7- Venous and Cap bld gas Flashcards
Capillary blood gas determinations are useful in
monitoring neonates or other patients when arterial collection is not practical. Capillary blood gas pH and pCO2 results are comparable to arterial blood.
capillary is a mixture of venous and arterial
deep arterial punctures should or should not be done on children?
Performing deep arterial punctures in newborns and young children is not recommended; therefore, unless blood can be obtained from umbilical or scalp arteries, blood gases are performed on capillary blood.
Capillary blood is a mixture of venous and arterial blood with higher concentration of arterial blood.
Specimens are collected in large bore heparinized capillary tubes.
Plugs or sealant clay are needed for both ends of the pipets and a magnetic flea and magnet are used to mix the specimen.
: Capillary blood gases are always drawn first if other capillary blood specimens will be collected
Method/Procedure
After warming the site for 5 to 10 minutes to increase the flow of arterial blood, 0.2 ml blood is collected.
Each capillary tube must be filled completely end to end as shown in the image, and must not contain air bubbles or air gaps.
Seal one end of the capillary tube and before sealing the other end, a magnetic flea is inserted into the open end. Seal the open end.
To mix, slide a magnet lengthwise back and forth on the outside of the tube about 20 times
Do Not expose the specimen to air.
The tubes are labeled, placed horizontally in an ice bath, and immediately transported to the laboratory.
Testing should be done within 15 mins.
Rejection Criteria
- Clotted specimen
- Unlabeled specimen or mislabeled specimens
- Specimens >30 minutes old
- Specimen contaminated with large air bubbles
Capillary Blood Gas Tube test time at 0-4o C
30 m
Capillary Blood Gas Tube test time at-20o C or -70oC
No good- frozen
PURPOSE OF CAPILLARY BLOOD GAS TEST
Useful for evaluating oxygen and carbon dioxide gas exchange; respiratory function, including hypoxia; and acid/base balance.
It is also useful in assessment of asthma; chronic obstructive pulmonary disease and other types of lung disease; embolism.
VENOUS BLOOD GAS (VBG)
Blood gases measures the pH and the amount of oxygen (O2) and carbon dioxide (CO2) present in a sample of blood, usually from an artery.
Blood Gas evaluates lung function and help detect an acid-base imbalance that could indicate a respiratory, metabolic or kidney disorder.
In the absence of an arterial line, a venous blood gas sample can be used to evaluate carbon dioxide, pH and bicarbonate
When drawing venous blood gas with other venous sample the VBG should be drawn last
Specimen type, container and how much venous gas blood required
Whole blood
Heparinized syringe
1 -2ml mL whole blood; minimum 0.4 mL.
How to collect
Step 1: Pull back plunger to pre-set the sample volume to be collected.
Step 2: Pull back pink safety shield, then remove the needle cover. Note: bevel of needle will always be in line with pink safety shield.
Step 3: Collect blood specimen
Step 4. After withdrawal of the needle, use finger or thumb on grip to close pink safety shield over needle.
Step 5: Unscrew and discard the safety shield and enclosed needle. Expel air, then screw green cap on.
Step 6: Mix sample correctly by 5 complete inversions and 5 seconds rolling in hands
SPECIMEN PROCESSING - transport temp
Room temperature (preferred). Transport immediately. If a delay in transport is anticipated, place specimen on an ice slurry
SPECIMEN PROCESSING - Specimen stability
Stable 30 minutes at room temperature, 1 hour on ice slurry
SPECIMEN PROCESSING - Rejection criteria
Stability limits exceeded (greater than 30 minutes at room temperature, greater than 1 hour from time of collection when on ice slurry),
specimens containing large clots
Specimen containing air bubbles
First choice for blood gas
First choice always arterial
if not available then only venous
but you can ..anything is better than nothing
