Chrono-log Corporation, USA


Whole blood aggregometers: Model 591 is a single channel impedance platelet aggregometer with washable reusable electrodes and version 591A with disposable electrodes, the choice based on special application needs. Complete with onboard software and ideal for POC and bedside usage and routine screening applications.


Whole blood aggregometers: 591 is a single channel impedance platelet aggregometer with washable reusable or electrodes and version 591A with disposable electrodes, the choice based on special application needs. Complete with on-board software and ideal for POC and bedside usage and routine screening applications.

Impedance Aggregation in Whole Blood

The Chrono-log whole blood aggregometers uses electrical impedance to measure platelet aggregation in whole blood. A diluted specimen of whole blood is in the sample cuvette which is placed in the instrument reaction well and sample receptacle heated to 37 degree C. There is provision made for stirring of the samples utilizing teflon-coated magnetic stir bars. Cuvettes containing the test sample and a stir bar are placed in the receptacles.

The impedance (or electrical resistance) method of aggregation is non-optical. An electrode probe assembly is inserted into a cuvette containing a test sample. The electrode probe assembly consists basically of two precious metal wires that are immersed in the sample. An AC voltage in the millivolt range is applied to the probe circuit. The instrument measures the electrical resistance or impedance between the two immersed wires. During a brief period of equilibration, a monolayer of platelets forms on the exposed portions of the wires, resulting in a stable impedance value. This stable baseline of impedance is assigned a value of zero ohms of resistance. An aggregating agent is added to the cuvette and the stimulated platelets aggregate to the platelet monolayer on the immersed wires. This accumulation of platelets adds electrical resistance to the circuit. The changes in resistance are measured and quantified in ohms (the measurement of electrical resistance). Tests are generally run for four to six minutes after the addition of an agonist. The increase in impedance is directly proportional to the mass of the
platelet aggregate. Results of impedance aggregation tests are quantified by:

1. ohms of aggregation at a given time in the test

2. Slope, or rate of the reaction, in ohms change per minute

3. Maximum extent of aggregation, in ohms


1.a. Model 591 the single channel whole blood aggregometer offers a great level of user convenience and lab level quality results in a POC type of machine.

b. With internal computer interface and onboard software, the system offers accurate, reliable, easy to use, with fewer hands-on testing in whole blood aggregometry.

2. The system gives reliable results even in case of secretion abnormalities and in patients presenting bleeding history.

3. Effectively handles the study of platelet function with high and low concentrations of collagen in detecting aspirin resistance and in conjunction with AA-induced whole blood platelet aggregation, the most sensitive and suitable method for detecting ASA and the extent of response.

4. The whole blood impedance aggregometry from Chrono-Log is able to detect aspirin resistance, as against many systems identifying only aspirin ingestion, but failing to detect aspirin non-responsiveness.

5. Chronolog whole blood aggregometry has proven useful for monitoring of ADP receptor antagonists, in-vitro with the highest sensitivity, in whole blood.

6. Offers adequate sensitivity in healthy subjects, with the study of ADP-induced aggregation in whole blood and best suited for clopidogrel response assessment.


 13”(D)  x 9”(W) x 6”(H)


115V/220AC+/- 10%, 50/60 Hz


Fixed Speed, 1200 RPM @ 60Hz
1000 RPM @ 50 Hz



Contains two carefully spaced precious metal alloy wires. The probe has a plug in cable, long enough to permit cleaning the probe without disconnecting.


Single push button for zero and gain setting.


Electronically controlled to 37°C +/- 0.3°C.


Digital display reports the output in ohms.


Analog output for optional strip chart recorder. AGGRO/LINK interface with USB connector.


Greater than 10,000 ohms.


1 well at 37°C


1 well at 37°C


LED digital display, temperature indicator, amber and green status LEDs, power switch


Fuse holder voltage select switch, output jacks

†applicable for models 591A 


1. Rapid reliable cost effective screen and detect specific platelet abnormalities

2. Conveniently screen for platelet defects

3. Diagnose specific bleeding disorders

4. Detect use of anti-platelet drugs like Asprin and Plavix

5.Confirm efficacy and monitor effectiveness of GP II b / III a drug therapy

6. Select and monitor patient for antithrombotic treatment.

7. Accurate results without possibilities of contamination, no residue or build up with disposable electrodes†

8. Offers great potential for accurately monitoring the optical balance of platelet functions after off-pump coronary artery bypass grafting

9. Functional vW test, detect Type 2B, monitor DDAVP therapy, diagnose Bernard Soulier Syndrome

†applicable for models 591A and 592A

Whole blood aggregometer, single channel / dual channel, with facility to use washable, reusable or disposable electrodes with the following technical attributes:

1. Portable whole blood aggregometer system for convenient screening of platelet defects, and detect use of anti-platelet drugs in patients

2. Should have one or two channels and based on impedance method for handling whole blood sample for quick turn around time

3. System should have automatic push button operation for zero and gain setting with results available in ohms in digital display, with temperature and status indication

4. The system should have stirring mechanism with stir speed of at least 1000 rpm, with temperature control to 37°C + 0.3°C

5. Shall have standard software on board for data reduction and present final results without the need for manual calculations, and at least one channel for measurement and one for the incubation

6. The sample volume should be typically 500ml of whole blood and the results available in about six minutes

7. Usage of optimised high concentration reagents should be possible with micro volume usage for low cost per test and higher accuracy

8. Facility shall be available to run the system with external PC or laptop with Windows based software with facility for data reduction and real time graphic display and recall of test results and export data file to spread sheet

Power: 230V / 50Hz operation

† applicable for only models 591A and 592A

†† When equipped with IBM compatible PC and printer of appropriate specification.

1. What is the principle of measurement?

It is based on impedance method.

2. What is the approximate sample volume needed for measurement?

The sample volume needed is typically 500µl of whole blood.

3. What is the time taken for the result?

Results can be obtained in about six minute.

4. Is the system portable?

Yes it is, and usable for bed side monitoring for point of care./h2>

5. a. Is the electrode used for impedance mode of measurement reusable?

Yes the electrode can be washed and reused.

5. b. Can the system handle sample without cross contamination?

Yes contamination can be avoided with the usage of disposable electrodes†.

6. Is it necessary to have recorder for the result tracing?

No, the result is directly displayed in ohms for ready interpretation.

7.Can the system handle haemolysed, icteric or lipemic samples?

Yes the impedance method based machine can handle above type of samples.

8.Does the machine have facility for data reduction?

The system is complete with on-board software†† for data reduction including facility to calculate maximum slope and amplitude, real time graphic display, storage and recall test curves, printing of clinical reports and export of data files for further analysis.

9.Is it possible to upgrade the single or two channel systems?

Yes, the Models 592-X and 592A-X will expand the System to up to four (4) channels.

10.Is the system open or closed to reagents?

System is open to other reagents but Chronolog reagents are optimised for easy adaptation, and since of high concentration calls for lower reagent volume and very low cost per test.

† applicable for only models 591A and 592A

†† When equipped with IBM compatible PC and printer of appropriate specification.

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