Exam I Clinical Monitoring (6/06/24 & 6/10/24) Flashcards
What physics law deals with pulse oximetry and the laws governing absorption of light?
Beer Lambert
A low concentration of hemoglobin results in a ____ light absorption rate.
lower
What should be utilized if oximetry is determined to be inaccurate?
Co-oximetry
What is co-oximetry?
Co-oximetry is the measurement of:
- O₂Hb
- DeO₂Hb
- MetHb
- CarboxyHb
all through differing wavelengths of light
Red wavelengths of light measure at ______ nanometers.
660
Infrared wavelengths of light measure at ______ nanometers.
940
Deoxyhemoglobin preferentially absorbs more ________ than oxyhemoglobin.
red
Oxyhemoglobin preferentially absorbs more ________ than deoxyhemoglobin.
Infrared
What makes up the AC portion of the graph below?
Light absorption from pulsatile arterial blood.
What makes up the DC portion of the graph below?
Light absorption from:
- Non-pulsatile arterial blood
- Venous and capillary blood
- Tissue
What will falsely elevate SpO₂ ?
Elevated carboxyhemoglobin
Each __% of COHb (carboxyhemoglobin) will increase SpO₂ by __%.
1 : 1
_______ will absorb as much 660nm light at oxyHb does.
COHb
What percent carboxyhemoglobin will smokers have?
> 6% usually
What are possible reasons for SpO₂ signal artifact and thus incorrect readings?
- Ambient light
- Low perfusion
- Venous blood pulsations
- Dyes (ex. Methylene blue)
- Nail polish
Where can a pulse ox be placed if the fingers won’t work?
- Forehead
- Tongue
- Cheek
less affected by vasoconstriction, reflects desaturation quicker
Where might be a more reliable location to place the pulse ox if performing an epidural block?
Toes
What are Korotkoff sounds related to?
Blood pressure (Through partial occlusion with the BP cuff)
How is MAP calculated?
DP + ⅓(SP - DP)
What Korotkoff phase is the loudest?
Quietest?
- Phase 1: loudest (SBP) due to turbulence
- Phase 5: Sounds disappear
How should a cuff fit on a person’s arm?
- 40% of arm circumference
- 80% of length of upper arm
- Centered over artery
A BP cuff that is too large will read a blood pressure that is _______.
too low
A BP cuff that is too small will read a blood pressure that is _______.
too high
Where can a blood pressure be obtained from an obese patient if the upper arm won’t work?
forearm
What is the best site for invasive blood pressure monitoring?
Radial artery
Describe Allen’s Test
- Examiner compresses radial and ulnar arteries
- Patient makes a tight fist
- Patient opens hand
- Examiner releases ulnar artery
- Color of palm should return in seconds
How does the Transfixion technique for arterial catheter placement differ from the seldinger technique?
Transfixion involves puncturing through the back of the artery and withdrawing until the needle can be removed.
Label the various parts of the arterial waveform.
- Systolic upstroke
- Systolic peak pressure
- Systolic decline
- Dicrotic notch
- Diastolic runoff
- End-diastolic pressure
What occurs to an arterial waveform as it moves centrally (aorta) to the periphery (ex. femoral artery) ?
- Arterial upstroke steepens
- ↑ systolic peak
- Dicrotic notch occurs later
- Lower EDP
How are summation waves formed?
Through the combination of Fundamental and Harmonic waves.
How many oscillations should follow a square wave test?
No more than two
What would the systolic pressure read in an underdamped system?
↑ SBP
What would the characteristics of an overdampened arterial waveform be?
- ↓SBP
- Absent dicrotic notch
- Loss of detail
- Narrowed pulse pressure w/ accurate MAP
What occurs with RV and LV afterload during the inspiratory phase?
RV afterload increases
LV afterload decreases
What occurs with RV and LV preload during the inspiratory phase?
RV preload decreases
LV preload increases
RV stroke volume ____ during early phase of inspiration.
drops
How much systolic pressure variation is typical in mechanically ventilated patients?
7 - 10 mmHg
What would increase systolic pressure variation be indicative of?
Volume responsiveness (i.e. patient needs fluids)
What is the normal change in pulse pressure variation over an entire respiratory cycle?
13 - 17%
If greater than 13 - 17% you need to give volume.
What is normal Stroke Volume Variation (SVV) ?
10 - 13%
If greater, patient will likely respond to fluids.
What are the two types of gas sampling systems?
- Side-stream (Diverting) monitoring
- Mainstream monitoring