ABG Equipment
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Transcript of ABG Equipment
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Arterial Blood Gases
- Sampling,Equipment, Calibration,and Quality Control
RET 2414L
Pulmonary Function Testing
Module 6.0
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Arterial Blood Gases
Equipment
Arterial Blood Gas (ABG) Kit
Prepackaged and contains all necessaryequipment 3 5 cc syringe
Pre-heparinized
22ga x 2 needle
Alcohol swap
Gauze pad
Biohazard bag
Misc. items
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ABG Specimen Collection/Handling
Site Selection
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ABG Specimen Collection/Handling
Site Selection
Radial Artery - 45insertion angle Requires modified Allens test for collateral circulation
Brachial Artery - 60- 90insertion angle
Femoral Artery - 90insertion angle
Dorsalis Pedis Artery
Site must be adequately compressed untilclotted Approximately 5 minutes Patients receiving anticoagulation therapy take longer
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ABG Specimen Collection/Handling
Hazards
Hematoma
Arterial laceration
Hemorrhage
Vasovagal reaction Sympathetic nervous system response to pain
Loss of limb
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ABG Specimen Collection/Handling
Handling
Blood gas specimen should collected
anaerobically Expel air bubbles immediately
In Vivo Values Air Contamination
pH 7.40 7.45
PCO2 40 30
PO2 95 110
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ABG Specimen Collection/Handling
Handling
Blood gas specimen must be adequately
anticoagulated Sodium heparin
Lithium heparin (electrolytes)
Sample volume should be 1 2 ml
Each laboratory has its own protocol
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ABG Specimen Collection/Handling
Handling
Sample should be analyzed as soon as
possible If iced sample can be stored
Glass syringe 1 hour
Plastic syringe 15 minutes
Remember: Blood is living tissue that continues toconsume O2 and produce CO2
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ABG Specimen Collection/Handling
Handling
Specimen should be adequately identified
Patient name / ID number Date / Time
Ordering physician
Accession number
Puncture site
Oxygen adjunct and FiO2
Ventilator settings (if applicable)
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ABG Specimen Collection/Handling
Handling
Transport specimen to laboratory in a
biohazard container
Analyze specimen on an instrument thathas been recently calibrated
Temperature correct specimen in analyzer Increase in patient temp: PO2, PCO2, pH
Decrease in patient temp: PO2, PCO2, pH
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Arterial Blood Gases
Equipment
Blood Gas Analyzer
Electronic Circuitry Electrolyte Solution
Electrodes
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Arterial Blood Gases
Equipment
Electronic circuitry
Takes electrical current changes produced in theelectrodes and provides a visual display
Electrolyte Solution
Helps to promote chemical reactions andelectrical current
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Arterial Blood Gases
Equipment
Electrodes
Utilized to measure values of ABG
pH, PCO2, PO2
All other blood gas values are calculated
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Arterial Blood Gases
Equipment
pH Electrode
Sanz Electrode
Consists of two electrodes:
sampling/measuring electrode
reference electrode and electrolyte solution
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Arterial Blood Gases
The pH electrode is amicroelectrode, shown here withits plastic jacket. At the tip is asilver-silver chloridewire in a
sealed-in buffer behind PH-sensitive quartz glass. Thereference electrode contains aplatinum wirein calomel pastethat rests in a 20% KCL solution.The blood sample is introduced in
such a way that it contacts themeasuring electrode tip and theKCL. A voltmeter measure thepotential difference across thesample, which is proportional tothe pH
Sanz Electrode(pH)
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Arterial Blood Gases
Equipment
PCO2 Electrode
Severinghaus Electrode
May also be referred to as a modified Sanzelectrode
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Arterial Blood Gases
The PCO2 electrode is a modifiedpH electrode. The electrode hasa sealed-in buffer; an Ag-AgClreference band is the other half-cell. The entire electrode is
encased in Lucite jacketfilledwith bicarbonate electrolyte. The
jacket is capped with a Teflonmembranethat is permeable toCO2. A nylon meshcovers thepH-sensitive glass, acting as aspacerto maintain contact withthe electrolyte. CO2 diffusesthrough the Teflon membrane,combines with electrolyte, andalter the pH. The change in pH isdisplayed as partial pressure ofCO2.
Severinghaus Electrode
(PCO2)
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Arterial Blood Gases
Equipment
PO2 Electrode
Clark Electrode
May also be referred to as a polarographicelectrode
Periodic/routing cleaning of the tip with pumiceisrequired because polypropylene attracts protein
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Arterial Blood Gases
The PO2 electrode contains aplatinum cathodeand a silveranode. The electrode is polarizedby applying a slightly negativevoltage of approximately 630 mV.The tip is protected by apolypropylene membranethatallows O2 molecules to diffuse butprevents contamination of theplatinum wire. O2 migrates to thecathode and is reduced, picking upfree electrons that have come fromthe anode through a phosphate-
potassium chloride electrolyte.Changes in the current flowingbetween the anode and cathoderesult from the amount of O2reduced in the electrolyte and areproportional to partial pressure ofO2.
