معمل إعتماد مشروعاإلكلينيكيه – الكمياء

الطوارئ مستشفى

Role of clinician in Role of clinician in lab result accuracylab result accuracy

Prof/Azza abd al bakyProf/Azza abd al baky

IntroductionIntroduction

Three phases of laboratory testing: Three phases of laboratory testing: pre-analytical, analytical and pre-analytical, analytical and post-analyticalpost-analytical

Pre-analyticalPre-analytical—specimen collection, —specimen collection, transport and processingtransport and processing

AnalyticalAnalytical—testing—testing Post-analytical—Post-analytical—testing results testing results

transmission, interpretation, follow-transmission, interpretation, follow-up, retesting.up, retesting.

Pre-analytical errorsPre-analytical errors Pre- and post-analytical errors are Pre- and post-analytical errors are

estimated to constitute estimated to constitute 9090% of errors% of errors Errors at any stage of the collection, Errors at any stage of the collection,

testing and reporting process can testing and reporting process can potentially lead to a serious patient potentially lead to a serious patient misdiagnosismisdiagnosis

Errors during the collection process are Errors during the collection process are not not inevitableinevitable but can be but can be preventedprevented with a diligent application of with a diligent application of quality quality control, continuing education and effective control, continuing education and effective collection systems.collection systems.

The steps of the The steps of the preanalytical phasepreanalytical phase

Preparation prior Preparation prior to to

samplingsampling

Sampling/handling

Storage/transport

Preparation prior to analysis

Implications of errorsImplications of errors

and and compromise compromise the diagnosis the diagnosis and treatment and treatment of the patientof the patient

• may influence the quality of the final measured results ...

• Errors made in the period prior to the analysis of the sample ...

No result is better than bad result

Complex and labor Complex and labor intensiveintensive

The The more steps more steps involved in a involved in a process, the process, the more likely more likely there will be there will be errors committederrors committed

32 - 75% of all test errors occur in 32 - 75% of all test errors occur in the preanalytical phasethe preanalytical phase

Stankovic 2008Stankovic 2008““Quality Improvements in the Preanalytical Phase: Quality Improvements in the Preanalytical Phase:

Focus on Urine Specimen Workflow”Focus on Urine Specimen Workflow”

Paying close Paying close attentionattention toto the the preanalyticalpreanalytical variablesvariables associated with blood collection associated with blood collection isis criticalcritical in ensuring in ensuring accurate testaccurate test results in all areas of the clinical results in all areas of the clinical laboratory. laboratory.

Effects of Pre-analytical Effects of Pre-analytical Variables on the Quality of Variables on the Quality of

Laboratory TestingLaboratory Testing

The Pre-Analytical process

Patient IdentificationPatient Identification

Sampling TechniqueSampling Technique

Test Collection ProceduresTest Collection Procedures

Specimen TransportSpecimen Transport

Specimen ProcessingSpecimen Processing

Collect Sample:Collect Sample: Locate PatientLocate Patient Prep PatientPrep Patient Draw SampleDraw Sample LabelLabel Dispose of suppliesDispose of supplies

The Pre-Analytical process

When When identifyingidentifying the patient, have them the patient, have them provide their provide their full full namename, address, , address, ididentificationentification numbernumber and/or and/or date of date of birthbirth. Hospital No . Hospital No inpatients should be inpatients should be wearing an wearing an ididentification entification bandband with the with the above information, which the above information, which the phlebotomist should confirm before the phlebotomist should confirm before the venipuncture. venipuncture.

Patient identificationPatient identification

Patient IdentificationPatient Identification:: It is important It is important to to identifyidentify a a patient accuratelypatient accurately so that so that blood is blood is collected collected from the from the correct correct personperson. Drawing blood from the . Drawing blood from the wrong person, or labeling the correct wrong person, or labeling the correct patient’s sample with a different patient’s sample with a different patient’s label can certainly contribute patient’s label can certainly contribute to laboratory error. (to laboratory error. (Mislabeling ???Mislabeling ???))

