Shock: Part 1

Shock and Hypoperfusion

• Shock: Defined as hypoperfusion, meaning insufficient blood flow to tissues.

• Perfusion: Indicates adequate delivery of oxygen and nutrients to tissues; requires three essential components:

  • Effective heart functioning as a pump.

  • Adequate oxygen and gas exchange.

  • Proper blood vessel integrity to prevent blood loss.

The Three Components of Adequate Perfusion

• Heart Function: Must effectively pump blood.

  • A malfunction leads to inadequate blood delivery and hypoperfusion.

• Oxygen: Essential for cellular functions; oxygen must move from the lungs to pulmonary capillaries and then to tissues through the aorta.

• Blood Vessels: Must maintain structure to avoid blood loss and ensure proper circulation.

  • Compromise in any element can lead to shock.

Stages of Shock

• Shock progresses through three stages:

  • Stage One: Compensation Stage

    • Body's crisis mode, attempting to compensate for shock through various mechanisms.

    • Symptoms include:

      • Tachycardia (increased heart rate).

      • Vasoconstriction (narrowing of blood vessels).

      • Increased respiratory rate.

      • Kidneys retain fluid to conserve blood volume.

    • Patient may exhibit confusion and cool extremities.

  • Stage Two: Decompensation Stage

    • Point of system failure; critical physiological changes occur.

    • Key features include:

      • Hypotension (systolic blood pressure falls below 90).

      • Severe alteration of mental status, potential unresponsiveness.

      • Further increased heart rate (e.g., from 110 to 130+).

      • Rapid respiratory rate increase (from 22 to 28-30+).

      • Physical changes such as delayed cap refill and cyanosis.

      • Overall systemic failure with cool extremities as blood diverts to core.

  • Stage Three: Irreversible Shock

    • Considered lethal; significant organ damage has occurred that cannot be reversed.

    • Symptoms include:

      • Severe hypotension.

      • Lethal EKG changes, such as V-tach or V-fib.

      • Heart may initially slow down (bradycardia) before arrest occurs.

      • Patient enters coma or multi-organ failure stage.

Body's Compensatory Mechanisms in Shock

• The body activates three main pathways during Stage One compensation:

  • Sympathetic Nervous System: Releases hormones aiming to stabilize.

    • Increases heart rate and vasoconstriction to elevate blood pressure and cardiac output.

  • Hormonal Responses:

    • ADH (Antidiuretic Hormone) from the pituitary helps retain fluid.

    • Aldosterone from adrenal glands retains sodium and water.

    • Epinephrine is crucial, affecting three receptor types:

      • Alpha receptors: Cause vasoconstriction.

      • Beta-1 receptors: Increase heart rate and contractility.

      • Beta-2 receptors: Open and dilate the airways for better oxygen exchange.

Summary

• Understanding shock involves recognizing how perfusion works and identifying stage progression in patients. Immediate recognition and intervention in these stages are critical to preventing irreversible damage.