Chapter 13: Shock

Overview

• Focus on understanding shock types, perfusion process, signs and symptoms, assessment, and emergency care.
• Shock is often referred to as hypoperfusion, defined as inadequate cellular perfusion.

Perfusion

• Diffusion: Passive process where molecules move from high to low concentration.
• Oxygen carried by hemoglobin; carbon dioxide transported in plasma, as bicarbonate, and attached to hemoglobin.
• Impaired carbon dioxide transportation can lead to waste buildup and cellular damage.

Shock

• A state of collapse and failure of the cardiovascular system.
• Blood flow directed from low tolerance organs (e.g., skin) to high tolerance organs (e.g., heart, brain).

Cardiovascular System

• Consists of the pump (heart), container (blood vessels), and contents (blood).
• Perfusion Triangle: Heart, blood vessels, blood. If shock occurs, one or more parts are malfunctioning.

Blood Pressure

• Systolic Pressure: Arterial pressure when heart contracts.
• Diastolic Pressure: Pressure in arteries between heartbeats.
• Pulse Pressure: Difference between systolic and diastolic pressures; less than 25 mm Hg can indicate shock.

Blood Flow Regulation

• Regulated by capillary sphincters controlled by the autonomic nervous system.
• Blood flow determined by cellular needs and requires adequate oxygen, nutrients, and waste removal.

Mechanisms Supporting Perfusion

• Autonomic Nervous System: Sympathetic side controls fight or flight.
• Hormones: Epi and norepi increase heart rate and contraction strength.

Causes of Shock

• Pump Failure: Cardiogenic and obstructive shock (e.g., cardiac tamponade, tension pneumo, pulmonary emboli).
• Poor Vessel Function: Distributive shock (e.g., septic, neurogenic, anaphylactic, psychogenic).
• Low Fluid Volume: Hypovolemic shock (e.g., hemorrhagic).

Types of Shock

1. Cardiogenic Shock:

   • Caused by inadequate heart function, often due to heart failure.
   • Can lead to pulmonary edema.

2. Obstructive Shock:

   • Caused by mechanical obstructions, preventing blood flow.
   • Includes cardiac tamponade, tension pneumothorax, and pulmonary embolism.

3. Distributive Shock:

   • Due to widespread vessel dilation.
   • Types: septic, neurogenic, anaphylactic, psychogenic.

4. Hypovolemic Shock:

   • Results from inadequate fluid volume (e.g., severe burns).

Stages of Shock

• Compensated Shock: Body compensates to maintain perfusion.
• Decompensated Shock: Body cannot maintain perfusion, leading to drop in blood pressure.
• Irreversible Shock: Late stage, difficult to determine onset.

Emergency Care and Assessment

1. Scene Size-Up:

   • Ensure scene safety, determine mechanism of injury.

2. Primary Assessment:

   • Rapid exam, assess LOC, and address life-threatening issues.

3. ABCs:

   • Airway and breathing checks.
   • Circulation assessment for shock indications.

4. Interventions and Transport:

   • Provide high flow oxygen, manage hypoperfusion aggressively, consider ALS support.

5. History and Secondary Assessment:

   • Obtain sample history, perform focused physical exam, and check vital signs.

Treatment Protocols

• Begin treatment as soon as shock is recognized.
• Control bleeding, ensure open airway, calm and reassure patient.
• Prevent heat loss; transport and treat injuries en route.

Specific Treatments by Shock Type

• Cardiogenic: High flow oxygen, prompt transport, avoid nitro if hypotensive.
• Obstructive: High flow oxygen, surgery for tamponade, ALS for tension pneumo.
• Septic: Hospital management and antibiotics.
• Neurogenic: Spinal stabilization, airway management.
• Anaphylactic: Administer epinephrine, high flow oxygen.
• Hypovolemic: Stop bleeding, maintain airway, rapid transport.

Considerations for Special Populations

• Older Patients:
  • Complications can be more severe; medications may affect symptoms.
• Pediatric Patients:
  • Similar treatment approach as adults, but be alert to rapid deterioration.

Conclusion

• Early recognition and aggressive treatment of shock are crucial.
• Monitor vital signs, maintain body temperature, and provide continuous reassessment.

This concludes the chapter on shock, emphasizing the importance of recognizing and treating shock promptly to improve patient outcomes.