Whole Blood and Optical Aggregometer 700-4 Four Channel

Whole blood/optical aggregometer, easy to use with rapid results with ability to handle whole blood and optical aggregation studies, facility to use disposable or reusable impedance electrodes, with the possibility to upgrade the two channel into a four channel version.

Optical method:

The Born-type aggregometer or optical aggregometer is a fixed wavelength spectrophotometer with a sample chamber (or chambers) heated to 37°C. Provision is made for stirring of the sample because platelet to platelet contact is necessary to the determination of in vitro platelet aggregation. A beam of infra red light shines through two cuvettes, one containing PRP (the sample) and one containing PPP (the reference). The difference in light transmission outputs from the photodiodes is transferred to recording devices. The optical aggregation output is proportional to the continuously measured difference in light transmission between the test and reference samples. When a stimulus is added to the cuvette containing PRP and the platelets respond, changes in light transmission occur and are recorded over time.

PRP, which is a turbid, is stirred in a test cuvette maintained at 37°C. The light transmittance through this turbid sample is measured relative to the PPP blank. When the agonist is added, the platelets will form increasingly larger aggregates and the PRP will begin to clear, allowing more light to pass through. This increase in light transmittance is directly proportional to the amount of aggregation and is amplified and recorded as a signal on chart paper or digitized into a computer using software.

Impedance method:

Relative merits of impedance method over the conventional optical method.

CHRONO-LOG® 700 Versions allow the study of platelet function in whole blood in the presence of other cells before the decay of labile modulators. It calls for an only micro sample volume of the whole blood for the measurement of aggregation and secretion rendering the Chrono-log system particularly suited for routine diagnostic and research applications, equally well. The simultaneous measurement of platelet aggregation with dense granule secretion study simplifies and reduces the cost of the platelet function testing.

The patented whole blood method as opposed to the optical method provides certain inherent advantages including the following:
1. It is possible to scan rapidly for the platelet function prior to the surgery, which is not practical with the time consuming optical based method.
2. The whole blood systems eliminate the elaborate and time-consuming preparation of the platelet-rich plasma.
3. It is possible with the usage of whole blood machines, to perform ex-vivo and bedside studies thanks to easy sample handling, with virtually no pretreatment of the sample involved.
4. The impedance technique does not suffer from the problems associated with centrifugation of blood to prepare PRP which results in the loss of giant or irregularly shaped platelets. The resultant effect is closer representative of the in vivo platelet environment, as the whole blood sample includes the RBCs and WBCs, which are known to interact with the platelets.
5. Impedance aggregometry in whole blood, according to the research papers, is a more adequate tool for detection of platelet hyperaggregability than the optical method. With the impedance method, patients at risk for thromboembolic complications can be identified. This greater sensitivity results from performing tests in the presence of erythrocytes and the leucocytes.
6. There are studies indicating increased platelet aggregation in patients with stable coronary heart disease, to explain their tendency to a heart attack during exercise, but the effect is temporary, lasting around 10 minutes. Whole blood aggregation studies, which can be conducted in less than 10 minutes, have been proven to be extremely useful in this type of testing.
7. Whole blood aggregation with ristocetin is closer to in-vivo condition and a far superior method, for detecting vW disease. The CoFactor Assay is useful in obtaining the ACTIVITY level of the patient’s plasma.
8. WB permits analysis with, (i) thrombocytopaenic samples with platelets as low as 50,000 and 100,000 with ADP (ii) icteric, lipemic and hemolysed samples.
9. Impedance method based on WB offers several merits over optical method in addition to the above, the following:
   1. the sample volume needed with whole blood is 6 ml as against 12 to 20 ml with optical method,
   2. total test time with WB mode is 60 minutes as opposed to 125 minutes with optical mode,
   3. WB permits platelet studies in a physiological milieu and in the presence of RBCs and WBCs, which is not possible in the case of optical mode, where artificial platelets are involved in the studies.
10. Whole blood aggregometer is very useful to
    1. Monitor administration of DDAVP by ristocetin-induced aggregation in whole blood
    2. Measure GPIIb/IIIa receptor blockage
    3. Identify patients at risk of thrombosis or bleeding

Basic merits of optical mode of aggregometry with 700-2/700-4 whole blood/optical aggregometers.

