Respiratory monitors and equipment 3 Flashcards
The pulse oximeter reads 80%. You estimate the PaO2 is approximately:
50
SpO2 monitoring is most useful when the patient’s
PaO2 aligns with the steep portion of the oxyhemoglobin dissociation curve
When you have an SpO2 of 90%, you can estimate your PaO2 at
60 mmHg
When you have an SpO2 of 80%, you can estimate your PaO2 at
50 mmHg
When you have an SpO2 of 70%, you can estimate your PaO2 at
40 mmHg
Methods that improve the SpO2 signal include
warming the extremity and protecting the extremity from ambient light
placing a digital block
applying a vasodilating cream
administering an arterial vasodilator
Once the SpO2 exceeds ______, you have no way of knowing if the PaO2 is 100 or 500 mmHg. For this, you’ll need to measure the PaO2 with
100%; an abg
A left shift of the oxyhemoglobin curve means
left= love
increased affinity for O2
What causes a left shift of the oxyhemoglobin curve?
decreased temperature
decreased 2,3-DPG
decreased CO2
decreased H+
increased pH
increased HgbMet
increased HgbCO
increased HgbF
What is a right shift of the oxyhemoglobin curve?
right= release
decreased affinity for O2
What causes a right shift of the oxyhemoglobin curve?
increased temperature
increased 2,3-DPG
increased CO2
increased H+
decreased pH
The pulse oximeter is a useful monitor of:
a. ventilation
b. bronchial intubation
c. anemia
d. vascular compression
d. vascular compression
The pulse oximeter is a noninvasive monitor of:
hemoglobin saturation
heart rate
fluid responsiveness (pulse pressure variation)
perfusion
The pulse oximeter is NOT a good monitor of
anemia
ventilation
bronchial intubation
The pulse oximeter may ___________ the SpO2 with severe anemia
overestimate
Which condition is LEAST likely to affect the reliability of the pulse oximeter?
a. jaundice
b. left ventricular assist device
c. carboxyhemoglobin
d. blue nail polish
a. jaundice
What circumstances decrease the reliability of the pulse oximeter?
dysfunctional hemoglobin (methemoglobin, carboxyhemoglobin)
decreased perfusion
non-pulsatile flow
motion artifact
altered optical characteristics (dyes, nail polish, ambient light)
The pulse oximeter has a margin of error of +/- _______ when the SpO2 is between 70-100%
2-3%
The SpO2 has a margin of error of _______ when the SpO2 is 50-70%.
3%
If O2 sat >85% in the presence of methemoglobin, SpO2 will be
falsely underestimated
If O2 sat is <85% in the presence of methemoglobin, SpO2 will be
falsely overestimated
How does carboxyhemoglobin affect the pulse oximeter?
overestimates SpO2
The pulse oximeter has been associated with the following negative outcomes:
burns
pressure injury
ischemic injury
electric shock
Issues of decreased perfusion that can lead to inaccuracy in pulse oximeter readings include
vasoconstriction
hypothermia
hypoperfusion
Raynaud’s disease
What issues of non-pulsatile blood flow can lead to issues with the pulse oximeter?
cardiopulmonary bypass
LVAD
Can dark skin affect the pulse oximeter?
yes
Can electrocautery affect the pulse oximeter?
yes
Venous pulsation (tricuspid regurgitation) _____________ SpO2
falsely decreases
Factors that DO NOT affect the reliability of the pulse oximeter include
Hemoglobin S
Hemoglobin F
jaundice
fluorescein
polycythemia
acrylic fingernails
What is the MOST common method of measuring exhaled gases inside the breathing circuit?
a. mass spectrometry
b. Raman scattering
c. piezoelectric crystals
d. infrared absorption
d. infrared absorption
Does infrared absorption spectrophotometry measure O2?
NO-you’ll need a separate way to measure O2 if you’re using IR absorption spectrophotometry
Pros of infrared absorption include that
it is more portable and energy-efficient
Mass spectrometry is
large and may be utilized for more than one patient at a time
Piezoelectric crystals is an analyzer using
piezoelectrical crystals that can detect inspired, expired, and breath to breath changes of a particular gas by incorporating a lipid layer on the crystal
A con of piezoelectric crystals to identify gases is
it cannot identify multiple gases at once making it impractical to use in the clinical setting
Raman scatter spectrometry uses a
high power argon laser to produce photons which in turn collide with gas molecules
Mass spectrometry bombards a
gas sample with electrons creating ion fragments
