Non Invasive Assessment of Carotid and Femoral Arterial Pressure: Differences in Calibration Using Measured and Calculated Mean Brachial Pressure

Abstract

AbstractApplanation tonometry or arterial distension waves has been proposed to assess non-invasive recording of the arterial pressure waveform and magnitude in both central and peripheral arteries. The value of mean arterial pressure (MAP) that is used in the calibration procedure is of vital importance. The aim of this study was to investigate the differences in carotid and femoral arterial pressure values after calibration using MAP calculated from brachial tonometry and from approximate formula. In 30 volunteers (56±10 years, range: 38-73; pulse pressure: 57±15 mmHg, range: 31-93) arterial pressure waveforms were consecutively obtained at the left brachial, left carotid and left femoral arteries by applanation tonometry. Diastolic (DBPbra) and systolic (SBPbra) brachial pressure were obtained with oscillometric device. Calibration of carotid and femoral waveforms was assessed assuming MAP minus diastolic pressure constant throughout the arterial tree. Calibrated tonometric signals were used as reference values. Error in estimating MAP from SBPbra and DBPbra values using the traditional formula resulted in an underestimation of MAP of 3% when compared with the brachial MAP obtained by applanation tonometry. This error tended to an underestimation of carotid and femoral systolic pressure of 5%. Moreover, absolute error increases with increasing pulse pressure (PP) levels. By other side, MAP computed as 38% of PP above diastolic pressure, introduces an error of 0.1% in brachial MAP and of 0.2% in carotid and femoral systolic pressure estimation, independent of PP levels.KeywordsMean Arterial PressurePulse PressureDiastolic PressurePressure WaveformApplanation TonometryThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.