Effect of position on valsalva maneuver: supine versus 20 degree position.
Blood pressure changes in response to the Valsalva maneuver (VM), which reflect the integrity of the baroreflex that regulates blood pressure. Performing this maneuver in the standard supine position often prevents adequate venous preload reduction, resulting in a rise rather than a fall in blood pressure, the "flat-top" Valsalva response. We determined whether performing the VM at a 20 degree angle of head-up tilt (20 degrees ) improves preload reduction, thereby reducing the frequency of flat-top responses, improving reflex vasoconstriction, and increasing the Valsalva ratio. One hundred thirty patients were evaluated in a prospective study. Each patient performed the VM in both supine and 20 degrees positions.Flat-top responses were present in 18% of subjects when supine. Twenty degree angle of head-up tilt position reduced the flat-top response by 87%. The components of the response that are dependent on preload reduction (Valsalva ratio and phases II_E, II_L, and IV) also showed significant improvement with 20 degrees .A 20 degree angle of tilt is sufficient to reduce venous preload, decreasing flat-top response rate and improving the Valsalva ratio and the morphology of the VM. We recommend this modification for laboratory evaluation of the VM, whenever a flat-top response is seen.
Vogel
Elizabeth R
ER
Department of Neurology, Mayo Clinic, Rochester, Minnesota, USA.
Corfits
Jeanne L
JL
Sandroni
Paola
P
Sletten
David M
DM
Benarroch
Eduardo E
EE
Fealey
Robert D
RD
Suarez
Guillermo A
GA
Gehrking
Tonette L
TL
Gehrking
Jade A
JA
Low
Phillip A
PA
D017704:Baroreflex / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016683:Supine Position; D018667:Tilt-Table Test / Q000379:methods*; D014636:Valsalva Maneuver / Q000502:physiology*; D014661:Vasoconstriction
J Clin Neurophysiol. 1998 Nov;15(6):535-40
9881927
J Appl Physiol (1985). 1990 Jan;68(1):147-53
2312453
J Appl Physiol (1985). 1991 Oct;71(4):1563-7
1757382
Neurology. 2005 Nov 22;65(10):1533-7
16301478
Arch Neurol. 2007 Mar;64(3):381-6
17353381
Clin Sci (Lond). 2001 Apr;100(4):433-40
11256984
Muscle Nerve. 2007 Nov;36(5):637-42
17654557
J Physiol. 1980 Jul;304:489-502
7441548
J Clin Neurophysiol. 1993 Jan;10(1):14-27
8458992