WorldCat Identities

Lacharme, Tiffany (1982-....).

Overview
Works: 2 works in 3 publications in 1 language and 4 library holdings
Roles: Author
Publication Timeline
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Most widely held works by Tiffany Lacharme
Optic-nerve-head blood-flow response to increase in arterial blood pressure in humans by Tiffany Lacharme( )

2 editions published in 2011 in English and held by 3 WorldCat member libraries worldwide

Purpose. Autoregulation in ocular tissues ensures constant blood flow despite variations in ocular perfusion pressure and may be impaired in ocular diseases. The purpose of this study was to investigate the effect of increased blood pressure (BP) and ocular perfusion pressure (OPP) during isometric exercise on optic-nerve-head blood flow (ONH-BF). Methods. In 21 healthy subjects, aged 18-40 years, BP was measured using a Nexfin™ pneumatic transcutaneous sensor and blood flow was measured using laser Doppler flowmetry (LDF). OPP was defined as (0.74 × mean BP) - intraocular pressure. Handgripping consisted of static contraction of the finger flexors at 30% maximum contraction force using a hand dynamometer for 2 min. Results. Data were analyzed in 15 healthy subjects, exhibiting a homogeneous response of BP to handgripping (linear regression of BP versus time). A large increase, up to 50%, in OPP during exercise was not associated with a proportional increase in ONH-BF; vascular resistance increased about 30%. The blood flow-pressure relationship showed blood flow significantly increased by approximately 30%, mainly due to the rise in velocity. Conclusion. These new data strongly support the notion of autoregulation in ocular blood flow, protecting the eye from overperfusion. However, the increase in OPP is not completely counterbalanced despite the regular increase in vascular resistance. This blood flow regulation is possibly due to vasoconstriction, taking place outside of the sampled volume, probably in the arterioles proximal to the capillary bed of the neuroretinal rim. In the future, real-time measurements of vascular resistance during handgripping could be investigated in glaucoma patients
Twenty-four-hour rhythm of ocular perfusion pressure in non-arteritic anterior ischaemic optic neuropathy( )

1 edition published in 2014 in English and held by 1 WorldCat member library worldwide

Abstract Purpose In non-arteritic anterior ischaemic optic neuropathy (NAAION) patients, circulatory insufficiency within the optic nerve has previously been hypothesized to be related to nocturnal systemic hypotension. The main objective of this prospective cohort study was to investigate the nyctohemeral variations in ocular perfusion pressure (OPP) in NAAION patients. Methods In 20 patients with NAAION, the intraocular pressure (IOP) was measured using the Tono-Pen XL™ electronic tonometer every hour for 24hr. Blood pressure (BP) was evaluated over 24hr. Mean OPP was calculated with the following formula: OPP sitting position=(0.74×mean BP) − IOP and OPP lying position=(0.84×mean BP) − IOP. A nonlinear least squares dual-harmonic regression analysis approach was used to model the 24-hr rhythms of OPP data. Results On average, a 24-hr amplitude of 4.7±2.6mmHg was found for OPP. The patients were classified as either having a diurnal OPP rhythm (i.e. with a diurnal acrophase, 10% of the cases), a nocturnal OPP rhythm (45%) or absence of OPP rhythm (45%). Four patients had a nocturnal reduction in OPP (mean, −11%). Conclusion The physiological nocturnal rhythm of OPP was maintained in 45% of the NAAION patients. The nocturnal reduction in OPP seen in 20% of the patients was within the range of OPP where optic nerve blood flow autoregulation is still fully operative. A high prevalence of obstructive sleep apnoea syndrome in our population (71%) may explain the low frequency of systemic nocturnal hypotension
 
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Audience level: 0.92 (from 0.88 for Twenty-fou ... to 0.94 for Optic-nerv ...)

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