ProMedix has developed a novel sensor and detection CRT assessment algorithm, which research has shown produces reliable and consistent capillary refill times (𝝆 = 0.91).
The Sensor
The device utilizes a state-of-the art integrated optical stack and 24-bit sigma-delta converter. It connects via Bluetooth to a mobile application that contains the signal-processing algorithms necessary for calculating CRTs in real-time that is reported to the provider.
The Algorithm
The signal processing algorithm incorporated in the smartphone app assesses the quality of the signals from the temperature, pressure, and optical sensors, reduces noise, and automatically identifies pressure application and release time points. In addition, it ensures a proper pressure level and duration are used. The algorithm tracks the signal change from the pressure release time point and then calculates the CRT when the signals meet the completion criteria.
The App
The application guides the user through proper pressure application and release, continuously recording and providing graphical feedback. Once the sensor detects the manual release of pressure, it applies the PeriFRL CRT algorithm and displays the CRT. This result, along with the raw data, are stored on a secure cloud server for later analysis.
The Results
Patient studies show an excellent correlation between our digital capillary refill device and our gold standard for CRT assessment, which, analogous to AAMI SP10, is the mean of manual waveform assessments performed by two trained biomedical engineers. This validates that our device produces a standardized measure of CRT.