At what velocity threshold are Analog Doppler devices unable to portray accurate measurements?

Analog Doppler devices typically struggle to obtain accurate velocity measurements at low blood flow velocities. Specifically, a threshold of less than 6 cm/sec is generally recognized as the point at which these devices become unreliable. At velocities below this limit, the signal-to-noise ratio diminishes. This means that the background noise interferes with the Doppler signal, leading to inaccuracies in the measurement of blood flow velocity.

The limitations of analog Doppler are a result of their reliance on continuous wave technology, which can make it difficult to distinguish between low-velocity signals and noise, thereby compromising the integrity of the data captured. As blood flow slows significantly, the device's ability to provide a clear and accurate reading diminishes, resulting in potential errors in diagnosis and treatment. Thus, 6 cm/sec serves as a critical benchmark, indicating the point where the performance of these devices is no longer reliable in measuring blood flow velocities accurately.