1. Arterial Blood Gas Sampling Flashcards
Who are Arterial Blood samples drawn from?
- Critically Ill Patients
2. Deteriorating Patients
How often are Arterial Blood samples taken from Patients?
Daily
What do Arterial Blood samples assess?
- Adequacy of the Patients Oxygenation (PaO2)
- Adequacy of the Patients Ventilation (PaCO2)
- The Patients Acid - Base Status
- Determine Electrolyte Levels
What is the name of the Machine which analyses the Arterial Blood samples?
Blood Gas Analyser
What can Blood Gas Analysers (commonly) also measure?
- Electrolytes
- Glucose
- Lactate
When is an Indwelling Arterial Cannula placed?
- When it is Anticipated that the Patient will require frequent Arterial Blood Samples
- Continuous Monitoring of Arterial Blood Pressure is Required
What is the Initial Tests required to determine the Site for the Procedure?
- Both Left and Right Radial Arteries are Palpable
- “Allen’s Test” - required in some hospitals
- Infection or Haematoma at the Site, on each side
Which hand is normally used for this procedure?
Non-Dominant Hand is normally chosen
What should always be prepared before the blood is drawn?
The Disposal of the Needle - Use an Equipment Trap with a Sharps Attached and immediately dispose of the needle in the Sharps Bin
- What Size of Gauge Needle is used?
2. Why?
- A Small Gauge Needle - most commonly (in adults) are 22G, 23G, or 25G
- a) Minimise damage to the Vessel
- b) Minimise Haematoma formation afterwards
- Is there a special “Arterial Blood Sampling Kit” available?
- What is special about them?
- Yes
- The syringe is pre-filled with the required amount of Heparin - to prevent clotting
Note - The Heparin is not normally seen but is there
If an “Arterial Blood Sampling Kit” is not available, what is the procedure?
- 1mL of 1000 micrograms/mL of Heparin is Drawn into a Syringe
- The Heparin is completely expelled, leaving a very small amount of Heparin in the Hub
- The Needle is Changed to a fresh 25 Gauge Needle
How much Heparin is required for the 2-3mL Blood Sample taken?
0.2mL - This is what will remain in the Hub of the Syringe
Are Tourniquets used in the Arterial Blood Sampling procedure?
No
What information needs to be put into the Blood Gas Analyser before it will work?
The Patients Details
In Clinical Practice, do all Arterial Punctures occur in the Radial Artery?
No, e.g. during resuscitation the Brachial / Femoral Artery might be used
What is important to bear in mind if the Arterial Puncture is taking place on the Radial Artery?
It is a Superficial Artery (if you go more than 0.5cm deep then you are probably too deep)
What are the general contraindications to performing an Arterial Puncture?
- The Patient is on Anticoagulation Medication
- The Patient has a Coagulopathy
- History of Vascular Disease in the Area being used (e.g. Reynaud’s Disease)
What are the Site - Specific Contraindications for a Raidal Arterial Puncture?
- Presence of an AV Fistula in that Arm
- Cellulitis, Broken Skin or Other Signs of Infection
- No Palpable Raidal Pulse
- Negative Allen’s Test
- Fractured Limb
How is an “Allen’s Test” performed?
- Occlude both the Radial and Ulnar Arteries of the Patient
- Ask the Patient to Clench their Fist several times
- Ask the Patient to Extend their Fingers
Note - Blanching should be seen - Release the Ulnar Artery
Note - If colour returns in 10-15 seconds, the Test is positive
What does a Positive “Allen’s Test” indicate?
Good Collateral Arterial Blood Flow
What does a Negative “Allen’s Test” mean?
That the Arterial Puncture should not (ideally) be attempted at that site
What needs to be considered to minimize the discomfort of the patient?
The Depth of the Raidal Artery
Note - If you go to far it is very painful as you will hit the Periosteum of the Radius
What may be given to reduce the pain of the needle insertion?
Local Anesthetic:
- Anesthetic Transdermal Cream
- Anesthetic Spray
- Intradermal Injection of Lidocaine
What is needed in order to interpret results?
