Evaluation of the Accuracy of a Video and AI Solution to Measure Lower Leg and Foot Volume

Abstract

Background and Objectives Peripheral edema, change in foot volume, is a marker of congestion which is regularly assessed in routine clinical care. A novel video and Artificial Intelligence (AI)-based solution used to measure anatomical parameters, including volume and foot length, Heartfelt HF-1, is compared to the laboratory gold standard (water displacement) and a medical disposable measuring tape. Design, Setting, Participants, and Measurements 58 healthy volunteers were measured with the Heartfelt device; 22 were also measured with the water displacement method and 19 with the medical tape. Bland–Altman analysis was performed for both volumes and foot lengths. Left/right foot differences provided covariance-corrected standard error of measurement (ccSEM) and minimum detectable difference (MDD) for each measurement method. Results Heartfelt device measured volumes displayed excellent correlation to the gold standard (water displacement), with Bland–Altman bias of +32mL ±81mL (1 std.dev). Clinically important change in foot volume is approximately 13%. Water displacement yielded ccSEM of ± 32.1mL and MDD of 90mL (6.7% of average foot volume), while the Heartfelt device measurements yielded ccSEM of ±12.6mL and MDD of 35.3mL (2.6% of average foot volume). The majority of differences were attributable to manual positioning of the patient foot in the waterbath. Conclusion This study finds that in clinical and non-clinical settings, the Heartfelt device measures foot volume and length more precisely than either the water displacement technique or manual foot length measurements using a medical disposable tape, while having an excellent agreement with these methods.

Enhancing Home Monitoring of Patients With Heart Failure: Primary Care Experience With an Autonomous Foot-Measuring Device

“…The Heartfelt device employs 3D imaging technology and AI to precisely measure foot volumes from captured images, compared to the gold standard of water displacement. 22 Subsequently, it automatically identifies patients at increased risk of readmission (as indicated by a rise in peripheral edema 23 ) for the clinical team to evaluate and determine the appropriate action(s). Approximately half of the affected patients regularly experience peripheral edema as an early warning sign of worsening or decompensation of heart failure.…”

Heart failure decompensation alerts in a patient’s home using an automated, AI-driven, point-of-care device

“…Peripheral/pitting oedema is a common symptom of HF with a predictable progression (10–14 days) into acute disease 4. Many strategies have been developed to monitor it and although the estimation of leg and foot volume is done in academic settings,5 the only practical methods are the evaluation of pitting oedema by a trained medical professional or the daily measurement of full body weight in the home as a proxy 6 7. This is often too demanding for patients and many struggle to keep up with the medical advice.…”