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Understanding Shock in Emergency Care

May 12, 2025

Chapter 13: Shock - Emergency Care and Transportation of the Sick and Injured (12th Edition)

Overview

  • Understanding different types of shock
  • Process of perfusion
  • Signs and symptoms associated with shock
  • Application of assessment process with shock patients
  • General and specific emergency care for shock patients

Definitions

  • Shock (Hypoperfusion): Inadequate cellular perfusion leading to cellular injury or death.
  • Perfusion: Movement of molecules (oxygen and carbon dioxide) across alveoli.
  • Carbon Dioxide Transport: Dissolved in plasma, as bicarbonate, or attached to hemoglobin.

Early Stages of Shock

  • Body attempts to maintain homeostasis.
  • Poor perfusion (shock) impairs carbon dioxide transportation, results in waste buildup.

Cardiovascular System

  • Consists of the heart (pump), blood vessels (container), and blood (contents).
  • Perfusion Triangle: Heart, blood vessels, blood.
    • Shock implies dysfunction in one or more components.

Blood Pressure and Pulse

  • Blood Pressure: Pressure within vessels.
    • Systolic: Peak arterial pressure during heart contractions.
    • Diastolic: Pressure between heartbeats.
  • Pulse Pressure: Difference between systolic and diastolic pressures.
    • Indicates heart’s force; less than 85 mmHg may indicate shock.

Capillary Blood Flow

  • Regulated by capillary sphincters under autonomic nervous system control.
  • Influenced by stimuli like heat, cold, oxygen, waste removal.

Sympathetic Nervous System in Shock

  • Releases hormones (epinephrine, norepinephrine) increasing heart rate and contractions.

Causes of Shock

  • Pump Failure: Cardiogenic, obstructive shock.
  • Poor Vessel Function: Distributive shock (septic, neurogenic, anaphylactic, psychogenic).
  • Low Fluid Volume: Hypovolemic shock (hemorrhagic, non-hemorrhagic).

Types of Shock

Cardiogenic Shock

  • Caused by inadequate heart function.
  • Results in pulmonary edema due to blood backup.
  • Often associated with heart attack.

Obstructive Shock

  • Mechanical obstruction prevents adequate blood flow.
    • Cardiac Tamponade: Fluid in pericardial sac impairs heart contraction.
    • Tension Pneumothorax: Air in chest cavity collapses lung, pressures heart.
    • Pulmonary Embolism: Blood clot blocks pulmonary vessels.

Distributive Shock

  • Septic Shock: Severe infection causing vessel dilation and plasma loss.
  • Neurogenic Shock: Spinal injury causes loss of vessel tone below injury level.
  • Anaphylactic Shock: Severe allergic reaction causing vessel dilation.
  • Psychogenic Shock: Sudden nervous system reaction causing fainting.

Hypovolemic Shock

  • Inadequate fluid or blood volume.
  • Includes hemorrhagic (bleeding) and non-hemorrhagic causes.

Stages of Shock

  • Compensated Shock: Body maintains perfusion.
  • Decompensated Shock: Body fails to compensate.
  • Irreversible Shock: Beyond recovery without intervention.

Recognizing Shock

  • Blood pressure is last to change; significant drop indicates advanced shock.
  • Infants/children maintain BP until severe volume loss.

Emergency Care for Shock

  • Scene safety and mechanism determination.
  • Rapid primary assessment (ABCs, life threats).
  • Control hemorrhage before airway
  • High-flow oxygen, rapid transport.
  • Secondary assessment (trauma focus if necessary).
  • Ongoing reassessment.

Specific Treatments

  • Cardiogenic Shock: Avoid nitroglycerin if hypotensive, transport quickly.
  • Obstructive Shock: Manage airways, support oxygenation; ALS needed.
  • Septic Shock: Manage airway, support oxygenation, antibiotics needed.
  • Neurogenic Shock: Maintain airway, support breathing, preserve heat.
  • Anaphylactic Shock: Administer epinephrine, monitor airway closely.
  • Psychogenic Shock: Ensure safety during syncopal episodes, assess for injuries.
  • Hypovolemic Shock: Control bleeding, maintain airway, rapid transport.

Special Considerations

  • Older Patients: More complications, medications may mask/mimic shock.
  • Treat all shock patients with inline spinal stabilization where needed, maintain warmth, high-flow oxygen, rapid transport.

Review Questions Recap

  • Shock defined as hypoperfusion.
  • Anaphylactic shock linked to urticaria (hives).
  • Signs of compensated shock exclude weak/absent peripheral pulses.
  • Cardiogenic shock not caused by bacterial infection.
  • Septic shock indicated by elevated temperature and shock symptoms.

This concludes the notes from Chapter 13 on Shock, covering the fundamentals of shock types, symptoms, and treatments. Use these notes to review and understand shock management in emergency care.

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