CPR APPLICATIONS FOUNDATION · CHAPTER 6 · NORMAL
Normal Foundations of the Cardiovascular System
Organize the chapter before drilling into individual CPR concepts.
Supplemental foundation map: this page orients the detailed CPR Applications for Chapter 6. It is not part of the canonical CPR object inventory.
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Normal Foundations · You are here
Abnormal Foundations
Treatment Foundations
6.1 · SOURCE CPR FOUNDATION
Concept
The cardiovascular system is a pressure-volume-flow system built around perfusion. Pressure, volume, resistance, heart rate, and contractility determine cardiac output and tissue oxygen delivery. Step 1 often asks how changing one variable shifts the rest of the system.
Pattern
Cardiovascular vignettes repeatedly wrap disease and drugs around the same hemodynamic core. Changes in preload, afterload, contractility, or heart rate predict cardiac output, blood pressure, murmurs, congestion, and perfusion symptoms. The clinical findings usually reflect either failed forward flow or backward congestion.
Rule
- Translate the vignette into hemodynamic variables: identify preload, afterload, contractility, and heart rate before naming the disease.
- Predict forward flow and backward pressure: low output causes hypoperfusion, while elevated upstream pressure causes congestion.
- Use symptoms to locate the failure: syncope, fatigue, and cool extremities suggest low forward flow; dyspnea, edema, and JVP elevation suggest congestion.
Applications
- Severe aortic stenosis → exertional syncope
- Left-sided backward failure → pulmonary congestion
- Right-sided backward failure → elevated JVP and edema
- Low forward flow → cool extremities and fatigue
- Increased demand with fixed output → exertional symptoms
CPR APPLICATIONS · ACTIVE REASONING
Predict flow, resistance, and congestion
Make a prediction before checking the explanation. Every worked answer is also available below without scripts. No learner answers are transmitted or retained.
Reveal worked answer and changed-variable prompt
Best answer: 5.25 L/min. Correct. Cardiac output equals heart rate multiplied by stroke volume: 75 × 70 = 5,250 mL/min.
Transfer: If stroke volume decreases to 50 mL while heart rate is unchanged, what is the new output? 3.75 L/min.
Reveal worked answer and changed-variable prompt
Best answer: Reduced baroreceptor firing and increased sympathetic outflow. Correct. Reduced stretch of carotid/aortic baroreceptors produces reflex sympathetic activation and vagal withdrawal.
Transfer: How would β-blockade modify the heart-rate component of this compensation?
Reveal worked answer and changed-variable prompt
Best answer: Pulmonary venous/capillary circulation. Correct. High left-sided filling pressure is transmitted backward to the pulmonary venous circuit and may cause interstitial or alveolar edema.
Transfer: If the predominant failure shifts to the right ventricle, which signs become more likely? Raised JVP and peripheral edema.
Change the mechanism
Reference consequences without scripts
- Increase systemic vascular resistance while cardiac function is limited: Greater afterload may lower stroke volume and reduce forward flow, depending on compensatory responses.
- Reduce preload acutely in a volume-dependent heart: Reduced filling may reduce stroke volume by the Frank–Starling relationship.
- Increase left-sided filling pressure: Pulmonary venous congestion and dyspnea become more likely.
Explain it back: State the causal chain in your own words and identify which observation would falsify your first prediction.
These are educational, unscored self-checks rather than validated assessments or clinical treatment advice.
How to use this foundation map
- Identify the organizing mechanism.
- Recognize the pattern.
- Restate the rule without looking.
- Test transfer with the applications and question practice.
Pair CPR with the 5P Approach™ when solving cases and questions.