Carotid Tonometry Versus Synthesized Aorta Pressure Waves for the Estimation of Central Systolic Blood Pressure and Augmentation Index

• Published in: American journal of hypertension Vol. 18; no. 9; pp. 1168 - 1173
• Main Authors: Segers, Patrick, Rietzschel, Ernst, Heireman, Steven, De Buyzere, Marc, Gillebert, Thierry, Verdonck, Pascal, Van Bortel, Luc
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01-09-2005; Oxford University Press; Elsevier Science
• Subjects: Adult; Algorithms; Aorta - physiopathology; Applanation tonometry; arterial function; Arterial hypertension. Arterial hypotension; Biological and medical sciences; Blood and lymphatic vessels; Blood Pressure - physiology; Blood Pressure Determination - instrumentation; Blood Pressure Determination - methods; Calibration; Cardiology. Vascular system; Carotid Arteries - physiopathology; Clinical manifestations. Epidemiology. Investigative techniques. Etiology; Female; Fundamental and applied biological sciences. Psychology; Hemodynamics. Rheology; Humans; Linear Models; Male; Manometry - methods; Medical sciences; Middle Aged; Radial Artery - physiopathology; Sphygmocor; transfer function; Vascular Diseases - physiopathology; Vertebrates: cardiovascular system; wave reflection; transfer function; Sphygmocor; arterial function; wave reflection; Applanation tonometry; Hypertension; Systolic pressure; Estimation; Cardiovascular disease; Aorta; Arterial pressure; Blood pressure; Comparative study
• ISSN: 0895-7061; 1879-1905; 1941-7225
• DOI: 10.1016/j.amjhyper.2005.04.005

To assess the interchangeability of carotid tonometry and synthesized aorta pressure waveforms for estimating central systolic blood pressure (SBP) and augmentation index (AIx).
Tonometry waveforms were acquired with a custom built hardware and software platform in 276 subjects (179 men/97 women; aged 45.5 ± 5.7 years; mean ± standard deviation) at the radial (P
wf,ra), brachial (P
wf,ba), and carotid artery (P
wf,ca). The P
wf,ba was calibrated using systolic (SBP
ba) and diastolic (DBP
ba) sphygmomanometer pressure. The DBP
ba and calculated mean (MAP
ba) brachial pressure were subsequently used for calibration of P
wf,ra and P
wf,ca. A central pressure waveform (P
wf,sao) was synthesized from P
wf,ra using a generalized pressure transfer function (TFF). The AIx and SBP were measured on P
wf,ra, P
wf,ca, and P
wf,sao.
The SBP
ra, SBP
ca, and SBP
sao were 138.5 ± 16.8, 130.0 ± 16.2, and 131.1 ± 16.6 mm Hg, respectively. The SBP
ra correlated well with the SBP
ca (
r = 0.93) and the SBP
sao (
r = 0.94), as did the SBP
ca and the SBP
sao (
r = 0.97) with a mean bias of 1.35 ± 3.90 mm Hg. The AIx derived from P
wf,ra, P
wf,ca, and P
wf,sao were −20.8% ± 14.5%, 12.4% ± 13.9%, and 20.0% ± 11.7%, respectively. The correlation between radial and carotid, and radial and central AIx was 0.72 and 0.94, respectively. The correlation between AIx derived from P
wf,ca and P
wf,sao was 0.75 with a bias of 11.0% ± 14% (all correlations
P < .001).
The use of a generalized TFF in combination with well-calibrated radial pressure curves yields estimates of SBP in good agreement with carotid tonometry. Although AIx derived from a measured radial pressure curve correlates surprisingly closely with AIx measured on a synthesized aortic pressure curve, the correlation with a directly measured AIx on carotid signals is relatively poor.