2. مشروع إعتماد معمل الكمياء الإكلينيكيه – مستشفى الطوارئ

3. Role of clinician in lab result accuracy
Prof/Azza abd al baky

4. Introduction
Three phases of laboratory testing: pre-analytical, analytical and post-analytical
Pre-analytical—specimen collection, transport and processing
Analytical—testing
Post-analytical—testing results transmission, interpretation, follow-up, retesting.

5. Pre-analytical errors
Pre- and post-analytical errors are estimated to constitute 90% of errors
Errors at any stage of the collection, testing and reporting process can potentially lead to a serious patient misdiagnosis
Errors during the collection process are not inevitable but can be prevented with a diligent application of quality control, continuing education and effective collection systems.

6. The steps of the preanalytical phase
Preparation prior to
sampling
Sampling/handling
Storage/transport
Preparation prior to analysis

7. Implications of errors
Errors made in the period prior to the analysis of the sample ...
may influence the quality of the final measured results ...
and compromise the diagnosis and treatment of the patient
No result is better than bad result

8. Complex and labor intensive
The more steps involved in a process, the more likely there will be errors committed
% of all test errors occur in the preanalytical phase
Stankovic 2008
“Quality Improvements in the Preanalytical Phase:
Focus on Urine Specimen Workflow”

9. Effects of Pre-analytical Variables on the Quality of Laboratory Testing
Paying close attention to the preanalytical variables associated with blood collection is critical in ensuring accurate test results in all areas of the clinical laboratory.

10. The Pre-Analytical process
Patient Identification
Sampling Technique
Test Collection Procedures
Specimen Transport
Specimen Processing

11. The Pre-Analytical process
Collect Sample:
Locate Patient
Prep Patient
Draw Sample
Label
Dispose of supplies

12. Patient identification
When identifying the patient, have them provide their full name, address, identification number and/or date of birth. Hospital No inpatients should be wearing an identification band with the above information, which the phlebotomist should confirm before the venipuncture.

13. Effects of Pre-analytical Variables on the Quality of Laboratory Testing
Patient Identification: It is important to identify a patient accurately so that blood is collected from the correct person. Drawing blood from the wrong person, or labeling the correct patient’s sample with a different patient’s label can certainly contribute to laboratory error. (Mislabeling ???)

14. Factor affecting lab result
Some patient variables that affect test results
Age Genetic variation
Gender Nutrition status
Diet Diagnostic and therapeutic Drugs procedures(PR&endoscopy)
Exercise Obesity
Posture Biorythm
Haemolysis,lipemia Special habits
& icterus

15. Test Collection Timing of Collection Therapeutic Drug Monitoring
Peak and trough collection times
Basal State Collections
Fasting requirements—no food or liquid except water(10-12h)
2h postprandial, from the start of food .
Specimens affected by time of day, for example, cortisol, iron and TSH.

16. Phlebotomy
Phlebotomy is a highly complex skill requiring expert knowledge, and critical judgment
venipuncture is a frequent medical procedure.
Phlebotomy errors may cause harm to patients or result in needle stick injury to the phlebotomist

17. Error Prevention Phlebotomy Education
Phlebotomists should have completed a standard academic course in phlebotomy and undergo thorough on-the-job training under the supervision of a senior phlebotomist
Continuing Education
Phlebotomists should participate in regular educational competency assessments (written and observational)
Professional Licensure
Phlebotomy Staffing
Adequate staffing to maintain collection standards
Technology
Use of barcode scanners for patient identification

18. 1-posture: 2- collection site.
The patient should be comfortably seated or supine for 20 minutes before sampling.Not standing
The patient arm should be extended in a straight line from the shoulder to the wrist.
2- collection site.
The median cubital vein is the preferred site.
Veins 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.

19. Phlebotomy Technique Correct collection system Venous access
Evacuated tube system (Vacutainer) for large veins in antecubital fossa
Syringe for small, fragile veins or veins outside antecubital fossa
Venous access
Needle entry should be at 15 to 30 degrees depending on depth of vein
Needle entry should be in same direction as vein, centered over vein
Anchor vein to prevent movement during needle entry and to reduce pain to patient

21. Phlebotomy Technique Errors
Tourniquet Application
Tourniquet tied too close to the venipuncture site can cause hematoma
Veins may not become prominent if tourniquet is tied too high (more than 3 to 4 inches above venipuncture site)
Tourniquet left on longer than one minute can result in hemoconcentration , affecting some test results
Tourniquet should be released as soon as needle is in the lumen of the vein and blood flow established

22. Phlebotomy Technique Cleansing of venipuncture site
Thorough cleaning with alcohol
Allow alcohol to dry completely to avoid stinging sensation upon needle entry and hemolysis of sample
Samples such as blood cultures should be collected using iodine to cleanse site to ensure sterility of sample
Recollection rate for blood cultures ranges due to contamination is as high as 50% in hospitals with increased costs, patient overtreatment

23. Test Collection
Additive : EDTA,citrat, lithium heparin ,oxalate,flourid
Hemolysis
Blood collected insufficient to amount of additive in tube,
Traumatic venipuncture
Blood collected from area with hematoma
Vigorous shaking of tubes after collection
Milking the site when collecting capillary samples and blood collected using a small diameter needle.

