Emerging radar-based technologies for cuffless blood pressure monitoring-a systematic review

Hypertension is the leading risk factor for cardiovascular disease, the most common cause of death worldwide. Less than half the people with high blood pressure are aware of their diagnosis, and only a fifth are adequately treated. Because symptoms are often absent, hypertension might be diagnosed only after irreversible end-organ damage. Cuff-based blood pressure measurement devices provide only intermittent monitoring and can be inaccurate in some individuals. Tackling the limitations of existing devices requires improved diagnostic tools. Radar-based devices have been proposed as alternatives to cuff-based devices as radar-based devices are safe, unobtrusive, and have the potential for continuous monitoring. Radar has been used to measure pulse transit time and perform pulse wave analysis in humans, allowing blood pressure to be tracked or predicted. This Review summarises published works comparing the accuracy of radar-based blood pressure measurement devices with that of gold-standard cuff-based devices. Additionally, the Review highlights the advantages and challenges of translating this technology into clinical practice. The search was performed using PubMed, MEDLINE, IEEE Xplore, Google Scholar, Cochrane Library, Web of Science, medRxiv and bioRxiv to identify relevant publications from January 1, 1990 up to August 31, 2024. This Review identified 23 articles and found that early feasibility studies indicate that radar-based blood pressure estimation is technically feasible and can achieve promising accuracy under controlled conditions. However, because of the use of heterogeneous methodologies, small sample sizes, and inclusion of narrow blood pressure ranges, the current evidence remains constrained. Clinical translation of this technology will require evaluation in large, multimorbid cohorts, including people with hypertension. In addition, the development of universally accepted validation protocols by authoritative bodies will be essential to ensure that new devices meet rigorous performance criteria before commercial introduction, thereby establishing their credibility.