Fundamentals of Hemodynamics Explained

Sep 25, 2024

Introduction to Hemodynamics

Understanding Hemodynamics

  • Hemodynamics is the study of blood flow and its equilibrium under external forces.
  • Essential for nurses to understand the basic parameters and how they interact.
  • Educational resources, including a free chart, available at NRSNG.com/hemodynamics.

Key Hemodynamic Terms

  • Heart Rate

    • Normal range: 60-100 beats per minute.
    • Affects the movement of blood through the body.
    • Directly impacts cardiac output.

  • Cardiac Output

    • Definition: Volume of blood leaving the left ventricle per minute.
    • Normal value: 4-8 liters per minute.
    • Varies based on individual body size.

  • Cardiac Index

    • Definition: Cardiac output divided by body surface area.
    • Normal range: 2.5-4 liters per minute per meter squared.
    • Provides a size-adjusted measure of cardiac output efficiency.

  • Stroke Volume

    • Definition: Volume of blood leaving the left ventricle per heart beat.
    • Normal value: 60-120 milliliters per beat.
    • Directly affects cardiac output.

Factors Affecting Stroke Volume

  1. Contractility (Inotropy)

    • Ability of the ventricles to squeeze blood out.
    • Influenced by drugs known as positive inotropes.

  2. Preload

    • End diastolic volume; the volume in ventricles at the end of filling.
    • Influenced by the amount of stretch in ventricles.
    • Increased by fluids/blood; decreased by diuretics/vasodilators.

  3. Afterload

    • The pressure ventricles must overcome to eject blood.
    • Influenced by systemic/pulmonary vascular resistance.
    • Modified by arterial vasodilators or vasopressors.

Managing Hemodynamic Parameters

  • Preload Adjustment

    • Increase: Administer fluids or blood.
    • Decrease: Use diuretics or ACE inhibitors.

  • Afterload Adjustment

    • Increase: Use vasopressors like norepinephrine or epinephrine.
    • Decrease: Use arterial vasodilators or intra-aortic balloon pumps.

Summary

  • Hemodynamics involves the interplay of heart rate, cardiac output, cardiac index, stroke volume, preload, afterload, and contractility.
  • Through therapeutic interventions, healthcare providers can adjust these parameters to optimize patient care.
  • Additional resources and educational materials are available online at NRSNG.com.

Note: Refer to the chart at NRSNG.com/hemodynamics for detailed values and therapy options. Feedback and questions are welcomed to enhance learning.