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The Chrono-log Model 490 4+4 Aggregometer is intended for use for in-vitro diagnostic use for measuring Platelet Aggregation in Platelet Rich Plasma.

This device is intended to be used in a clinical laboratory environment by laboratory technicians.

For use only with light transmission aggregometry assays cleared for use with the Chrono-log Platelet Aggregometry systems.

The Chrono-log™ Model 490 4+4 Aggregometer measures platelet function on patient samples using LTA which measures a change in optical density of platelet rich plasma. The Model 490 4+4 is also used to run the Ristocetin Cofactor Assay to aid in diagnosis of patients with von Willebrand disease. The instrument comes with a starter kit of reagents and supplies. The output of the Model 490 4+4 can be connected to either a strip chart recorder or to a Computer. Software is provided with the computer interface option. The computer interface option is used to collect data only. The computer is not used for diagnosis or treatment and does not have any control over or input into the Model 490 4+4 Aggregometer.

LTA or Born method of platelet aggregation measures the change in optical density of a Platelet Rich Plasma (PRP) sample in comparison to optical density of a Platelet Poor Plasma (PPP) sample. The PRP sample, platelets in a suspension of plasma, is isolated from an anticoagulated blood sample by a relatively low centrifugation. The PPP sample is prepared by centrifuging the blood sample at a relatively high force. The Chrono-log sample chambers are designed so that a beam of infra red light shines through two cuvettes. one containing PRP (the sample) and one containing PPP (the reference). Silicon photodiodes detect the light able to pass through the samples: PRP is arbitrarily considered to be 0% light transmission or 0% aggregation: PPP is considered to be 100% light transmission or 100% aggregation. When a stimulus is added to the cuvette containing PRP and the platelets respond forming aggregates, more light is allowed to pass through the PRP sample. The change in light transmission, recorded over time, shows a trend towards the platelet poor plasma, or 100% light transmission. A graphical tracing of the change in optical density during the course of platelet aggregation is produced either on a strip chart recorder or on a computer using Chrono-log provided software. This device is designed to be used in the clinical laboratory as an in vitro diagnostic tool. The 490 4+4 varies from the predicate devices only in the number of channels.

The document describes the acceptance criteria and the study proving the device, Chrono-log™ Platelet Aggregometer, Model 490 4+4, meets these criteria, primarily through demonstrating substantial equivalence to a predicate device (Chrono-log™ Whole Blood Lumi-Aggregometer Model 700).

Here's the breakdown of the requested information:

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria are implicitly defined by demonstrating "strong correlation" and "good agreement" with the predicate device, as well as maintaining performance specifications (though specific numerical targets for metrics like R-squared or bias are not explicitly stated as pre-defined acceptance criteria, they function as such in the reported performance metrics). The device's performance is gauged by the Coefficient of Variation (which seems to be used interchangeably with R-squared in this context, given the R2 mentions in the conclusion) between the new device and the predicate.

2. Sample Size Used for the Test Set and Data Provenance

• Test Set Sample Size:
  • Optical Aggregation: 114 comparison tests in total.
  • Volume Comparison: A "small subset" of tests was used to compare 500uL and 250uL samples (8 normal samples in 500 µL, 8 aspirin samples in 500 µL, 8 normal samples in 250 µL, 8 aspirin samples in 250 µL).
• Data Provenance:
  • The study involved "patient samples" from "four normal, healthy, drug-free subjects" and "a subject taking aspirin." Additionally, samples treated with ticagrelor and GPIIb/IIIa antagonist, and deficient vW plasma with lyophilized platelets were used to demonstrate abnormal results.
  • The document does not explicitly state the country of origin for the data/samples but implies it was conducted by the manufacturer, Chrono-log Corp., based in Havertown, PA, USA.
  • Retrospective or Prospective: The testing appears to be prospective or specially collected for this comparison study, as it describes the collection and testing of specific subject samples (normal, aspirin, treated with inhibitors) on both the new and predicate devices.

3. Number of Experts Used to Establish Ground Truth and Qualifications

The document does not describe the use of experts to establish a "ground truth" for the performance study. The study focuses on demonstrating equivalence to a predicate device using measured values of platelet aggregation, not on expert interpretation of results. The "ground truth" for the device's function is the direct measurement of optical density changes in plasma samples, interpreted as percentage aggregation.

4. Adjudication Method for the Test Set

Not applicable. The study compares objective quantitative measurements from two devices, not subjective interpretations requiring adjudication.

