Unit 7 Preanalytical Considerations

UNIT 7: Preanalytical Considerations

Preanalytical or Pre Examination Phase

  • Definition: Begins when a test is ordered and ends when testing begins in the laboratory.

  • Implications of Errors:

    • Can compromise specimen quality.

    • Jeopardize patient safety and health.

    • Increase the cost of medical care.

  • Role of the Phlebotomist:

    • Must possess technical skills.

    • Ability to recognize and manage preanalytical factors that may alter results.

Overview of Preanalytical Factors

  • Patient Complications:

    • Troubleshooting failed venipuncture.

    • Understanding reference ranges and physiological variables.

  • Problematic Venipuncture Sites:

    • Types of Vascular Access Devices (VADs).

    • Procedural errors impacting specimen quality issues.

Reference Range/Interval

  • Purpose: Tests used to confirm health, screen, diagnose, and monitor diseases.

  • Definition: Range of values established from specimens of healthy individuals, typically fasting.

  • Example: Normal body temperature of 98.6°F.

Basal State

  • Definition: The resting state of the body after fasting for 12 hours.

  • Importance: Ideal for establishing reference ranges on inpatients; minimizes diet and exercise effects.

  • Influencing Factors:

    • Age, gender, and body conditions (e.g., fever affects hormone levels, cortisol).

Physiological Variables

  • Effects of Variables on Lab Values:

    • Causes of Hemoconcentration:

      • Increased RBC, FE, Na, Ca, Coagulation factors from dehydration.

    • Dietary Influences:

      • Increased ammonia, urea, uric acid with protein intake.

      • Elevated cortisol and ACTH levels with caffeine.

    • Age Factors:

      • Increased RBC, Hb, Hct, CRP, uric acid; decreased creatinine levels.

    • Altitude Impact: Elevated RBC, Hct, and Hb levels.

Diet and Lipid Levels

  • Lipid Alteration:

    • Abnormally high blood lipids can be present for up to 12 hours.

    • Lipemic specimens appear cloudy and can alter analyte values; necessitate a 12-hour fast.

Additional Physiological Changes

  • Exercise and IM Injection Effects:

    • Decrease arterial pH and CO2, increase various metabolites and hormones.

    • Icterus and jaundice conditions can interfere with test results.

Problematic Venipuncture Sites

  • Factors Affecting Draw Quality:

    • Damaged veins (burns, scars, tattoos) can lead to inaccurate results.

    • Mastectomy and Hematoma Implications:

      • Mastectomy sites can lead to lymphedema.

Vascular Access Devices

  • Types of IV Access:

    • Intravenous Line: Quick access for medication, fluid, and blood delivery.

    • Central Vascular Access Devices (CVADs): Used for long-term administration.

  • Avoid Drawing From Sites: Where IV lines are established; always draw distal.

Patient Complications & Conditions

  • Potential Issues:

    • Allergies, excessive bleeding, pain, or adverse reactions.

    • Monitor for signs of distress such as paleness or sweating.

Procedural Errors

  • Common Risks:

    • Hematoma formation from blood leakage into tissues; hold pressure to mitigate.

    • Nerve injury and potential infections can arise without aseptic techniques.

Troubleshooting Failed Attempts

  • Assess Issues:

    • Ensure the tube is in the correct position.

    • Ensure the bevel is properly aligned in the vein for a successful draw.

  • Techniques for Adjustment:

    • Evaluate needle depth and angle to achieve optimal blood flow.

    • Recognize when to withdraw and readjust to avoid further issues.

Conclusion and Review

  • Key Variables Affecting Results:

    • Age, altitude, dehydration, diet, diurnal variation, drug therapy, and more.

  • Proper handling, awareness of patient conditions, and adherence to procedural protocols are vital for quality assurance in blood sample collection.

UNIT 7: Preanalytical Considerations

Slide 1: Introduction to Preanalytical Phase

  • Definition: The preanalytical phase initiates when a healthcare provider orders a test, extending until the testing actually begins in the laboratory.

  • Significance: This phase is critical as it covers all preparatory activities related to specimen collection, influencing the quality and reliability of laboratory results.

Slide 2: Implications of Errors

  • Compromised Specimen Quality: Inaccuracies during this phase can degrade the integrity of biological samples.

  • Patient Safety Risks: Errors can lead to misdiagnoses or incorrect treatment protocols, potentially endangering patients' health.

  • Economic Impact: Increased errors may lead to additional costs due to the need for retests or extended patient care.

