2. CONTENTS
I. Introduction.
II. The working principle.
III. Components of the device (diagrams and explanation).
IV. Components of the device (in detail).
V. Circuit Diagram for a device model.
VI. Comparison between device manufacturers.
VII. Service manual.
VIII. Common faults and how to fix them.
IX. References.
3. Blood gas analysis, also called arterial blood
gas (ABG) analysis, and refers to the measur
ement of pH and the partial pressures of oxyg
en (O2) and carbon dioxide (CO2) in arterial
blood.
Introduction
I.
4. Introduction
This device can be found in many departments around the hospital including, Respirator
y department, Intensive care units, emergency rooms, operating rooms, and blood chemi
stry lab.
It is a very important tool in the diagnosis of many horrifying disease with high mortalit
y for example:
kidney failure: Estimates are that 2 million people worldwide suffer from kidney fail
ure, and the number of patients diagnosed with the disease continues to increase at a
rate of 5-7% per year. Mortality rates vary depending on the kidney failure treatment
. After one year of treatment, those on dialysis have a 15-20% mortality rate, with a 5
-year survival rate of under 50%.
heart failure: An estimated 64.3 million people are living with heart failure worldwid
e. 17.9 million people die each year from CVDs, an estimated 32% of all deaths worl
dwide.
5. The ABG device has many sectors, each perf
orm a different task than the other, to study h
ow it works, we need to dive fairly deep into
each one of these sectors.
The Working Principle
II.
Electrodes are used in blood gas/pH analyzers to
determine the pH, partial pressure of carbon dioxi
de, and partial pressure of oxygen in the blood. A
dry reagent pad system is used in chemistry analy
zers, in which a filter pad impregnated with all ch
emicals necessary for a specific reaction is put on
a thin plastic strip.
7. ii. Partial Pressure of Carbon Dioxide (CO2):
The Severinghaus Electrode is the mainstay of carbon dioxide measurement from the art
erial blood gas. It is essentially a pH electrode but contains the pH and reference elect
rodes within one device. The result takes a long time to determine (1 – 3 minutes) due
to the prolonged equilibration, and calibration. (PaCO2 α [H+]).
𝐶𝑂2 + 𝐻2𝑂 ⇌ 𝐻2𝐶𝑂3 ⇌ 𝐻2𝐶𝑂3− + [𝐻+]
9. iii. Partial pressure of oxygen (PaO2):
The partial pressure of oxygen in blood is measured using an electrode. The principle is
that a certain number of O2 molecules within a salt solution will produce a current.
Ohm’s Law is the governing principle:
V = IR
BUT, R (resistance) is constant, and thus:
V α I
Thus increasing [O2] results in a higher current produced.
11. Calculated Values:
As for the main calculated values that are deduced from these three parameters and the
entered data:
1. Bicarbonate Value (HCO3-):
HCO3-(P) includes ions of hydrogen carbonate, carbonate and carbamate in the plasma.
It is calculated from the Henderson Hasselbalch equation which is shown in the next sli
de.
The ABG machine rearranges this equation in order to derive an actual bicarbonate conc
entration from the pCO2 and pH measurements.
The reference manual for the local unit does not elaborate on how the constants were sel
ected uses a slightly simpler equation:
HCO3
- = 0.03 × pCO2 × 10(pH- 6.1)
13. Calculated Values:
2. Partial Alveolar Oxygen (PAO2):
The alveolar gas equation is of great help in calculating and closely estimating the partia
l pressure of oxygen inside the alveoli. The alveolar gas equation is used to calculate a
lveolar oxygen partial pressure:
PaO2 = (Patm - PH2O) FiO2 - pCO2 / RQ
The value of inspired oxygen fraction concentration (FiO2) needs to be fed into the mac
hine. And RQ is the amount of CO2 liberated per minute divided by amount of O2 util
ized per minute. Normal values are 200 ml/250 ml =0.8.
3. O2 sat:
Proportion/percentage of hemoglobin which is saturated with oxygen. To calculate this
parameter, the hemoglobin value must be either entered to the device or calculated by
a separate internal module.
14. Calculated Values:
4. Base Excess (BE), Base Buffer (BB):
BE refers to actual base excess in variance from (above or below) total bu
ffer base (BB). Normal BB is 48-49 mmol/L. If BB is 40, it means buffer
base is reduced by nearly 8 Deorari, AIIMS 2008 12 mmol/L, or BE is –8
(also called base deficit). If BB is 60, it means buffer base is increased by
nearly 12 mmol/L, or BE is +12. BB is dependent on hemoglobin, as 25%
of BB is constituted by hemoglobin buffer. Fifty percent of BB is contrib
uted by bicarbonate and 25% by other buffers (proteins, phosphate, sulph
ate).
15. III. Components of the device (diagra
ms and explanation):
Size, power consumption, pricing, and convenie
nce of use are all key factors to consider when e
ntering atypical markets, the instruments must b
e Small enough to fit on benchtops.