Clark Electrode (PO2)
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Arterial Blood Gases
Calibration Procedures
To assure appropriate electronic function of
the electrodes, calibration procedures areperformed
Performed automatically every 30 minutes bythe ABG machine
Performed on the pH, PCO2, PO2electrodes
Specific procedure for each electrode
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Arterial Blood Gases
Calibration Procedures
2-Point Calibration
A low concentration and a highconcentration is used at both ends of thephysiological range to be measured
Multiple-Point Calibration (3 or more points)
Verifies whether the gas analyzer is linear ornot
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Arterial Blood Gases
Calibration Procedures
pH Electrode
Uses two specific buffers with approximatevalues of:
6.840 buffer referred to as the zero point or low point buffer
7.384 buffer high point or slope point buffer
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Arterial Blood Gases
Calibration Procedures
pH Electrode
Each buffer is injected into the sample chamber,one at a time
The values of the buffer that is injected, shouldbe displayed on the ABG machine within aspecific SD (standard deviation)
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Arterial Blood Gases
Calibration Procedures
pH Electrode
Standard deviation for pH is + .005
If value displayed is within the SD, machine iselectronically calibrated
If value displayed is outside of the SD, machineneeds to be adjusted to assure electronic function
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Arterial Blood Gases
Calibration Procedures
PO2& PCO2Electrode
Uses two specific concentration of gases for eachelectrode with approximate concentrations of CO2and O2
Uses two different tanks of gas to accomplish this
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Arterial Blood Gases
Calibration Procedures
PO2 & PCO2 Electrode
Tank One Low CO2 (5%) - balance High O2 (12% or 20%) Balance Nitrogen
Tank Two High CO2 (10%) slope O2 (0%) Balance Nitrogen
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Calibration Procedures
PO2 & PCO2 Electrode
Must convert tank concentration from % tomm Hg
(PBPH2O) x tank concentration = mm Hg
(760 47) x 0.12 = 85.65 mm Hg
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Arterial Blood Gases
Calibration Procedures
PO2& PCO2Electrode
The values calculated for the CO2and O2concentration should be displayed on the ABGanalyzer within a specific SD (standard deviation)
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Arterial Blood Gases
Calibration Procedures
PO2 & PCO2 Electrode
Standard deviation for PO2and CO2is + 0.5
If values displayed are within the SD, machine is
electronically calibrated
If value displayed is outside of the SD, machineneeds to be adjusted to assure electronic function
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Arterial Blood Gases
Calibration Procedures
Troubleshooting
If the ABG machine will not calibrate, check:
The buffers
The mixed gases
The electrodes membrane
The electrode itself
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Arterial Blood Gases
Quality Control
Calibration vs. Quality Control
Calibration is when the equipment is adjustedor correctedto match the control standards
Quality Control testing must be performed on a
regular basis to determine the accuracyandprecisionof the equipment against a knownstandard
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Arterial Blood Gases
Quality Control
Accuracy vs. Precision
Accuracy refers to the mean (average) value ofseveral measurements
Precision refers to how consistently the same
measurement will produce the same results
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Arterial Blood Gases
Quality Control
Must be run every shift
Utilize a knownconcentration of gasesand buffers in a vial ofliquid
Run three levels of QC
Level 1 Acidosis
Level 2 Normal
Level 3 - Alkalosis
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Arterial Blood Gases
Quality Control
KNOWN VALUE IN MUST EQUAL
KNOW VALUE OUT!
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Arterial Blood Gases
Quality Control
When QC is run it must be recorded
and maintained onsite; in the ABGlaboratory
Must be available for review by State
agencies on demand
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Arterial Blood Gases
Quality Control Plotting
In control
Trend
Random Error
Out of Control
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Arterial Blood Gases
Quality Control
In control
All QC runs are within the acceptable +SD
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Arterial Blood Gases
Quality Control
Trend
All QC runs within the acceptable +SD buttrending towards one side of the SD
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Arterial Blood Gases
Quality Control
Random Error
All QC runs within the acceptable +SD exceptfor one run
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Quality Control
Out of control
Two or more QC runs are out of theacceptable +SD
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Capnography
Capnography is the continuous, noninvasivemonitoring of expired CO2 and analysis of thesingle-breath CO2 waveform
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Capnography
Capnography is performed utilizing:
Infrared analyzer
CO and CO2 absorb infrared radiation
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Capnography
Capnography is performed utilizing:
Infrared analyzer
Requires accurate calibration
2 gas concentrations used
Room air 5% CO2 mixture
Inaccurate reading can occur when:
Condensation of water in sample tubing,connectors, or sample chamber
Flow changes after calibration
Saturation of a desiccant column
Long sampling lines can cause waveformdamping