Effects of Pre-analytical Effects of Pre-analytical Variables on the Quality of Variables on the Quality of

Laboratory TestingLaboratory Testing

Factor affecting lab Factor affecting lab resultresult

Some patient variables that affect test resultsSome patient variables that affect test resultsAge Genetic variationAge Genetic variation

Gender Nutrition statusGender Nutrition status

Diet Diagnostic and therapeutic Diet Diagnostic and therapeutic Drugs Drugs procedures(PR&endoscopy) procedures(PR&endoscopy)

Exercise ObesityExercise Obesity

Posture BiorythmPosture Biorythm

Haemolysis,lipemia Special habitsHaemolysis,lipemia Special habits

& icterus& icterus

Test CollectionTest Collection Timing of CollectionTiming of Collection

Therapeutic Drug MonitoringTherapeutic Drug Monitoring PeakPeak and and troughtrough collection times collection times

Basal State Collections Basal State Collections FastingFasting requirements—no food or requirements—no food or

liquid except liquid except waterwater(10-12h)(10-12h) 2h postprandial, from the 2h postprandial, from the startstart of food of food

.. Specimens affected by time of daySpecimens affected by time of day, for , for

example, cortisol, iron and TSH.example, cortisol, iron and TSH.

PhlebotomyPhlebotomy

Phlebotomy is a highly complex skill Phlebotomy is a highly complex skill requiring expert requiring expert knowledgeknowledge, and , and criticacritical judgmentl judgment

venipuncture is a frequent medical venipuncture is a frequent medical procedure.procedure.

Phlebotomy errors may cause Phlebotomy errors may cause harmharm to patients or result in to patients or result in needle stick needle stick injury to the phlebotomistinjury to the phlebotomist

Error PreventionError Prevention Phlebotomy EducationPhlebotomy Education

Phlebotomists should have completed a standard Phlebotomists should have completed a standard academic course in phlebotomy and undergo academic course in phlebotomy and undergo thorough on-the-job training under the supervision thorough on-the-job training under the supervision of a senior phlebotomistof a senior phlebotomist

Continuing EducationContinuing Education Phlebotomists should participate in regular Phlebotomists should participate in regular

educational competency assessments (written and educational competency assessments (written and observational) observational)

Professional LicensureProfessional Licensure Phlebotomy StaffingPhlebotomy Staffing

Adequate staffing to maintain collection standardsAdequate staffing to maintain collection standards TechnologyTechnology

Use of barcode scanners for patient identificationUse of barcode scanners for patient identification

1-posture:1-posture:The patient should be comfortably seated or The patient should be comfortably seated or

supine for 20 minutes before sampling.Not supine for 20 minutes before sampling.Not standingstanding

The patient arm should be extended in a straight The patient arm should be extended in a straight line from the shoulder to the wrist.line from the shoulder to the wrist.

2-2- collection site.collection site.The median cubital vein is the preferred site.The median cubital vein is the preferred site.Veins on the hand or at ankle may be usedVeins on the hand or at ankle may be used..Avoid the arm with:Avoid the arm with:Extensive scarring or hematoma .,infection , Extensive scarring or hematoma .,infection ,

edema ,burn ,edema ,burn ,Containing I.V. access for I.V. infusion.Containing I.V. access for I.V. infusion.On the side of mastectomy.On the side of mastectomy.

Phlebotomy TechniquePhlebotomy Technique Correct collection systemCorrect collection system

Evacuated tube system (Vacutainer) for Evacuated tube system (Vacutainer) for large veins in antecubital fossalarge veins in antecubital fossa

Syringe for small, fragile veins or veins Syringe for small, fragile veins or veins outside antecubital fossaoutside antecubital fossa

Venous accessVenous access Needle entry should be at 15 to 30 degrees Needle entry should be at 15 to 30 degrees

depending on depth of veindepending on depth of vein Needle entry should be in same direction Needle entry should be in same direction

as vein, centered over veinas vein, centered over vein Anchor vein to prevent movement during Anchor vein to prevent movement during

needle entry and to reduce pain to patientneedle entry and to reduce pain to patient

