Summary
Highlights
Shock is a critical condition characterized by decreased tissue perfusion, leading to organ failure and death, with severely low blood pressure as a classic sign. The four stages of shock are: Initial (anaerobic metabolism, no visible symptoms), Compensatory (body attempts to maintain perfusion with tachycardia, tachypnea, sympathetic nervous system activation), Progressive (compensatory mechanisms fail, key sign is cold and clammy skin, indicating worsening perfusion), and Irreversible (death is imminent).
There are five main types of shock: septic (widespread bloodborne infection), neurogenic (spinal cord injury T6 or higher), hypovolemic (significant blood or fluid loss), cardiogenic (heart failure to pump blood), and anaphylactic (severe allergic reaction).
Septic shock results from widespread bloodborne infection causing extreme vasodilation and capillary fluid leakage. Key signs include severely low blood pressure (<80 systolic), cool clammy skin, mental status changes (confusion/disorientation due to hypoxemia), high WBC count, and initially high then very low core body temperature (below 96°F). Emergency treatment involves intravenous fluids and antibiotics.
Neurogenic shock is caused by spinal cord injury (T6 or higher), leading to sympathetic nervous system blockage and parasympathetic dominance. This causes widespread vasodilation and hypotension, resulting in 'low and slow' vitals: bradycardia (<60 bpm), hypotension (<80 systolic), and warm, pink, dry skin due to blood pooling. Priority intervention is IV normal saline to increase blood pressure and perfusion. A deadly complication is autonomic dysreflexia, triggered by bladder distension, constipation, or tight clothing.
Hypovolemic shock results from low blood or fluid volume due to severe loss (diarrhea, vomiting, burns, hemorrhage, surgery). Key signs include cold clammy skin (a priority sign of progressive stage), hypotension (<80 systolic), tachycardia (compensatory mechanism), and low central venous pressure (<2). Low urinary output (<30 mL/hr) is also a classic sign. Interventions include lowering the head of the bed to promote blood flow to the brain and core, and administering IV normal saline *before* vasopressors. Maintaining MAP >65 mmHg and CVP between 2-6 mmHg are critical goals. If CVP is <2, increase IV fluids; if >6, administer diuretics. Pulse oximetry on the forehead is recommended due to shunting of blood from extremities.
Cardiogenic shock occurs when the heart fails to pump blood effectively, as seen in heart attacks or heart failure exacerbations. It's characterized by severely low blood pressure. Key treatments involve medications with inotropic properties to increase the force of heart contraction: dopamine (also a vasopressor) and digoxin. A caution with vasopressors like dopamine is the potential for adverse effects like tachycardia (>100 bpm) and arrhythmias. Digoxin helps achieve a 'deeper contraction' for a failing heart.
Anaphylactic shock is a severe allergic reaction (e.g., bee sting, food allergy) causing deadly hypotension and bronchoconstriction. The first-line treatment is epinephrine (EpiPen) injected immediately into the outer thigh (90° angle, hold for 10 seconds). Epinephrine should be repeated every 5-15 minutes if symptoms persist until they resolve. Signs of deadly anaphylaxis affect ABCs (airway, breathing, circulation) or cause hives. After symptoms resolve, other medications like diphenhydramine (Benadryl), albuterol, and steroids may be given. Post-injection, seek immediate medical attention as epinephrine wears off (10-20 minutes). EpiPens should be stored in a dark place at room temperature.