Background

We propose using compression sonography to observe the deformation and collapse of the radial artery as a surrogate for automated cuff blood pressures. We hypothesize that the pressure required to achieve coaptation and complete collapse of the artery will correlate to the diastolic and systolic blood pressure, respectively.

Objective

Our primary aim was to assess the feasibility of Ultrasound-guided Radial Artery Compression (URAC) for blood pressure measurement. Our secondary aim was to compare patient comfort levels during automated cuff and URAC measurements.

Methods

This was a prospective cohort study with a convenience sampling of 25 adult patients at a single urban ED. URAC pressure was measured followed by cuff manometry on the same arm. A 100mL NS bag was connected to the Stryker pressure monitor and placed on the volar wrist. Pressure was applied to the bag with a linear transducer and the radial artery was observed for coaptation of the anterior and posterior walls (diastolic pressure) and complete collapse (systolic pressure). Pressures were subsequently recorded. Patient level of comfort was also documented during the URAC method, with patients reporting either ‘more’, ‘same’ or ‘less’ comfort in comparison to automated cuffs. Data were analyzed using intraclass correlation and paired t-tests.

Results

The mean cuff systolic BP was 138.6 ± 22.1 mmHg compared to 126.9 ± 19.8 mmHg for the URAC systolic BP(p=0.02).  For diastolic blood pressure, there was no significant difference between the cuff BP and the URAC BP (83.7 ± 13.0 cuff vs. 86.5 ± 19.8 URAC, p=0.46). The intraclass correlation (ICC) for systolic BP was 0.48 (p=0.04) and 0.57 (p=0.02) for diastolic BP. 80% (20/25) of subjects found the URAC method more comfortable than the cuff measurement, and the remainder found it the same (5/20).

Conclusion

This preliminary study concluded there was a statistically significant moderate correlation between automated cuff and URAC measurements, though stronger for the diastolic measurement. Additionally, most patients found the URAC method more comfortable than traditional cuff measurements. Compression ultrasonography shows promise as a surrogate for BP measurement, though future studies are needed.