Cobas 6000

Akshay Deshpande

2011A9PS275U

Glucose

Cholesterol

Alkaline Phosphatase

CRP

Sodium ion

Ferritin

The e601 module is a multi-test immunoassay analyser with random access capability. It has a capacity to carry out up to 170 tests per hour. It can be used to analyse samples such as hormones. It works on the principle of electrochemiluminescence

Electrochemiluminescence is a process in which highly reactive species are generated from stable precursors at the surface of an electrode. These highly reactive species react with one another, producing light

This light which is emitted can be analysed with the help of spectroscopy and compared with standard values to measure the quantity of a particular analyte in the test sample

It is made up of two subunits. One is the photometric subunit and the other is the ISE subunit.

The photometric subunit provides the analyser with a flexible photometric method based on the principle of bichromatic analysis. It can process up to 600 in vitro tests per hour.

The ISE subunit provides the analyser with a potentiometric method for assaying of Na+, K+ and Cl- ions from samples. It can process up to 200 samples per hour

It has two different modules available namely, c501 and e601 modules

c501 module is a chemistry analyser

The e601 module is an immunoassay analyser

Cobas 6000

Shifts in QC data represent a sudden and dramatic positive or negative change in test system performance. Shifts may be caused by:

Sudden failure or change in the light source

Change in reagent formulation

Change of reagent lot

Major instrument maintenance

Sudden change in incubation temperature (enzymes only)

Change in room temperature or humidity

Failure in the sampling system

Failure in reagent dispense system

Inaccurate calibration/recalibration

A trend indicates a gradual loss of reliability in the test system

Trends are usually subtle and causes of trending may include:

Deterioration of the instrument light source

Gradual accumulation of debris in sample/reagent tubing

Gradual accumulation of debris on electrode surfaces

Aging of reagents

Gradual deterioration of control materials

Gradual deterioration of incubation chamber temperature (enzymes only)

Gradual deterioration of light filter integrity

Gradual deterioration of calibration

Systematic errors occur by a deviation of QC results from the mean of the control values

The change in the mean may be gradual and demonstrated as a trend in control values or it may be abrupt and demonstrated as a shift in control values

When quality control results are plotted on a Levey-Jennings chart, an assessment of the runs can be made from the chart itself. Errors can be spotted more easily and can also be classified more easily into systematic errors or random errors

For example, consider the mean for a particular potassium control to be 4.1 mmol/L and the standard deviation to be 0.1 mmol/L. The ranges for ±1s, ±2s and ±3s quality control limits in the Levey-Jennings chart can be calculated as follows

Coefficient of variance or simply CV, is defined as the ratio between the standard deviation and the mean of given data

CV is independent of the unit in which the measurements are taken

Hence, CV can be used to compare data with different measurement units from each other and also data with greatly varying means

Imprecision may result due to the chemistry involved or due to a malfunction

If it is a malfunction, steps must be taken to correct the problem

It is desirable to get precise results, especially for tests that are repeated regularly on the same patient to track treatment or disease progress

Quantifies how close numerical values (i.e. QC values) are in relation to each other

Standard deviation is calculated from the same data used to calculate the mean

It provides the laboratory an estimate of the precision of the testing method in use

The repeatability of a test may be consistent (low standard deviation, low imprecision) or inconsistent (high standard deviation, high imprecision)

Quality control in the medical laboratory is a statistical process used to monitor and evaluate the analytical process that produces patient results

QC results are used to validate whether the instrument is operating within pre-defined specifications, inferring that patient test results are reliable

Quality Control

A random error is any deviation away from an expected result

For QC results, any positive or negative deviation away from the calculated mean is defined as random error

There can be acceptable random errors as defined and quantified by standard deviation

There can also be unacceptable random errors that are any data points outside the acceptable limits of the data (e.g., a data point outside the ±3s limits)

The Levey-Jennings chart is used to graph successive (run-to-run or day-to-day) quality control values

A chart is created for each test and level of control

The first step is to calculate decision limits. These limits are ±1s, ±2s and ±3s from the mean.

How well a series of measured values agree with each other

The repeatability of a particular result

The result of an individual measurement of a quantifiable property

The known and accepted value of a quantifiable property

Accuracy

How well a measured value agrees with a the true value

Precision

True Value

Measured Value

Mean

The mean (or average) is the laboratory’s best estimate of the analyte’s true value for a specific level of control

To calculate a mean for a specific level of control, we first add all the values collected for that control. Then we divide the sum of these values by the total number of values

Quality Control

To ensure accuracy and precision of results:

Daily quality control runs

Constant monitoring of instrument

Routine calibrations

Routine maintenance

Accuracy vs. Precision

Mean

Standard Deviation

Standard Deviation

Coefficient of Variance

Levey-Jennings Chart

Levey-Jennings Chart

Levey-Jennings Chart

Levey-Jennings Chart

Levey-Jennings Chart

Systematic Errors

Trends

Shifts

Random Errors

Cobas 6000

c501 module

e601 module

Analytes I have chosen…

Standard Deviation

Standardising the Instrument

Manufacturer

Machine Calibration

Levey-Jennings Charts

Optics

Stability of light source

Pipetting

Carryover

Voltage

**{**

Precision

Accuracy

Internal Quality Control

External Quality Assessment

Westgard Rules

Got quality control related data from the instrument for each analyte

My work...

Calculated the unbiased population mean and standard deviation for the data collected

Using the analysed data, I prepared Levey-Jennings charts for each of the analytes

Analysed the same and cross referenced the abnormalities to check for the corrective actions taken

Mean

S.D.

CV

Glucose

Cholesterol

Alkaline Phosphatase

CRP

Ferrittin

106

246.66

92.97

179.46

25.34

196.20

14.17

40.95

92.33

213.71

113.55

137.05

Na

+

4.2

11.23

3.96

4.55

3.38

6.86

3.64

3.82

5.9

11.65

6.39

5.45

0.377

0.927

2.66

2.26

3.36

1.53

2.96

1.11

1.67

14.74

6.59

7.51

**Thank You**