Studies of access for minimally invasive surgery

Introduction: The advantages of laparoscopic cholecystectomy over open cholecystectomy are now well established. Nevertheless, small changes in technique and careful attention to detail can result in further improvements in clinical outcome. The aim of this thesis was to apply this concept to studies of the trocar and cannula system used to gain access to the peritoneum. Methods and Results: Patients were randomised to conventional laparoscopic cholecystectomy (CLC) or micropuncture laparoscopic cholecystectomy (MPLC, three 3.3mm, one 10mm cannulae). The duration of each operative stage and the procedure were recorded. Interleukin-6, adrenocorticotropic hormone (ACTH) and vasopressin were sampled for 24 hours. Pain scores and analgesic consumption were recorded for one week. Pulmonary function and quality of life (EQ-5D) were monitored for four weeks. Forty patients participated. Groups were comparable for age, duration of symptoms and indications for surgery. Total operative time was similar but the time to clip the cystic duct after cholangiography was significantly longer for MPLC. Significantly fewer patients required postoperative parenteral opiates in the MPLC group but oral analgesic consumption was similar in both groups. Median pain scores were lower at all time points for MPLC but this was not statistically significant. There were no significant differences in interleukin-6, ACTH or vasopressin responses, pulmonary function or EQ-5D scores. The purpose of the second study was to compare the maximum depth of penetration of the peritoneal cavity by the tips of pyramidal, sharp conical and blunt conical trocars. Sections of abdominal wall from pigs were stretched across a jig so that the skin and peritoneal surfaces could be visualised. Each trocar was inserted ten times by hand and then with a mechanical device. The findings were similar for trocar s inserted by hand or the mechanical device. In the third study, the incidence and characteristics of injury sustained by the bowel, when impinged by pyramidal, sharp conical and blunt conical trocars were compared. Rates of deflection were also recorded. Pyramidal trocars caused stellate penetrating injuries and the sharp conical trocars, small round puncture wounds. The bowel did not deflect upon contact with either the pyramidal or the sharp conical trocar. The blunt conical trocars however, was more likely to cause deflection, never breached the serosa and only created a small round "dimple." These differences were all statistically significant. Conclusions: Diameter of trocar Cholecystectomy using smaller trocars, cannulae and instruments is widely applicable to elective cholecystectomy in a westernised population. Although the change from a 10mm to a 3mm laparoscope increased the time to clip and divide the cystic duct and artery, this had no impact on the overall time of the procedure. Despite a reduction in the consumption of parenteral analgesia among the patients in the micropuncture group, there was no corresponding reduction in pain scores. Overall, this study found no evidence that fine calibre instruments conferred any obvious major clinical benefits to the patients. Profile of the trocar Pyramidal trocars encroach less into the abdominal cavity during the process of insertion, but will injure bowel or aorta upon contact. Sharp conical trocars depress the abdominal wall to a greater extent before they facilitate entry of the cannula and will injure bowel or aorta upon contact. Blunt conical trocars require to be inserted to the same depth as sharp conical trocars but are unlikely to traumatise bowel. They can deflect aorta and are less likely to cause injury than trocars with a sharp tip. It is not clear whether the risk of injury fi om a pyramidal trocar that facilitates entry of the cannula with less depression of the abdominal wall is safer than a blunt conical trocar' that encroaches further into the abdomen but is less likely to cause injury should it contact bowel or aorta. However, it can be deduced that blunt conical trocars are unlikely to cause injury if bowel is inadvertently contacted during open or closed access. Trocars with a sharp tip should probably be avoided. (Abstract shortened by ProQuest.)

Design and construction of a laboratory system for neuromuscular stimulation of the lower extremities during cycling

Functional Neuromuscular Stimulation (FNS) is a method by which paralyzed muscles are stimulated electrically in order to produce a useful movement. The design and testing of a laboratory system for the modulated control of the lower extremities during FNS-induced cycling on an exercising device (Paracycle) is described. The system hardware, which is designed around a standard IBM compatible Personal Computer, features six independent stimulation channels. Waveform characteristics such as pulse frequency, width and amplitude are defined as a function of the crank position of the Paracycle for each channel. An extensive software package allows programmability of the waveform parameters and supports the user in the definition of stimulation sequences. The effective performance of the complete FNS-controller/ Paracycle system has been demonstrated during a controlled case study with two paraplegic subjects

Carmen Perez, Suing Individually and on Behalf of All Others Similarly Situated v. Capital One Bank

Supreme Court of Virginiahttps://scholarlycommons.law.wlu.edu/va-supreme-court-records-vol258/1069/thumbnail.jp

The exploitation of acoustic-to-seismic coupling for the determination of soil properties

