COMPARISON OF CONTINUOUS MEAN ARTERIAL PRESSURE BY A WEARABLE CUFF-LESS DEVICE AGAINST INTRA-ARTERIAL MEASUREMENTS

Abstract

Objective: Wearable cuff-less blood pressure (BP) devices may overcome cuff limitations and offer continuous non-invasive BP monitoring. However, their accuracy in different clinical settings is not yet clarified. This study aimed to evaluate the accuracy of mean arterial pressure (MAP) measurements from a novel continuous cuff-less chest belt against intra-arterial measurements. Design and method: Patients in an intensive care unit with an indication of intra-arterial BP monitoring were included. Reference BP was measured with a radial artery catheter connected to a pressure transducer. Cuff-less measurements were obtained continuously with a chest belt, of which a model for BP estimation was trained on a non-intensive care unit population and consisted of a one-channel electrocardiogram, a photoplethysmography sensor and a tri-axis accelerometer. The data collection was monitored by an investigator to reliably exclude periods where the transducer was not properly levelled. Estimated MAP from the chest-belt was calibrated initially with intra-arterial MAP. In cases where the pressure transducer had to be repositioned, re-calibration was performed due to variability of the repositioned transducer levels. Pairwise comparisons of reference and cuff-less MAP were performed in 15-second epochs. Results: Preliminary data from 9 subjects were analysed. The subjects had a median (interquartile range) age of 64 (58–73) years, median BMI was 28.6 (25.4–32.7) kg/m2and 77.7% were males. A total of 21.5 h of data were analysed with an average of 2.39 ± 1.05 h per subject. The mean difference of estimated versus reference MAP was 3.9 ± 4.2 mmHg. The Bland-Altman bias was 2.06 mmHg with limits of agreement from -9.7 mmHg to 14 mmHg. The Figure displays typical data for one subject (A) and the Bland Altman plot for all subjects (B). Conclusions: After initial calibration with a reference measurement, the cuff-less chest belt estimated changes in mean arterial pressure in close agreement with reference intra-arterial measurements. This study illustrates the potential of a wearable cuff-less device for estimating mean arterial pressure continuously and non-invasively in ospitalised patients.