scholarly journals Incidence of Extravascular Perivertebral Artery Contrast Flow During Cervical Transforaminal Epidural Injections

Pain Medicine ◽  
2020 ◽  
Vol 21 (9) ◽  
pp. 1753-1758
Author(s):  
Joshua Levin ◽  
Manoj Mohan ◽  
David Levi ◽  
Scott Horn ◽  
Matthew Smuck
Keyword(s):  
Vertebral Artery ◽  
Flow Pattern ◽  
Epidural Injection ◽  
Flow Patterns ◽  
Rater Reliability ◽  
Epidural Injections ◽  
Kappa Value ◽  
Transforaminal Epidural Injection ◽  
Contrast Flow

Abstract Background During a cervical transforaminal epidural injection, injectate flows along the path of least resistance. Given the proximity of the vertebral artery to the intervertebral foramen, injected contrast may flow along the external wall of the artery. The incidence of this contrast flow pattern during cervical transforaminal epidural injections is unknown. Purpose To determine the incidence of extravascular perivertebral artery contrast flow patterns during cervical transforaminal epidural injections. Study Design/Setting Retrospective, observational, in vivo study. Patient Sample Patients receiving cervical transforaminal epidural injections at a single outpatient spine clinic. Outcome Measures The presence or absence of extravascular perivertebral artery contrast flow. Methods The saved images from 100 consecutive patients were reviewed by two independent observers and classified with or without extravascular perivertebral artery contrast flow. The incidence was determined and kappa was used to examine inter-rater reliability. All disagreements were reviewed, and the final classification was determined by consensus. Results The inter-rater reliability was moderate, with a kappa value of 0.69. The incidence of extravascular perivertebral artery contrast flow patterns was 49% by consensus. No statistically significant differences in incidence were present when comparing three different final needle tip positions. Conclusions During a cervical transforaminal epidural injection, an extravascular perivertebral artery contrast flow pattern is frequently encountered. This includes flow along the exiting nerve and then around the vertebral artery, as suggested by this study. Although this contrast pattern does not represent an intravascular injection into the vertebral artery, practitioners should remain cautious to exclude intravascular needle placement before injecting medication.

Analysis of Intravascular Flow Patterns following Cervical Transforaminal Epidural Injection

2009 ◽  
Vol 22 (1) ◽  
pp. 52 ◽  
Author(s):  
Su Jin Hwang ◽  
Kyung Ream Han ◽  
Sae Young Kim ◽  
Nan Seol Kim ◽  
Chan Kim
Keyword(s):  
Epidural Injection ◽  
Flow Patterns ◽  
Transforaminal Epidural Injection

Contrast Flow Patterns Based on Needle Tip Position During Cervical Transforaminal Epidural Injections

PM&R ◽  
2021 ◽  
Author(s):  
Josh Levin ◽  
David Levi ◽  
Nolan Gall ◽  
Scott Horn ◽  
Matthew Smuck
Keyword(s):  
Flow Patterns ◽  
Epidural Injections ◽  
Tip Position ◽  
Contrast Flow

scholarly journals Flow Pattern Map of Flow Boiling in a Rectangular Channel Filled with Porous Media

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2440
Author(s):  
Youngwoo Kim ◽  
Dae Yeon Kim ◽  
Kyung Chun Kim
Keyword(s):  
Porous Media ◽  
Flow Pattern ◽  
Flow Regime ◽  
Annular Flow ◽  
Flow Boiling ◽  
Rectangular Channel ◽  
Flow Patterns ◽  
Flow Pattern Map ◽  
Mist Flow ◽  
Churn Flow

A flow visualization study was carried out for flow boiling in a rectangular channel filled with and without metallic random porous media. Four main flow patterns are observed as intermittent slug-churn flow, churn-annular flow, annular-mist flow, and mist flow regimes. These flow patterns are clearly classified based on the high-speed images of the channel flow. The results of the flow pattern map according to the mass flow rate were presented using saturation temperatures and the materials of porous media as variables. As the saturation temperatures increased, the annular-mist flow regime occupied a larger area than the lower saturation temperatures condition. Therefore, the churn flow regime is narrower, and the slug flow more quickly turns to annular flow with the increasing vapor quality. The pattern map is not significantly affected by the materials of porous media.