Comprehensive diagnostic capability with

Whole blood/ Optical Lumi Aggregometer:

To measure platelet function using impedance in whole blood, optical density in plasma, while simultaneously measuring ATP release by the luminescence method. Optical aggregation with turbidimetry feature permits platelet function testing for RiCoF and sticky Platelet Syndrome tests.

Platelet disorders shown below can be detected using whole blood/ optical aggregometry and or luminescence modes.

von Willebrand Disease, Extracorporeal circulation , Glanzmann’s Thrombasthenia, Heparin-Induced Thrombocytopenia, Storage Pool Deficiency (SPD), Sticky Platelet Syndrome, Thrombopathia or Thrombocyopathy, Bernard-Soulier Syndrome (BSS), May-Heggelin Anomaly, Gray Platelet Syndrome, Defective early responses (primary defects), Secretion defects, Non steroidal, Anti-inflammatory drugs, Hyperaggregability, Deficiency of the enzyme cyclo-oxygenase, Deficiency of the enzyme thromboxane synthetase, Thrombocyopenia with absent raddi (TAR syndrome), Risk of thrombosis, Membrane receptor site defects etc.

Whole blood electrical impedance Aggregometer:

Detect specific platelet abnormalities, screen platelet defects, diagnose specific bleeding disorders, detect the use of antiplatelet drugs such as aspirin and plavix, monitor patients for anti-thrombotic treatment. Screen rapidly prior to surgery for platelet function, monitor therapeutic program, testing platelet function for clinical screening + , diagnostic studies, pharmaceutical research and platelet research ++ studies. Measure GPIIb/IIIa receptor blockage, identify patients at risk for thrombosis or bleeding.

+ Clinical: Detect Heparin-Induced Thrombocytopenia, screen for aspirin-like a defect, differentiate between hereditary and acquired platelet disorders; monitor therapeutic dosage and patient compliance to inhibitory therapy.

++ Research: Study the effects of drugs on platelet aggregation, Study the effects of food substances on platelet function, Study platelet to membrane receptor site defects.

Aggregometer specifications

Two channel Platelet aggregometer with upgradability into four channel, and capable of measuring whole blood in impedance mode, and PRP by turbidimetry , the classic Born method and shall have FDA clearance For 230V 50Hz operation.

Technical:

Test channels:

Impedance aggregation – Aggregation in whole blood sample of 1ml using disposable or reusable electrodes with automatic baseline setting and gain.

Optical aggregation – Aggregation in PRP, gel filtered or washed platelets. Sample volume: 450µl PRP or 250ul with accessory.

System shall have capability for upgradation for the luminescence mode for quantitative analysis of dense granule release with ATP release with either PRP or Whole blood.

Sample volume:

Whole blood ::500ul or less
Optical ::250ul PRP or less

Display and controls:

Should have clear LCD, one per channel for display of :

1. Heater block temperature in°C
2. Stirring speed in RPM
3. Operating mode ( Optical or Impedance)
4. Warning messages.

Should have key-activated calibration of optical circuits.

Adjustable stirrer speed between 400 to 1200 RPM in 100-RPM steps with “stirrer stopped” position, and error detection to prevent operation, if not within + 10 RPM.

PC and software:

1. Data reduction system: Computer, appropriate to run system software with CD-Writer for convenient storage and retrieval of data , colour monitor and colour inkjet printer should be included. Software package (Windows 10, or the applicable one) should be included.
2. Should include internal computer interface and software for measuring upto at least two (2) samples for simultaneous aggregation, for a total of two (2) tracings.
3. Shall have provision for :
   1. Real time display of two channels of amplitude of aggregation.
   2. Storage facility for reagent data for tracking test value, demography details, for later recall should be available.
   3. Running with computation of slope log time and area under the curve.
4. vW cofactor:
   1. On-screen guidance for operator for running the test and incorporate facility for calculation of percent of vW activity and reporting.
   2. Should allow rerun or deletion of serial point with facility to store curves with lot number, best-fit standard curve and CD calculated for upto six points, should be available.

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