24. Test Collection Capillary Collections—finger stick or heel stick
Appropriate site
Heel stick—sides of the bottom surface of the heel
Finger stick—third or fourth fingers, perpendicular to fingerprint lines on fleshy pads on finger surface
Warming—Warm before collection to increase capillary blood flow near skin surface
Cleaning—cleanse site with alcohol and allow to air dry
Discard first drop of blood.

25. Recommended order of draw (NCCLS):
Blood Culture Bottles (Aerobic-Anaerobic)
Coagulation Tube
Serum Tube with or without clot activator, with or without gel separator
Heparin Tube with or without gel plasma separator
EDTA
Glycolytic Inhibitor

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

27. Proper Tube Mixing: All tubes with additives need to be inverted to mix the additive evenly with the blood. Improper mixing of the tube after venipuncture could contribute to sample clotting.

28. E) Specimen transport
Temperature Light

29. Transport Errors Temperature Transport Container
Specimens must be transported at the appropriate temperature for the required test
On ice—ABGs, Ammonia
Warmed -- (37 C), cryoglobulins
Avoid temperature extremes if transported via vehicle from other collection site
Transport Container
Some samples need to be protected from light, for example, bilirubin
Transport in leak-proof plastic bags in lockable rigid containers ,avoid agitation.

30. Blood Specimen Transport
Transport of blood specimens in the proper manner after collection ensures the quality of the sample
Timing
Some specimens must be transported immediately after collection, for example Arterial Blood Gases.
Specimens for serum or plasma chemistry testing should be centrifuged and separated within two hours

31. Special Handling of Blood Specimens: Certain chemistry analytes will require the tube of blood to be chilled after collection in order to maintain the stability of the analyte. A slurry of ice and water is recommended for chilling the tubes of blood. Examples : adrenocorticotropic hormone (ACTH), angiotensin converting enzyme (ACE), acetone, ammonia, catecholamines, free fatty acids, lactic acid, pyruvate and renin ,PTH

32. Blood 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”

33. What is so special about blood gases?
NOT like other blood samples
STAT parameters
Short Turn Around Time
Must be analyzed within a short time
pO2, pCO2, pH, LAC, GLU
Valuable results right now
Not in one hour
Sample composition changes
Patient status changes

34. Some points to keep in mind - sampling from A-lines
Preparation prior to sampling
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
Sampling/handling

35. 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.
Storage/transport
Before transferring the sample into the analyzer mix thoroughly
Visually inspect the sample for clots and air bubbles
Enter patient ID in analyzer logs
Preparation prior to
sample transfer

36. Stabilization of the respiratory condition
To get a true picture of the patient’s respiratory condition the patient should ideally be in a steady state of ventilation
Patients should be at rest for 5 min
Ventilatory settings should be unchanged for 20 min
Pain and anxiety from arterial puncture may influence the steady state of respiration and should thus be minimized

37. Storage recommendations
General storage recommendation
Do not cool the sample
Analyze within 30 minutes
For samples with high pO2
Analyze within 5 minutes
For special studies, e.g. shunt
For samples with high leukocyte or platelet count
Expected delayed analysis
When analysis is expected to be delayed for more than 30 minutes, the use of glass syringes and storage in ice slurry is recommended
Storage and transport time should be kept at a minimum
Volatile nature of gases
Continued metabolism in blood
For parameter panels including GLU/LAC, be aware that 30 minutes storage might lead to biased results
It is recommended by the NCCLS to avoid cooling of samples when kept in plastic
Plastic syringes are not impermeable to gas diffusion, and will allow exchange of oxygen and carbon dioxide with the ambient air.
When the sample is cooled, the blood can dissolve more gas, I.e. a cooled, stored sample will potentially take up enough oxygen to bias the sample.

38. Continued cellular metabolism in sample
pO2 since oxygen will still be consumed
pCO2 since carbon dioxide will still be produced
pH primarily due to the change in pCO2 and glycolysis
cCa2+ since the change in pH will influence the binding of Ca2+ to protein
cGlu since glucose will be metabolized
cLac due to glycolysis
Metabolically active cells, such as leukocytes and thrombocytes, will continue to metabolize O2 to CO2
The fall in pO2 is accelerated if the original sample pO2 is high
High levels of leukocytes, such as found in leukemic patients, may cause a significant fall in pO2 in a short period of time

39. Slowing down the metabolism
pO2
Blood gas samples in glass samplers can be cooled
Storing the sample at a lower temperature (0-4 °C) will slow down the metabolism by at least a factor of 10 [NCCLS]
Cool samples in an ice slurry or other suitable coolant
Never store the samples directly on ice as this causes hemolysis of the blood cells
Time
0-4 C
25 C
NCCLS Document C27-A; Blood Gas Pre-Analytical Considerations: Specimen Collection, Calibrations and Controls; Approved Guideline

