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Phillip S Gordon, Maja Kostic, Pedro Monsalve, Hong Jiang, Byron L Lam, John McSorley, Luis Vazquez, Elizabeth Hodapp, Vittorio Porciatti; Estimates of central artery pressure: age and posture-dependent changes. Invest. Ophthalmol. Vis. Sci. 2020;61(7):618.
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© ARVO (1962-2015); The Authors (2016-present)
Assessment of Ocular Perfusion Pressure (OPP) requires estimation of the Mean Central Artery Pressure (MCAP) [OPP=MCAP-IOP]. In a standing or seated posture, MCAP is typically estimated as 2/3 of Mean Arterial Pressure (2/3MAP) as MAP decreases at eye level for hydrostatic reasons. We tested a surrogate method for direct MCAP assessment by measuring MAP with arm-up and cuff at head level (AUMAP). We also investigated the effect of age and posture on 2/3MAP and AUMAP.
Seated 2/3MAP and AUMAP were assessed in a mixed population of 136 subjects (mean age 44±17.39 years) including healthy controls (N=30) and patients with optic neuropathies (Glaucoma suspects, N=14; Open Angle Glaucoma, N=26, LHON, N=19; MS, N=47) not expected to alter systemic blood pressure. None of the subjects had history of carotid stenosis or pharmacological treatment to regulate blood pressure. AUMAP was also tested in two subgroups in supine (N=42) and -10° head down tilt position (HDT, N=46).
Seated 2/3MAP and AUMAP were highly correlated (R2=0.72) and both linearly (P<0.001) increased with age, with a steeper slope for AUMAP (2/3MAP=59.5+0.1146*age; AUMAP= 61.2+0.2297*age). This resulted in similar pressures at young ages but substantially higher AUMAP pressures at older ages. In supine and HDT posture, AUMAP increased in linear proportion to the sine of the angle of body tilt and depended on age (Supine AUMAP=78.5+0.132*age; HDT AUMAP=71.9+0.33*age).
Surrogate measurement of MCAP in individual subjects at different posture positions is feasible using ordinary clinical measurement of arterial pressure with arm up and cuff at head level. Compared to seated standard 2/3MAP, seated AUMAP displays a stronger age-related increase, arguably better reflecting the known age-related increase of vascular resistance to maintain adequate blood flow at head level. AUMAP linearly increases with the sine of angle of body tilt as expected from hydrostatic considerations. Clinical estimation of OPP would benefit from the use of AUMAP.
This is a 2020 ARVO Annual Meeting abstract.
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