Two-Phase Flow and Heat Transfer in Rectangular Micro-Channels

2003 ◽  
Author(s):  
Weilin Qu ◽  
Seok-Mann Yoon ◽  
Issam Mudawar
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Flow Pattern ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Heat Sinks ◽  
Phase Flow ◽  
Micro Channel ◽  
Two Phase ◽  
Micro Channels

Knowledge of flow pattern and flow pattern transitions is essential to the development of reliable predictive tools for pressure drop and heat transfer in two-phase micro-channel heat sinks. In the present study, experiments were conducted with adiabatic nitrogen-water two-phase flow in a rectangular micro-channel having a 0.406 × 2.032 mm cross-section. Superficial velocities of nitrogen and water ranged from 0.08 to 81.92 m/s and 0.04 to 10.24 m/s, respectively. Flow patterns were first identified using high-speed video imaging, and still photos were then taken for representative patterns. Results reveal that the dominant flow patterns are slug and annular, with bubbly flow occurring only occasionally; stratified and churn flow were never observed. A flow pattern map was constructed and compared with previous maps and predictions of flow pattern transition models. Annual flow is identified as the dominant flow pattern for conditions relevant to two-phase micro-channel heat sinks, and forms the basis for development of a theoretical model for both pressure drop and heat transfer in micro-channels. Features unique to two-phase micro-channel flow, such as laminar liquid and gas flows, smooth liquid-gas interface, and strong entrainment and deposition effects are incorporated into the model. The model shows good agreement with experimental data for water-cooled heat sinks.

Preservation of sickle cell blood-flow patterns during MR imaging: an in vivo study

1988 ◽  
Vol 151 (1) ◽  
pp. 139-141 ◽  
Author(s):  
AS Brody ◽  
SH Embury ◽  
WC Mentzer ◽  
ML Winkler ◽  
CA Gooding
Keyword(s):  
Blood Flow ◽  
Mr Imaging ◽  
Sickle Cell ◽  
Flow Patterns ◽  
In Vivo Study ◽  
Blood Flow Patterns

scholarly journals Footprints of a flapping wing

2017 ◽  
Vol 818 ◽  
pp. 1-4 ◽  
Author(s):  
Jun Zhang
Keyword(s):  
Flow Pattern ◽  
External Force ◽  
Thrust Force ◽  
Flow Patterns ◽  
Flapping Wing ◽  
Flapping Wings ◽  
Left Behind ◽  
Full Picture

Birds have to flap their wings to generate the needed thrust force, which powers them through the air. But how exactly do flapping wings create such force, and at what amplitude and frequency should they operate? These questions have been asked by many researchers. It turns out that much of the secret is hidden in the wake left behind the flapping wing. Exemplified by the study of Andersen et al. (J. Fluid Mech., vol. 812, 2017, R4), close examination of the flow pattern behind a flapping wing will inform us whether the wing is towed by an external force or able to generate a net thrust force by itself. Such studies are much like looking at the footprints of terrestrial animals as we infer their size and weight, figuring out their walking and running gaits. A map that displays the collection of flow patterns after a flapping wing, using flapping frequency and amplitude as the coordinates, offers a full picture of its flying ‘gaits’.

scholarly journals Suspended sediment distribution under varied currents in the largest river-connected lake of China

2017 ◽  
Vol 18 (3) ◽  
pp. 994-1004 ◽  
Author(s):  
Hua Wang ◽  
Yijun Zhao ◽  
Fengnian Zhou ◽  
Huaiyu Yan ◽  
Yanqing Deng ◽  
...  
Keyword(s):  
Flow Pattern ◽  
Suspended Sediment ◽  
Flow Patterns ◽  
Field Investigation ◽  
Gravity Flow ◽  
Shear Stresses ◽  
Sediment Distribution ◽  
Back Flow ◽  
The North ◽  
Dry Seasons

Abstract Poyang Lake was selected as the research area. Based on laboratory experiment, field investigation and numerical simulation, the spatial distributions of suspended sediment (SS) under the gravity-flow, jacking-flow and back-flow patterns were quantitatively analysed. An annular flume experiment was conducted to determine the critical starting shear stresses of the sediments in the flood and dry seasons. By numerical experiment, the SS transport under different flow patterns was explored. Several results stand out. (1) The critical starting shear stresses of the sediments in the flood and dry seasons were 0.35 N·m−2 and 0.29 N·m−2, respectively. (2) Due to the strongest flow disturbance and scouring effect, SS under the gravity-flow pattern was characterized by the highest loads. The lowest SS was observed during the jacking-flow pattern, which could be attributed to the lowest water level gap between the lake and external rivers. The loads ranged from 0.053 kg·m−3 to 0.068 kg·m−3. (3) Under the back-flow pattern, SS in the north lake was evidently influenced by the Yangtze River, and the mean value was approximately 0.12 kg·m−3. With the gradually weakened back-flow impact, the SS load was decreased from the north to the middle of the lake.

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