Phlebotomy Technique Phlebotomy Technique ErrorsErrors

Tourniquet ApplicationTourniquet Application Tourniquet tied too close to the venipuncture site Tourniquet tied too close to the venipuncture site

can cause hematomacan cause hematoma Veins may not become prominent if tourniquet is Veins may not become prominent if tourniquet is

tied too high (more than 3 to 4 inches above tied too high (more than 3 to 4 inches above venipuncture sitevenipuncture site))

Tourniquet left on longer than one minute can Tourniquet left on longer than one minute can result in result in hemoconcentration hemoconcentration , affecting some test , affecting some test resultsresults Tourniquet should be released as soon as Tourniquet should be released as soon as

needle is in the lumen of the vein and blood needle is in the lumen of the vein and blood flow establishedflow established

Phlebotomy TechniquePhlebotomy Technique

Cleansing of venipuncture siteCleansing of venipuncture site Thorough cleaning with alcohol Thorough cleaning with alcohol Allow alcohol to dry completely to avoid stinging Allow alcohol to dry completely to avoid stinging

sensation upon needle entry and sensation upon needle entry and hemolysishemolysis of of samplesample

Samples such as blood cultures should be Samples such as blood cultures should be collected using collected using iodineiodine to cleanse site to ensure to cleanse site to ensure sterility of samplesterility of sample Recollection rate for blood cultures ranges Recollection rate for blood cultures ranges

due to contamination is as high as 50% in due to contamination is as high as 50% in hospitals with increased costs, patient hospitals with increased costs, patient overtreatmentovertreatment

Test CollectionTest Collection AdditiveAdditive : EDTA,citrat, lithium : EDTA,citrat, lithium

heparin ,oxalate,flouridheparin ,oxalate,flourid HemolysisHemolysis

Blood collected insufficient to amount of Blood collected insufficient to amount of additive in tube, additive in tube,

Traumatic venipunctureTraumatic venipuncture Blood collected from area with hematomaBlood collected from area with hematoma Vigorous shaking of tubes after collectionVigorous shaking of tubes after collection Milking the site when collecting capillary Milking the site when collecting capillary

samples and blood collected using a small samples and blood collected using a small diameter needle. diameter needle.

Test CollectionTest Collection Capillary Collections—finger stick or heel Capillary Collections—finger stick or heel

stickstick Appropriate siteAppropriate site

Heel stick—sides of the bottom surface of the heelHeel stick—sides of the bottom surface of the heel Finger stick—third or fourth fingers, perpendicular Finger stick—third or fourth fingers, perpendicular

to fingerprint lines on fleshy pads on finger surfaceto fingerprint lines on fleshy pads on finger surface Warming—Warming—Warm before collection to increase Warm before collection to increase

capillary blood flow near skin surfacecapillary blood flow near skin surface Cleaning—cleanse site with alcohol and allow Cleaning—cleanse site with alcohol and allow

to air dryto air dry Discard first drop of blood.Discard first drop of blood.

Recommended order of draw (NCCLS):Recommended order of draw (NCCLS):

1.1. Blood Culture Bottles (Aerobic-Anaerobic)Blood Culture Bottles (Aerobic-Anaerobic)

2.2. Coagulation TubeCoagulation Tube

3.3. Serum Tube with or without clot activator, with Serum Tube with or without clot activator, with or without gel separatoror without gel separator

4.4. Heparin Tube with or without gel plasma Heparin Tube with or without gel plasma separatorseparator

5.5. EDTAEDTA

6.6. Glycolytic InhibitorGlycolytic Inhibitor

Correct Specimen VolumeCorrect Specimen Volume:: All blood collection All blood collection tubes need to be filled to the correct volumetubes need to be filled to the correct volume. This . This will ensure the will ensure the proper amount of blood proper amount of blood for the for the amount of amount of additiveadditive in the tube (blood to additive in the tube (blood to additive ratio). For example, ratio). For example, if a 5 mL draw heparin tubeif a 5 mL draw heparin tube is is only filled with 3 mLonly filled with 3 mL of blood, of blood, the heparinthe heparin concentration concentration is erroneously highis erroneously high and and maymay potentially potentially interfere with some chemistry analytes, interfere with some chemistry analytes, tube for Coagulation Studies incomplete filling tube for Coagulation Studies incomplete filling results in specimen dilution and erroneous results in specimen dilution and erroneous Prothrombin and aPTT test results. Prothrombin and aPTT test results.

