title: Estimation of central aortic systolic pressure from the second systolic peak of the peripheral upper limb pulse depends on central aortic pressure waveform morphology.
abstract: BACKGROUND
  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.
  
  
  OBJECTIVE
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Mei-Mei
authors.initials: MM
authors.lastname: Lin
authors.forename: Hao-Min
authors.initials: HM
authors.lastname: Cheng
authors.forename: Shih-Hsien
authors.initials: SH
authors.lastname: Sung
authors.forename: Chao-Feng
authors.initials: CF
authors.lastname: Liao
authors.forename: Ying-Hwa
authors.initials: YH
authors.lastname: Chen
authors.forename: Po-Hsun
authors.initials: PH
authors.lastname: Huang
authors.forename: Chen-Huan
authors.initials: CH
authors.lastname: Chen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001011:Aorta / Q000502:physiology*; D001794:Blood Pressure; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D013599:Systole; D034941:Upper Extremity / Q000098:blood supply