Effect of inhalation of different mixtures of O2 and CO2 on retinal blood flow

Luksch, Alexandra

doi:10.1136/bjo.86.10.1143

Cited by 75 publications

(74 citation statements)

References 16 publications

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“…Retinal blood flow varies inversely with arterial PO 2 to maintain retinal oxygenation at a relatively constant level (25,51) and also varies directly with arterial PCO 2 (34). Numerous studies have investigated retinal vascular reactivity using a hyperoxic stimulus.…”

Section: Discussionmentioning

confidence: 99%

“…In three previously published studies (22,24,34), researchers have investigated the time course of the changes in diameter or velocity using a hyperoxic stimulus (referred to in this report as response time and response lag). To the best of our knowledge, this is the first time that the response characteristics of arteriolar diameter and blood velocity have been simultaneously quantified due to hyperoxic provocation.…”

Section: Discussionmentioning

confidence: 99%

“…Alternatively, others have measured retinal vessel diameter and separately employed a bidirectional laser Doppler system to measure centerline retinal blood velocity to calculate flow (22,31,34,(37)(38)(39)42 In general, previous studies using 100% O 2 to assess retinal vascular reactivity have tended to find a greater magnitude of vasoconstriction, which we attribute to a compounded effect of elevated arterial O 2 and reduced CO 2 (22,37,38,42). Most of these studies have measured vascular reactivity in venules, possibly because the derived velocity profile was nonpulsatile.…”

Section: Discussionmentioning

confidence: 99%

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Retinal arteriolar diameter, blood velocity, and blood flow response to an isocapnic hyperoxic provocation

Gilmore¹,

Hudson²,

Preiss³

et al. 2005

American Journal of Physiology-Heart and Circulatory Physiology

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Fisher. Retinal arteriolar diameter, blood velocity, and blood flow response to an isocapnic hyperoxic provocation. Am J Physiol Heart Circ Physiol 288: H2912-H2917, 2005. First published February 11, 2005 doi:10.1152/ajpheart.01037.2004.-The aim of this study was to simultaneously quantify the magnitude and response characteristics of retinal arteriolar diameter and blood velocity induced by an isocapnic hyperoxic provocation in a group of clinically normal subjects. The sample comprised 10 subjects (mean age, 25 yr; range, 21-40 yr). Subjects initially breathed air for 5-10 min, then breathed O 2 for 20 min, and then air for a final 10-min period via a sequential rebreathing circuit (Hi-Ox; Viasys) to maintain isocapnia. Retinal arteriolar diameter and blood velocity measurements were simultaneously acquired with a Canon laser blood flowmeter (CLBF-100). The response magnitude, time, and lag of diameter and velocity were calculated. In response to hyperoxic provocation, retinal diameter was reduced from control values of 111.6 (SD 13.1) to 99.8 (SD 10.6; P Ͻ 0.001) m and recovered after withdrawal of hyperoxia. Retinal blood velocity and flow concomitantly declined from control values of 32.2 (SD 6.4) mm/s and 9.4 (SD 2.5) l/min to 20.7 (SD 3.4) mm/s and 5.1 (SD 1.3) l/min, respectively (P Ͻ 0.001 for both velocity and flow), and recovered after withdrawal of hyperoxia. The response times and response lags were not significantly different for each parameter between effect and recovery or between diameter and velocity. We conclude that arteriolar retinal vascular reactivity to hyperoxic provocation is rapid with a maximal vasoconstrictive effect occurring within a maximum of 4 min. Although there was a trend for diameter to respond before velocity to the isocapnic hyperoxic provocation, the response characteristics were not significantly different between diameter and velocity. vascular reactivity; laser Doppler velocimetry; isocapnic hyperoxia THE BLOOD SUPPLY TO THE INNER retina is derived from the central retinal artery, whereas the choriocapillaris supplies the outer retina and photoreceptors. The retinal tissue is one of the most metabolically active in the body and, correspondingly, an uninterrupted nutrient supply is essential (50). The inner retinal blood vessels (i.e., past the lamina cribrosa) are thought to be unique due to the absence of an autonomic nerve supply to regulate vascular tone (53). Blood supply to the inner retina is regulated via local feedback signals that alter retinal perfusion in response to changes in systemic blood pressure or the concentration of certain metabolites (11,18). In particular, retinal blood flow is strongly dependent on the partial pressure of oxygen (PO 2 ; Refs. 14,25,31,42,48).The retinal vasculature can be noninvasively visualized and, consequently, its hemodynamic parameters quantified. Impairment of vascular reactivity has been demonstrated in the pathogenesis of various ocular diseases including diabetic retinopathy (13,20,25,32). Administration of O 2 has p...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Retinal arteriolar diameter, blood velocity, and blood flow response to an isocapnic hyperoxic provocation

Gilmore¹,

Hudson²,

Preiss³

et al. 2005

American Journal of Physiology-Heart and Circulatory Physiology

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show abstract

“…Our data show a reduction of 50 to 60% in retinal blood flow, which is closer to the values obtained in humans. [41][42][43][44][45][46] Studying the response of retinal blood flow to hyperoxia is interesting, because it has been shown to be disturbed early in diabetes. 47 However, the mechanisms which lead to this reduced vasoconstrictor response to hyperoxia are poorly understood.…”