They must be tuned for battery operation if they
are portable. They should also be affordable to a
llow point-of-care providers to get them, as well
as adaptable enough to do various tests for great
er cost efficiency.
16. Design
Testing adaptability improves the device's cost-effectiveness.
- and Most blood gas analyzers feature many sensors that are sent to an analogue
-to-digital converter (ADC). through an amplifier multiplexer. The data is proce
ssed in the microcontroller, which is linked to a PC or other instruments throug
h RS-232, USB, or Ethernet. A digital-to-analogue converter (DAC) is often us
ed to calibrate sensor amplifiers to enhance electrode sensitivity.
27. Comparison Between Device Manufacturers
Manufacturer Flagship Model Features Measured Parameters
Siemens
(German)
RapidLab1200
(Benchtop).
Testing panels can be customized to meet specific needs
Capable of running the full test menu on short-sample patient draw
s (microsamples).
Extensive test menu includes full CO-oximetry and neonatal total bil
irubin
Ready Sensor® electrode technology for industry-proven reliability
Cost-effective, cartridge-based system
Simplified operation with biosafe sampling
Automatic quality control and documentation
Seamless integration with your LIS/HIS
Dedicated technical support and on-site service
Ultra-fast sample processing enables immediate physician intervent
ion
Clinical accuracy reduces the need to repeat tests
Microsample capability enables testing of very small sample volume
s without compromising accuracy
Full test menu from a single sample
Get a complete picture in just 1 minute.
Blood Gas (pH, pCO2, pO2).
Electrolytes (Na+, K+, Ca++,
Cl-).
Metabolites (Glucose, Lactat
e, Neonatal Total Bilirubin).
CO-oximetry (tHb, HHb, O2H
b, sO2, COHb, MetHb).
Abbott Laboratories
(American)
i-Stat Alinity (Hand
held).
A robust, award-winning, user-friendly design.
High-resolution color touchscreen and large touchscreen enables si
mple, intuitive navigation.
Ergonomic design makes use balanced, comfortable, and secure.
Audio, color & light cues signal to operator completion of test result
s.
Robust construction for fast-paced environments; built with materi
als that can resist damage.
High-resolution camera captures 2-D barcodes with picture ID
Rechargeable battery designed to be easy to attach and remove.
acid-base, blood gas, el
ectrolyte, chemistry, an
d hematology.
28. F Hoffman La Roch
e
(Swiss)
Cobas b221 (Benchto
p).
Results in less than 2 minutes to support tim
ely clinical decision making.
Comprehensive parameter menu to meet var
ying department needs.
Long-life, maintenance-free electrodes and m
inimal preventative maintenance
Control reagents consumption
Blood gases (pH, pO2, pCO2, pH) /
Co-oximetry
Electrolytes (Na+, K+, Ca2+-) / Hem
atocrit
Metabolites (Glu / Lac)
Metabolites (Glu / Lac / Urea (BUN
))
Bilirubin
Medica Corporatio
n
(American)
EasyBloodGas Medica’s EasyBloodGas is designed to meet the la
boratory’s need to deliver sample results econom
ically. Compact electrode design and precise cont
rol of calibrator volumes ensure economical oper
ation and a low cost per sample.
pH, PCO2, and PO2 and calculates 11 a
dditional parameters. Patient paramete
rs, including FIO2 and Hb, can be enter
ed using the digital keypad.
Danaher Corporati
on (Radiometer)
(American)
ABL90 Flex Plus (Port
able)
The ABL90 FLEX PLUS analyzer gives you relia
ble results in only 35 seconds on 17 paramet
ers – blood gas, electrolytes, metabolites, an
d co-oximetry – from a syringe, capillary tube
, or test tube.
All on one blood sample of only 45 µL.
Blood gases: pH, pCO2, pO2
Metabolites: cGlu, cLac
Electrolytes: cCa2+, cCl-, cK+, cNa+
Oximetry: FCOHb, ctBil, ctHb, FHbF
, FHHb, FMetHb, sO2, FO2Hb
Comparison Between Device Manufacturers:
29. Instrumentation Labo
ratory
(American)
Gem Premier 5000
(Portable)
potential errors are detected not only before and after, but al
so during sample analysis, along with real-time correction an
d documentation. Plus, it’s simple—just change the all-in-on
e GEM PAK once a month. So regardless of testing location o
r point-of-care operator, quality results and compliance are a
ssured with every sample on the portable GEM Premier 5000
system.
pH, pCO2, pO2, Na+, K+, Cl-, Ca++, Glu, L
ac, tHb, O2Hb,
COHb, MetHb, HHb, sO2, tBili or any co
mbination of
Electrochemical* analytes and CO-Oxim
etry** and/or tBili
tHb, O2Hb, COHb, MetHb, HHb, sO2, tBil
i and/or tBili
Nova Biomedical
(American)
Stat Profile pHOx ultra 20 critical care tests from one small, 210-microliter sample in
only 2 minutes. Other partial test panels are available in less
than one minute
pHOx Ultra can be custom configured with as few as 5 tests t
o as many as 20 tests to satisfy the exact test menu requirem
ents of each department
Measured SO2%, Hb, and Hct on Each Sample Without CO-O
ximetry
Optional On-Board CO-Oximeter
pH, PCO2, PO2, SO2% Na, K, ,iCa , iMg, Cl,
Glucose, BUN/Urea, Creatinine, Lactate, Hc
t, Hb, O2Hb, HHb, COHb, MetHb, and tBil.
