CLINICAL CLINICAL CHEMISTRY CHEMISTRY SPECIMEN SPECIMEN

REQUIREMENTSREQUIREMENTS

DR . Naglaa Makram DR . Naglaa Makram Asistant. Prof . clinical Asistant. Prof . clinical

pathologypathology

Role of Role of specimen in specimen in lab result lab result accuracyaccuracy

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

Pre- analytical errors are estimated to Pre- analytical errors are estimated to constitute constitute 7070% of errors% of errors

Errors at any stage of the collection, Errors at any stage of the collection, transport can potentially lead to a transport can potentially lead to a serious patient serious patient misdiagnosismisdiagnosis

Errors during the collection process Errors during the collection process are not are not inevitableinevitable but can be but can be preventedprevented with with continuing education continuing education and effective collection systems.and effective collection systems.

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 ...

Preparation prior Preparation prior to to

samplingsampling

Sampling/handling

Storage/transport

Preparation prior to analysis

No result is better than bad result

Sampling TechniqueSampling Technique

Test Collection ProceduresTest Collection Procedures

Specimen TransportSpecimen Transport

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

When When identifyingidentifying the patient, have the patient, have them provide their them provide their full full namename, , ididentificationentification numbernumber and/or and/or date of birthdate of birth. .

Hospital No Hospital No inpatients should be wearing inpatients should be wearing an an ididentification entification bandband with the above with the above information, which the phlebotomist information, which the phlebotomist should confirm before the venipuncture. should confirm before the venipuncture.

Patient identificationPatient identification

It is important to It is important to identifyidentify a a patient patient accuratelyaccurately so that blood is so that blood is collected collected from from the the correct personcorrect person. .

Drawing blood from the wrong person, or Drawing blood from the wrong person, or labeling the correct patient’s sample with a labeling the correct patient’s sample with a different patient’s label can certainly different patient’s label can certainly contribute to laboratory error. contribute to laboratory error. ((Mislabeling ???Mislabeling ???))

All All specimens must be labeled at the specimens must be labeled at the bedsidebedside

Effects on the Quality of Effects on the Quality of Laboratory TestingLaboratory Testing

Factor affecting lab Factor affecting lab resultresult

Some patient variables that affect Some patient variables that affect test resultstest resultsAgeAgeGenderGenderDietDietExerciseExercisePosturePostureHaemolysis, lipemiaHaemolysis, lipemia IcterusIcterus DrugsDrugs

TSH 6.5 TSH 6.5 • NEONATE UP TO 8.3NEONATE UP TO 8.3• ADULT UP TO 4.2 ADULT UP TO 4.2

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 The patient should be comfortably seated

or supine for 20 minutes before sampling . or supine for 20 minutes before sampling . Not standingNot standing

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

2-2- collection site.collection site.• The median cubital vein is the preferred The median cubital vein is the preferred

site.site.• Veins on the hand or at ankle may be usedVeins on the hand or at ankle may be used..

Avoid the arm with:•Extensive scarring or hematoma .,infection , edema ,burn .•Containing I.V. access for I.V. infusion.•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 needle Tourniquet should be released as soon as needle

is in the lumen of the vein and blood flow is in the lumen of the vein and blood flow establishedestablished

Change the position of the needle. Move it forward (it may not be in

the lumen)

or move it backward (it may have penetrated too far).

Adjust the angle (the bevel may be against the vein wall).

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 Allow alcohol to dry completely to avoid

stinging sensation upon needle entry stinging sensation upon needle entry and and hemolysishemolysis of sample of sample

Factors Leading to Factors Leading to Difficult Vein ConditionsDifficult Vein Conditions

Anxiety Anxiety Cold Cold Vasoconstriction of veinsVasoconstriction of veins Repeatedly punctured veinsRepeatedly punctured veins Sclerosed veinsSclerosed veins Rolled veinsRolled veins Delicate veins (children / women)Delicate veins (children / women) Poor hydrationPoor hydration Pre-shock or shockPre-shock or shock Brittle veinsBrittle veins Long term treatment with steroidsLong term treatment with steroids

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

flouridflourid HemolysisHemolysis

Blood collected insufficient to amount of Blood collected insufficient to amount of additive in tubeadditive 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.

1.1. Blood Culture Bottles (Aerobic-Anaerobic)Blood Culture Bottles (Aerobic-Anaerobic)2.2. Coagulation TubeCoagulation Tube3.3. Serum Tube with or without clot activator, Serum Tube with or without clot activator,

with or without gel separatorwith or without gel separator4.4. Heparin Tube with or without gel plasma Heparin Tube with or without gel plasma

separatorseparator5.5. EDTAEDTA6.6. Glycolytic InhibitorGlycolytic Inhibitor

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

All blood collection All blood collection tubes need to be filled to the tubes need to be filled to the correct volumecorrect volume. .

This will ensure the This 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). ratio).

For example, For example, if a 5 mL draw heparin tubeif a 5 mL draw heparin tube is only is only filled with 3 mLfilled 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,

Correct Specimen VolumeCorrect Specimen Volume

All All tubes with additives need to be tubes with additives need to be invertedinverted to mix the additive evenly to mix the additive evenly with with the blood.the blood.

