(204 days)
The Citizen CH-611B and CH-611C digital wrist sphygmomanometers (blood pressure meters) are intended to be used for the oscillometric measurement of systolic and diastolic blood pressure and pulse. They are intended to be sold over-the-counter and to health care professionals, and not primarily under the order or direction of a physician.
The Citizen CH-611B and CH-611C digital wrist sphygmomanometers are small handheld noninvasive blood pressure measurement systems that measure systolic and diastolic blood pressure and pulse from the user's left wrist. The units are contained in a hard plastic housing that contains a user interface panel to which an adjustable wrist cuff is attached by rubber tubing. The user interface panel has a power switch, and a liquid crystal display ("LCD") for displaying the systolic and diastolic blood pressure and pulse, and a memory switch. The device measures blood pressure through the use of an automatically-inflating wrist cuff. The cuff automatically deflates during blood pressure measurement. The only difference between the CH-611B and the CH-611C is that the CH-611B has a memory function which is able to display the last measured systolic and diastolic blood pressure readings (but not the pulse) when a memory recall switch is pressed, while the CH-611C is able to display the last seven measured systolic and diastolic blood pressure readings (but not the pulse) as well as an average of the seven.
Here's an analysis of the provided text regarding the acceptance criteria and study for the Citizen CH-611B and CH-611C Digital Wrist Sphygmomanometers:
1. Table of Acceptance Criteria and Reported Device Performance
| Acceptance Criteria (Predicate Device Performance) | Reported Device Performance (Citizen CH-611B/C) |
|---|---|
| Blood Pressure Measurement Accuracy: ± 3mm Hg or ± 2% of the reading (whichever is greater) | Blood Pressure Measurement Accuracy: ± 3mm Hg or ± 2% of the reading (whichever is greater) |
| Pulse Measurement Range: 40 to 200 pulses/minute | Pulse Measurement Range: 40 to 200 pulses/minute |
| Pulse Measurement Accuracy: ± 5% of the measured pulse frequency | Pulse Measurement Accuracy: ± 5% of the measured pulse frequency |
| Wrist Cuff Circumference: 135 mm to 195 mm | Wrist Cuff Circumference: 135 mm to 195 mm |
| Oscillometric measurement method | Oscillometric measurement method |
| Microcomputer controlled, digital, auto-inflate | Microcomputer controlled, digital, auto-inflate |
Note: The document explicitly states that the Citizen devices and the predicate (Omron HEM-601) have the same accuracy and range specifications for blood pressure and pulse measurements. The acceptance criteria are therefore directly derived from the predicate device's established performance. The study aimed to demonstrate that the Citizen device met these same specifications.
2. Sample Size Used for the Test Set and Data Provenance
The provided text only states: "Citizen submitted laboratory testing data to establish the accuracy of its Sphygmomanometers for comparison to the Omron predicate device."
- Sample Size: The specific sample size used for this laboratory testing is not mentioned in the provided document.
- Data Provenance: The data was generated through "laboratory testing," implying a controlled environment. The country of origin is implicitly Japan, as the submitter, Citizen Watch Company, Ltd., is located in Tokyo, Japan. The data is prospective in the sense that it was specifically generated to support this 510(k) submission for the new devices.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of those Experts
This information is not provided in the document. For blood pressure monitors, the "ground truth" for accuracy is typically established by trained technicians or clinicians using a calibrated reference sphygmomanometer (e.g., a mercury sphygmomanometer) simultaneously with the device under test. The document does not detail the methodology for establishing this ground truth.
4. Adjudication Method for the Test Set
This information is not provided in the document. Adjudication methods are typically relevant for studies where multiple human readers interpret data, and their findings need to be reconciled. Since this is a device performance study for a blood pressure monitor, an adjudication method in the traditional sense (e.g., 2+1 for image interpretation) would not be applicable.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
A Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not done. This type of study is relevant for diagnostic devices that involve human interpretation of results (e.g., imaging devices). The Citizen CH-611B/C are automated blood pressure monitors, not devices requiring human interpretation in this manner.
6. Standalone (i.e. algorithm only without human-in-the-loop performance) Performance
Yes, a standalone performance study was done. The entire premise of the submission is to demonstrate the accuracy of the algorithm and hardware of the CH-611B and CH-611C devices themselves, without operator intervention once the measurement process is initiated, against established accuracy standards. The "laboratory testing data" directly assesses the device's ability to measure blood pressure and pulse accurately.
7. Type of Ground Truth Used
The type of ground truth used would have been a reference measurement from a highly accurate and calibrated blood pressure measurement device, typically a mercury sphygmomanometer or an equivalent validated device operated by a trained professional. The text does not explicitly state "mercury sphygmomanometer" but "laboratory testing data to establish the accuracy" implies comparison to a gold standard.
8. Sample Size for the Training Set
The concept of a "training set" in the context of machine learning is not directly applicable here. While the oscillometric method involves algorithms, the document describes a traditional device validation approach rather than a machine learning model that would require a separate training phase with a distinct dataset. Therefore, no "training set sample size" is mentioned or implied in the document.
9. How the Ground Truth for the Training Set Was Established
As noted above, the concept of a training set in the machine learning sense is not applicable. The device's underlying oscillometric algorithm would have been developed and refined based on engineering principles and potentially internal testing, but this document focuses on the validation of the final device's performance against established standards.
§ 870.1130 Noninvasive blood pressure measurement system.
(a)
Identification. A noninvasive blood pressure measurement system is a device that provides a signal from which systolic, diastolic, mean, or any combination of the three pressures can be derived through the use of tranducers placed on the surface of the body.(b)
Classification. Class II (performance standards).