title: Estimating central systolic blood pressure during oscillometric determination of blood pressure:  proof of concept and validation by comparison with intra-aortic pressure recording and arterial tonometry.
abstract: OBJECTIVE
  Central systolic blood pressure is usually estimated by transformation of a peripheral arterial waveform obtained by tonometry and calibrated from conventional measurements of brachial artery blood pressure from a brachial cuff using the oscillometric principle. We investigated whether central blood pressure could be obtained directly from a brachial cuff waveform, allowing the measurement of central blood pressure to be incorporated into the standard oscillometric determination of blood pressure.
  
  
  METHODS
  Values of central systolic blood pressure obtained from a brachial cuff waveform were compared with those obtained using a pressure-tipped intra-aortic catheter in 29 individuals undergoing cardiac catheterization. To remove errors introduced by the measurement of peripheral blood pressure, transformed brachial waveforms were calibrated using values of mean and diastolic pressure from the intra-aortic catheter. In a second study, the values obtained from the brachial cuff were compared with those obtained using a noninvasive tonometric method using calibration from mean and diastolic and from systolic and diastolic blood pressure derived from a standard oscillometric algorithm in 100 individuals (46 women, 19-81 years) with blood pressure ranging from 89/52 to 230/117 mmHg.
  
  
  RESULTS
  In study 1, the mean difference ± SD of brachial cuff-derived values and intra-aortic values was 0.0 ± 5.9 mmHg. In study 2, the mean difference for brachial cuff-derived values and tonometer values was -0.6 ± 3.9 and 1.6 ± 4.5 mmHg when calibrated using brachial mean and diastolic and brachial systolic and diastolic pressures, respectively.
  
  
  CONCLUSIONS
  Central systolic blood pressure can be obtained from a brachial cuff waveform with an accuracy comparable to that of a tonometer.
authors.affiliation: Department of Clinical Pharmacology, British Heart Foundation Centre, Cardiovascular Division, King's College London, St Thomas' Hospital, UK. sally.brett@kcl.ac.uk
authors.forename: Sally Emma
authors.initials: SE
authors.lastname: Brett
authors.forename: Antoine
authors.initials: A
authors.lastname: Guilcher
authors.forename: Brian
authors.initials: B
authors.lastname: Clapp
authors.forename: Phil
authors.initials: P
authors.lastname: Chowienczyk
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001158:Arteries / Q000502:physiology; D001794:Blood Pressure; D001795:Blood Pressure Determination / Q000379:methods*; D002138:Calibration; D006328:Cardiac Catheterization; D005260:Female; D006801:Humans; D008297:Male; D008365:Manometry / Q000379:methods; D008875:Middle Aged; D009991:Oscillometry / Q000379:methods; D013599:Systole; D055815:Young Adult