12 Questions
What is the primary cause of the dicrotic notch in the arterial waveform?
Aortic valve closure
In the central venous pressure waveform, what event corresponds to the X descent?
Atrial relaxation
What is the effect of aortic regurgitation on pulse pressure?
Pulse pressure increases
During which phase of the cardiac cycle is the mean arterial pressure primarily determined?
2/3 diastole + 1/3 systole
What is the primary cause of a narrow pulse pressure?
Heart failure
During which phase of the cardiac cycle does the C wave occur in the central venous pressure waveform?
Tricuspid valve closure
What is the primary purpose of an arterial line?
To continuously monitor blood pressure
Which of the following is NOT a common access site for arterial lines?
Ulnar artery
What can be inferred from a Wiggers diagram?
Ventricular contraction and atrial repolarization
What is the main advantage of a central venous line over an arterial line?
It provides access for infusing fluids and medications
Which of the following is NOT a function of a Swan-Ganz catheter?
Monitoring of pulse rate and rhythm
What can be monitored using an arterial line, but not using a central venous line?
Blood pressure
Study Notes
Arterial Lines
- Provide continuous monitoring of blood pressure
- Access sites: radial, brachial, femoral, and tibial arteries (radial and femoral are most common due to easy accessibility)
- Allow continuous monitoring of: • Blood pressure (real-time readings) • Pulse rate and rhythm • Effects of dysrhythmia on perfusion • Measurement of cardiac output and stroke volume (SV) • Specific wave form morphologies that might be diagnostic
Central Venous Lines
- Use Swan-Ganz catheters
- Access sites: right jugular vein (or left), subclavian vein, and femoral vein
- Allow continuous monitoring of: • Right atrial pressure (and right-sided preload) • Central venous pressure • Infusion of fluids or medicines (e.g., chemotherapy) • Specific wave form morphologies that might be diagnostic
Wiggers Diagram
- QRS complex: ventricular contraction (atrial repolarization is masked by the QRS wave)
- T wave: ventricular repolarization
- Stages of cardiac cycle: • Atrial systole • Isovolumetric contraction • Mid-to-late ventricular systole: rapid ejection • Mid-to-late ventricular systole: reduced ejection • Early ventricular diastole/isovolumetric relaxation
Arterial Waveform
- Aortic valve closure: induces pressure, causing the dicrotic notch
- Mean arterial pressure: area under the curve (2/3 diastole + 1/3 systole)
- Pulse pressure: difference between systolic and diastolic blood pressure (usually ~40 mmHg)
- Pulse pressure significance: • Wide pulse pressure: aortic regurgitation (increase in stroke volume and systolic blood pressure) • Narrow pulse pressure: heart failure or stenosis
Central Venous Pressure Waveform
- A wave: atrial contraction
- C wave: tricuspid valve closure (backward push into the vena cava)
- X descent: atrial relaxation (pressure decrease)
- V wave: venous filling
- Y descent: emptying of right atrium
This quiz covers the importance and applications of arterial lines and central venous lines in medical settings. Learn about the different access sites and benefits of using these lines.
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