Week 2 - Point of Care Testing (POCT) in Diagnosis of Disease

What is Point of Care Testing (POCT)?

• Definition: POCT refers to the analysis of biological specimens outside of the central laboratory. Common alternative terms include:

  • Near patient testing

  • Bedside testing

  • Ancillary testing

  • Extra-laboratory testing

  • Decentralized testing

Benefits of POCT

• Quick Turnaround Time:

  • Timely results facilitate quicker clinical decisions and interventions.

  • Reduces hospital stay as waiting time for lab results is minimized.

  • Accelerates patient transfer to appropriate wards.

• Optimized Drug Treatment:

  • More precise drug usage tailored to patient needs.

  • Less reliance on blood products (e.g., Rotem).

• Resource Efficiency:

  • Potential reductions in laboratory staffing and equipment usage, although this may vary.

  • Enables care of elderly/frail patients in community settings, allowing treatment in the comfort of their homes.

Central Laboratory Sample Pathway

• Delays in the Pathway:

  • Flow: Sample booking → Analysis → Result release.

  • Can include delays from sample transport or staff availability, affecting patient care.

Drawbacks of POCT

• Cost:

  • Devices can be expensive (e.g., D-dimer testing costs around £20 per test for POCT vs. less than £5 in a lab due to bulk operations).

• Quality of Results:

  • Results may be less reliable from clinical staff compared to trained laboratory technicians.

  • Needs stringent risk assessments due to varied experience levels among POCT operators.

• Training and Certification:

  • Challenges in training due to large operator numbers compared to lab staff (3000 operators vs. <10 lab staff).

Implementation

• Business Case Development: Budget must sustain the lifecycle of the device (minimum contract values: £10,000).

• Device Verification: Team includes various specialists (scientists, admin, IT) for thorough oversight.

• Training: Required for all healthcare staff interacting with POCT.

• Daily Maintenance: Vital for the operational integrity of devices.

• POCT Committee: Develops and oversees guidelines aligned with organizational policies.

Location Requirements for POCT

• Testing Environment:

  • Should be designated 'clean' areas with easy access to handwashing facilities and IT equipment.

  • Requirements for dedicated rooms include proper electrical supply, safe storage, and access controls.

Risk Assessments

• Evaluate processes, reagents, and chemicals based on COSHH guidelines.

  • Mistakes during sampling or data entry can lead to wrong patient results.

  • Quality control measures (IQC/EQA) are essential to prevent systematic errors in testing.

POCT Devices

• Types of Technologies:

  • Benchtop Analyzers: Smaller versions of laboratory systems.

  • Handheld Devices: Portable and easier to access at bedside.

• Testing Methods:

  • Lateral Flow Tests: Basic qualitative tests requiring confirmatory testing (e.g., for drugs or pregnancy).

  • Reflection Photometry: Measures substance concentration.

  • Electrochemical Glucose Meters: Provide rapid and sensitive measurement results.

  • Spectrophotometry and Potentiometry: Used in blood gas analysis to determine various biochemical parameters.

Quality Control (QC) & Assurance

• Levy Jennings Plot: Utilized for assessing variability and accuracy in test results.

• Continuous monitoring ensures reliability in patient testing over time.

Case Studies

• Pregnancy Testing:

  • hCG testing can provide qualitative assessments to confirm or rule out pregnancy, but additional quantitative measures are needed to understand pregnancy status (e.g., ectopic or miscarriage).

• Blood Gas Analysis:

  • Essential for maintaining acid-base homeostasis and understanding patient health.

  • Measurement of parameters like pH, pCO2, and electrolytes are critical for accurate patient assessment.

Conclusion

• POCT is rapidly evolving, providing significant benefits in patient care through timely and decentralized testing, albeit with challenges in implementation and operational costs.

• Ensuring quality and safety through training and thorough operational policies remains paramount to patient outcomes and effective healthcare delivery.