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study

No, a multi-reader multi-case (MRMC) comparative effectiveness study was not conducted. This device is a measurement instrument (platelet aggregometer) and its performance is evaluated based on quantitative agreement with a predicate device, not on human reader performance or improvement with AI assistance.

6. Standalone (Algorithm Only) Performance

Yes, the study primarily demonstrates standalone performance of the device (Chrono-log Model 490 4+4) by comparing its measurements directly to those of the predicate device (Chrono-log Model 700). There is no AI algorithm involved; it's a direct hardware and measurement comparison. The software provided with the computer interface option is explicitly stated to "collect data only" and "is not used for diagnosis or treatment and does not have any control over or input into the Model 490 4+4 Aggregometer."

7. Type of Ground Truth Used

The "ground truth" is established by the measurements from the predicate device (Chrono-log Model 700). The study aims to show that the new device's measurements are substantially equivalent to those of the already legally marketed and established predicate device. It relies on the predicate device's accepted performance as the de facto standard for comparison.

8. Sample Size for the Training Set

Not applicable. This device is a medical measurement instrument, not an AI/ML model that requires a "training set" in the conventional sense. The "training" for the device would be its engineering design, calibration, and manufacturing processes.

9. How the Ground Truth for the Training Set Was Established

Not applicable, as there is no training set for an AI/ML model. The predicate device's established performance serves as the reference point for the new device's engineering design and verification.

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For in-vitro diagnostic use for measuring platelet aggregation and ATP secretion in whole blood or platelet rich plasma.

The Chrono-log Model 700 Aggregometer measures platelet function on patient samples using electrical impedance in whole blood or optical density in plasma. The Model 700 Aggregometer has the capability to simultaneously measure ATP release with either method using luminescence. The Model 700 Aggregometer is also used to run the Ristocetin Cofactor Assay which is used to diagnose patients with von Willebrands disease. The instrument comes with a starter kit consisting of the following Chrono-log reagents and supplies: ADP, Arachondic Acid, Collagen, Epinephrine, Ristocetin, Thrombin, a CHRONO-LUME® Kit, a Ristocetin Cofactor Kit, cuvettes, stir bars and pipettes. The output of the Model 700 can be connected to either a strip chart recorder or to a Computer. Software is provided the computer interface option. The computer interface option is used to collect data only. The computer is not used for diagnosis or treatment and does not have any control over or input into the Model 700 Aggregometer.

Here's an analysis of the provided text, focusing on the acceptance criteria and study details for the Chrono-log Model 700 Whole Blood Lumi-Aggregometer:

Acceptance Criteria and Device Performance

The provided document describes a 510(k) submission, which aims to demonstrate "substantial equivalence" to a legally marketed predicate device, rather than establishing explicit acceptance criteria with pre-defined thresholds for performance. The "acceptance criteria" here are implicitly linked to achieving a high correlation with the predicate devices, indicating comparable performance.

Here's a table summarizing the reported device performance, with the understanding that the "acceptance criteria" were met by demonstrating strong correlation:

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The Chrono-log WBA, Model 591A/592A is intended for determination of platelet function in a whole blood specimen, using ADP, Collagen and Ristocetin reagents.
For Platelet Function testing of Whole Blood specimens using Impedance Aggregometry. For Prescription Use.

The Chrono-log WBA, Model 591A/592A uses electrical impedance to measure platelet aggregation in a whole blood sample. The Impedance is measured using a Disposable electrode with two precious metal pins. A small voltage is applies across these two pins. When the electrode is placed into a diluted whole blood specimen and a monolayer is formed around the two pins. In the absence of an agonist, the platelet build-up stabilizes and a baseline is established. When an agonist is added to the specimen, the platelets begin to aggregate and collect on the electrode pins causing a change in impedance. The change of impedance is directly proportional to the amount of Aggregation in the specimen. This change of impedance is displayed on a front panel readout. The instrument has an analog output which produces an aggregation curve when connected to a strip chart recorder or AGGRO/LINK interface. Model 591 A is a single channel version; Model 592A is the duel channel version.

This document describes the performance testing of the Chrono-log Whole Blood Aggregometer (WBA), Model 591A/592A, and its substantial equivalence to the predicate device, Model 591/592, with the primary difference being the introduction of disposable electrodes.

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria were primarily based on demonstrating substantial equivalence to the predicate device through correlation, statistical significance, and the ability to detect aggregation changes and patient conditions similarly. New normal ranges were also established.

*Note on R for ADP 20μM: The Pearson's R value of 0.61 is marked with an asterisk indicating p

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The Chrono-log WBA, Model 591/592 is intended for determination of platelet function in a whole blood specimen.