40. Potential preanalytical errors
Preparation prior to 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

41. Sampling /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 transport
Visually inspect the sample for clots
Inadequate mixing of sample before analysis
Failure to identify the sample upon analysis
Prep prior to transfer

42. Mixture of venous and arterial blood
When puncturing an artery it is important not accidentally to get the arterial blood mixed with venous blood
This may, for instance, occur, if you hit a vein before locating the artery
Even an admixture of a small amount of venous blood may significantly bias the results
This is especially true of pO2 and sO2, but other parameters may also be affected
Vein
Artery
40 mmHg / 5.3 kPa
100 mmHg / 13.3 kPa

43. Mixture of venous and arterial blood
In arteries the blood pressure is high enough to fill a self-filling syringe
If a self-filling syringe does not fill it may be because a vein has been hit
In that case a new sample should be taken
Vein:
Pressure rarely > 10 mmHg
Self-filling syringes typically fill upon a pressure of 20 mmHg
Artery:
Systolic blood pressure normally > 100 mmHg

44. Inadequate removal of flush solution
Flush solutions used in a-lines must be removed completely from the system to avoid a dilution of the blood sample
It is recommended to withdraw a volume equal to three to six times the “dead space” of the catheter system (NCCLS)

45. Inadequate removal of flush solutions
Sample B and A are both a-line samples taken from the same patient immediately after each other
Before taking sample B only 1 mL of saline solution was removed - the tubing, however, looked red
Before taking sample A saline solution was removed as recommended
Sample A
ctHb 6.2 mmol/L
cGlu 9.6 mmol/L
cK+ 3.8 mmol/L
cNa+ 130 mmol/L
cCa mmol/L
cCl- 101 mmol/L
pH 7.271
pCO mmHg / 6.7 kPa
pO mmHg / kPa
Sample B
ctHb 4.6 mmol/L
cGlu 6.9 mmol/L
cK+ 2.5 mmol/L
cNa+ 137 mmol/L
cCa mmol/L
cCl- 113 mmol/L
pH 7.275
pCO mmHg / 4.8 kPa
pO mmHg / 17.2 kPa
Saline solution is kept in a plastic bag which is permeable to air. Oxygen and carbon dioxide equilibrates with the ambient air and thus represents high tensions.

46. Air bubbles
Any air bubbles in the sample must be expelled as soon as possible after the sample has been drawn
before mixing the sample with heparin
before any cooling of the sample
Even small air bubbles may seriously affect the pO2 value of the sample, normally resulting in increased values
An air bubble whose relative volume is 0.5 to 1.0 % of the blood in the syringe is a potential source of a significant error

47. Effect of air bubbles - an example
Sample A and B were taken from the same patient immediately after each other
Sample A without air bubbles was analyzed immediately after collection
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
Sample A
pO mmHg / 38.5 kPa
(FIO )
Sample B
pO mmHg / 33.8 kPa
(FIO )

48. Insufficient mixing with heparin
Insufficient mixing can cause coagulation of the sample
It is recommended to mix the blood sample thoroughly with heparin
Invert the syringe 10 times and roll it between your palms
Red blood cells tend to stack (like coins or plates) due to their concave shape. Stacking is prevented by mixing in two dimensions.

49. Inadequate mixing - an example
Sample A and B were taken from the same patient immediately after each other and stored cold for 10 minutes
Sample A was mixed in a rotator (14 revolutions/min) for 3 minutes
Sample B was mixed in a rotator (14 revolutions/min) for 1 minute
Sample A
ctHb 6.2 mmol/L
Sample B
ctHb 4.5 mmol/L

50. Hemolysis of blood cells
The blood cells are relatively fragile, and therefore hemolysis may easily occur during blood sampling
Hemolysis may, for instance, occur due to
high filling pressure through a narrow entrance (e.g. during too vigorous sample aspiration, sample transfer to the analyzer, etc.)
vigorous rubbing or squeezing of the skin during capillary sampling
too vigorous mixing of the sample
cooling down the sample below 0 °C

51. “The weak link” Blood gas analyzers of today are highly accurate
Make sure that sample represents patient status
The preanalytical phase is the weak link in the Patient Focus Circle
Many potential errors
Can be overcome by
Training
User guidelines
Sampling products
BG Analyzers of today are highly accurate.
The results reflect the composition of the sample – i.e. make sure that the sample represents the patient!
Studies have shown that up to 60% of all errors in blood sampling are related to the preanalytical phase.
Conclusion: need for training and samplers that are easy to use and do not introduce errors.

52. Specimen Quality Markers for Rejection
Clotted
Hemolyzed
Underfilled, overfilled
Insufficient quantity
Incorrect labeling
Unlabeled specimen
Incorrect patient
Incorrect specimen
Contaminated
Lost sample
Too old to process
Broken and leaking

53. Finally…
The human role in sample collection makes complete elimination of errors associated with laboratory testing unrealistic
However, good practices and compliance with the new strategies for error prevention can lead to a substantial reduction in pre-analytical errors.