Shock and Its Management

Shock: Understanding and Management

Fuel Tank Analogy for Shock

• Understanding shock requires visualizing the body as a system with a gas tank (blood volume), fuel lines (blood vessels), and a fuel pump (heart).
• The heart acts as the fuel pump, circulating blood.
• Blood vessels (arteries and veins) are the fuel lines.
• The volume of blood in the body represents the fuel tank's contents.
• All components are interconnected; the failure of one affects the others.
  • If the pump (heart) fails, blood circulation ceases, regardless of fluid volume or vessel condition.
  • Excessively dilated vessels leading to low pulse pressure (less than 20 or 25) render pump function and fluid volume irrelevant.

Causes of Fluid Loss and Vessel Dilation

• Severe trauma can cause fluid loss from the system.
• Vessel dilation can result from:
  • Medications like Viagra, especially in elderly patients when combined with other drugs.
  • Infections, particularly UTIs in geriatric patients, leading to sepsis and universal vasodilation.
  • Nursing homes may delay calling for help until blood pressure drops, the last sign of shock.

Native Feedback Loops

• Perfusion relies on native feedback loops managed by the autonomic nervous system.
• The body attempts to compensate for problems via a negative feedback loop, sending signals to the brain to trigger responses.
• The autonomic nervous system releases hormones that stimulate:
  • Increased heart rate and force of contraction to compensate for falling blood pressure.
  • Vasoconstriction to increase blood pressure.

Why Understanding Shock Matters

• Identifying the specific type of shock helps determine the appropriate treatment course.
• Aggressive treatment is essential for patients presenting in shock; immediate action is crucial.

Initial Steps in Managing Shock

• Control major bleeding with:
  • Direct pressure.
  • Gauze.
  • Tourniquets (increased use in EMS).
  • Wound packing (to be taught later).
• Secure and maintain the airway by:
  • Opening it using head-tilt/chin-lift or jaw-thrust maneuvers.
  • Ensuring it is patent (clear).
  • Assessing if it's protected (patient can speak and swallow).
    • A patent airway requires the patient to speak and swallow, indicating it's clear and protected.
    • Unconscious patients may have a patent but unprotected airway.
• In trauma cases, maintain C-spine stabilization due to its role in breathing and heart stimulation.
• Calm and reassure panicking patients, keeping them informed about the situation, and refrain from offering food or drink.

Impact of Body Temperature

• Patients losing blood volume become cold as their body temperature drops.
• Hypothermia can lead to blood vessel dilation and decreased heart rate, exacerbating shock.
• A key treatment is to cover the patient with a blanket to conserve body heat, irrespective of the ambient temperature.

Prioritization and Reassessment

• Patients in shock are high priority and require frequent reassessment (every 3 to 5 minutes).

Types of Shock

• Four main categories: cardiogenic, obstructive, distributive, and hypovolemic.

Cardiogenic Shock

• Pump failure due to heart malfunction.
• Example: myocardial infarction (heart attack) where cellular tissue dies due to a clot.

Obstructive Shock

• Pump failure due to an obstruction preventing the heart from pumping effectively, not directly the heart's fault.
• Examples:
  • Tension Pneumothorax:
    • Air accumulates in the thoracic cavity due to lung trauma, collapsing the lung.
    • Pressure constricts the heart, limiting its ability to expand and fill with blood.
    • Requires ALS intervention for needle decompression.
  • Cardiac Tamponade:
    • Blood accumulates in the sac around the heart (pericardial sac) due to chest trauma (e.g., motor vehicle accidents, sports injuries).
    • Pressure prevents the heart from expanding and filling with blood.
    • The heart is essentially bleeding into its own sac, restricting movement.
  • Pulmonary Embolism:
    • A clot in the lungs blocks blood flow, reducing the amount returning to the heart.
    • Tissue death occurs around the clot, further restricting blood flow.

