Invasive BP Flashcards
What is the average blood flow velocity?
80-300 ml/sec
What is the accepted form of blood pressure ?
Distending wall pressure
As vessels get more narrow, what happens to distending wall pressure?
More energy is displaced upon the wall which increases the pressure. This is why the farther down the leg you go, the larger the systolic pressure gets and lower the diastolic pressure gets
What is the dicrotic notch?
Is the point at which pressure is decreasing from maximum, and the sudden small increase spike is when aortic valve closes and pressure begins to decrease once again
A normal waveform for invasive blood pressure should have how many dicrotic notches?
1
What is the term for when the waveform has more than 1 dicrotic notch?
Ringing
Ludwig in 1846 was the first to have an invasive monitor that produced a waveform, what kind of machine did it use?
Kymograph (kymo = smoke) so used a smoked drum
What are the 4 systems of the clinical pressure measurement device (think A line setup)?
Mechanical coupling
Transducer
Display
Electronic components
How many mL is automatically/continuously flushed into artery to prevent clotting?
3 mL / hour
What are the 2 static sources of error for IBP?
1) Incorrect zero —–making voltage on wheatstone bridge, telling system what is zero pressure mark and which is atmospheric mark
2) Incorrect gain —–the system can no longer adjust gain (in reality is testing/changing the display)
What are sources of dynamic error for IBP?
Waveform is altered due to monitor
Waveform alteration due to pressure propagation through the vasculature
What is difference between zero and reference points for IBP?
Zero point is atmospheric pressure that can be zeroed at any point
Reference point is point where transducer is placed and will read and display at. (normally want to be at heart level)
What do you want to keep your CPP above at which to satisfactorily perfuse the brain?
at least 60 mmHg
When doing upright crani’s, where do you want to put the transducer?
Level of the brain because that is the most important part to be infused
What pressure do you want to pressurize the pressurized bag during A-line setup?
300 mmHg
What is point of greatest uptake of energy in the vessel?
Point of resonance
When something is said to resonate, what does that mean?
That the input and output have frequencies that are nearly identical
What is an integral multiple of the base frequency?
Harmonics
Arterial blood pressure waveforms are produced by summation of sine waves from the fundamental wave and 63% of the second harmonic wave. T or F?
TRUE
Dampening device takes away energy that sometimes can worsen the system. T or F?
TRUE
Dynamic errors arise when significant frequency components of the pressure waveform interact with the Resonant Frequency of the measurement system
This was outlined by biggs, so there ya go
What is the ideal dampening coefficient?
0.7
What is the most common way of adding dampening to the system?
Addition of air
What is the frequency component of IBP waveform determined by?
Where waveform orginates from HR
Contractility
Durometer measures what?
Stiffness of the tubing
What are the variables we can adjust?
Tubing compliance
Tubing length (remember a short stiffy is better than a long floppy)
If you dampen a system too much, what will be the only pressure that will be given?
Mean
So if you have any of increased HR, then you have a increased frequency, which will cause an increase in harmonics, this will cause what?
Increased ringing in the waveform
When a A line has narrowing pulse pressures, what is the term called?
Overdamped