Determination of central aortic systolic and pulse pressure from the radial artery pressure waveform

Objective: Measurements of central aortic systolic and pulse pressure, either gauged directly or estimated indirectly, have been shown to be superior to brachial pressure in outcome studies. While the radial pressure convolution method has proved to satisfy the criteria for 'substantial equivalence' to measure central pressure non-invasively, this study sought simpler methods to generate central systolic and pulse pressure directly from the radial artery waveform. Methods: Two sets of data were used, in which radial artery pressure waves were measured by applanation tonometry and ascending aortic pressure was generated by the SphygmoCor® process. Different approaches were applied to each dataset: firstly, using the time period from wave foot to systolic peak in central arteries; secondly, through identifying the pressure surge from the reflected wave in the radial artery; and thirdly from extrapolation and calibration of carotid systolic pressure when mean and diastolic pressure considered to be equal with radial values. Results: Both datasets showed good correspondence between the central systolic and pulse pressure obtained with each of the three approaches and respective pressures generated by SphygmoCor® process; all were within AAMI SP10 criteria and grade A for BSH criteria. Conclusion: All three approaches gave results similar substantially equivalent to those obtained with the SphygmoCor® system for aortic, systolic and pulse pressure. Hence, simple inspection of the radial waveform has the potential to improve the estimation of aortic systolic and pulse pressure.