Inspired Oxygen Concentration (FiO2) at the time of the sampling
What needs to happen if the Arterial Blood Gas Sample will not be Analysed, by the Blood Gas Analyser, for 30 minutes or more?
- The Cap is Securely Fitted
- The Sample is Labelled with:
a) Patient’s Details
b) Time and Date of the Sample
c) FiO2 at the time of Sampling - The Syringe is placed in a Biohazard Bag and sealed
- The Biohazard Bag is placed in Ice
Why is the Sample placed in Ice if it will not be analysed for 30+ minutes?
To limit ongoing metabolism in the Blood Cells. Otherwise may result in:
- Increased CO2
- Decreased pH
- Decreased PaO2
What may affect the sample in the Syringe?
Air Bubbles present
Why does there need to be Heparin in the Syringe?
To Prevent the Sample from Clotting
What, other than Heparin, helps prevent the Sample Clotting?
Gently Mixing the Sample
What does the Procedure Documentation for an Arterial Blood Sample include?
- Indication for the Procedure
- Type of Equipment used
- The Location and Details of any Unsuccessful Attempt
- Successful Site
- Details of Site Preparation
- Any Local Anesthetic Used
- Patient’s Response to Procedure and that Valid Consent was Obtained if possible
- Date and Time of the Procedure
- Patients FiO2 at the Time of the Sampling
- Results of the Investigation
- Any Complications or Porblems with the Procedure
How is the Risk of Infection Reduced?
Following a Strict Aseptic Non-Touch Technique with Equipment and Insertion Site
How is the Risk of Haematoma Reduced?
- Appropriate Insertion Technique
- Minimal Movement of the Needle when Inserted
- Not pushing down on the Cotton Wool Ball / Swab when the Needle is still Inserted
- Actively Applying Pressure to the Site for several minutes after removing the Needle
How is the Risk of Pain Reduced?
- Rotating Sites
- Ensuring Good Insertion Technique
- Considering Use of Local Anesthetic
- Not pushing down on the Cotton Wool Ball / Swab when the Needle is still Inserted
How is the Risk of Fear / Anxiety Reduced?
- Explaining the Procedure to the Patient
2. Reassuring them throughout
How is the Risk of Arterial Spasm Reduced?
- Let the Syringe fill itself
2. If Aspirating, do so slowly
How is the Risk of Radial Nerve Damage Reduced?
- This should be considered if the Patient complains of Pins and Needles
- Don’t use a Broad Stabbing Movement once the Needle has penetrated the Skin
How is the Risk of Embolus and Thrombosis Reduced?
- Air Embolus:
a) Remove all of the Air from the Syringe Prior to a Puncture - Thrombosis / Thromboembolus:
a) Avoid repeated Punctures at the Same Site
b) Avoid a Radial Arterial Puncture through an existing Haematoma
How is the Risk of Anaphalaxis to Lidocaine Reduced?
Ask the Patient if they are Allergic to the Drug
How is the Risk of Transfixation Reduced?
- Entering at an Angle of 30-45 Degrees
2. Only inserting a Minimal Amount of the Needle to get the sample
What Equipment is Required for an Arterial Blood Gas Sample to be Taken from an Arterial Puncture?
- Clean Tray with a Sharps Container and Clinical Waste Container (Bag)
- Heparinised Arterial Blood Gas Syringe
- Gloves and Apron
- Alcohol Swabs / Alternative Agent
- Alcohol Based Hand Gel
- Hypoallergenic Tape
- Appropriate Specimen Request Form and Bag - If the Sample is to be sent to a Lab
- Anesetheic (If Required)
- Ice (if Required)
What is the first part of the Radial Arterial Puncture Procedure?
Identify the Patient (First Name, Surname, Date of Birth against the Patients I.D. Band)
What is the Rationale for the Identification of the Patient as the First Step of the Procedure?
To Ensure that you are performing the procedure on the correct patient - Patient Safety
After the Correct Patient has been Identified, What Happens Next?