ImproperImproper mixingmixing of the tube after of the tube after

venipuncture venipuncture could contribute to could contribute to sample clotting.sample clotting.

Proper Tube MixingProper Tube Mixing

POINTS TO CONSIDER REGARDING POINTS TO CONSIDER REGARDING COLLECTING BLOOD SPECIMEN COLLECTING BLOOD SPECIMEN

FROM A LIMB WITH I.VFROM A LIMB WITH I.V Blood specimen should not be drawn from an Blood specimen should not be drawn from an

arm with I.V.arm with I.V. * If it’s no way except to use an arm with an IV * If it’s no way except to use an arm with an IV

line, do the following:line, do the following: Specimen should be collected Specimen should be collected below below IVF IVF

infusion site, infusion site, never abovenever above, and use the following , and use the following procedure:procedure:

Turn off the IVF for a minimum of 2 minutes Turn off the IVF for a minimum of 2 minutes prior to collection.prior to collection.

Apply the tourniquet Apply the tourniquet distaldistal to the IVF infusion to the IVF infusion site.site.

Perform the venipuncture in a different Perform the venipuncture in a different vein other than the one with the IVF.vein other than the one with the IVF.

Collect a 5ml tube of blood prior to test Collect a 5ml tube of blood prior to test specimen or 10 ml prior to coagulation specimen or 10 ml prior to coagulation tests and discard then collect the tests and discard then collect the required specimen.required specimen.

State on the requisition form thatState on the requisition form that “the “the specimen was collected from an arm specimen was collected from an arm with an IVF”. It’s also helpful to with an IVF”. It’s also helpful to indicate the type of the IV fluid infused.indicate the type of the IV fluid infused.

* Drawing a specimen from a limb with * Drawing a specimen from a limb with I.V. therapy is a cause of wrong results.I.V. therapy is a cause of wrong results.

CEREBROSPINAL FLUID (CSF)CEREBROSPINAL FLUID (CSF) Each tube should contain 4ml.Each tube should contain 4ml. Tubes should be in the following order, in sterile plain Tubes should be in the following order, in sterile plain

tube.tube. Tube No: 1 for Chemistry or Serology.Tube No: 1 for Chemistry or Serology. Tube No: 2 for Microbiology.Tube No: 2 for Microbiology. Tube No: 3 for Cytological examination Tube No: 3 for Cytological examination

(Hematology).(Hematology). up to 20 ml of fluid could be removed safely from an up to 20 ml of fluid could be removed safely from an

adult.adult. Rapid processing of specimen is important especially Rapid processing of specimen is important especially

glucose measurement.glucose measurement. Specimen for blood glucose must accompany CSF Specimen for blood glucose must accompany CSF

sample for glucose.sample for glucose.

Pleural, Pericardial and Pleural, Pericardial and Ascitic Fluid Ascitic Fluid

lain tube. lain tube. Please forward blood sample in plain Please forward blood sample in plain

tube for chemical analysis along tube for chemical analysis along with the above fluids to aid with the above fluids to aid differentiating exudates and differentiating exudates and transudatestransudates

Glucose Tolerance TestGlucose Tolerance Test Instruct the client to fast for 10 to 16 hours before Instruct the client to fast for 10 to 16 hours before

the test.the test. Instruct the client to avoid strenuous exercise for 8 Instruct the client to avoid strenuous exercise for 8

hours before and after the test.hours before and after the test. Instruct the client that the test will take 3 to 5 hours, Instruct the client that the test will take 3 to 5 hours,

requires extraction of multiple blood samples.requires extraction of multiple blood samples. The patient is asked to drink 75mg glucose dissolved The patient is asked to drink 75mg glucose dissolved

in cold water or patient can be given standard in cold water or patient can be given standard glucose solution (in children the dose of glucose is glucose solution (in children the dose of glucose is 1.75mg/kg body weight.1.75mg/kg body weight.

Blood samples should be collected in 30 min, 60 min, Blood samples should be collected in 30 min, 60 min, 90 min, 120 min and 180 minutes.90 min, 120 min and 180 minutes.

  

URINE PRESERVATIVESURINE PRESERVATIVES Preservatives have different roles but are usually Preservatives have different roles but are usually

added to reduce bacterial action oradded to reduce bacterial action or chemical decomposition or chemical decomposition or to solubilize constituents that might otherwise to solubilize constituents that might otherwise

precipitate out of solution. precipitate out of solution. Another application is to decrease atmospheric Another application is to decrease atmospheric

oxidation of unstable compounds.oxidation of unstable compounds. One of the most satisfactory forms of preservation One of the most satisfactory forms of preservation

of urine specimens is refrigeration immediately of urine specimens is refrigeration immediately following collection; it is even more successful following collection; it is even more successful when combined with chemical preservationwhen combined with chemical preservation

COMMONLY USED URINE COMMONLY USED URINE PRESERVATIVESPRESERVATIVES

Analyte None FreezeConcentrated

Hydrochloric Acid

Mild Base

(pH 8-9)