Section: Discussionmentioning

confidence: 99%

Measurement of retinal blood flow in the rat by combining Doppler Fourier-domain optical coherence tomography with fundus imaging

et al. 2014

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Abstract. A wide variety of ocular diseases are associated with abnormalities in ocular circulation. As such, there is considerable interest in techniques for quantifying retinal blood flow, among which Doppler optical coherence tomography (OCT) may be the most promising. We present an approach to measure retinal blood flow in the rat using a new optical system that combines the measurement of blood flow velocities via Doppler Fourier-domain optical coherence tomography and the measurement of vessel diameters using a fundus camera-based technique. Relying on fundus images for extraction of retinal vessel diameters instead of OCT images improves the reliability of the technique. The system was operated with an 841-nm superluminescent diode and a charge-coupled device camera that could be operated at a line rate of 20 kHz. We show that the system is capable of quantifying the response of 100% oxygen breathing on the retinal blood flow. In six rats, we observed a decrease in retinal vessel diameters of 13.2% and a decrease in retinal blood velocity of 42.6%, leading to a decrease in retinal blood flow of 56.7%. Furthermore, in four rats, the response of retinal blood flow during stimulation with diffuse flicker light was assessed. Retinal vessel diameter and blood velocity increased by 3.4% and 28.1%, respectively, leading to a relative increase in blood flow of 36.2%. The presented technique shows much promise to quantify early changes in retinal blood flow during provocation with various stimuli in rodent models of ocular diseases in rats. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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“…The autoregulating ability of the retinal blood vessels has been reported previously. [7][8][9][10][11][12][13][14][15] Several studies have demonstrated changes in retinal vessel diameter, velocity, and flow to various provocative stimuli, such as carbon dioxide (CO 2 ), O 2 and flicker in healthy 12,16,17 and diseased cohorts. [18][19][20][21] Hypoxia, a decrease in O 2 concentration, has been shown to vasodilate the retinal vessels.…”

mentioning

confidence: 99%

Intervisit Repeatability of Retinal Blood Oximetry and Total Retinal Blood Flow Under Varying Systemic Blood Gas Oxygen Saturations

Rose

Kulasekara

Hudson

2016

Invest. Ophthalmol. Vis. Sci.

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Citation: Rose K, Kulasekara SI, Hudson C. Intervisit repeatability of retinal blood oximetry and total retinal blood flow under varying systemic blood gas oxygen saturations. Invest Ophthalmol Vis Sci. 2016;57:188-197. DOI:10.1167/iovs.15-17908 PURPOSE. The aim of the study is to validate and calibrate the Doppler spectral-domain optical coherence tomography (SD-OCT) derived total retinal blood flow (TRBF) and metabolic hyperspectral retinal camera (MHRC) derived oxygen saturation (SO 2 ) of major retinal vessels in human volunteers using a novel and exact provocation technique (RespirAct) that allows the precise control of the end-tidal partial pressure of oxygen (P ET O 2 ). Between visit repeatability of the TRBF and retinal blood SO 2 also were studied.METHODS. One eye of 11 young healthy subjects was chosen randomly for the study. Total retinal blood flow and retinal SO 2 measurements were obtained under conditions of normoxia, hyperoxia, and hypoxia. The order of hyperoxia and hypoxia was randomized between subjects. The measurements were repeated after a week interval.RESULTS. When the arterial P ET O 2 was increased from baseline (P ET O 2 ¼ 100 mm Hg) to 200 and 300 mm Hg, the TRBF significantly reduced (P ¼ 0.02) from 44.60 (68.9) to 40.28 (68.9) and 36.23 (64.6) lL/min. Lowering the arterial P ET O 2 , from baseline to 80, 60, and 50 mm Hg, TRBF significantly increased (P ¼ 0.04) from 43.17 (612.7) to 45.19 (65.5), 49.71 (613.4), and 52.89 (610.9) lL/min with simultaneous reduction in the arterial blood SO 2 content from 99.3% (65.8) to 95.6% (65.1), 89.6% (62.8), and 83.3% (63.9), respectively (P ¼ 0.00). The coefficient of repeatability (COR) of TRBF, retinal arterial, and venous blood SO 2 values are 21.8 lL/min, 18.4%, and 15.2%, respectively. CONCLUSIONS.Total retinal blood flow and retinal blood SO 2 measurements performed under safe levels of hypoxia and hyperoxia were repeatable in healthy adults over the range of SO 2 investigated.

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Effect of inhalation of different mixtures of O2 and CO2 on retinal blood flow

Cited by 75 publications

References 16 publications

Retinal arteriolar diameter, blood velocity, and blood flow response to an isocapnic hyperoxic provocation

Retinal arteriolar diameter, blood velocity, and blood flow response to an isocapnic hyperoxic provocation

Measurement of retinal blood flow in the rat by combining Doppler Fourier-domain optical coherence tomography with fundus imaging

Intervisit Repeatability of Retinal Blood Oximetry and Total Retinal Blood Flow Under Varying Systemic Blood Gas Oxygen Saturations

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