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17 Cards in this Set
- Front
- Back
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Indications for ABG sampling
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Evaluation
Ventilation (PaCO2) Acid-base (pH) Oxygenation (PaO2 & SaO2) any hypoxemia? O2 carring capacity of blood PaO2, HbO2, total Hb, & dyshemoglobins Assess pt. response to therapy Diagnostic testing Monitor severity/progression of disease |
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Contraindications for ABG sampling
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Negative Modified Allen's test
Positive test essential If negative: Use other arm Then another site Not through lesion or distal to dialysis shunt Relative: High dose anticoagulation therapy |
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SaO2
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Measured on ABG
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SpO2
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Measured from pulse oximeter - noninvasive
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Pulse Oximetry
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Red & infrared light beams absorbed by hemoglobin
Various hemoglobins absorb differently - HbO2, HbCO, HbMet, etc Needs strong pulse beat to detect light absorption - Relates to BP. |
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Modified Allen's Test
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Required: ensure collateral circulation in ulnar artery
Hand flushes pink within 10 to 15 seconds - positive test ( **** NBRC ******) |
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ABG Sampling
3 Main Sites |
Invasive Procedure Dr. Order required!
Radial artery preferred / primary site Advantages Near surface Easy to palpate & stabilize Collateral circulation from ulnar artery No large veins nearby Relatively pain free Brachial Artery Next choice when impossible to use radial artery Femoral Codes No other access Dorsalis pedis Uncommon, but possible |
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ABG Analyzer
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Measurement of
pH, paCO2 & PaO2 Calculated plasma bicarbonate - HCO3 Base excess or deficit Self-calibration Correction for temperature |
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Sanz Electrode
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Measures pH
Uses pH sensitive glass & membrane |
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Severinghaus Electrode
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Measures PaCO2
uses chemical reaction |
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Clark Electrode
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Measures PaO2
Membrane permeable to oxygen Chemical reaction measures electron flow |
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Point of Care Testing
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Portable/hand-held
Uses small quantity of blood analyze within 3 min Do NOT place in ice ( **** NBRC *****) Uses disposable cartridge with calibration component Available testing ABGs, hemoglobin, hematocrit, electrolytes, glucose, BUN, creatinine |
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Co-oximeters
Capabilities |
Measures Hb, HbO2, & HbCO
Also measures methemoglobin (HbMet) Ferrous iron oxidiezed to ferric iron cannot transport O2 Cause: certain dyes, potassium chlorate, nitrate contamination, atypical response to benzocaines, hereditary |
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Co-oximeter Principles
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Spectrophotometry
measures level of CO & other molecules bound to blood Hb Blood sample hemolyzed creates translucent solution Monochromatic light beams pass through sample Photodetectors analyze results Can run venous blood for co-oximeter use **** for carboxyhemoglobin |
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Quality Control
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CLIA certification allows lab to operate
Quality controls (QC) run every 8 hours 3 levels: acidotic/hypoxemic alkalotic/hyperoxemic normal Log must be maintained Perform remedial actions if out of range External organization control run every 3 months Assures accuracy of results |
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What is the first step to trouble shooting an ABG analyzer?
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Change the batteries
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Oxygenation
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90% of Hb molecules with O2 bonded
Corresponds to PaO2 of about 60 at 37 degree C body temp 40-50-60/70-80-90 rule p 260 mini-clini |
