Quiz 5 Flashcards
How is CO2 measured
CO2 electrode uses the Severinghaus electrode
What are some complications of pulse ox?
- poor perfusion
- cold or shivering
- poor connection
- fake nails or dar colored nails
- florescent lighting
Stead wells water seal has a _____ version and a _____ version
wet and dry
Dry version rubber seal connects
bell to wall of container to bell rolls over itself
What is another name for bellows spirometer ?
Wedge spirometer
What is another name for flow sensing spirometer?
Pneumotachometer
Pneumotachometer measures the
flow of gas
There are 5 types of basic types of flow sensors, what are they?
- turbine
- pressure differential
- heated-wire
- pitot flow sensors
- ultrasonic flow sensors
Turbine flow sensor is also called
wrights respirometer
Turbine flow sensor directly measure
gas volumes (Ve, VT,VC)
What is heated wire sensors based on?
the cooling effect of gas flow
Pitot flow sensor is the pressure of gas
flowing against small tubes is related to gas density and velocity
Pitot flow sensor usually has 2 sets of tubes so that
bidirectional flow can be measured
Pitot flow sensor is aslo used in the
exercise testing
Ultrasonic flow sensor uses frequency
sound waves across a stream of gas
“sound waves”
Two types of portable spirometry
- interface w/ a computer
- stand-alone devices that incorporate a microprocessor
Portable spirometer uses
disposable flow sensors
Recommendations for spirometer are set forth by the
National Lung Health Education Program
Peak flow is the
maximum inhalation followed by a forced expiration
What is the low range used for small children while performing a peak flow?
400 L/min
What is the high range used for adults?
850L/min
(less than 5% variability)
What are the 2 types of body plethysmography
- constant volume
( pressure plethysmography) - variable volume (Flow plethysmography)
Boyle’s law states?
Pressure and volume vary inversely
body plethysmography is a
very accurate form of testing
With pressure plethysmography volume change
are inversely related to pressure change (if temp stays constant)
Flow plethysmography uses a
transducer in the box wall to measure volume changes in box
Both plethysmography use
flow sensors
Flow plethysmography is the most accurate
for measuring volumes
Free-breathing valves must be cautious of
dead space (must remain less than 100mL)
ABG analysis can be used to assess
gas exchange and acid-base status
Normal PH
7.35-7.45
PO2
70-100
PCO2:
35-45
BE
-2 to +2 mEq/L
HCO3
22-26
PVO2
40
PVCO2
40-60
Negative logarithm value of hydrogen ion in the blood used as a positive number
pH
PCO2 is the measurement of partial pressure exerted by CO2 in the blood and is
inversely related to pH
PO2 is the partial pressure exerted by the O2 content in the blood influenced by the
altitude and temp
pH is measured in ___ ways
2
Related to the PCO2 by the
Henderson Hasslebach equation
Whole blood, blood obtained anaerobically diffused through a polarographic electrode called
Clark electrode
As temperature increases
CO2 increases and inversely pH decreases
What is the body’s response to an increased CO2 level?
To take take deeper and more breath (compensated), when this happens PO2 increases as well
Where can abgs be performed from
- usually radial or brachial artery
- femoral
- dorsalis pedis
- posterior tibial
Mixed venous sample come from the
Swan Ganz (pulmonary artery catheter)
Venous samples form peripheral veins are not
useful for assessing oxygenation
What happens when air is mixed in the sample?
it causes CO2 to go down, therefore pH goes up, PO2 reads high
PCO2 correlates w/
ventilation
Hypoventilation =
CO2 increases
Hyperventilation =
CO2 decreases
If dead space is increased the body’s natural response is to
increase ventilation to compensate
Hypercapnia is defined as
excessive carbon dioxide in the bloodstream, typically caused by inadequate respiration
Alveolar air equation
PAO2=(PB-H2O) x FiO2- (PaCO2 x 1.25)
What can oxygen be estimated with?
SpO2; pulse ox
Demand valves are also called
Demand flow regulators
Demand valves require
pressure to trigger gas flow and responds to pt effort
O2 analyzer polarographic is also called
Clark electrode
Polargraphic is good for
monitoring during exercise testing but not metabolic studies
Zirconium fuel cell can be used for
exercise and metabolic studies
Zirconium fuel cell has a FAST response but
it has to be heated to 650- 800 degrees celsius
What measures aterial pressure of o2?
polargraphic and zirconium
Galvanic is the
most popular (no polarizing voltage needed)
Gas chromatograph is very
accurate and can analyze multiple gases
(as many gases as it has tubes)
Thermal conductivity analyzer utilizes
helium analyzers
Chemoluminescent analyzers measures
nitric oxide (NO)
Chemoluminescent analyzers are routinely used to assess
airway inflammation
Ph electrode
Sanz electrode
Paco2 elctrode
Severinghaus electrode
PO2 electrode
clark electrode
PO2 (clark) electrode needs
a polarizing voltage
Portable blood gas analyzer provides
rapid results; accuracy is comparable to large machines
Why can amenia may cause inaccurate ready with pulse ox
Anemia may cause the pulse ox to read higher than it truly is (estimates oxygenation at the tissue, it’s not a measure of PAO2)
