Chapter 13: Shock - Emergency Care and Transportation of the Sick and Injured

Key Concepts

• Understanding different types of shock, the process of perfusion, signs and symptoms, assessment, and emergency care
• Shock is often referred to as hypoperfusion, indicating inadequate cellular perfusion
• Early stages involve the body attempting to maintain homeostasis

Perfusion and Shock

• Perfusion: Inadequate circulation leading to cellular injury or death
• Diffusion: Passive process where molecules move from high to low concentration (e.g., oxygen and carbon dioxide across alveoli)
• Oxygen is carried attached to hemoglobin; carbon dioxide transported in blood as dissolved in plasma, bicarbonate, or attached to hemoglobin
• Poor perfusion (shock) leads to impaired CO2 transportation, waste buildup, and cellular damage

Cardiovascular System and Perfusion Triangle

• Consists of heart (pump), blood vessels (container), and blood (contents)
• Perfusion Triangle: When in shock, one or more parts fail
• Blood Pressure: Systolic (peak pressure) and diastolic (resting pressure)
  • Pulse pressure = Systolic - Diastolic
• Capillaries: Blood flow regulated by sphincters controlled by autonomic nervous system
• Regulation: Requires sufficient oxygen, nutrients, and waste removal

Causes of Shock

• Pump Failure: Cardiogenic and obstructive shock
  • Cardiogenic: Poor heart function, often post-heart attack
  • Obstructive: Mechanical obstruction (e.g., cardiac tamponade, tension pneumothorax, pulmonary emboli)
• Poor Vessel Function: Distributive shock (septic, neurogenic, anaphylactic, psychogenic)
• Low Fluid Volume: Hypovolemic shock (hemorrhagic and non-hemorrhagic)

Types of Shock

• Cardiogenic Shock: Inadequate heart function, often due to heart failure
• Obstructive Shock:
  • Cardiac Tamponade: Fluid in pericardial sac (Beck's triad: JVD, muffled heart tones, narrowing pulse pressure)
  • Tension Pneumothorax: Air pressure in chest cavity
  • Pulmonary Embolism: Blood clot blocking pulmonary vessels
• Distributive Shock:
  • Septic Shock: Severe infection leading to vessel dilation and plasma loss
  • Neurogenic Shock: Spinal cord injury causing vessel dilation
  • Anaphylactic Shock: Severe allergic reaction
  • Psychogenic Shock: Sudden nervous system reaction causing fainting
• Hypovolemic Shock: Low blood volume from bleeding or dehydration

Stages of Shock

• Compensated Shock: Body attempts to compensate
• Decompensated Shock: Body unable to maintain blood pressure
• Irreversible Shock: Organ damage is permanent

Shock Management

• Scene Size-Up: Ensure safety, determine MOI/NOI
• Primary Assessment: Rapid exam, assess LOC, ABCs, manage life threats
• History Taking: Chief complaint, SAMPLE history
• Secondary Assessment: Focused physical exam, reassess as needed
• Treatment:
  • Control bleeding, provide oxygen, maintain body temperature
  • Specific treatments for different shock types (e.g., epi for anaphylaxis, surgery for cardiac tamponade)
• Transport Considerations: Determine priority, consider ALS

Special Considerations

• Pediatric and Geriatric Patients: Higher risk, differences in physiological response
• General Care: Spinal stabilization if needed, control bleeding, oxygen, warmth, rapid transport

Review Questions

• Shock defined as hypoperfusion
• Anaphylactic shock often involves urticaria (hives)
• Signs of compensated shock differ from decompensated shock
• Cardiogenic shock excludes bacterial infections, which are typically distributive
• Septic shock indicated by high temperature
• Neurogenic shock lacks tachycardia due to nervous system compromise

These notes summarize the key points from Chapter 13 on shock, covering the types, causes, symptoms, and emergency management strategies, providing a useful reference for study and review.