Past Papers · SAQ
Intra-arterial Blood Pressure Monitoring
2019A Q02
Exam questionOutline the components required to measure blood pressure from an intra-arterial catheter (75% of marks). What information (other than blood pressure) may be gained from an arterial line trace (25% of marks)?
CICMWrecks answer
Master answer
Process
- BP pulsations transmitted from arterial cannula up the tubing to transducer
- Woks by hydraulic coupling between blood and saline
- Transducer converts pressure waves to electrical signals (via strain gauge and wheatstone bridge)
- Signal amplified and displayed on monitor
Information which may be gained from an arterial line trace:
- Normal trace
- Pulse rate and rhythm
- Arrhythmias
- Morphology:
- Slow rising in AS
- Steepness of ascending phase:
- Increased: Inc Systemic vascular resistance, vasopressors, inc contractility
- Decreased: Septic shock, vasodilators
- Dicrotic ‘fall-off’ : changes with changes in SVR
- Variation with insertion site: Further from aorta: taller systolic peak, delayed dicrotic notch, lower end diastolic pressure, later arrival of pulse
- Dampened trace
- Kinks/bubbles/clots
- Overly compliant tubing
- Hyperactive trace
- Noncompliant tubing, reverberations, increased vascular resistance
- Arterial line swing
- Reduction in venous return
- Hyperexpansion of lungs
- Pulse pressure variation (~fluid responsiveness)
- Pulsus alternans in tamponade
- Adjuncts: Pulse contour analysis with PICCO / other devices
JC 2019
Past papers
Exam appearances
| Exam | Exact exam wording | Candidate success |
|---|---|---|
| 2019A Q02 | Outline the components required to measure blood pressure from an intra-arterial catheter (75% of marks). What information (other than blood pressure) may be gained from an arterial line trace (25% of marks)? | 44% |