Erba Mannheim
(German)
EBG Stat 820/1020 Simple 3 step operation
Results in 60 seconds
Zero maintenance
True liquid quality control
Controls run automatically at by the user selected intervals.
Low running costs
Lithium heparinized whole blood (arterial, venous, or capillar
y blood)
100 µl of whole blood for full menu
Up to 10 measured parameters (pH, pO2
, pCO2, Hct, Na, K, Cl, iCa, Glu, Lac)
20 calculated parameters (SO2%, HCO3-
, TCO2, BE-ecf, BE-b, SBC, O2Ct, O2Cap,
A, AaDO2, a/A, RI, P50, PO2/FIO2, Hb, a
nion gap, nCa, temperature corrected p
H, PO2, pCO2)
Comparison Between Device Manufacturers:
31. VII. Service Manual:
The calibration is performed using high precision standard
solutions and gravimetrically prepared gas mixtures
to determine the cassette’s measurement characteristics at
multiple points within the analyte’s measurable range.
Every cassette package is then labeled with a bar code
containing this calibration information
During the calibration and measurement processes,
diagnostic tests are automatically performed to assure
correct operation measurement of the cassette.
32. Types of Blood Gas Analysis calibration:
1. Calibration before analyzing the sample:
calibration is a possible source of analytical error. Blood gas instruments must be periodically
calibrated using known value samples. A one-point calibration is required at least every
30 minutes and a two-point calibration is required at least every 8 hours
A test of linearity also is required at least twice a year. Failure to assure proper calibration
within the required time of running a sample can result in inaccurate results
being produced and reported
2. Calibration after corrective maintenance:
after corrective maintenance we found an error in the results of blood gas analyzer to
adjustment the error verifying the value of potentiometer and measure the volt on it
to calibrate the blood gas analyzer.
33. Types of Calibration
3. Calibration for electrodes
Calibration of an electrode involves contacting the electrode with at least two standard
solutions or gases having known concentrations of the substance being analyzed the
electrode provides an electrical response that is used to generate a calibration slope.
The electrode then is contacted with the blood sample, generating electrical respons,
Electrodes in blood gas analyzers are calibrated periodically because the response
provided by an electrode for a particular sample tends to drift (vary)
with the passage of time.
34. Maintenance of the analyzer
Care and Maintenance The system needs little care and maintenance. Clean and
maintain it periodically to ensure its optimum performance. Cleaning and Disinfecting
the Exterior Surfaces Clean and disinfect the exterior surfaces to remove dust, splatters,
blood, etc. Policies regarding the cleaning and disinfecting intervals are at the discretion
of your individual institution.
Following the procedures below to clean and disinfect the exterior surfaces: 1. Turn off
the analyzer. 2. Disconnect the power cord and the power adaptor. Disconnect
the connecting cables if the system is connected to other pieces of equipment. Dampen
a lint-free cloth with 0.5% sodium hypochlorite solution.
35. Preventive Maintenance
The following safety checks should be performed at least once every 24 months by
a qualified person who has training, knowledge, and practical experience to perform
these tests.
Inspect the analyzer and accessories for mechanical and functional damage.
Inspect the safety related labels for legibility.
Verify the analyzer functions properly as described in the instructions for use.
If the analyzer is not functioning properly or fails any of the above tests,
it has to be repaired.
It is recommended by the manufacturer to perform the preventive
maintenance every 4 months
36. VIII. Common Faults and How
to fix them:
1-Out-of-date buffer solutions.
2-No calibration gas.
3- Bad electrode.
4- Poor Flushing
5-blood clotting in the sample tube
37. How to fix the faults
(1) The analyzer is easy to maintain, with up to 30 days (about 4 and a half weeks) in-
use lifetime of consumables. You can customize pre-warnings, and easily reuse tests
from one consumable.
(2) We describe a new instrument that performs on-site mixing of oxygen (O2),
carbon dioxide (CO2), and nitrogen (N2) to create compositions that can replace gases
from standard premixed cylinders.
(3) Switch with a new electrode .
(4) Sterilization is done after each test procedure.
(5) adding Heparin or water to sample tube
38. Cartlidge of the device
A picture of Cartlidge of the device which
contains gases and prop which takes the sample
and blood pass through the small tube in the
photo, and the roller in the photo is responsible
for the prop mechanical movement
