equipment operation Flashcards
types of gas analyzer
- gas chromatograph/absorption
- mass spectrometer
- infrared absorption
- thermal conductivity analyzer
- geissler tube ionizer
what is the carrier gas in a gas chromatograph analyzer
usually helium but neon can be used if helium is being measured
gas chromatography
AKA Absorption
- multiple gases
- gases move though separator column different size molecules make gases exit at different rates
- affected by water and co2
disadvantages of gas chromatograph
not fast or breath to breath
gas chromatograph measures what gases
- Ne
- CO
- Nitrogen
- oxygen
mass spectrometry
measuring the mass of each ass by drawing into ionization chamber with vacuum then shot out and distance determines mass
- can analyze several patients at once
mass spectrometry advantages
- rapid response time
- breath to breath
- allows for multiple gas analysis
troubleshooting mass spectrometry
make sure all gas % = 100%
if not increase or decrease gain until 100% is reached
infrared absorption analyzer
quick response for diffusion
has a chopper motor
not affected by partial pressures
infrared absorption analyzer measures?
- carbon dioxide
- carbon monoxide
- methane
how do you calibrate infrared absorption analyzer
calibration will read 0% for room air then add 0.03% CO rezero then adjust gain
troubleshooting infrared absorption analyzer
long sample lines
moisture
thermal conductivity analyzer
AKA wheatstone bridge
helium goes through hot wires cooling them down changing resistance and current
do not use with flammable gases
helium dilution procedures
what does thermal conductivity analyzer measure
helium
Geissler tube ionizer
measures gas %
sample pumped into chamber where a light is emitted then the intensity of the light = % of nitrogen
provides breath to breath
Geissler tube ionizer measures?
nitrogen
trouble shooting geissler tube ionizer
- water though needle valve
2. leak
3 types of blood gas analyzers
- clark electrode
- servinghaus electrode
- sanz electrode
severinghaus electrode
measures co2
glass electrode which includes nylon spacer and Teflon membrane
clark electrode
measures PO2
not smooth- traps blood particles and needs cleaned with pummus
requires polarizing voltage
sanz electrode
reference electrode contains a KCl buffer solution with a known pH that is sealed and has a ceramic plug
has a constant electrical potential
silver-silver choloride wire
calibrating PCO2 and PO2 on Blood Gas analyzer
displayed in mmHg need to make %
PCO2- 5% low
10% high
PO2- 0% low
12 or 20% high
changing mmHg to %
(PB- Ph20) x % in decimal
(760- 47) x %
Troubleshooting Blood Ga Analyzers
- worn or ruptured membranes
- clot= use protein remover
- erratic reading= remembrance
- check solutions and gas cylinders
types of oxygen analyzers
- galvanic fuel cell
2. polarographic
galvanic fuel cell
measures partial pressure displayed as FIO2
accuracy affected by water, high pressure, and altitude
replace the fuel cell if unable to calibrate
two point calibrate
polarographic oxygen analyers
similar to galvanic except that it requires a battery
tonometry
quality control
gas mixture equilibrated with buffer solution of blood sample
cost savings
in a unidirectional valve if the patient can inhale but not exhale what does that mean
the exhalation valve was positioned incorrectly or backwards
all breathing valves should have
- low deadspace
- low compliance
- low resistance
- easy to clean
gas and water absorbers
co2 absorber (scrubber)
h20 absorber (desiccant)
co2 absorber
aka scrubber
only necessary for tests that require rebreathing
if not in line for these tests- patient will complain of being hot and being tachypneic
changes co2 to water
change co2 absorber when?
- .exhausted
- color change
- weekly
h20 absorber
aka desiccant
gets rid of moisture
calcium sulfate
inline after co2 absorber
starts blue then changes to pink when needs changed
placement of absorbers
co2
h2o
analyzer
flow measuring spirometers
pneumotachometer
peak flow meter
pneumotachometer
a device that measures flow and converts it to a volume display
types of pneumotachometer
wright respirometer
pressure differential
thermal element
pilot tube
ultrasonic
wright respirometer
accurate for flows of 3-300 L/min
should not be used for peak flow measurements
estimated volumes
pressure differential
contains a resistive element that causes pressure to drop as gas flows across it
bundle of capillary tubes that are heated to keep moisture out
found in body box
thermal element
heated platinum wire that cools as gas flows across it requiring an increased amount of current to maintain the temperature
decreased resistance (hole in mesh screen) will give false low readings
pilot tube
disposable and portable
condensation and secretions will not affect
peak flow meter
used to measure PEFR at bedside
exhale forcefully
great for asthma patients
low range= 300-400 (kids/elderly)
high range= 600-800 (normal healthy adult)
volume measuring spirometers
directly measure volume then add time to create flow
3 types of volume displacement spirometers
water seal
dry rolling deal
wedge bellows
water seal volume spirometer
consists of large bell that is submersed in a column of water- will move proportionally as patient breathes in and out
dry rolling seal
calibration done with a 3L syringe
most problems are related to potentiometer malfunction
can be used to assess pre and post bronchodilator changes
wedge bellows
collapsible bellows that folds and unfolds as the patient breathes in and out
if measured volume increases while the wedge is positioned at zero with the gas inlet plugged- there a leak in the system
If there is a loss of volume checks for cracks or holes in bellows
calibration of volume displacement spirometer
use a 3L syringe
3L syringe
use to calibrate with daily
range- 2.9-3.1 L
if calibrating with the 3l syringe and volume not in range
if higher than 3.1= potentiometer
bent bell
leak into the system
if lower than 2.9 then there is a leak
rotameter
better method for reproducing flow rates for calibration
pneumotachometers may become alinear as a result of
contamination
bent vanes
moisture
debris
body box
based on boyles law if temp consistent
measures thoracic gas volume which is the same as FRC also measures Raw
calibration of body box primarily involves three things
mouth pressures is verified with mercury or water barometer
flows are verified with a rotameter
box pressure is calibrated by using a sine-wave rotary pump
ergometers
two types: arm and leg
used in exercise testing
decreased danger of fall
subject can stop at anytime
easier to obtain vitals and data recordings
results are independent of body weight since patient is sitting
leg ergometer
beneficial for patients who have difficulty walking
pedaling freq and resistance can be adjusted by putting direct pressure on the fly wheel
exercise testing treadmill
most common
walking natural motion
disadvantage- patient cannot stop exercising on their own, vitals are harder to obtain
electrocardiograph
instrument used for recording the electrical activity of the heart
1 millivolt produces a 10mm vertical deflection
the speed of the recording should be 25 mm per second
best leads for the ekg
limb lead- II
chest lead- #5
