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Tomas Strömberg - One of the best experts on this subject based on the ideXlab platform.

Ingemar Fredriksson - One of the best experts on this subject based on the ideXlab platform.

S. Copeland - One of the best experts on this subject based on the ideXlab platform.

  • ASSESSMENT OF BLOOD FLOW IN THE ROTATOR CUFF BY LASER Doppler Flowmetry
    2018
    Co-Authors: B. Venkateswaran, T. Zaman, Tirtza Even, S. Copeland, A. Kapila, A Bargava, Ofer Levy
    Abstract:

    Aim: Despite many studies the implications of perfusion and blood flow abnormalities in the rotator cuff (RC) in vivo are not clearly understood. Laser Doppler Flowmetry (LDF) is an established technique for the measurement of perfusion in tissue, which has been applied in animal and human studies. This study aims to evaluate Laser Doppler Flowmetry (LDF) as a technique for the assessment of blood flow in the normal and diseased RC.Methods: With Ethics committee approval and informed consent patients undergoing arthroscopy for impingement or cuff tear (diseased cuff) and instability (normal cuff – BO) were recruited. Following diagnostic arthroscopy and bursoscopy measurements of the LDF in the RC tear were made at 6 points. Five of these were in the cuff over a 4 cm. 2 are from the insertion at the greater tuberosity and one in the deep surface.Diseased RC were sub grouped into mild (B1), moderate (B2) and severe (*B3 – cuff tear) impingement grades (Copeland – Levy Classification). The arthroscopy, grad...

  • Measurement of blood flow in the rotator cuff using laser Doppler Flowmetry
    The Journal of bone and joint surgery. British volume, 2008
    Co-Authors: Ofer Levy, J. Relwani, T. Zaman, Tirtza Even, B. Venkateswaran, S. Copeland
    Abstract:

    The aim of this study was to define the microcirculation of the normal rotator cuff during arthroscopic surgery and investigate whether it is altered in diseased cuff tissue. Blood flow was measured intra-operatively by laser Doppler Flowmetry. We investigated six different zones of each rotator cuff during the arthroscopic examination of 56 consecutive patients undergoing investigation for impingement, cuff tears or instability; there were 336 measurements overall. The mean laser Doppler Flowmetry flux was significantly higher at the edges of the tear in torn cuffs (43.1, 95% confidence interval (CI) 37.8 to 48.4) compared with normal cuffs (32.8, 95% CI 27.4 to 38.1; p = 0.0089). It was significantly lower across all anatomical locations in cuffs with impingement (25.4, 95% CI 22.4 to 28.5) compared with normal cuffs (p = 0.0196), and significantly lower in cuffs with impingement compared with torn cuffs (p < 0.0001). Laser Doppler Flowmetry analysis of the rotator cuff blood supply indicated a significant difference between the vascularity of the normal and the pathological rotator cuff. We were unable to demonstrate a functional hypoperfusion area or so-called 'critical zone' in the normal cuff. The measured flux decreases with advancing impingement, but there is a substantial increase at the edges of rotator cuff tears. This might reflect an attempt at repair.

Sohan Singh Hayreh - One of the best experts on this subject based on the ideXlab platform.

  • laser Doppler Flowmetry and optic nerve head blood flow
    American Journal of Ophthalmology, 1999
    Co-Authors: Benno L Petrig, Charles E Riva, Sohan Singh Hayreh
    Abstract:

    Abstract Purpose: Ischemic disorders of the optic nerve head constitute an important cause of visual loss. The optic nerve head is supplied by two main sources of blood flow: the superficial layers by the central retinal artery and the deeper layers by the posterior ciliary arteries. This study was conducted in rhesus monkey eyes to obtain a better understanding of which part of the optic nerve head circulation is measured by laser Doppler Flowmetry. Methods: By means of a fundus camera–based laser Doppler Flowmetry technique to measure blood flow in the optic nerve head tissue, laser Doppler Flowmetry measurements were taken at baseline and then after experimental occlusion of central retinal artery (12 eyes), posterior ciliary arteries (nine eyes), and combined occlusion of central retinal artery and posterior ciliary arteries (nine eyes). Optic nerve head, choroidal, and retinal circulations were investigated by fluorescein fundus angiography after the various arterial occlusions. Reseults: Average laser Doppler Flowmetry flow during central retinal artery occlusion alone was significantly decreased ( P P P > .20). After posterior ciliary artery occlusion alone, however, measurements showed a nonsignificant increase in laser Doppler Flowmetry flow of 17% ± 37%. Conclusions: The findings of this study suggest that the standard laser Doppler Flowmetry technique is predominantly sensitive to blood flow changes in the superficial layers of the optic nerve head and less sensitive to those in the prelaminar and deeper regions, and their relative proportions are not known. In this laser Doppler Flowmetry technique, the weaker Doppler signal from the deep layers cannot be separated from the dominant signal from the superficial layers to exclusively study the circulation in the deep layers; the latter circulation is of interest in optic nerve head ischemic disorders, including glaucoma. Emerging new optical modalities of the laser Doppler Flowmetry technique may help in selectively measuring blood flow in the deeper layers.

M. Groh - One of the best experts on this subject based on the ideXlab platform.