What is the primary challenge cited for cuffless monitoring solutions like PPG or ultrasound?

Ensuring readings maintain necessary clinical accuracy over time

While cuffless solutions integrated into smartwatches or trackers, utilizing technologies like PPG or ultrasound, offer extremely high wearability and continuous data collection, their main hurdle lies in reliability compared to established standards. The text notes that ensuring these newer, continuous monitoring methods maintain the necessary clinical accuracy over extended periods remains a significant challenge. Although they provide invaluable data, such as tracking nocturnal dips or spikes that might be missed by infrequent checks, the inherent difference in measurement principles often mandates a more demanding and frequent calibration process against a validated cuff standard to maintain user trust.