Ch 6 - 8 Pressure Monitoring Systems Flashcards
Fluid-Filled Monitoring Systems
• Physical Principle: A change in pressure at any point in an unobstructed _____________ results in a _______________ at all other points of a system •
Fluid Filled System
Similar Pressure Change
Fluid medium is not very ____ accurate _______ of pressure
Compressible
Transmission
Guide wire > Introducer > vessel
> removal of introducer > Insertion of dilator/sheath > removal of dilator > Sheath advanced.
Fluid-filled Monitoring Components
- On site Catheter
- LOW Compliance pressure tubing.
- Transducer
- Amplifier / Monitor
- Auto-flush System
Name the procedure whereby the pressure transducer and tip on the on site vascular catheter are on the same plane
Leveling
Reference points for leveling ?
Heart Level / Tricuspid / Mid-chest
The effects of differences in transducer/midchest position on hemodynamic monitoring Principle: Liquid has a ___?
Weight
pressure exerted on the transducer diaphram by the weight of fluid within the monitoring tubing.
Hydrostatic Pressure
For every 1” the transducer is BELOW mid-chest level, the weight of the fluid on the transducer diaphragm will add how many mmHg?
2 mmHg ABOVE the true intravascular or intra-cardiac pressure.
For every 1” the transducer is ABOVE mid-chest level, the weight of the fluid on the transducer diaphragm will add how many mmHg?
2 mmHg below the true intravascular or intra-cardiac pressure.
Zero Referencing is Used to eliminate the effect of ?
Atmospheric Pressure
A reliable monitoring system should be as simple as possible.
Monitoring catheter bore size? Connecting tubing ? Tubing Connectors? Pressure bag ? System must be free of ? No patient moving
> 18 gaugue or 7 Fr
Low Compliance
Overdamping waveform distortion :
(Exaggerated response)
Caused by tubing connections that are too compliant or too long
Underdamping waveform distortion :
(Blunted response)
Caused by air bubble in the circuit, partial obstruction of catheter or tubing that is too compliant or too long.
Appropriate length for tubing in fluid filled monitoring systems?
< 3 - 4 ft
Fluid-filled monitoring systems:.
4 SYSTEM related variables ?
- ) Pressure transducer + - H2O
- ) Air bubbles in system
- ) Compliance of tubing
- ) Catheter lumen size
Fluid-filled monitoring systems:
2 Patient -Related Variables ?
1.) hyperdynaminc due to sepsis,
AI, or stress.
2.) Tachycardia
loss of energy and vibrations within the monitoring system due to frictional resistance to movement of the pressure signal and absorption of the pulsatile energy.
Damping
Movement of the catheter tip in the circulation in response to pulsatile flow.
Catheter whip (fling)
The introduction of a selected pressure to the amp/ monitor of transducer to verify faithful reporduction of the pressure signal
Calibration
false signal superimposed on the true signal
Artifact (noise
The monitoring system’s ability to measure physiologic pressure changes, Dynamic response relates to the natural frequency & damping characteristics of the system.
Dynamic response
pressure produced by fluid in motion
Hydrodynamic pressure