Proper Tube MixingProper Tube Mixing:: All All tubes with tubes with additives need to be additives need to be invertedinverted to to mix the additive evenlymix the additive evenly with the with the blood. blood. ImproperImproper mixingmixing of the of the tube after venipuncture tube after venipuncture could could contribute to sample clotting.contribute to sample clotting.

E) Specimen transportE) Specimen transport

TemperatureTemperature

LightLight

Transport ErrorsTransport Errors TemperatureTemperature

Specimens must be transported at the Specimens must be transported at the appropriate temperature for the required testappropriate temperature for the required test On ice—ABGs, AmmoniaOn ice—ABGs, Ammonia Warmed -- (37 C), cryoglobulinsWarmed -- (37 C), cryoglobulins Avoid temperature extremes if transported Avoid temperature extremes if transported

via vehicle from other collection sitevia vehicle from other collection site Transport ContainerTransport Container

Some samples need to be protected from Some samples need to be protected from light, for example, bilirubinlight, for example, bilirubin

Transport in leak-proof plastic bags in Transport in leak-proof plastic bags in lockable rigid containers ,avoid agitation.lockable rigid containers ,avoid agitation.

Blood Specimen Blood Specimen TransportTransport

Transport of blood specimens in the Transport of blood specimens in the proper manner after collection proper manner after collection ensures the quality of the sampleensures the quality of the sample

TimingTiming Some specimens must be transported Some specimens must be transported

immediatelyimmediately after collection, for after collection, for example Arterial Blood Gasesexample Arterial Blood Gases..

Specimens for serum or plasma Specimens for serum or plasma chemistry testing should be centrifuged chemistry testing should be centrifuged and separated within two hoursand separated within two hours

Special Handling of Blood SpecimensSpecial Handling of Blood Specimens:: CertainCertain chemistry chemistry analytesanalytes will will requirerequire the the tube of blood tube of blood to be to be chilledchilled after collection in after collection in order order to maintainto maintain the the stabilitystability of the analyte. of the analyte. A slurry of ice and water is recommended for A slurry of ice and water is recommended for chillingchilling the tubes of blood. Examples : the tubes of blood. Examples : adrenocorticotropic hormone (adrenocorticotropic hormone (ACTHACTH), ), angiotensin converting enzyme (angiotensin converting enzyme (ACEACE), ), acetone, acetone, ammoniaammonia, catecholamines, free fatty , catecholamines, free fatty acids, lactic acid, pyruvate and renin ,PTH acids, lactic acid, pyruvate and renin ,PTH

Blood gases analysisBlood gases analysis“Collection of a blood specimen, as well as its handling and transport, are key factors in the accuracy of clinical laboratory analysis and ultimately in delivering quality patient care”

”Arterial blood is one of the most sensitive of the specimens sent to the clinical laboratory for analysis”

”Blood gas and pH analysis has more immediacy on patient care than any other laboratory determination”

”In blood gas and pH analysis an incorrect result can often be worse for the patient than no result at all”

What is so special about What is so special about blood gases?blood gases?

