Clinical Monitoring (Exam I) 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 formula is used to determine the ratio of AC to DC light absorption? (and thus give our pulse oximetry)
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
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 6: Sounds disappear (DBP)
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
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