Recent Advances in Cochlear Blood Flow Measurements

1988 ◽  
Vol 97 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Jonathon S. Sillman ◽  
Michael J. Larouere ◽  
Alfred L. Nuttall ◽  
Merle Lawrence ◽  
Josef M. Miller
Keyword(s):  
Blood Flow ◽  
Hearing Loss ◽  
Inner Ear ◽  
Laser Doppler ◽  
Control Mechanisms ◽  
Clinical Value ◽  
Cochlear Blood Flow ◽  
Flow Measurements ◽  
Local Flow ◽  
Doppler Flowmetry

Changes in blood flow to the inner ear have been thought to influence or underlie a number of cochlear diseases, including some forms of noise-induced hearing loss, sudden hearing loss, and Meniere's disease. Recently, important advances have been made in two technologies for the study of cochlear blood flow. The first is in the area of vital microscopic studies of cochlear microcirculation, and the second is based on the introduction of laser technology in the form of laser Doppler flowmetry. In this report, measurements are given of changes in cochlear circulation caused by carbon dioxide breathing, intravenous phenylephrine injection, systemic hemodilution, positive end expiratory pressure, and direct electrical stimulation of the cochlea. From these changes, we observe that cochlear blood circulation responds to systemic blood pressure alterations and is subject to local flow control mechanisms. Linearity and speed of response of the laser Doppler instrumentation also are shown. These advances show promise for contributing to our knowledge of control mechanisms of inner ear blood flow and for revealing the influence of various pharmacologic agents of potential clinical value.

Blood Flow Measurements in the Ears of Patients Receiving Cochlear Implants

2002 ◽  
Vol 111 (11) ◽  
pp. 998-1001 ◽  
Author(s):  
Tsutomu Nakashima ◽  
Taku Hattori ◽  
Eisuke Sato ◽  
Michihiko Sone ◽  
Mitsuo Tominaga
Keyword(s):  
Blood Flow ◽  
Cochlear Implants ◽  
Cochlear Implantation ◽  
Internal Auditory Canal ◽  
Laser Doppler ◽  
Outer Diameter ◽  
Cochlear Blood Flow ◽  
Flow Measurements ◽  
Doppler Flowmetry ◽  
Blood Flow Measurements

We measured cochlear blood flow in 12 patients who received cochlear implants, using a laser-Doppler probe with an outer diameter of 0.8 mm. The subjects had congenital deafness, idiopathic progressive sensorineural hearing loss, Waardenburg's syndrome, narrow internal auditory canal, or sudden deafness. Putting the probe tip to the site of drilling for cochlear implantation, we measured blood flow before, during, and after the cochlear bony wall was opened. The laser-Doppler output was confirmed even after the tip of the probe was inserted into the perilymphatic space in all cases. Our results revealed that blood flow was maintained in all cochleas, although there was a probability of reduction in blood flow volume. We conclude that laser-Doppler flowmetry is both relatively safe and useful for measuring blood flow in the ears during cochlear implantation procedures.

Provoked Flux Motion of Cochlear Blood Flow Measured with Laser Doppler Flowmetry in Guinea Pig

1993 ◽  
Vol 113 (5) ◽  
pp. 609-614 ◽  
Author(s):  
Tian-Ying Ren ◽  
A. L. Nuttall ◽  
J. M. Miller
Keyword(s):  
Blood Flow ◽  
Guinea Pig ◽  
Laser Doppler Flowmetry ◽  
Laser Doppler ◽  
Cochlear Blood Flow ◽  
Doppler Flowmetry ◽  
Flux Motion

Validation of laser-Doppler flowmetry in measurement of spinal cord blood flow

1989 ◽  
Vol 257 (2) ◽  
pp. H674-H680 ◽  
Author(s):  
P. J. Lindsberg ◽  
J. T. O'Neill ◽  
I. A. Paakkari ◽  
J. M. Hallenbeck ◽  
G. Feuerstein
Keyword(s):  
Spinal Cord ◽  
Blood Flow ◽  
Cord Blood ◽  
Laser Doppler Flowmetry ◽  
Laser Doppler ◽  
Microvascular Blood Flow ◽  
Base Line ◽  
Spinal Cord Blood Flow ◽  
Flow Measurements ◽  
Doppler Flowmetry

Laser-Doppler flowmetry (LDF) is a non-invasive method for continuous on-line monitoring of microvascular blood flow. LDF has previously been validated with established methods in various tissues, yet its validity and resolution in the central nervous system (CNS) remain unclear. We compared LDF with the microsphere method (MS) using two independent laser probes placed on the dorsal lumbar spinal cord (L5 laminectomy) of anesthetized rabbits (n = 9). After base-line flow measurements, spinal cord blood flow (SCBF) was increased (up to 50%) with phenylephrine (10-80 micrograms.kg-1.min-1 iv) and decreased (up to 50%) with chlorisondamine (10 mg/kg iv) or other stimuli. The percentage changes of lumbar SCBF and vascular resistance (VR) from the base line obtained by LDF and MS excellently agreed (rBF = 0.86, rVR = 0.94, P less than 0.0001). LDF estimated also the absolute SCBF values parallel to MS (r = 0.77, P less than 0.001). In conclusion, the validity of LDF in estimating the SCBF and dynamic changes of BF and VR is confirmed. Therefore, LDF may prove useful for monitoring CNS microcirculation in normal or pathophysiological states.

scholarly journals Skin blood flow measurements during heat stress: technical and analytical considerations

