Review of measurement methods and clinical validation studies of noninvasive blood pressure monitors: accuracy requirements and protocol considerations for devices that require patient-specific calibration by a secondary method or device before use.

Existing standardized protocols for clinical validation of noninvasive blood pressure (BP) monitors do not have specific provisions for monitors that require patient-specific calibration by a secondary method or device before use. This article seeks to identify accuracy requirements and protocol considerations for such monitors. Measurement methods that require patient-specific calibration were reviewed to identify their clinical accuracy requirements. Validation studies of monitors that use these methods were reviewed to identify limitations in their protocols. For a monitor that requires patient-specific calibration, inadequate adaptation of existing protocols can fail to validate the accuracy of the monitor for its intended use. A protocol for such a monitor must have provisions to assess the monitor's accuracy in tracking intrapatient BP changes, from the calibrated level, after a calibration or between calibrations. Performing a patient-specific calibration with a patient at rest and immediately evaluating the monitor against a reference method with the patient also at rest will not assess this accuracy, because changes in BP at rest and over a short time are generally small compared with those that occur over 24 h. For validation purposes, intrapatient BP changes can be achieved by validating the monitor over an extended period or induced by means of physical maneuvers or pharmacological interventions. The secondary method or device used for the calibration must be accurate. The protocol must also have provisions to assess the monitor's ability to correct for changes in hydrostatic pressure, reject or correct for motion artefacts, and correct for other factors that affect measurement accuracy during use. There is a need to establish protocol provisions to ensure that noninvasive BP monitors that require patient-specific calibration are properly validated for their intended use before they are placed on the market or introduced into clinical use.