Calcium X

Magnesium &Ph X X

Osmolality X X

Porphyrins X

Uric acid-creat-protein X

Vanillylmandelic A X

E) Specimen transportE) Specimen transport

TemperatureTemperatureLightLight

Transport ErrorsTransport Errors TemperatureTemperature

Specimens must be transported at the Specimens must be transported at the appropriate temperature for the required appropriate temperature for the required testtest On ice—ABGs, Ammonia,ACTHOn ice—ABGs, Ammonia,ACTH 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

Certain chemistry Certain chemistry analytesanalytes will will requirerequire the tube the tube of blood of blood to be to be chilledchilled after collection in order after collection in order to to maintainmaintain 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. the tubes of blood.

Examples : adrenocorticotropic hormone (Examples : adrenocorticotropic hormone (ACTHACTH), ), angiotensin converting enzyme (angiotensin converting enzyme (ACEACE), acetone, ), acetone, ammoniaammonia, catecholamines, free fatty acids, lactic , catecholamines, free fatty acids, lactic acid, pyruvate and renin ,PTH acid, pyruvate and renin ,PTH

Special Handling of Blood Special Handling of Blood SpecimensSpecimens

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

Preparation prior Preparation prior to samplingto sampling

Sampling/handling

•Label the sampler with patient ID

•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 condition patient’s respiratory condition the patient should ideally be in the patient should ideally be in a steady state of ventilationa steady state of ventilationPatients should be at rest for Patients should be at rest for 5 min5 min

Ventilatory settings should be Ventilatory settings should 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 recommendationsStorage recommendations Storage and transport time should be Storage and transport time should be

kept at a minimumkept at a minimumVolatile nature of gases Volatile nature of gases Continued metabolism in blood Continued metabolism in blood

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

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

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 binding of CaCa2+2+ to protein to protein

ccGluGlu since glucose will be metabolizedsince glucose will be metabolized

ccLacLac due to glycolysis due to glycolysis

Continued cellular metabolism Continued cellular metabolism in samplein sample

Potential Potential preanalytical errorspreanalytical errors

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

• Air bubbles in the sample

• Incorrect storage• Hemolysis of blood cells

Storage and transport

Prep 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 artery it When puncturing an artery it

is important not accidentally is important not accidentally to get the arterial blood to get the arterial blood mixed with venous bloodmixed with venous blood

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

Even an admixture of a small Even an admixture of a small amount of venous blood may amount of venous blood may significantly bias the resultssignificantly bias 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 blood In arteries the blood pressure is high pressure is high enough to fill a self-enough to fill a self-filling syringefilling 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 in Flush solutions used in a-lines must be removed a-lines must be removed completely from the completely from the system to avoid a system to avoid a dilution of the blood dilution of the blood samplesample

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 space” times the “dead space” of the catheter system of the catheter system (NCCLS)(NCCLS)

Inadequate removal of Inadequate removal of flush solutionsflush solutions

Sample B and A are both a-line samples taken from the same Sample B and A are both a-line samples taken from the same patient immediately after each otherpatient 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 kPapO2 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 kPapO2 129.3 mmHg / 17.2 kPa

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

expelled as soon as possible after the expelled as soon as possible after the sample has been drawnsample has been drawnbeforebefore mixing the sample with heparin mixing the sample with heparinbeforebefore any cooling of the sample any cooling of the sample

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

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

Effect of air bubbles - an Effect of air bubbles - 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 otherafter each other

Sample A without air bubbles was analyzed immediately after Sample A without air bubbles was analyzed immediately after collectioncollection

100 µL air was added to sample B (1 mL). It was stored cold (0-4 100 µL air was added to sample B (1 mL). It was stored cold (0-4 °C) for 30 minutes and mixed for 3 minutes before sample analysis °C) for 30 minutes and mixed for 3 minutes 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 to It is recommended to mix the blood sample mix the blood sample thoroughly with thoroughly with heparinheparin

Invert the syringe 10 Invert the syringe 10 times and roll it 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 after Sample A and B were taken from the same patient immediately after each other and stored cold for 10 minuteseach other and stored cold for 10 minutes

Sample A was mixed in a rotator (14 revolutions/min) for Sample A was mixed in a rotator (14 revolutions/min) for 3 minutes3 minutesSample B was mixed in a rotator (14 revolutions/min) for Sample B was mixed in a rotator (14 revolutions/min) for 1 minute1 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 fragile, and The blood cells are relatively fragile, and

therefore hemolysis may easily occur therefore hemolysis may easily occur during blood samplingduring blood sampling

Hemolysis may, for instance, occur due Hemolysis may, for instance, occur due toto 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, 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

HemolyzedHemolyzed Underfilled, Underfilled,

overfilledoverfilled Insufficient Insufficient

quantityquantity Incorrect labelingIncorrect labeling Unlabeled Unlabeled

specimenspecimen

Incorrect patientIncorrect patient Incorrect Incorrect

specimenspecimen ContaminatedContaminated 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..

Thank u