2020 ◽  
Vol 318 (1) ◽  
pp. R57-R69 ◽  
Author(s):  
Georgia K. Chaseling ◽  
Craig G. Crandall ◽  
Daniel Gagnon
Keyword(s):  
Blood Flow ◽  
Heat Stress ◽  
Skin Blood Flow ◽  
Research Question ◽  
The Body ◽  
Control Mechanisms ◽  
Vascular Control ◽  
Subsequent Increase ◽  
Flow Measurements ◽  
Doppler Flowmetry

During heat stress, the skin vasculature can greatly increase conductance secondary to vasodilation. The subsequent increase in skin blood flow allows for convective heat transfer from the core to the skin and between the skin surface and the surrounding environment. Measurement of skin blood flow, therefore, provides valuable information regarding heat exchange between the body and the environment. In addition, assessment of skin blood flow can be used to study vascular control mechanisms. Most often, skin blood flow is measured by venous occlusion plethysmography, Doppler ultrasound, laser-Doppler flowmetry, and, more recently, optical coherence tomography. However, important delimitations to each of these methods, which may be dependent on the research question, must be considered when responses from these approaches are interpreted. In this brief review, we discuss these methods of skin blood flow measurement and highlight potential sources of error and limitations. We also provide recommendations to guide the interpretation of skin blood flow data.

Evaluation of cochlear blood flow measurement by laser Doppler flowmetry

2003 ◽  
Author(s):  
T. Tamura ◽  
A. Okamoto ◽  
N. Kobayashi ◽  
K. Yokoyama ◽  
M. Hasegawa ◽  
...  
Keyword(s):  
Blood Flow ◽  
Laser Doppler Flowmetry ◽  
Flow Measurement ◽  
Laser Doppler ◽  
Blood Flow Measurement ◽  
Cochlear Blood Flow ◽  
Doppler Flowmetry

scholarly journals Cochlear blood flow increases after systemic hemodilution: Comparison of simultaneous laser doppler flowmetry and radioactive microsphere measurements

1988 ◽  
Vol 34 (3) ◽  
pp. 215-223 ◽  
Author(s):  
Alfred L. Nuttall ◽  
Elisabeth Hultcrantz ◽  
Hans-Christian Larsen ◽  
Clarence Angelborg
Keyword(s):  
Blood Flow ◽  
Laser Doppler Flowmetry ◽  
Laser Doppler ◽  
Cochlear Blood Flow ◽  
Doppler Flowmetry ◽  
Radioactive Microsphere

scholarly journals Cochlear blood flow measured by averaged laser Doppler flowmetry (ALDF)

1994 ◽  
Vol 77 (1-2) ◽  
pp. 200-206 ◽  
Author(s):  
Tianying Ren ◽  
P. Bradley Brechtelsbauer ◽  
Josef M. Miller ◽  
Alfred L. Nuttall
Keyword(s):  
Blood Flow ◽  
Laser Doppler Flowmetry ◽  
Laser Doppler ◽  
Cochlear Blood Flow ◽  
Doppler Flowmetry

scholarly journals Sound-induced artifact in cochlear blood flow measurements using the laser Doppler flowmeter

1987 ◽  
Vol 31 (3) ◽  
pp. 229-234 ◽  
Author(s):  
P.R. Thorne ◽  
A.L. Nuttall ◽  
F. Scheibe ◽  
J.M. Miller
Keyword(s):  
Blood Flow ◽  
Laser Doppler ◽  
Laser Doppler Flowmeter ◽  
Cochlear Blood Flow ◽  
Flow Measurements ◽  
Blood Flow Measurements ◽  
Doppler Flowmeter

A Comparison of Laser Doppler and Intravital Microscopic Measures of Cochlear Blood Flow

1989 ◽  
Vol 101 (3) ◽  
pp. 375-384 ◽  
Author(s):  
M. J. LaRouere ◽  
J. S. Sillman ◽  
A. L. Nuttall ◽  
J. M. Miller
Keyword(s):  
Blood Flow ◽  
Measurement Techniques ◽  
Lateral Wall ◽  
Laser Doppler ◽  
Spontaneous Respiration ◽  
Cochlear Blood Flow ◽  
Doppler Flowmetry ◽  
Two Measures ◽  
Positive Correlations ◽  
Relationship Of

Many inner ear disorders may be caused by alterations in cochlear blood flow (CBF). However, each measurement technique used to monitor CBF has limitations in examining the relationship between otopathologic states and blood flow. This study Investigates laser Doppler flowmetry (LDF) and its fundamental drawback: The unknown relationship of LDF output to actual CBF. LDF readings are directly compared with concurrent intravital microscopy (IVM) measures of erythrocyte velocity in the lateral wall of the guinea pig cochlea. Positive end expiratory pressure, spontaneous respiration of 5% and 10% carbon dioxide, phenylephrine, and direct electrical stimulation of the cochlea were used to manipulate CBF. High, positive correlations were found between simultaneous LDF and IVM measurements of CBF. In addition, the study demonstrated that current microdissection techniques used to perform IVM do not cause changes in CBF. IVM measurements of CBF are a more sensitive indicator of CBF changes than are LDF measures. Despite the high correlation between measurement techniques within a single manipulation, simultaneous LDF and IVM measurements differed between manipulations. This may reflect regional changes in CBF affected by these manipulations and differences in the sampled vascular beds contributing to these two measures. It is unlikely that a single calibration factor can be defined that would allow the conversion of LDF output to actual units of blood flow across different manipulations used to alter CBF.

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