Complications and pitfalls of lumbar interlaminar and transforaminal epidural injections

Lumbar interlaminar and transforaminal epidural injections are used in the treatment of lumbar radicular pain and other lumbar spinal pain syndromes. Complications from these procedures arise from needle placement and the administration of medication. Potential risks include infection, hematoma, intravascular injection of medication, direct nerve trauma, subdural injection of medication, air embolism, disc entry, urinary retention, radiation exposure, and hypersensitivity reactions. The objective of this article is to review the complications of lumbar interlaminar and transforaminal epidural injections and discuss the potential pitfalls related to these procedures. We performed a comprehensive literature review through a Medline search for relevant case reports, clinical trials, and review articles. Complications from lumbar epidural injections are extremely rare. Most if not all complications can be avoided by careful technique with accurate needle placement, sterile precautions, and a thorough understanding of the relevant anatomy and contrast patterns on fluoroscopic imaging

A NOTE ON MODELING OF NANO-SCALE THERMAL FLOW VIA THE LATTICE BOLTZMANN METHOD IMECE2012-89923

ABSTRACT Lattice Boltzmann (LB) method models have been demonstrated to provide an accurate representation of the flow characteristics in rarefied flows. Conditions in such flows are characterized by the Knudsen number (Kn), defined as the ratio between the gas molecular Mean Free Path (MFP, λ) and the device characteristic length (L). As the Knudsen number increases, the behavior of the flow near the walls is increasingly dominated by interactions between the gas molecules and the solid surface. Due to this, linear constitutive relations for shear stress and heat flux, which are assumed in the Navier-StokesFourier (NSF) system of equations, are not valid within the Knudsen Layer (KL). Various methods have been explored to extend the applicability of LB models to higher Knudsen number flows, including using higher order velocity sets, and using walldistance functions to capture the effect of the walls on the mean free path by incorporating such functions on the determination of the local relaxation parameters. In this study, a high order velocity model which contains a two-dimensional, thirteen velocity direction set (e.g., D2Q13), as shown in , derived by Arlemark et al The performance of the present LB model coupled with the implementation of the two wall-distance functions is tested using two classical flow cases. The first case considered is that of isothermal, shear-driven Couette flow between two parallel, horizontal plates separated by a distance H, moving in opposite directions at a speed of U 0 . The results obtained show that the effective MFP relationship based on the exponential function improves the results obtained with the high order LB model for both sheardriven and Fourier flows up to Kn~1. The results also show that the effective MFP relationship based on the Power Law distribution function greatly enhances the results obtained with the high order LB model for the two cases addressed, up to Kn~3. In conclusion, the resulting LB models represent an effective tool in modeling non-equilibrium gas flows expected within micro/nano-scale devices

Heat and mass transfer analysis of bacon-type hydrogen-oxygen fuel cells: the volume average velocity

A model is developed to study the transient electrolyte water evaporation and heat rejection in an operating fuel cell. The model applies to fuel cells which circulate reactant gas in excess of that consumed in the electrochemical reaction to remove the product water as well as heat.The model mass transfer equations are expressed in terms of volume average velocity. It has been shown that the mathematical representation of the volume average velocity model is attractive for computational purposes, since the volumetric disappearance of electrolyte volume for a fixed control volume in space would yield a change in concentration as would actually occur due to dilution.Because of the non-linearities associated with the developed model equations, the finite-difference technique is used to obtain solutions. The implicit finite-difference scheme was selected so as to avoid the stability criteria associated with the explicit form, which places an undesirable restriction on the size of the time increment that can be used. After its accuracy had been established, the method was used to study an operating Bacon-type Hydrogen-oxygen fuel cell.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23029/1/0000598.pd