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

Overview

• Shock, also known as hypoperfusion, is defined as inadequate cellular perfusion.
• It can lead to cellular injury or death due to inadequate circulation.
• Key elements of shock:
  • Perfusion: Passive diffusion process of molecules from high to low concentration across alveoli.
  • Oxygen delivery via hemoglobin.
  • Impaired carbon dioxide transport leading to waste buildup.

Cardiovascular System and Shock

• Comprised of three parts: heart (pump), blood vessels (container), and blood (contents).
• Shock results from failure in one or more of these parts.
• Systolic pressure: Peak arterial pressure during heart contraction.
• Diastolic pressure: Arterial pressure during heart rest.
• Pulse pressure: Difference between systolic and diastolic pressures; low pulse pressure indicates potential shock.

Types of Shock

1. Pump Failure

• Cardiogenic Shock: Caused by inadequate heart function or heart attack, leading to pulmonary edema.
• Obstructive Shock: Due to mechanical obstructions:
  • Cardiac Tamponade: Fluid in pericardial sac, identified by Beck's Triad (jugular vein distension, muffled heart tones, narrowing pulse pressures).
  • Tension Pneumothorax: Collapsed lung causing pressure on organs.
  • Pulmonary Embolism: Blood clot in pulmonary circulation.

2. Poor Vessel Function (Distributive Shock)

• Septic Shock: Severe infection causing vessel dilation and plasma loss.
• Neurogenic Shock: Spinal cord injury leading to vessel dilation.
• Anaphylactic Shock: Severe allergic reaction.
• Psychogenic Shock: Nervous system response causing vasodilation.

3. Low Fluid Volume

• Hypovolemic Shock: Inadequate blood volume, caused by factors such as hemorrhage or burns.

Stages of Shock

• Compensated Shock: Body maintains perfusion.
• Decompensated Shock: Advanced stage with declining physiological function.
• Irreversible Shock: Beyond recovery; requires early intervention.
• Blood pressure drop is a late sign of shock, especially critical in infants and children.

Emergency Care and Management

• Scene Size-Up: Ensure scene safety, determine mechanism of injury or illness.
• Primary Assessment: Rapid exam, address life-threatening issues immediately.
• Airway Management: Ensure airway is clear and patent.
• Circulation: Assess circulatory status, manage bleeding.
• Treatment Priorities: Control bleeding, provide high-flow oxygen, maintain body temperature, transport promptly.
• Reassessment: Continuously monitor patient's vital signs and condition.

Specific Treatments by Shock Type

• Cardiogenic Shock: Avoid nitroglycerin if hypotensive; provide high-flow oxygen.
• Obstructive Shock:
  • Cardiac Tamponade: Requires surgery.
  • Tension Pneumothorax: Requires chest decompression.
  • Pulmonary Embolism: Requires specific medical interventions.
• Septic Shock: Requires antibiotics; maintain body temperature.
• Neurogenic Shock: Maintain airway and provide support.
• Anaphylactic Shock: Administer epinephrine immediately.
• Hypovolemic Shock: Control bleeding, provide oxygen and rapid transport.

Treatment in Special Populations

• Older Patients: More complications and potential for masked symptoms due to medications.
• Children and Infants: Require careful monitoring as blood pressure drops are critical signs of advanced shock.

Conclusion

• Early recognition and rapid treatment of shock are crucial to patient survival.
• Always consider shock in patients with serious injuries or conditions and manage aggressively.