Acute blood pressure (BP) changes might influence augmentation index (AIx), an integrated dimensionless measure of reflected wave timing and amplitude.

In 30 healthy subjects (49±16 years, 43% men), supine brachial BP and radial-artery waveform (applanation tonometry, SphygmoCor) were obtained with the right arm supported in 3 different positions: at the heart level (0°), raised by 30° (+30°), and lowered by 30° (−30°). BP and tonometric measures were also obtained on the contralateral arm, which was held at the heart level during the examination.

Brachial systolic/diastolic BP was 121/67±18/8 mmHg. Radial AIx was 84±19%, and estimated central AIx 27±14%. As expected, changes in arm position modified substantially mean BP (96±12 mmHg at −30°, 85±11 mmHg at 0°, 74±11 mmHg at +30°, all p<0.001).

Radial and central AIx were both reduced at −30° (71±22% and 17±17%), and increased at +30° (97±21% and 30±14%, all p<0.001) vs corresponding values at 0°. Heart rate and contralateral BP and AIx did not change. Changes in radial and aortic AIx were strongly related each other (r=0.76, p<0.001). Percent variation in radial AIx (highest minus lowest, divided by AIx at heart level) had a strong inverse relationship with age (r=−0.43, p<0.001) and systolic BP (r=−0.37, p<0.001).

In conclusion, acute gravitational upper-limb BP changes generate opposite changes in radial AIx. Acute changes in radial Aix decrease with age and BP levels, and might represent a novel index of vascular aging. Artifactual changes in aortic AIx may arise in the presence of radial-aortic distending pressure gradient.