms: – Fluid loss – Significant vasodilation – Pump failure Cardiac Output = Stroke Volume x Peripheral Vascular Resistance 5 Stages of Shock Shock is a progressive syndrome • Three phases – Compensated – Decompensated – Irreversible 6 Types of Shock Types of Shock: • • • • • Hypovolemic shock Cardiogenic shock Neurogenic shock Anaphylactic shock Septic shock 7 Types of Shock Hypovolemic Shock = Low Volume • Trauma – Non-traumatic blood loss – Vaginal, GI,GU • Burns • Diarrhea • Vomiting • Diuresis • Sweating • Third space losses 8 Types of Shock Cardiogenic Shock = Pump Failure • • • • • Acute M I CHF Bradyarrhythmias Tachyarrhythmias Mechanical obstruction – Cardiac tamponade – Tension pneumothorax – Pulmonary embolism 9 Types of Shock Distributive Shock = Low Resistance *VASCULAR TONE IS LOST • Spinal cord trauma – neurogenic shock • Depressant drug toxicity • Simple fainting • Sepsis • Anaphylaxis 10 Stages of Shock -Shock is a progressive syndrome -Signs and symptoms due to hypotension and compensatory responses. • Three phases – Compensated – Decompensated – Irreversible 11 Stages of Shock Compensated Shock • Baroreceptors detect fall in BP – Usually 60-80 mm Hg (adult) • Sympathetic nervous system (compensatory mechanisms) activates » Peripheral Vasoconstriction » Increase HR » etc 12 Stages of Shock Decompensated Shock • Compensatory mechanisms begin to fail. » » » » » Drecreased Blood Pressure Tachycardiac Tachpnea Altered LOC etc 13 Stages of Shock Irreversible Shock » » » » » » Loss of Peripheral Vascular Resistance Decreased Blood Pressure Slow, weak Irreg Pulse Slow Shallow Resp. Altered LOC, Coma etc 14 Shock Considerations • Tissue ischemic sensitivity – Heart, brain, lung: 4 to 6 minutes – GI tract, liver, kidney: 45 to 60 minutes – Muscle, skin: 2 to 3 hours Resuscitate Critical Tissues First! 15 Shock Considerations • Falling BP = LATE sign of shock • BP is NOT same thing as perfusion • Pallor, tachycardia, slow capillary refill = Shock, until proven otherwise PREPARE & TREAT FOR SHOCK EARLY: Recognize & Treat during the compensatory phase 16 Shock Considerations Restlessness, anxiety, combativeness = Earliest signs of shock Best indicator of resuscitation effectiveness = Level of Consciousness 17 Shock Management • Airway – Open, Clear, Maintained – Consider Intubation • Breathing – High concentration oxygen • Oxygen = Most Important Drug in Shock – Assist ventilation as needed • When in Doubt, Ventilate • BVM – Decompress Tension Pneumothorax 18 Shock Management • Circulation – Control bleeding – Establish venous access (Large bore IV x 2) *Do not delay transport, IV’s can be established during transport. – Elevate extremities (as indicated) – Pneumatic anti-shock garment (as per local protocols) • Maintain body temperature – Cover patient with blanket if needed – Avoid cold IV fluids • Monitor: Mental Status, Pulse, Respirations, Blood Pressure, ECG 19 Shock Management Pharmacological interventions – Hypovolemic shock • Volume expanders – Cardiogenic shock • Volume expanders • Positive cardiac inotropes • Vasoconstrictor • Rate altering medications Treat rate, then rhythm, then BP Avoid vasopressors until hypovolemia ruled out, or corrected. 20 Shock Management Pharmacological interventions (cont.) • Distributive shock – – – – • Obstructive shock – • Volume expanders Positive cardiac inotropes Vasoconstriction PASG Volume expanders Spinal shock – Volume expanders 21 QUESTIONS ? 22
