Injection Of Particulate Matter Research Articles

Cervical Myelopathy Caused by Injections into the Neck.

Three cases of longitudinally extensive cervical myelopathies temporally associated with neck injections are presented. The spinal cord injury was similar radiographically, despite a number of different needle approaches and substances injected. In recent years, there have been reports of an acute cervical myelopathy immediately following an injection procedure in the neck. Various explanations have been offered for this unfortunate complication, including (1) direct injection into the cord leading to traumatic injury, (2) injection of particulate matter into the arterial supply of the cord causing microvascular embolism and spinal cord infarction, and (3) intraneural injection of the chemical with centripetal spread of the injectant from the nerve trunk to the substance of the cord. The merits of each of these 3 mechanisms in explaining these cases are discussed. Albeit rare, acute cervical myelopathy should be considered a potential complication from any deep injection of chemicals into the neck.

Coherent and incoherent scattering by a plume of particles advected by turbulent velocity flow

Studies of acoustic remote sensing of the plumes that result from the injection of particulate matter in the ocean, either naturally or by dumping or dredging activities, have assumed the scattering is incoherent. These plumes are always turbulent, however. The particle density is a passive scalar that is advected by the turbulent velocity flow. The possibility exists, therefore, that the scattered waves from a significant number of particles add coherently as a result of Bragg scattering. In this paper, we investigate this possibility. We derive an expression for the ratio of the coherent intensity to the incoherent one in terms of the turbulent spectrum and the properties of the particles that make up the plume. The sonar is modeled as a high-Q, monostatic, pulsed sonar with arbitrary pulse envelope and arbitrary, but narrow, beam pattern. We apply the formalism to acoustic remote sensing of black smoker hydrothermal plumes. We find that, at most, the coherent intensity is less than 1% of the incoherent one. The implications are that Bragg scattering does not lead to a significant coherent component and in analyses of scattering from this type of plume, one can ignore the complications of turbulence altogether.

Paraplegia after lumbosacral nerve root block: report of three cases

Background context: Lumbar nerve root blocks and epidural steroid injections are frequently employed in the management of degenerative conditions of the lumbar spine, but relatively few papers have been published that address the complications associated with these interventions. Serious complications include epidural abscess, arachnoiditis, epidural hematoma, cerebrospinal fluid fistula and hypersensitivity reaction to injectate. Although transient paraparesis has been described after inadvertent intrathecal injection, an immediate and lasting deficit has not been previously described as sequelae of a nerve root block. Purpose: We present three cases in which either persisting paraplegia or paraparesis occurred immediately after administration of a lumbar nerve root block and propose a mechanism for this devastating but previously unreported complication. Study design/setting: Case reports of three patients. Patient sample: Three patients, two women and one man ranging in age from 42 to 64 years, underwent three procedures performed at three different facilities, in the hands of two different injectionists. In each instance, penetration of the dura was not thought to have occurred. In two procedures the needles were placed transforamenally, one at L3–4 on the left and one at L3–4 on the right, and in the third the needle tip was placed immediately lateral to the S1 nerve root. Outcome measures: Patient follow-up data from medical office records. Methods: In each case, needle placement was verified with injection of a contrast media in conjunction with either computerized tomography or biplanar fluoroscopy. No backbleeding or cerebrospinal fluid was encountered upon aspiration in any of the procedures. Magnetic resonance imaging (MRI) was performed within 48 hours of injury in all patients. Results: In each patient, paraplegia suddenly ensued after instillation of the steroid solution and, in each instance, postprocedure MRI revealed increased signal in the low thoracic spinal cord on T2-weighted imaging consistent with edema. The sudden onset of neurological deficit and the imaging changes noted in the spinal cord point to a vascular explanation for these injuries. We postulate that in these patients the spinal needle either penetrated or caused injury to an abnormally low dominant radiculomedullary artery, a recognized anatomical variant. This vessel, also known as the artery of Adamkiewicz, in 85% of individuals arises between T9 and L2, usually from the left, but in a minority of people may arise from the lower lumbar spine and rarely even from as low as S1. The artery of Adamkiewicz travels with the nerve root through the neural foramen and irrigates the anterior spinal artery. Injury of it or injection of particulate matter into it, as what may happen with the commonly used epidural steroid injectates, may result in infarction of the lower thoracic spinal cord, producing the clinical and imaging findings seen in these three patients. Conclusions: We present the cases of three patients who had lasting paraplegia or paraparesis after the performance of a nerve root block. We propose that the mechanism for this rare but devastating complication is the concurrence of two uncommon circumstances, the presence of an unusually low origin of the artery of Adamkiewicz and an undetected intraarterial penetration of the procedure needle.

Behavior of particulates in thermal plasma flows

Injection of particulate matter into a thermal plasma represents one of the approaches used in thermal plasma processing. The injected particles are usually treated as a dispersed phase, governed by the equation of motion and the rate equations for heat and mass transfer in Lagrangian coordinates. A stochastic approach is introduced to take particle dispersion into account due to turbulent fluctuations by randomly sampling instantaneous flow fields. Three-dimensional effects are also considered which are mainly due to particle injection and the presence of a swirl component. A modified approach for investigating noncontinuum effects on plasma-particle heat transfer is proposed, incorporating both electric and aerodynamic effects on the boundary layer around a particle immersed into a thermal plasma. Comparisons of theoretical predictions based on the present model with available experimental data are, in general, in reasonable agreement.

Experimental myocardial infarction in the closed-chest dog: a new technique.

The reliable and safe production of myocardial infarction in closed-chest animals is of paramount research interest. To date, the injection of particulate matter and the introduction of occlusive solid plugs have been described. Because of the limited size of the catheter, only small branches could be occluded, which resulted in a high incidence of mortality. A new simple technique is described that allows occlusion of a major coronary artery at a preselected site. An Ivalon (polyvinyl alcohol) plug compressed around the tip of an introducing wire is advanced through a selectively placed catheter into the coronary artery. It is felt in place for 5 minutes and assumes its original size upon contact with blood. Once the plug is re-expanded, the wire is withdrawn. The new technique was carried out successfully on nine dogs with no immediate fatality and myocardial infarction as demonstrated by cine ventriculography and histopathologic examination.

Reaction of the Rat Omentum to Injections of Particulate Matter

Summary and ConclusionsThe rat omentum, following the injection of particulate matter of various types, undergoes hypertrophy due to accumulation of histiocytes which are transformed into macrophages. The macrophages collect just beneath the surface and phagocytose the material which enters through and between the mesothelial cells. Secondary collections of macrophages appear about the smaller blood vessels and take up the particles which have traversed the vascular walls. The taches laiteuses increase in size and produce numerous macrophages.With the advent of phagocytic activity the Golgi net increases in size and undergoes fragmentation. The fragments become associated with the ingested granules and apparently aid in bringing about their coalescence into masses which are stored by the cells. The changes found in the Golgi material never occur in cells which do not collect and store particulate matter.