NOT like other blood NOT like other blood samplessamples

STAT parametersSTAT parameters Short Turn Around TimeShort Turn Around Time Must be analyzed within Must be analyzed within

a short timea short time ppOO22, , ppCOCO22, pH, LAC, , pH, LAC,

GLUGLU Valuable results right nowValuable results right now

Not in one hourNot in one hour Sample composition Sample composition

changeschanges Patient status changesPatient status changes

Some points to keep in mind Some points to keep in mind - sampling from A-lines- sampling from A-lines

Preparation prior Preparation prior to samplingto sampling

Sampling/handling

•Label the sampler with patient ID

•Use dry electrolyte balanced heparin

•Endeavor to keep the patient’s respiratory condition stable for a certain period prior to sampling

•Make sure that the a-line has been adequately cleared of flush solution

•Aspirate the sample slowly to prevent degassing and hemolysis

•Expel any air bubbles immediately after sampling

•Mix the sample thoroughly with heparin after sampling

Storage/transport

•Analyze sample immediately

•If storage is unavoidable, store the sample at room temperature for max. 30 min. Samples with expected high pO2 values should be analyzed within 5 min.

Preparation prior to sample transfer

•Before transferring the sample into the analyzer mix thoroughly

•Visually inspect the sample for clots and air bubbles

•Enter patient ID in analyzer logs

To get a true picture of the To get a true picture of the patient’s respiratory patient’s respiratory condition the patient should condition the patient should ideally be in a steady state of ideally be in a steady state of ventilationventilationPatients should be at rest Patients should be at rest for 5 minfor 5 min

Ventilatory settings should Ventilatory settings should be be unchanged for 20 minunchanged for 20 min

Pain and anxiety from arterial Pain and anxiety from arterial

puncture may influence the puncture may influence the steady state of respiration steady state of respiration and should thus be minimizedand should thus be minimized

Stabilization of the respiratory condition

Storage Storage recommendationsrecommendations

Storage and transport time Storage and transport time should be kept at a should be kept at a minimumminimumVolatile nature of gases Volatile nature of gases Continued metabolism in Continued metabolism in blood blood

For parameter panels For parameter panels including GLU/LAC, be including GLU/LAC, be aware that 30 minutes aware that 30 minutes storage might lead to biased storage might lead to biased resultsresults

It is recommended by the It is recommended by the NCCLS to avoid cooling of NCCLS to avoid cooling of samples when kept in samples when kept in plasticplastic

General storage recommendationDo not cool the sampleAnalyze within 30 minutes

For samples with high pO2

Analyze within 5 minutes

For special studies, e.g. shuntAnalyze within 5 minutes

For samples with high leukocyte or platelet countAnalyze within 5 minutes

Expected delayed analysisWhen analysis is expected to be delayed for more than 30 minutes, the use of glass syringes and storage in ice slurry is recommended

ppOO22 since oxygen will still be consumedsince oxygen will still be consumed

ppCOCO22 since carbon dioxide will still be producedsince carbon dioxide will still be produced

pHpH primarily due to the change in primarily due to the change in ppCOCO22 and andglycolysisglycolysis

ccCaCa2+2+ since the change in pH will influence the since the change in pH will influence the binding of Cabinding of Ca2+2+ to protein to protein

ccGluGlu since glucose will be metabolizedsince glucose will be metabolized

ccLacLac due to glycolysisdue to glycolysis

Continued cellular metabolism Continued cellular metabolism in samplein sample

Slowing down the Slowing down the metabolismmetabolism

Blood gas samples in glass Blood gas samples in glass samplers can be cooled samplers can be cooled

Storing the sample at a Storing the sample at a lower temperature (0-4 °C) lower temperature (0-4 °C) will slow down the will slow down the metabolism by at least a metabolism by at least a factor of 10 [NCCLS]factor of 10 [NCCLS]

Cool samples in an ice Cool samples in an ice slurry or other suitable slurry or other suitable coolantcoolant

Never store the sampleNever store the samples s directly on ice as this directly on ice as this causes hemolysis of causes hemolysis of the blood cellsthe blood cellsNCCLS Document C27-A; Blood Gas Pre-Analytical Considerations: Specimen Collection, Calibrations and Controls;

Approved Guideline

25 C

0-4 C

pO2

Time

Potential Potential preanalytical errorspreanalytical errors

Preparation prior Preparation prior to samplingto sampling

• Missing or wrong patient/sample identification

• Use of the wrong type or amount of anticoagulant - dilution due to the use of liquid heparin - insufficient amount of heparin - binding of electrolytes to heparin