Understand and Explain Indications for the Procedure in the Particular Patient:
- What will hapen
- Positive Outcomes / Expected Outcomes
- Possible Unexpected Outcomes / Possible Complications
What is the Rationale for Explaining the Procedure?
- To inform that Patient, and Reduce Stress and Anxiety
2. Must have Valid Consent to do an Invasive Procedure
After the Procedure is Explained, what must happen?
Obtain and Document Informed Valid Consent
What is the Rationale of Obtaining and Documenting Informed Valid Consent?
It is a Patient Safety and Legal Requirement
After Informed Consent is Given, What Happens Next?
An Appropriate Site for the Procedure is Selected, Checking for any Contraindications
- What must be done if a Prescription is Necessary for the Procedure?
- Why?
- That this is Correct
2. It is a Legal Requirement
What must be done before the Procedure is Started?
All Equipment Needed should be Gathered Together
Once all the Equipment is Gathered, What happens next?
- All Other Packaging for Access (using Aseptic Non-Touch Technique (ANTT))
- Assemble the Equipment
- Check for the Expiration Date
What is initially recorded?
The FiO2 - Inspired Oxygen Concentration
- What Must be performed before the rest of the Procedure Takes Place?
- Why?
- Hand Hygiene
2. To Minimize the Risk of Infection
After all of the Preparation, and Appropriate Hand Hygiene, Has been Performed, What happens next?
The Artery Position is located
Note - Allen’s Test can be Performed Here
After the Artery is Located, What happens next?
Preparation of the Site to Minimize the Risk of Infection, Wipe with Alcohol Wipes
What must happen after the Site Preparation has finished?
- Hand Hygiene Must be Performed Again and Application of Gloves, for Infection Prevention and Control
- Preparation of the Finger on the Non- Dominant Hand for Re-Palpation, to put the Palpating Fingers at the same Level of Cleanliness as the Puncture Site
When you (and the Patient) are Prepared and Comfortable to perform the Invasive Procedure:
- What happens next?
- Why?
- The Patient’s Wrist is Extended to Approximately 30 Degrees Downward, Palm Up
- It Assists the Artery to be Closer to the Skin Surface
Note - This can be achieved by resting the wrist on a rolled towel or over the edge of the bed and pulling the hand down
Once the Patient’s Wrist is in Position, What happens next?
The Needle is Inserted into the Area
Which Hand Holds the Syringe as it is Inserted?
The Dominant Hand
What Angle is the Needle Inserted at?
30-45 Degrees
What guides the Needle?
The Cleaned Index Finger of the Non-Dominant Hand
Where is the Needle guided?
Towards the Max. Pulsation - SLOWLY
What may happen as you enter into the Artery?
Blood may Gush
Once the Needle is Inserted, What may happen at the Syringe?
Often a Vented Syringe will Fill on its own
If the Syringe does not Fill on its Own, What should you do?
Slowly Draw back on the Plunger, until the appropriate amount of Blood is taken
Once the Appropriate Amount of Blood is Taken, What happens?
The Needle is Removed
As the Needle is Removed, what happens Immediately After?
Direct Pressure is Applied to the Site with a Cotton Wool Ball / Swab until the Bleeding Stops
Is the Needle recapped?
No - The Needle Should be Removed into the Sharps Bin
- What must you initially do to the sample?
2. Why?
- Remove the Air Bubbles and place a Cap on the Syringe
2. This prevents Falsely Elevated PaO2 and Spillage etc.
Once the Syringe is Capped, What do you do?
Roll the Syringe to Mix the Blood and Heparin
Once the Sample is Safely Contained and Rolled, What is the Next Step?
Remove all Gloves and Aprons
Where are the Gloves and Aprons Disposed of?
The Orange Clinical Waste Bags
After you have got rid of the PPE , What do you do next?
- Decontaminate your Hands
- Label the Syringe with Patient Details
- Thank the Patient and make sure they are comfortable
(4. Ice if appropriate) - (5.) Complete Documentation
- (6.) Analyse the Sample and Complete the Documentation
