EMT PREP

CHAPTER 13: Shock

Introduction to Shock

  • Shock (hypoperfusion): Defined as inadequate cellular perfusion.
    • Any compromise in perfusion can lead to cellular injury or death.
    • Early stages: Body attempts to maintain homeostasis.

National EMS Education Standard Competencies

  • Shock and Resuscitation:
    • Integral knowledge of causes, pathophysiology, and management of:
    • Shock
    • Respiratory failure/arrest
    • Cardiac failure/arrest
    • Post-resuscitation management
  • Pathophysiology:
    • Applying knowledge of respiration and perfusion to assess and manage patients.

Pathophysiology of Shock (Detailed)

Fundamental Processes
  • Diffusion: Passive process where molecules move from areas of high concentration to low concentration.
    • Oxygen and carbon dioxide exchange occurs across alveolar walls.
Impairments in Shock
  • Poor Perfusion:
    • Transportation of carbon dioxide out of tissues is compromised.
    • Leads to buildup of waste and potential cellular damage.
Cardiovascular System Overview
  • Components of the Cardiovascular System:
    1. Pump: Heart
    2. Set of Pipes: Blood vessels or arteries
    3. Contents: Blood
  • Shock is a failure state of the cardiovascular system leading to inadequate circulation.
  • Perfusion Triangle: Implies that when a patient is in shock, one or more parts of this triangle are malfunctioning.
Blood Pressure and Perfusion
  • Blood Pressure: The force of blood in vessels at any moment.
    • Systolic Pressure: Peak arterial pressure.
    • Diastolic Pressure: Arterial pressure while the heart rests.
  • Pulse Pressure: The difference between systolic and diastolic pressures; a pulse pressure below 25 mm Hg can indicate shock.

Mechanisms and Needs for Perfusion

  • Blood flow regulation occurs in capillary beds through capillary sphincters, managed by the autonomic nervous system based on cellular requirements.
  • Effective perfusion requires:
    • Adequate oxygen exchange in the lungs.
    • Nutritional glucose in the bloodstream.
    • Waste removal, especially via lungs.
Body’s Response Mechanisms
  • Respiratory and Cardiovascular Support:
    • Hormonal responses triggered by perceived drops in pressure.
    • Resulting increases in:
    • Heart rate
    • Striking strength of heart contractions
    • Peripheral vasoconstriction
    • These responses induce the signs and symptoms associated with shock.

Causes of Shock

Major Causes of Shock
  1. Pump Failure: Inadequate function of the heart.
  2. Poor Vessel Function: Vascular dilation leading to insufficient blood retention.
  3. Low Fluid Volume: Often due to bleeding.
Examples of Shock Types
  • Cardiogenic Shock:
    • Caused by heart inadequacy.
    • Results in pulmonary fluid accumulation (pulmonary edema).
  • Obstructive Shock:
    • Mechanical obstruction preventing heart filling (e.g., cardiac tamponade, tension pneumothorax, pulmonary embolism).
  • Distributive Shock:
    • Caused by widespread blood vessel dilation (e.g., septic shock, neurogenic shock, anaphylactic shock).
  • Hypovolemic Shock:
    • Insufficient fluid volume in circulation.

Stages of Shock

  • Compensated Shock: Initial stage where the body can still compensate for blood loss.
  • Decompensated Shock: Advanced stage with dropping blood pressure; needs immediate treatment.
  • Progression: Blood pressure is often the last measurable change indicating shock severity.

Assessment and Treatment of Shock

Scene Evaluation and Patient Assessment
  • Keep safety in mind; use protective gear where necessary.
  • Evaluate mechanism of injury/nature of illness during scene size-up.
Primary Assessment Steps
  1. Perform a rapid exam and determine consciousness level.
  2. Identify life-threatening concerns and prioritize transport.
  3. Provide high-flow oxygen if hypoperfusion is suspected.
  4. Look for vital signs (cool, clammy skin, rapid pulse as indicators of shock).
Reassessment Procedure
  • Regularly reassess vital signs, interventions, and mental status. Ensure adequate oxygen supply and warmth for the patient.

Emergency Medical Care for Shock

  • Begin treatment immediately upon recognition of shock.
  • Key steps:
    • Control bleeding.
    • Ensure open airway.
    • Provide reassurance and comfort to the patient.
    • Avoid oral intake until evaluated.
    • Monitor vital signs continuously, recording approximately every 5 minutes.

Specific Shock Treatments

Cardiogenic Shock
  • Main goal: Increase cardiac output.
  • Avoid nitrates due to hypotensive risk.
Obstructive Shock Management
  • Cardiac tamponade: Prioritize increasing cardiac output and arrange for surgical intervention.
  • Tension pneumothorax: Immediate chest decompression is required.
Septic Shock
  • Treatment focuses on oxygen support and body warming; notify the sepsis team if needed.
Neurogenic Shock
  • Maintain airway and provide spinal immobilization. Attend to breathing assistance and circulation control.
Anaphylactic Shock
  • Administer epinephrine, transport promptly, and ensure oxygenation.

Shock in Older Patients

  • Recognize that older patients may have more severe complications, especially with medications that can mask shock signs.

Review Questions

  1. Shock is most accurately described as:
    • A: Cardiovascular collapse leading to inadequate perfusion. (Correct)
  2. Anaphylactic shock is associated with:
    • A: Urticaria (hives). (Correct)
  3. In cardiogenic shock, potential causes include:
    • A: Impaired electrical systems or inadequate heart function (Correct); severe bacterial infection is not primarily a cause of cardiogenic shock.
  4. A patient exhibiting hypotension following venous pooling and bradycardia indicates neurogenic shock. Tachycardia would be absent.
  5. Recognition of hypovolemic shock is critical, especially in injuries like internal bleeding cases.