8. Shock .pdf

Learning Objectives • Shock definition SHOCK • Types of shock • Causes of shock • Signs and symptoms • Pharmacology of Shock • Recommendation Definition Causes of shock • Shock is a serious condition where insufficient • Failure of blood circulating system to deliver sufficient blood flow r...

Learning Objectives • Shock definition SHOCK • Types of shock • Causes of shock • Signs and symptoms • Pharmacology of Shock • Recommendation Definition Causes of shock • Shock is a serious condition where insufficient • Failure of blood circulating system to deliver sufficient blood flow reaches the body tissues. oxygen to tissues. • Intravascular deficit ↳ blotage of blood flow • Medical shock is an emergency and one of the leading causes of death for critically ill people. • Myocardial pump failure • Peripheral vasodilation ↳ Parasympathetic action Types of Shock • Hypovolaemic Shock • Cardiogenic Shock • Distributive Shock • Extracardiac obstructive shock Types of Shock Hypovolaemic Shock Decreased circulating blood volume Causes: A-Excessive blood loss: e.g., bleeding from the gastrointestinal tract, external trauma, ruptured ectopic pregnancy, ruptured aortic aneurysm, haemoperitoneum, burns, surgery. Ectopic pregnancy B- Excessive fluid loss: External loss, e.g., severe vomiting, diarrhoea, burns, diabetes mellitus, diabetes insipidus, excessive use of diuretics, diuretic phase of acute renal failure, extensive muscle injury. Internal sequestration of fluid, e.g., peritonitis, pancreatitis, intestinal obstruction, ascites. Types of Shock Types of Shock Cardiogenic Shock Distributive Shock Decreased pumping function of the heart • It is relative hypovolaemia due to vasodilation: Cause: Types: • Acute myocardial infarction, cardiac arrhythmias, acute • Septic shock aortic, ruptured interventricular septum, myocardial • Neurogenic shock rupture, myxoma, progressive myocarditis, myocardial • Anaphylactic shock depression. There is usually profound decrease in peripheral vascular resistance. Types of Shock Causes: • Barbiturate poisoning Extracardiac obstructive shock • Acute spinal cord injury Due to: • Anaesthesia • Drugs like nitrates • Calcium-channel blockers • Pericardial tamponade • Constrictive pericarditis • Ganglion blockers • Massive pulmonary embolism • Adrenergic blocking agents • Severe pulmonary hypertension. Pericardial tamponade Symptoms of Shock • Thirst • Weakness • Light-headedness Signs of Shock Pharmacological Treatment • Hypotension (SBP less than 90 mm Hg) • Tachycardia hypovolemic shock • Hypothermia 1- Fluid therapy • Oliguria 2- Blood transfusion • Dark-yellow colored urine 3- Vasopressors and Inotropies • Confusion and coma • Organ dysfunction Fluid theory Type of fluids: 1- Crystalloids 2- Colloids 3- Blood products Crystalloids (Electrolyte-Base solutions) Colloids (Large molecular weights solutions) They are fluids with electrolytes compositions approximates • Albumin plasma or have a total osmolality similar to plasma (280 - • Hydroxyethyl starch 295 mmol/kg) • Dextran Examples: - Normal Saline: 0.9% NaCl - Lactated Ringer: Na, Cl, K, Ca, Lactate - Plasma-Lyte A: Na, Cl, K, Mg, Acetate They are associated with fluid overload, renal dysfunction and bleeding Recommendations Blood products They used with patients who looses more than 1500 ml blood from hemorrhage. Types: - Whole blood - Packed red blood cells - Fresh frozen plasma (FFP) - Platelet All fluids must be warmed to 37 before using to prevent: • Hypothermia • Arrhythmia • Coagulopathy They are associated with virus transmission, hypocalcaemia, increased blood viscosity Vasopressors and Inotropies Epinephrine • Vasopressor and Inotropies agents are required in patients with shock when volume resuscitation fails to maintain adequate blood pressure and • Drug of choice for anaphylactic shock and 2nd choice for septic shock MOA • It stimulates beta 1 receptors in the heart which increase heart rate organ and tissues remain hypo-perfused • It stimulates alpha 1 receptors results in vasoconstriction (high dose) • It also stimulates beta 2 receptors (low dose). Pharmacokinetics ➢ Epinephrine has a rapid onset but a brief duration of action (due to rapid degradation). The preferred route is intramuscular. Dose: Infusion rates of 0.04 – 1mcg/kg/min ➢ In emergency situations, epinephrine is given intravenously (IV) for the most rapid onset of action. ➢ It may also be given subcutaneously and by inhalation. ➢ It is rapidly metabolized by MAO and COMT, and the metabolites Side effects: -hypertension -dysrhythmias -angina -nervousness and tremors metanephrine and vanillylmandelic acid are excreted in urine. Pharmacokinetics Norepinephrine • It is the drug of choice in septic shock. MOA ➢Norepinephrine is given IV for rapid onset of action. ➢The duration of action is 1 to 2 minutes. • It stimulates alpha1 receptors results in vasoconstrictions • It has minor activity to beta 1 receptors so it increase cardiac output to a certain extent. • It has a weak beta 2 effects. ➢It is rapidly metabolized by MAO and COMT, and inactive metabolites are excreted in the urine. Dopamine Dose: It is initialed at 0.05 to 0.1 mcg/kg/min, the increased till reach the MAP goals. Side effects: • Hypertension • Dysrhythmia • Used for treatment of shock, sepsis, heart failure and renal failure MOA • It stimulates alpha1 receptors results in vasoconstrictions • It also stimulate beta 1 receptors so it increase cardiac output and heart rate • It also stimulate doapamergic receptors which helps to increase renal perfusion which helps in renal failure Renal and visceral effects • Dopamine dilates renal and splanchnic arterioles by activating dopaminergic receptors, thereby increasing blood flow to the Dose: Dopamine (IV – 5-15 μg/kg/min) kidneys and other viscera. • Therefore, dopamine is clinically useful in the treatment of shock, • in which significant increases in sympathetic activity might compromise renal function. Side effects: • angina • dysrhythmias Dobutamine • It used for treatment of cardiogenic shock and heart Dose • 2-20 mcg/kg/min failure • It stimulate beta 2. • It also stimulate beta 1 receptors, so it increase cardiac output with less effect on heart rate Side effects: • hypertension • angina, • dysrhythmias.