Shock Flashcards
Types of shock
Hypovolemic
Cardiogenic
Circulatory Shock (Distributive)
Septic Shock
Neurogenic Shock
Anaphylactic Shock
Obstructive
Shock
is a condition where the blood pressure is inadequate to deliver oxygen and nutrients to support vital organs and cell function.
Hypovolemic shock
- decrease in intravascular volume S/S Hypotension Tachycardia Rapid, shallow respirations; cracks Decreased peripheral pulses Pale, cool extremities Decreased urinary output/oliguria Irritability, restlessness, lethargy
Cardiogenic shock
- impaired heart pumping
Circulatory shock
- maldistribution or mismatch of blood flow to the cells
Distributive shock
is defined as a change in vascular capacitance resulting in peripheral vasodilation and abnormal redistribution of blood flow.
Obstructive shock
is due to an obstruction of blood flow in the cardiovascular system. Caused by either
impairment of diastolic filling (decreased ventricular preload) excessive afterload (increased ventricular afterload)
Causes of obstructive shock
Impaired diastolic filling
- Cardiac (pericardial) tamponade
- Tension pneumothorax
- Hemothorax
- Mechanical ventilation
- Asthma
- Intrathoracic obstructive tumours
Impaired systolic contraction
- Right ventricle
Pulmonary embolus (massive)
Acute pulmonary hypertension
- Left ventricle
Saddle embolus
Aortic dissectionDescribe the hemodynamics of the hypovolemic, distributive and cardiogenic shock.
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Causes of cardiogenic shock
1) Coronary
- More common, seen most often in patients with an MI
- Occurs when a significant amount of left ventricular myocardium has been destroyed
2) Noncoronary
- Severe metabolic problems - severe hypoxemia, acidosis, hypoglycemia, and hypocalcemia
- Tension pneumothorax
Pharm. for cardiogenic shock
Vasoactive med therapy consists of using multiple drug therapies to restore and maintain adequate CO. The aim is to improve cardiac contractility, decrease preload and afterload, or a stable heart
1) Dobutamine (Dobutrex) - inotropic effects by stimulating myocardial beta receptors improving CO. Alpha-adrenergic receptors are also stimulated, decreasing pulmonary and systemic vascular resistance.
2) Nitroglycerin - by IV, venous vasodilator reducing preload. At high doses, causes arterial vasodilation and reduces afterload also.
3) Dopamine - vasoactive effects dependent on dosage
May be used with dobutamine and nitroglycerin to improve tissue perfusion
Low-dose dopamine (0.5-3.0 mcg/kg/min) increased renal perfusion and mesenteric flow. Does not affect cardiac output
Medium-dose dopamine (4-8 mcg/kg/min) has sympathomimetic properties and improves contractility and slightly increases heart rate
High-dose dopamine (8-10 mcg/kg/min) predominantly causes vasoconstriction, which increases afterload and thus increases cardiac workload. This is NOT DESIRED!
Central venous pressure (CVP)
Normal CVP is 3 to 8 mm Hg: pressure within the superior vena cava,
a) elevated indicates an increase in blood volume ie sodium and water retention, excessive IV fluids,alteration in fluid balance, or kidney failure
b) Decrease indicates a decrease in circulating blood volume ie fluid imbalance, hemorrhage, severe vasodilation, pooling of blood in extremities
Septic Shock
Type of circulatory (distributive shock), when the blood volume is abnormally displaced in the vasculature, causing relative hypovolemia, leading to inadequate tissue perfusion
Pathophysiology of septic shock
Microorganism invades body tissues and the patient exhibits an immune response
Activation of inflammatory response, producing increased capillary permeability and vasodilation
Phases of septic shock
1) Hyperdynamic, progressive phase - High cardiac output with systemic vasodilation;
2) Hypodynamic, irreversible phase - Low cardiac output with vasoconstriction - Reflects the body trying to compensate for the hypovolemia cause by the loss of intravascular volume through the capillaries
