Blood Gas Analyser Training

By David SeeruthunSenior Biomedical Scientist-Biochemistry & POCT

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Analysers

• Trust currently has 14 analysers – A&E (4 analysers)

– ITU (2 analysers)

– Tilgate Annex

– AMU

– SAU

– SCBU

– Capel Annex

– Copthorne

– Labour Ward

Most analysers have all the same measuring parameters: pH, pO2, pCO2, Na2+, K+, Cl-, Ca 2+ (ionised calcium), Glu, Lac, tHb, O2Hb, COHb, MetHb

Apart from Labour- which has only basic gas parameters

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Basic Analyser Overview

Touch Screen

Sampling area

Cartridge housing

Enabled analytes

Barcode Scanners also attached to all analysers

Touch screen- For typing in information, patient details.

Enabled analytes- Shows you which analytes are enabled on the gas machines. Highlights with a green tick that the analyte will analysed for that sample.

Cartridge housing: Self contained cartridge, contains all the solutions, the waste and quality control. Internally it is split into 2 halves. One side is for co-ox measurements and the other side for ion measurements.

Sampling area: Here is where the sample probe ejects ready for sample aspiration and analysis.

Barcode Scanners also attached to all analysers for data entry.

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• Only Heparinised samples can be processed on the GEM 4000/5000 gas machine (minimum volume 150 ul required)

• Syringe samples must be mixed thoroughly immediately after sample collection.

• The syringe should be inverted as least 3 times and also rolled between outstretched palms at least 5 times.

• Expel a few drops of sample before analysis to ensure no clot in syringe tip.

• Samples must be analysed within 10 minutes.

• If there is a delay in analysis, thoroughly remix the sample before testing.

Patient Sampling -Syringes

1. With wet heparin syringes make sure Heparin has been expelled before sampling blood.

2. Make sure sample is mixed immediately before analysis.

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• Capillary samples must be mixed thoroughly immediately after collection. This may be done by rolling the capped capillary tube with outstretched palms for 5 seconds.

• Always present the clean end of the capillary to the analyser.

• Capillary samples must be analysed within 5 minutes.

• Note Sample Volumes Required For Analysis:– 150μL pH, pCO2, pO2, Hct, Na, K+, Ca, Cl-, Glu, Lac, or any subset of the

menu that includes CO-Ox– 95μL pH, pCO2, pO2, Hct, Na, K+, Ca, Cl-, Glu, Lac, or any subset of the

menu that does not include CO-Ox– 65μL (Micro Mode Only) pH, pCO2, pO2, Hct, Na, K+, Ca, Cl-, Glu, Lac,

(Capillary Only)

Patient Sampling - capillaries

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Sample Analysis- Main Screen/Quick Start Screen

• Make sure all the analyte tabs are green and ready for sampling

• 4000 only- Select Normal / Micro mode by pressing the on-screen toggle button

Status Bar- Visual check

Check the status bar- This will tell you the overview of the analyser. There maybe a countdown timer displayed with a yellow banner which may mean analyser is processing previous sample or running an internal quality control.

If so wait until it says ready.

Two important counters top right hand side- tests remaining and days left. Which ever gets to 0 first will cause cartridge to eject and be changed.

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Sample Analysis 4000- Pre analysis

3. Select sample type by using the drop down menu.

To display the drop down menu, press the show all button.

Default setting is arterial

For a full list- press show all. They are Arterial/Capillary/Mixed venous/Venous/ or other

The default sample type for all samples (bar capillary) is a syringe so the analyser is expecting a syringe sample. Only selection of capillary or micro sample will retract the needle allowing capillary analysis.

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Sample Analysis-4000

4. Press Go

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Sample Analysis- Password- Both

5. Scan your individual user password using the barcode scanner.

Remember…

It is against trust policy to share passwords

Password is required prior to any analysis. Passwords should be scanned in using the barcode scanner.

Passwords are issued to individuals only. They are all added onto system along with your details.

Gives us full audit capabilities for sample analysis. You only receive your password once you have received the training.

Remember do not share passwords- Lots of medico-legal issues if you share passwords.

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Sample Analysis- Aspiration

Press OK or Start Aspiration

6. The sample probe will lower. Present the sample for aspiration

• Do not allow the end of the probe to touch the bottom of the syringe.

If the probe touches the plunger a ‘No sample Detected’ error message will be displayed.Do not push syringe too far onto the probe as this can cause a vacuum and no sample detected.

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Sample Analysis- Sample removal

7. When you hear the audible bleeps remove the syringe /capillary from the sampler.

Sample will aspirate and when its finished you will hear an audiable bleep informing you to remove the syringe.

There is a countdown timer of 15 seconds after aspiration at which point the probe will retract into the analyser. This will occur automatically even if you don’t remove the syringe.

Leaving it attached will cause syringe to fly across the room and potentially damage probe.

Don’t walk away during analysis until the syringe has been removed!

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Sample Analysis- Patient Information-40008. Complete the

information section i.e. patient detailsThe sections marked with a star means the field is mandatory and must be filled in before viewing theresults.

IMPORTANT : The GEM analysers are soon to be networked.Incorrect patient information will cause results to be stored in the wrong patient’selectronic records.

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Sample Analysis- Patient Information-5000

Select ‘Patient ID’ ‘Key entry’-If Possible scan in the Patient ID.

If areas not automatically populated enter Patient demographics.Mandatory fields are marked with an ‘!’ and on the left hand side

Correct Patient ID must be enteredFrequent audits conducted

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Sample Analysis- Results Tab9. When all the information tabs have been filled in and checked, press the view results tab.

Patients temperature can be added if not normal (37oC) and percentage Oxygen if on ventilation (default 21% i.e.air)

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Sample Analysis- Results tab

10. Once the results are available a print out will be produced.

Results will be flagged via a colour coded system and directional arrow: Yellow- WarningRed-CriticalGrey- No reference range (normally on venous sampling)

Only reference ranges for Arterial samples, all other samples results are shown with grey background i.e. No reference range available.

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Database Search

To recall any previous result:

• Select Menu>View Last Results>Print

• A more in-depth search can be performed by selecting ‘Search Results’ and completing the required fields.

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Common Causes of Error• Room Air: Especially samples with a very low or high pO2 content.

Similarly, pCO2 may be affected and subsequently pH.

• Metabolic Changes: Errors can occur due to metabolic changes if there is a delay in sample analysis.

• Improper Mixing: Errors observed for CO-Ox parameters if the sample is not properly mixed (Hb,HCT).

• Under-Heparinised: Sample blood clot can form in the sensor chamber causing various sensor failures if sample is not properly heparinised.

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Considerations

• Analyser measures ionised calcium and not total calcium.

• No Haemolysis check for K+ results

• Transfusion will not issue blood based on a gas tHb result.

• Lab does not have an analyser

• Cartridge takes 45 mins to warm up

• Don’t share passwords!

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Requests for advice & training

• There are also key operators on wards that can assist with basic troubleshooting and training

• Any complex issue with a gas machine or for training contact POCT department– At ESH - ext 2477– David.seeruthun1@nhs.net or Jake.mitchell3@nhs.net

Thank you for listeningAny Questions?

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