This is an instructional video
about how to collect a venous blood gas sample,
and the proper handling of the sample
immediately after obtaining the blood
and just prior to performing the blood gas analysis.
Follow your local hospital procedures
to prepare the patient and collection site
for obtaining the blood sample.
Arterial blood may be difficult to obtain
due to a patient's diminished pulse rate
or low blood pressure, whereby a venous blood collection
represents a viable option.
Venous samples for blood gas analysis
may be obtained from a peripheral vein by venipuncture,
or particularly for patients in the intensive care unit,
from a central venous catheter
or from the distal port of a pulmonary artery catheter,
which is referred to as a mixed venous sample.
Typically, the antecubital veins
are the common draw site for venipuncture.
Draw the sample slowly
within less than one minute of applying the tourniquet.
A peripheral venous sample is suitable
to determine the acid-base balance of a patient
and to monitor the acid-base balance trends
or to screen for systemic acidosis.
In addition, electrolytes, metabolites, hemoglobin,
and the dyshemoglobin variants
may be reported on a venous sample.
However, venous oxygen values may be different
from the arterial blood oxygenation status.
Many patients in the intensive care unit
have a central venous catheter
from which venous blood can be easily obtained for testing.
Attention should be taken and reported
as to the site of the catheter placement,
such as a jugular, subclavian line,
a PICC, or a femoral line.
The oxygen exchange in the various regions of the body
can lead to extreme differences of the values.
This information is critical
and aids the clinician in the interpretation of the results.
When it comes to mixed venous sample analysis,
blood is collected from an indwelling catheter
in the pulmonary artery,
typically referred to as PAC or Swan-Ganz catheter.
The blood obtained from the pulmonary artery catheter
is used for the dynamic diagnostic evaluation and management
of the critically ill patients.
When mixed venous blood gases from the pulmonary artery
are combined with arterial blood gas measurements,
the results frequently clarify the cardiopulmonary status
and assist in determining
appropriate therapeutic procedures to be initiated.
Blood gas analysis is performed to test vitals
in critically ill patients.
Blood gas testing gives information on pH, the gases,
electrolytes, metabolites, total hemoglobin,
CO-oximetry, and neonatal total bilirubin.
Ensure you have all the materials you need
to draw the patient's sample.
Depending on the type of venous sample drawn,
materials may include
a heparinized syringe with a filter cap,
a central line kit or pulmonary artery catheter kit,
a saline flush syringe,
an empty waste syringe to clear the CVC line,
alcohol or a decontaminated wipe, and dressing,
just to name a few of the items.
The syringe used for blood gas analysis
should include dry electrolyte balanced lithium heparin
as the preferred anticoagulant
in a concentration of approximately
23 international units per milliliter of blood.
Before obtaining the venous sample,
confirm the patient's identity.
Follow your hospital directives for the proper protocol
when obtaining a blood gas sample by venipuncture
or from either a central line
or a pulmonary artery catheter.
Clean the venous blood draw site
or the central line cannula port.
Let it dry.
Do not use a cleaning wipe that contains
quaternary ammonium substance, such as benzalkonium,
as it may affect the electrolyte parameters reported,
particularly sodium.
Perform a saline flush.
And attach the waste syringe and remove the initial fluid
from the central line or the pulmonary artery catheter.
The amount of fluid that needs to be withdrawn
varies with the line system used.
Remove and discard the waste syringe.
Attach the heparinized syringe to the line cannula port
and slowly withdraw the desired volume of blood
from the patient.
Once the desired amount of blood is obtained
without bubbles or frothing,
remove the syringe from the line cannula.
Attach the filter cap on the luer tip of the syringe
and hold the syringe vertically and gently tap the syringe
so that air bubbles are forced to the top.
Expel any air bubbles into the filter cap.
Mix the sample thoroughly
by rotating your wrist back and forth
for a minimum of 20 seconds.
This helps to dissolve the heparin
and minimize clot formation in the syringe.
Label the syringe with the patient ID
and immediately transport the sample
to a Siemens Healthineers Blood Gas System.
Follow a two-step mixing process,
first by rotating your wrist back and forth
and then rolling the syringe between your hands
about 10 times.
Remove the cap from the syringe
and expel the first few drops of blood into a gauze pad.
Present the sample to the analyzer and start analysis.
Recognize that a sample containing blood clots
should not be used on the blood gas analyzer,
because it can affect
not only the accuracy of the patient results,
but also, negatively impact the operation
of the blood gas analyzer.
The patient's blood gas results
will be ready within 60 seconds.
Remove the syringe from the analyzer,
reattach the filter cap, and de-bubble the sample.
If you need to repeat the test,
remix the sample prior to analysis.
According to the CLSI guidelines,
blood gas testing should be completed within 10 minutes
and not longer than 30 minutes after drawing the sample.
If testing is delayed longer than 30 minutes,
sample should be placed in an ice slurry
and will require additional mixing prior to analysis.
Dispose of the syringe according to the hospital guideline.
Proper sample handling, mixing, and time to analysis
helps to ensure accurate patient results.