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The Terumo Khuri™ Myocardial pH Monitoring System is intended for use in monitoring local tissue pH and temperature, typically during procedures in which specific tissues may be subjected to conditions which may result in ischemia, such as the myocardium, during cardiac operations. These parameters are displayed at 37°C corrected value. For documentation purposes, the integral printer provides a hard copy of displayed parameter.

The Terumo Khuri™ Myocardial pH Monitoring System (Khuri MpH system) is an AC-powered (battery support for memory retention), microprocessor-based device consisting of a monitor, sensor and interface module'. The myocardial pH sensor will consist of two pH measurement probe electrodes and a reference electrode for the purpose of monitoring continuous myocardial tissue pH and temperature during cardiac surgery. The system uses electrochemical technology to measure the hydrogen ion content of the myocardial tissue, and report that information via electrical cable back to the monitor, where a processing unit coverts the electrical signal into pH units for display on the monitor.

The Khuri MpH system Monitor consists of a single board computer and a dedicated circuit that contains digital circuitry to interface with the interface module that connects to the sensor (pH electrodes and reference probe). The system will have an LCD flat touch screen display that will control the mode and operation of the monitor. The monitor will have a printer that will enable the user to print out case results. The monitor will be able to be mounted on a vertical pole or rest on a flat surface.

Each Khuri MpH system Sensor consists of two pH electrodes and one reference electrode. The pH electrodes are designed with a pointed tip for insertion into tissue with minimal resistance. The pH electrode consists of a closed end glass tube made from pH sensitive glass. The tube is filled with a phosphate based internal buffering solution in which a silver wire coated with silver chloride is inserted. The wire is attached to a cable, which is encased in an electrically shielded sheath and attaches to the monitor. The tip of the glass is pointed to allow easy insertion in to the myocardial tissue during use. The thermistor is a metal oxide ceramic tip. which is imbedded in the plastic surrounding the rear of the glass tube.

A reference electrode is used to complete the circuit. The reference electrode consists of an Ag/AgCl wire inserted into a plastic tube of KCI electrolyte solution. The front end of the tube is tapered to a small diameter to facilitate insertion into the tissue (usually near the sternum) during use. It is plugged with a semi-permeable material that prevents bulk leakage of fluid but maintains electrical contact with the patient during pH measurement. The wire protrudes from the sealed back end of the tube and is attached to a cable, which connects to the monitor.

The analog voltage signal from the sensor is fed into an interface module that amplifies and conditions the analog signal to remove any interfering noise. The analog signal is then converted into digital information in the A to D converter. This digital signal is then fed from the interface module to the monitor where a conversion algorithm, in the monitor, is used to convert digital information into pH units. The values are then displayed on the monitor screen.

The provided document does not contain acceptance criteria or a study proving the device meets specific acceptance criteria in the manner typically seen for performance evaluation studies of diagnostic or AI-driven medical devices.

Instead, this is a 510(k) summary for a medical device (Terumo Khuri Myocardial pH Monitoring System) seeking substantial equivalence to a predicate device. The "study" described is a nonclinical performance comparison to demonstrate that the new device is substantially equivalent to the predicate device.

Here's a breakdown based on the request, with explanations for why certain information is not present:

Acceptance Criteria and Device Performance

1. Table of Acceptance Criteria and Reported Device Performance

Explanation: This is a Class II device (pH monitor), and the 510(k) pathway for substantial equivalence often relies on demonstrating that the new device's technological characteristics and performance are comparable to a legally marketed predicate, rather than meeting specific quantitative diagnostic performance thresholds (like sensitivity/specificity for an AI algorithm). The nonclinical tests were likely focused on engineering specifications, physiological measurements (pH and temperature accuracy), and safety, rather than a clinical outcome or diagnostic accuracy study.

Study Details

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. The document refers to "exhaustive testing" and comparison with the predicate device's performance characteristics. This implies laboratory or bench testing, possibly animal studies, but not a human clinical test set in the conventional sense for diagnostic accuracy.
• Data Provenance: Not specified. Given it's "nonclinical performance," it would likely be laboratory or internal testing data, not clinically derived patient data.

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. Ground truth in this context would likely be established by known chemical/physical standards (e.g., buffer solutions of known pH) or controlled physiological environments, not human expert interpretation of images or patient data.
• 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. This type of device (pH monitor) does not involve subjective interpretation requiring adjudication of results from multiple readers.

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 Study: No. This device is a direct measurement tool, not an imaging or AI-assisted diagnostic device where human interpretation is a primary component.

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

• Standalone Performance: Yes, in a sense. The "nonclinical performance" reported is the standalone performance of the device itself (the monitor and sensor system) in measuring pH and temperature, independent of human interpretation or assistance in the measurement process. There is no complex algorithm like in AI that would have a human-in-the-loop scenario. The algorithm mentioned only converts digital signals to pH units.

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

• Type of Ground Truth: Not explicitly stated but would most likely be known physical/chemical standards (e.g., certified pH buffer solutions) for calibration and accuracy checks. In ex vivo or in vivo physiological testing (if conducted), the "ground truth" for temperature would be a calibrated thermometer, and for pH, potentially another highly accurate, validated pH measurement system.

8. The sample size for the training set

• Training Set Sample Size: Not applicable/Not specified. This device describes electrochemical technology and a conversion algorithm from electrical signal to pH units. There is no mention of a machine learning or AI model that requires a "training set" in the conventional sense for pattern recognition or diagnostics. The "algorithm" is a deterministic conversion based on established electrochemical principles.

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

• Ground Truth for Training Set: Not applicable. As there's no machine learning training set, this question is not relevant. The "ground truth" for the device's fundamental function (converting electrical signals to pH) would be based on the physical chemistry of the pH electrodes and the calibration process using known pH standards.

Summary of the "Study" from the Document:

The provided text details a nonclinical performance evaluation comparing the new "Terumo Khuri Myocardial pH Monitoring System" to its predicate device, the "Khuri Regional Tissue pH Monitor."

• Purpose: To demonstrate substantial equivalence to the predicate device.
• Methodology: "The performance characteristics of the Khuri MpH system were exhaustively tested and compared with the performance characteristics of the predicate device."
• Key Finding: "All new and existing performance characteristics of the Khuri MpH system have been validated." And concluded, "The Khuri MpH system performs as intended according to its performance specifications. The Khuri MpH system is substantially equivalent to the predicate device."

This type of submission focuses on validating the engineering and functional integrity of the device in comparison to an existing standard, rather than a clinical trial or AI performance study with traditional diagnostic metrics.

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