• Inadequate stabilization of the respiratory condition of the patient

• Inadequate removal of flush solution in a-lines prior to blood collection

Sampling /handlingSampling /handling• Mixture of venous and arterial blood during puncturing

• Air bubbles in the sample

• Insufficient mixing with heparin

• Incorrect storage• Hemolysis of blood

cells

Storage and transportStorage and transport

Prep prior to transferPrep prior to transfer

• Visually inspect the sample for clots

• Inadequate mixing of sample before analysis

• Failure to identify the sample upon analysis

Mixture of venous and Mixture of venous and arterial bloodarterial blood

When puncturing an When puncturing an artery it is important not artery it is important not accidentally to get the accidentally to get the arterial blood mixed with arterial blood mixed with venous bloodvenous blood

This may, for instance, This may, for instance, occur, if you hit a vein occur, if you hit a vein before locating the arterybefore locating the artery

Even an admixture of a Even an admixture of a small amount of venous small amount of venous blood may significantly blood may significantly bias the resultsbias the results

This is especially true of This is especially true of ppOO22 and and ssOO22, but other , but other parameters may also be parameters may also be affectedaffected

Vein

Artery

40 mmHg / 5.3 kPa100 mmHg / 13.3 kPa

Mixture of venous and Mixture of venous and arterial bloodarterial blood

In arteries the In arteries the blood pressure is blood pressure is high enough to fill a high enough to fill a self-filling syringeself-filling syringe

If a self-filling If a self-filling syringe does not fill syringe does not fill it may be because a it may be because a vein has been hitvein has been hit

In that case a new In that case a new sample should be sample should be takentaken

Vein:Pressure rarely> 10 mmHg

Artery:Systolic bloodpressure normally> 100 mmHg

Inadequate removal of Inadequate removal of flush solutionflush solution

Flush solutions used Flush solutions used in a-lines must be in a-lines must be removed completely removed completely from the system to from the system to avoid a dilution of the avoid a dilution of the blood sampleblood sample

It is recommended to It is recommended to withdraw a volume withdraw a volume equal to equal to three to six three to six times the “dead times the “dead space” of the catheter space” of the catheter system (NCCLS)system (NCCLS)

Inadequate removal of Inadequate removal of flush solutionsflush solutions

Sample B and A are both a-line samples taken from the Sample B and A are both a-line samples taken from the same patient immediately after each othersame patient immediately after each other

Before taking sample B Before taking sample B onlyonly 1 mL of saline solution was 1 mL of saline solution was removed - the tubing, however, looked redremoved - the tubing, however, looked red

Before taking sample A saline solution was removed as Before taking sample A saline solution was removed as recommendedrecommended

Sample ActHb 6.2 mmol/L cGlu 9.6 mmol/LcK+ 3.8 mmol/LcNa+ 130 mmol/LcCa2+ 1.00 mmol/LcCl- 101 mmol/LpH 7.271pCO2 50.5 mmHg / 6.7 kPa

pO2 116.7 mmHg / 15.56 kPa

Sample BctHb 4.6 mmol/L cGlu 6.9 mmol/LcK+ 2.5 mmol/LcNa+ 137 mmol/LcCa2+ 0.61 mmol/LcCl- 113 mmol/LpH 7.275pCO2 35.9 mmHg / 4.8 kPa

pO2 129.3 mmHg / 17.2 kPa

Air bubblesAir bubbles Any air bubbles in the sample Any air bubbles in the sample

must be expelled as soon as must be expelled as soon as possible after the sample has possible after the sample has been drawnbeen drawnbeforebefore mixing the sample mixing the sample with heparinwith heparin

beforebefore any cooling of the any cooling of the samplesample

Even small air bubbles may Even small air bubbles may seriously affect the seriously affect the ppOO22 value value of the sample, normally of the sample, normally resulting in increased valuesresulting in increased values

An air bubble whose relative An air bubble whose relative volume is 0.5 to 1.0 % of the volume is 0.5 to 1.0 % of the blood in the syringe is a blood in the syringe is a potential source of a potential source of a significant errorsignificant error

