Measurement of flow-mediated vasodilation of the brachial artery: a comparison of measurements in the seated and supine positions.
BACKGROUND
Measurement of flow-mediated vasodilation (FMD) is used to assess endothelial function in humans and according to the guidelines, subjects must remain supine during the study. However, measurement of FMD while seated would be more comfortable and convenient for patients, so the purpose of this study was to determine the effect of the patient's position on FMD results.


RESULTS
High-resolution ultrasonography, a linear array transducer (13 MHz) and an arm-holding device were used to measure arterial diameter in response to reactive hyperemia (FMD, cuff inflated to 50 mmHg above systolic blood pressure for 5 min) and in response to sublingual nitroglycerine (NTG, 75 microg) in 31 subjects, which included those with cardiovascular diseases. There was no significant difference between basal or peak hyperemic blood flow in the seated or supine position. Basal brachial artery diameter, FMD and vascular response to NTG were similar in both positions (basal diameter: 3.8+/-0.4 vs 3.9+/-0.4 mm, FMD: 7.3+/-4.3% vs 7.2+/-4.5%, NTG: 13.1+/-5.1% vs 12.8+/-5.6%).


CONCLUSIONS
The findings suggest that measurement of FMD in the seated position is as useful as measuring it in the supine position for assessing endothelial function. This flexibility of position is better for patients and physicians, and should lead to more widespread measurement of FMD.
Soga
Junko
J
Department of Medicine and Molecular Science, Hiroshima University Graduate School of Biomedical Sciences, Minami-ku, Kiroshima, Japan.
Nishioka
Kenji
K
Nakamura
Shuji
S
Umemura
Takashi
T
Jitsuiki
Daisuke
D
Hidaka
Takayuki
T
Teragawa
Hiroki
H
Takemoto
Hiroaki
H
Goto
Chikara
C
Yoshizumi
Masao
M
Chayama
Kazuaki
K
Higashi
Yukihito
Y
D000328:Adult; D000368:Aged; D001916:Brachial Artery / Q000000981:diagnostic imaging / Q000187:drug effects / Q000503:physiopathology*; D004730:Endothelium, Vascular / Q000503:physiopathology; D006801:Humans; D006940:Hyperemia / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D005996:Nitroglycerin / Q000494:pharmacology; D011187:Posture; D012039:Regional Blood Flow; D016683:Supine Position; D014159:Transducers; D014463:Ultrasonography; D014664:Vasodilation; D014665:Vasodilator Agents / Q000494:pharmacology
D014665:Vasodilator Agents; D005996:Nitroglycerin