Slide 3: Role of the Phlebotomist

  • Technical Proficiency Required: Phlebotomists must have strong technical skills for performing venipunctures accurately.

  • Preanalytical Management: A thorough understanding of factors that can alter results, including patient preparation and specimen handling protocols is essential.

Slide 4: Overview of Preanalytical Factors

Patient Complications:

  • Troubleshooting: Skills necessary to address common venipuncture issues such as difficulty accessing veins or managing patient anxiety.

  • Understanding Reference Ranges: Knowledge of how individual differences (e.g., age or sex) affect laboratory values is crucial to interpreting test results accurately.

Slide 5: Problematic Venipuncture Sites

  • Vascular Access Devices (VADs): Understanding various types of devices (IVs, central lines) and choosing appropriate collection techniques is essential to avoid complications.

  • Procedural Errors: Common mistakes that might happen during collection can lead to contamination, hemolysis, or failure to obtain the required sample.

Slide 6: Reference Range/Interval

  • Purpose of Reference Ranges: These are established value ranges used for health confirmation, disease screening, and diagnoses.

  • Definition: Typically derived from the analysis of specimens from healthy individuals, often in a fasting state to minimize variations.

  • Example: Normal body temperature is acknowledged as approximately 98.6°F, though it can vary.

Slide 7: Understanding Basal State

  • Definition of Basal State: The resting physiological state post a minimum of 12 hours of fasting, crucial for accurate test result interpretation.

  • Importance in Lab Values: This state ensures minimal external influences from diet or activity, which could skew results.

  • Influencing Factors: Age, gender, underlying health conditions like fever which may affect hormones.

Slide 8: Physiological Variables Impacting Lab Results

  • Hemoconcentration: Understand how dehydration can increase RBC and electrolyte concentrations.

  • Dietary Influences: Probe into how protein intake can elevate blood components like ammonia and urea.

  • Age Factors and Altitude Effects: Increased levels of certain blood constituents in relation to aging and high altitudes can significantly impact lab interpretations.

Slide 9: Diet and Lipid Levels

  • Lipid Alteration: Discuss how eating can lead to increased blood lipids for up to 12 hours post-meal and potentially necessitate fasting for accurate results.

  • Lipemic Specimens: Recognition of cloudy sample appearance could affect test outcomes.

Slide 10: Additional Physiological Changes

  • Exercise Effects: Elaborate on how physical activity modifies arterial pH and CO2 levels, affecting various metabolites and hormones.

  • Conditions like Icterus and Jaundice: How they can complicate test results through interference with light absorption and other chemical assays.

Slide 11: Recognizing Problematic Venipuncture Sites

  • Factors Affecting Draw Quality: A breakdown of how conditions like damaged veins from injury or medical procedures influence blood draws.

  • Mastectomy Considerations: Safety protocols around areas affected by surgical procedures to avoid lymphedema risks.

Slide 12: Understanding Vascular Access Devices

  • Types of IV Access Overview: Introduce peripheral IV lines and central vascular access devices, detailing their administrative use and protocols.

  • Best Practices: Importance of drawing samples distal to IV sites to avoid contamination and compromise of specimen quality.

Slide 13: Patient Complications & Conditions

  • Identifying Potential Issues: Preemptively address challenges like allergies, bruising, or signs of distress during venipuncture procedures.

  • Monitoring Protocols: Recognize vital signs to act promptly should a patient exhibit adverse reactions.

Slide 14: Managing Procedural Errors

  • Common Risks Identified: Address hematoma formation, nerve injury, and infection risks related to improper technique or aseptic failures.

  • Mitigation Strategies: Techniques such as applying pressure to minimize hematoma risk and ensuring sterile practices during blood collection.

Slide 15: Troubleshooting Failed Blood Draws

  • Assessing Issues: Evaluating proper tube positioning and bevel alignment to optimize fluid collection.

  • Techniques for Adjustment: Practical tips on adjusting needle position, depth, and angle to enhance blood flow and avoid unnecessary pain or samples errors.

  • When to Withdraw and Retry: Guidance on recognizing when to cease a draw attempt in order to minimize complications for the patient.

Slide 16: Conclusion and Summary

  • Key Variables Affecting Results: Understanding the multi-faceted aspects such as age, altitude, hydration level, diet, circadian rhythms, and medication that contribute to test accuracy.

  • Commitment to Quality Assurance: Emphasis on appropriate specimen handling, continuous monitoring of patient conditions, and strict adherence to procedural protocols to ensure optimal outcomes in blood collection.