Direct identification of second systolic peaks of peripheral upper limb pulses (pSBP2) has been used to represent central systolic blood pressure (cSBP), but its accuracy at low SBP was questioned.Objectives:
We investigated the relationship of pSBP2 with characteristics of central pressure waveforms.Methods:
High-fidelity central aortic and right brachial pressure waveforms were simultaneously recorded using a custom-made dual pressure sensor catheter in 78 patients (65.9 ± 12.9 years) during catheterization for 285 measurements.Results:
Overall agreement between cSBP and pSBP2 was good (mean difference −0.9 ± 4.8, r = 0.98), with a systematic bias at low SBP. We examined agreements of different waveform types according to the relationship of the second systolic peak of aortic pressure waveforms (cSBP2) to cSBP. Of type A (positive late systolic augmentation) and type B (zero augmentation) aortic pressure waveforms, in which cSBP = cSBP2, agreement between pSBP2 and cSBP was excellent (mean difference −0.4 ± 4.1, r = 0.99). There were 40 type C aortic pressure waveforms (negative augmentation; cSBP > cSBP2) with cSBP 107.2 ± 13.9 mmHg. Their cSBP2, compared with cSBP, showed closer agreement (mean difference −0.6 ± 3.2 vs. −4.0 ± 7.2 mmHg) and better correlation (r = 0.97 vs. 0.85, P = 0.03) with pSBP2.Conclusion:
pSBP2 can be used with type A and B aortic pressure waveforms for estimation of cSBP. However, it should not be used with type C aortic pressure waveforms, typically at low SBP, because pSBP2 is closer to cSBP2 than cSBP. This explains why pSBP2 underestimates cSBP at low SBP.