Distributive Shock

• Poor vessel function leading to universal vasodilation.
• Includes septic, neurogenic, anaphylactic, and psychogenic shock.
  • Septic Shock:
    • Often caused by UTIs, leading to widespread vasodilation.
    • Heart function and blood volume remain unchanged; the problem lies in vessel dilation.
  • Neurogenic Shock:
    • Results from spinal injuries, causing the body to lose its ability to compensate, leading to vasodilation.
  • Anaphylactic Shock:
    • A severe allergic reaction causing vasodilation and dropping blood pressure.
    • Treated with epinephrine (alpha-1 agonist that causes vasoconstriction and increased heart rate) and Benadryl (histamine receptor blocker).
  • Psychogenic Shock:
    • Stress-induced, often from anxiety attacks.
    • The body suddenly vasodilates, leading to fainting.
    • Usually self-corrects once the patient is supine.

Hypovolemic Shock

• Caused by inadequate fluid volume, mainly due to trauma.
• Types:
  • Hemorrhagic: bleeding.
  • Non-Hemorrhagic: nausea, vomiting, diarrhea.
• Cardiac tamponade is classified as obstructive rather than hypovolemic shock because its primary mechanism involves external compression of the heart, impairing its function rather than direct blood loss from the circulatory system.

Cardiogenic Shock Treatment Considerations

• Avoid nitro, as it worsens the condition by dilating vessels when the heart is already failing.
• Distinguishing between cardiac tamponade and myocardial infarction:
  • Cardiac tamponade presents with Beck's Triad: JVD, muffled heart tones, and narrowing pulse pressure (less than 25).

Beck's Triad

• Jugular Vein Distension (JVD): blood has difficulty returning to the heart, causing jugular veins to protrude.
• Muffled Heart Tones: auscultation reveals quiet heart sounds due to blood around the heart.
• Narrowing Pulse Pressure: systolic and diastolic pressures equalize as blood pressure drops due to blood loss.

Obstructive Shock Presentations

• Hypotension, hypoxia, and potential trauma.

Distributive Shock Treatment

• Causes widespread vasodilation, leading to blood pooling and reduced circulation.

Septic Shock Treatment

• High-flow oxygen (10-15 liters per minute via non-rebreather mask).
• Blankets for warmth.
• Immediate transport with notification to the hospital of "code sepsis".

Anaphylactic Shock Treatment

• High-flow oxygen, potentially ventilatory assistance (BVM with 15-25 liters per minute).
• Epinephrine (adult dose: 0.3 mg intramuscularly, pediatric dose: 0.15 mg intramuscularly).
  • Use a filter needle to draw medication and a hypodermic needle to inject.
• Benadryl (adult dose: 25-50 mg, route: IM).
  • Blocks histamine receptors.

Psychogenic Shock Treatment

• Oxygen, trauma management if needed, C-spine maintenance if needed.
• Offer transport.

Neurogenic Shock Treatment

• Trauma management, C-spine maintenance, high-flow oxygen.
• ALS contact if needed for transport to appropriate facility.

Hospital Levels

• Level 1 & 2: Can handle anything.
• Level 3: Basic Management.
• Level 4: band-aids (urgent care).

Hypovolemic Shock

• Inadequate fluid volume (hemorrhagic or non-hemorrhagic).
• Severe thermal burns lead to fluid loss through the integumentary system.
  • Superficial (epidermis).
  • Deep (dermis + blistering presentation).
  • Third degree (burns through and affects everything).: burn off fat to bone.

Burn Management

• Cover with dry, sterile burn blankets.
• Immediately call ALS and a helicopter.
• Control bleeding and maintain warmth and airway.

Burns and Their Impact on the Body

• Insulation
• Maintains homeostasis
• Protects Blood
• Potentially cauterizes the vessel shut

Compensated vs. Decompensated Shock

• Blood pressure drops and radial pulse disappears
• Pulse disappears around a 60-70 systolic

Factors Affecting Older Patients Experiencing Shock

• Their bodies are generally weaker, with compromised immunity and organ function.
• Older individuals may be less receptive to pain.
• They may have a reduced ability to compensate for shock.
• Polypharmacy: older people often take multiple medications that can mask signs of shock.
• Blood pressure medications can interfere with shock presentation.