Shock Dr Mojitha Fernando Contents Introduction Types of

Shock Dr Mojitha Fernando

Contents • • • Introduction Types of Shock Cardiogenic Shock Obstructive Shock Distributive Shock – Types Septic Shock Anaphylactic Shock Neurogenic Shock Stages of Shock Signs and Symptoms of Shock

Shock • Shock (circulatory failure) occurs when the metabolic needs of cells are not being met because of inadequate blood flow. • In effect, there is a reduction in circulating blood volume, in blood pressure and in cardiac output. • This causes tissue hypoxia, an inadequate supply of nutrients and the accumulation of waste products • There are 04 types of shock: i. iii. iv. Hypovolemic shock Cardiogenic shock Obstructive shock Distributive shock

Hypovolemic Shock • Occurs due to inadequate circulating volume. • Causes include severe hemorrhage (typical cause), diarrhea , vomiting • S/S : - Tachycardia, decreased circulating blood volume, rapid, shallow breathing, hypothermia, thirst and dry mouth, rapid, weak pulse.

Cardiogenic Shock • Cardiogenic shock is a condition of insufficient cardiac output due to damage caused to heart muscles causing inadequate tissue perfusion and resulting in tissue hypoxia. • Occurs mainly due to MI. • It is the main cause of death in acute myocardial infarction. • S/S (similar to those of hypovolemic, additions symptoms are): Ø Arrythmia Ø Distended jugular veins

Obstructive Shock • Obstructive shock occurs due to an obstruction of blood flow outside the heart. • Occurs due to insufficient venous return or due to blockage of the aorta. Causes of obstructive shock • Cardiac tamponade • Pulmonary embolism Symptoms of obstructive shock • Respiratory symptoms – SOB and fast but shallow breathing. • Other symptoms include sweating, oliguria, clammy skin, pallor, and cold hands and feet.

Distributive Shock • Distributive shock (aka vasodilatory shock) is caused by anomalous distribution of blood supply to the tissues and organs of the body. • There are 03 types based on the cause: i. Septic Shock ii. Anaphylactic Shock iii. Neurogenic Shock

Septic Shock • Septic shock is a result of sepsis. Most common cause of distributive shock. . • It is caused by an extreme infection which cannot be cleared by the immune system. • It results in life-threatening hypotension and vasodilation. • Complications of septic shock: Ø HF Ø Kidney failure Ø Respiratory failure • S/S : - fever, warm and sweaty skin

Anaphylactic Shock • Caused by an overwhelming reaction to an allergen, resulting in the release of histamine. • Causes widespread hypotension and vasodilation. • Occurs due to prior sensitization to an allergen. • S/S: - hives, localized edema (especially around the face), weak and rapid pulse, breathlessness, cough, swelling of the throat

Neurogenic Shock • Occurs due to damage to the CNS. • Impairs cardiac function by decreasing HR and loosening blood vessel tone. • Results in relaxation of blood vessels causing them to dilate and allowing blood to pool in the venous system. • This results in severe hypotension. • S/S: - slow HR, vasodilation of superficial vessels, warm skin

Stages of Shock • There are 04 stages of shock. Ø Initial Stage Ø Compensatory Stage Ø Progressive Stage Ø Refractory Stage

1. Initial Stage • • • Tissues are hypoperfused. Hypoxia Increased anaerobic metabolism Lactic acid is building. (Lactic acidosis) There is diminished cardiac output without any clinical symptoms.

2. Compensatory Stage • Reversible • Characterized by neural, hormonal and biomechanical attempts of the body to reverse lactic acidosis. • Hyperventilation – to get rid of increased carbon dioxide • Baroreceptors detect hypotension and release epinephrine and norepinephrine to increase HR and BP. • Impaired renal perfusion activates renin-angiotensin system to retain water and sodium which will cause vasoconstriction.

3. Progressive Stage • Not treating the underlying cause for shock will lead to the progressive stage. • • Compensatory mechanisms start failing. Increased acidosis due to continuing anaerobic metabolism. Fluid leakage out of the capillaries. Increased blood concentration and viscosity causing blockage of microcirculation.

4. Refractory Stage • • • Failure of vital organs. Severe cerebral ischemia and cell death. Widespread cell necrosis. Shock is irreversible at this point. Myocardial ischemia. There is no recovery from this stage (multiple organ failure) Complications: - cardiopulmonary arrest, dysrhythmias, organ failure, stroke and eventually death.

Signs and Symptoms of Shock • Clinical symptoms of shock vary based on the type of shock. • Some general symptoms for all types of shock are: q Hypotension q Oliguria q Confusion • But these symptoms may not always be present.

References • Amboss. com. (2019). Shock – Knowledge for medical students and physicians. [online] Available at: https: //www. amboss. com/us/knowledge/Shock [Accessed 27 Nov. 2019]. • Courses. lumenlearning. com. (2019). Circulatory Shock | Boundless Anatomy and Physiology. [online] Available at: https: //courses. lumenlearning. com/boundless-ap/chapter/circulatoryshock/ [Accessed 27 Nov. 2019]. • Healthline. 2019. Septic Shock: Symptoms, Causes, Diagnosis, Treatment & More. [ONLINE] Available at: https: //www. healthline. com/health/septic-shock#symptoms. [Accessed 26 November 2019]. • Medicine. Net. (2019). Definition of Neurogenic shock. [online] Available at: https: //www. medicinenet. com/script/main/art. asp? articlekey=85479 [Accessed 27 Nov. 2019]. • Nursing. unboundmedicine. com. (2019). Cardiogenic Shock | Diseases and Disorders. [online] Available at: https: //nursing. unboundmedicine. com/nursingcentral/view/Diseases-and. Disorders/73546/all/Cardiogenic_Shock [Accessed 27 Nov. 2019]. • Study. com. (2019). [online] Available at: https: //study. com/academy/lesson/obstructive-shockcauses-symptoms-treatment. html [Accessed 27 Nov. 2019].