Effect of air bubbles - an Effect of air bubbles - an exampleexample

Sample A and B were taken from the same patient Sample A and B were taken from the same patient immediately after each otherimmediately after each other

Sample A without air bubbles was analyzed immediately Sample A without air bubbles was analyzed immediately after collectionafter collection

100 µL air was added to sample B (1 mL). It was stored 100 µL air was added to sample B (1 mL). It was stored cold (0-4 °C) for 30 minutes and mixed for 3 minutes cold (0-4 °C) for 30 minutes and mixed for 3 minutes before sample analysis before sample analysis

Sample ApO2 288.6 mmHg / 38.5 kPa(FIO2 1.000)

Sample BpO2 253.3 mmHg / 33.8 kPa(FIO2 1.000)

Insufficient mixing with Insufficient mixing with heparinheparin

Insufficient mixing Insufficient mixing can cause can cause coagulation of the coagulation of the samplesample

It is recommended It is recommended to mix the blood to mix the blood sample thoroughly sample thoroughly with heparinwith heparin

Invert the syringe Invert the syringe 10 times and roll it 10 times and roll it between your palmsbetween your palms

Inadequate mixing - an Inadequate mixing - an exampleexample

Sample A and B were taken from the same patient immediately Sample A and B were taken from the same patient immediately after each other and stored cold for 10 minutesafter each other and stored cold for 10 minutes

Sample A was mixed in a rotator (14 revolutions/min) for 3 minutesSample A was mixed in a rotator (14 revolutions/min) for 3 minutesSample B was mixed in a rotator (14 revolutions/min) for 1 minuteSample B was mixed in a rotator (14 revolutions/min) for 1 minute

Sample BctHb 4.5 mmol/L

Sample ActHb 6.2 mmol/L

Hemolysis of blood cellsHemolysis of blood cells The blood cells are relatively The blood cells are relatively

fragile, and therefore hemolysis fragile, and therefore hemolysis may easily occur during blood may easily occur during blood samplingsampling

Hemolysis may, for instance, occur Hemolysis may, for instance, occur due todue to high filling pressure through high filling pressure through

a narrow entrance (e.g. during a narrow entrance (e.g. during too vigorous sample aspiration, too vigorous sample aspiration, sample transfer to the analyzer, sample transfer to the analyzer, etc.)etc.)

vigorous rubbing or squeezing vigorous rubbing or squeezing of the skin during capillary of the skin during capillary samplingsampling

too vigorous mixing of the too vigorous mixing of the samplesample

cooling down the sample cooling down the sample below 0 °Cbelow 0 °C

““The weak link” The weak link” Blood gas analyzers of Blood gas analyzers of

today are highly accuratetoday are highly accurate Make sure that sample Make sure that sample

represents patient statusrepresents patient status The preanalytical phase The preanalytical phase

is the is the weak linkweak link in the in the Patient Focus CirclePatient Focus Circle

Many potential errors Many potential errors Can be overcome by Can be overcome by

TrainingTrainingUser guidelinesUser guidelinesSampling productsSampling products

Specimen Quality Specimen Quality Markers for RejectionMarkers for Rejection

ClottedClotted HemolyzedHemolyzed Underfilled, Underfilled,

overfilledoverfilled Insufficient Insufficient

quantityquantity Incorrect labelingIncorrect labeling Unlabeled Unlabeled

specimenspecimen

Incorrect patientIncorrect patient Incorrect Incorrect

specimenspecimen ContaminatedContaminated Lost sampleLost sample Too old to Too old to

processprocess Broken and Broken and

leakingleaking

Finally…Finally… The The human rolehuman role in sample collection in sample collection

makesmakes complete eliminationcomplete elimination of errorsof errors associated with laboratory testing associated with laboratory testing unrealisticunrealistic

However, However, good practicesgood practices and and compliancecompliance with the new with the new strategiesstrategies forfor errorerror preventionprevention can leadcan lead to a to a substantial substantial reductionreduction in in pre-analytical pre-analytical errorserrors..