Comparison of central systolic pressure estimates obtained from ultrasound images and applanation tonometry

Abstract

Current non invasive assessment methods to estimate central pressure are based on the use of arterial tonometry: directly on the carotid artery or using a mathematical transfer function applied to the radial artery waveform. The first one is not recommended in obese patients or in the presence of carotid plaques, whereas the use of a unique transfer function to different population has been questioned. In this work we evaluated two alternative methods to assess systolic local arterial blood pressure: 1) from the analysis of B-mode carotid diameter waveforms (SBP_Dia) and 2) from the radial artery pressure waveform using an n-point moving average filter (SBP_Rad), and we estimated the accuracy of both when compared to direct carotid tonometry (SBP_Ton). In 20 asymptomatic subjects (49±11 years, range: 38-73; pulse pressure: 53±9 mmHg, range: 36-70), SBP_Ton was 132±13 mmHg (range 115-154) and correlated significantly with SBP_Dia (R=0.96, p<0.05) and with SBP_Rad (R=0.93, p<0.05). Mean difference between SBP_Dia and SBP_Ton was 0.85±4.0 mmHg, and 0.18±5.0 mmHg between SBP_Rad and SBP_Ton, independent of pressure levels. In conclusion, both alternative methods were found to allow an accurate and precise estimation of systolic local arterial pressure, when compared to direct carotid tonometry.