This episode breaks down the complex topic of hemodynamics into simple terms for nursing students, especially those preparing for the NCLEX. Learn how blood flows through the body and how the heart functions as a pump to deliver oxygen to vital organs. We explore key concepts like stroke volume, heart rate, cardiac output, and the factors that influence blood flow, including preload, afterload, and contractility. Through practical examples and easy-to-remember tools, this episode equips nurses with the knowledge to monitor and intervene in hemodynamic imbalances, making it an essential guide for both new nurses and NCLEX prep.
Episode Notes:
What is Hemodynamics?
Hemodynamics refers to how blood flows through the body, with the heart acting as a pump, blood vessels as pipes, and blood as the carrier of oxygen to the body’s organs.
The nurse's role: monitor blood flow and intervene to prevent complications.
The Three Big Pieces of the Heart Pump
Stroke Volume (SV): Amount of blood pumped per heart beat (60-100 mL).
Heart Rate (HR): Number of heart beats per minute (60-100).
Cardiac Output (CO): Total blood pumped per minute (SV x HR).
Example: SV of 70 mL and HR of 80 = 5.6 L/min of cardiac output.
What Controls Stroke Volume?
Preload: Blood volume returning to the heart.
Afterload: Resistance in the arteries that the heart must push against.
Contractility: Strength of the heart muscle's contraction.
How Do We Measure These?
Blood Pressure: Tells how hard the heart is pushing.
Heart Rate: Monitored via pulse or ECG.
CVP (Central Venous Pressure): Shows how full the right side of the heart is.
Urine Output: A sign of kidney perfusion.
Skin Temperature/Capillary Refill: Indicates blood flow to tissues.
What Goes Wrong?
Hypovolemic Shock: Low blood volume → Low BP, high HR, low CVP.
Cardiogenic Shock: Weak heart muscle → Low BP, high CVP, fluid in lungs.
Septic Shock: Wide blood vessels → Low BP despite high heart rate.
Heart Failure: Heart gradually loses pumping efficiency, causing fluid retention.
Basic Medications & Interventions
IV Fluids: Boost preload if too low.
Diuretics (Lasix): Reduce preload if too high.
Vasodilators (Nitroglycerin): Lower afterload.
Vasopressors (Norepinephrine): Raise BP when afterload is low.
Inotropes (Dobutamine): Increase contractility if the heart is weak.
Nurse’s Simple Checklist
Blood Pressure and Heart Rate: Normal?
Skin Warmth & Capillary Refill: Fast return to color?
Urine Output: More than 30 mL/hr?
Lungs: Clear or crackly?
Neck Veins: Flat or bulging?
Weight Gain: More than 2 lbs overnight?
Real-Life Examples (NCLEX Exam Style)
Mr. Jones (Hypovolemic Shock): Low BP, high HR, no urine—needs fluids.
Mrs. Smith (Heart Failure): High BP, crackling lungs, swollen legs—needs Lasix.
Ms. Lee (Sepsis): Low BP, high HR, warm skin—needs norepinephrine.
Why Novice Nurses Must Know This
Nurses are the first line of defense at the bedside. Understanding hemodynamics helps catch problems early and saves lives.
Quick Reference Card (Print & Keep in Your Pocket!)
CO = SV × HR → Goal: 4–8 L/min
↓ Preload → IV Fluids
↑ Preload → Lasix
↑ Afterload → Nitroglycerin
↓ Afterload → Norepinephrine
↓ Contractility → Dobutamine
Red Flags: ↓ BP, ↓ Urine, Cold Skin, Crackles, Swelling → CALL MD!