The Chrono-log WBA, Model 591/592 uses electrical impediance to measure platelet aggregation in a whole blood sample. The Impedance is measured using an electrode with two platinum alloy wires. A small voltage is applies across these two wires. When the electrode is placed into a diluted whole blood specimen and a monolayer is formed around the two wires. In the absence of an agonist, the platelet build-up stabilizes and a baseline is established. When an agonist is added to the specimen, the platelets begin to aggreazate and collect on the electrode wires causing a change in impedance. The change of impedance is directly proportional to the amount of Aggregation in the specimen. The change of impedance is displayed on a front panel readout. An analog output which, when connected to a strip chart recorder, provides an aggregation curve. Model 591 is a single channel version; Model 592 is the duel channel version.

The provided 510(k) summary for the Chrono-log Whole Blood Aggregometer (WBA), Model 591/592, does not contain the detailed information required to answer many of your specific questions regarding acceptance criteria and the comprehensive study design.

This document primarily focuses on establishing substantial equivalence to previously cleared devices (Chrono-log Whole Blood Aggregometer K830749 and Centocor AggreStat K954997) rather than providing a standalone performance study with explicit acceptance criteria.

However, I can extract the information that is present and indicate where the requested details are missing.

Here's a breakdown of the available information and the missing details:

1. A table of acceptance criteria and the reported device performance

2. Sample size used for the test set and the data provenance (e.g. country of origin of the data, retrospective or prospective)

• Sample Size for Test Set: Not specified in the provided document.
• Data Provenance: Not specified in the provided document. It only mentions "tests data included in this application."
• Retrospective or Prospective: Not specified in the provided document.

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts (e.g. radiologist with 10 years of experience)

• Number of Experts: Not applicable/Not specified. For a device measuring a physiological parameter like platelet aggregation, the "ground truth" would likely be derived from the existing, validated methods (e.g., light transmission aggregometry, or the predicate devices themselves) rather than expert consensus on interpretation.
• Qualifications of Experts: Not applicable/Not specified.

4. Adjudication method (e.g. 2+1, 3+1, none) for the test set

• Adjudication method: Not applicable/Not specified. Adjudication methods are typically used in studies where human interpretation of results is a primary outcome, such as imaging studies. For a device measuring a quantitative physiological parameter, adjudication of an expert consensus on a subjective finding is generally not relevant.

5. If a multi-reader multi-case (MRMC) comparative effectiveness study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance

• MRMC Comparative Effectiveness Study: No. This type of study is not relevant for this device. The Chrono-log WBA is a diagnostic device that directly measures platelet aggregation; it does not involve human readers interpreting images or data for diagnosis in a way that AI assistance would "improve" their performance.

6. If a standalone (i.e. algorithm only without human-in-the loop performance) was done

• Standalone Performance: Yes, in principle. The Chrono-log WBA is a standalone device that provides a measurement (change in impedance reflecting aggregation). Its performance would be evaluated on its ability to accurately and precisely make this measurement, rather than as an "algorithm only" component of a larger system. The document, however, does not provide the specific results of such a standalone performance study, only that it was found substantially equivalent to predicate devices.

7. The type of ground truth used (expert consensus, pathology, outcomes data, etc)

• Type of Ground Truth: Not explicitly stated, but it would most likely be:
  • Comparison to predicate devices: The primary ground truth for establishing substantial equivalence would be the measurements obtained from the predicate devices (Chrono-log Whole Blood Aggregometer K830749 and Centocor AggreStat K954997) or other established methods for measuring platelet aggregation (e.g., Light Transmission Aggregometry).
  • Clinical correlation: While not detailed in this summary, the "ground truth" for the predicate devices and the underlying science of platelet aggregation measurement relies on clinical correlation with platelet function and bleeding disorders.

8. The sample size for the training set

• Sample Size for Training Set: Not applicable/Not specified. This device does not appear to be an AI/machine learning-based device that would require a separate "training set" in the conventional sense. Its function is based on direct electrical impedance measurement.

9. How the ground truth for the training set was established

• How Ground Truth for Training Set was Established: Not applicable. As noted above, this does not appear to be an AI/machine learning device.

Summary of Limitations of the Provided Document:

The provided 510(k) summary is extremely high-level and serves the purpose of demonstrating substantial equivalence. It lacks the detailed study methodology, performance metrics, and specifics about data collection that would be present in a comprehensive study report or a more detailed technical submission. It relies on the assertion that "examining the tests data included in this application" led to the finding of substantial equivalence, without providing those details in this public summary.

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