Laboratory measurements of three predicted wave types (two compressional or P-waves and one shear S-wave) have been made in artificial soils. The Type-I P and S-wave are predicted to be most sensitive to the macroscopic elastic properties of the frame, whilst the Type II P-wave is predicted to be most sensitive to the hydrodynamic material properties. A loudspeaker source has been used for the preferential excitation of the Type II P-wave whilst preferential excitement of the Type-I P-wave has been accomplished using a mechanical shaker. Probe microphone measurements of the Type-II wave allowed the flow resistivity and tortuosity of the material to be determined using a rigid frame model, whilst deduction of elastic moduli has been made from signals received at buried geophones. It has been shown that microphone signals include Type-I P-wave energy in a high flow resistivity soil. Acoustically deduced soil properties are consistent with mechanically derived values. A systematic investigation of outdoor measurements of acoustic-to-seismic coupling ratio has been made. From the measurements, it has been found that the geophone-ground coupling has a great effect upon the measured coupling ratio. In-situ calibration methods have been developed to overcome this problem. whilst the novel use of a Laser Doppler Vibrometer has been proposed to provide a completely non-invasive method of measuring motion in soils. The measured coupling ratio has been compared with theoretical predictions, using a modified Bio-Sto11 formulation. The model can be used to predict values of flow resistivity, porosity, bulk and shear moduli and layer depths. Reasonable agreement has been obtained between the model and data. Procedures that exploit acoustic-to-seismic coupling data and models to determine soil properties have been developed and used to measure the soil properties of friable agricultural soils where more standard investigation techniques have proved unsuitable

Scheduling language and algorithm development study. Volume 3, phase 2: As-built specifications for the prototype language and module library

Detailed specifications of the prototype language and module library are presented. The user guide to the translator writing system is included

The influence of soil particle surfaces and soil porosity on the biodegradation of key refuse leachate organic molecules.

Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1995.Many studies have been undertaken to determine the effects of soil and soil properties on migrating metal pollutants. Organic pollutants, however, in addition to their interactions with soil components , are also susceptible to degradation (catabolism) by microorganisms. Soil-microorganism-pollutant interactions have, traditionally, been studied in soil columns (microcosms). One of the shortcomings of column and in situ studies is that the identity and specific effect(s) of the soil component(s) affecting or influencing attenuation are not known and cannot readily be determined. Attenuation effects of the soil components are, therefore, difficult to interpret. ("Attenuation" in this context is the combined effects of both soil adsorption and microbial catabolism). Attenuation studies often only consider the physical conditions such as aeration, permeability, flow rate, temperature, etc. This approach assumes the soil to be a homogeneous matrix with no specific physico-chemical properties attributable to different components within the matrix. Soil physical factors suspected of influencing pollutant attenuation could be misleading without consideration of the physico-chemical interactions between soil components, microorganisms and pollutants. Adhesion of pollutants and microorganisms seems to be most important in this regard. The initial phase of this study was undertaken to examine the effects of three different soil materials on attenuation of key landfill leachate molecules. Examination of the effects of soil surface type on attenuation focused on adsorption / desorption of the pollutant molecules and microorganisms. These experiments sought to investigate the physico-chemical effects of soil, microorganism, pollutant interactions and were done as batch slurry experiments as well as in soil columns. Two soil horizons from the Inanda soil form (humic A and red apedal B) and the topsoil (vertic A) from a Rensburg soil form were used. The Inanda topsoil had a high organic matter content and both the topsoil and subsoil had a kaolinitic clay mineralogy; the Rensburg topsoil clay mineralogy was predominantly smectitic with a relatively low organic matter content. From the batch experiments, the adsorption of a hydrophobic molecule (naphthalene) and a heavy metal (cadmium) were found to be influenced to a significant extent by soil characteristics. Adsorption of naphthalene was due to the soil organic matter (SOM) content whereas cadmium adsorption was due to the cation exchange capacity (CEC) of the soil. Soil characteristics did not seem to have a significant influence on the adsorption of a water soluble compound such as phenol at the concentrations used. Attenuation of naphthalene was found to be affected by adsorption of the pollutant molecule (related to SOM) as well as the CEC of the soil. The attenuation of hydrophobic molecules can possibly be ascribed to the influence of CEC on the microbial population responsible for attenuation. This would seem to indicate interaction between the soil surfaces and the catabolizing microbial population. Desorption of the pollutant (and possibly also of the microbial population) was achieved by the addition of acetonitrile and methanol both of which reduced the polarity of the water. These solvents were also found to be toxic to the catabolizing microbial population at high concentrations. The toxicity thresholds of both solvents for catabolizing microorganisms differed significantly between soil- (> 15 %, v/v) and soil free (< 5 %, v/v) treatments. This discrepancy cannot be accounted for by adsorption and is ascribed to physico-chemical interaction between microorganisms and the soil surfaces. This interaction probably affords protection from, otherwise, toxic concentrations of solvents or metals. The important effects of soil surfaces on attenuation processes were thought to be due to the strong adsorption of naphthalene. Surface attachment of microorganisms was, however, also inferred from results obtained with phenol. This seemed to indicate that microbial attachment to soil surfaces was an important aspect in attenuation and did not occur only because of pollutant adsorption. Soil column experiments were made with both naphthalene and phenol. The naphthalene, which was adsorbed to the soil, did not leach from the columns to any appreciable extent. This was despite the addition of acetonitrile to some columns. This was probably due to greater microbial catabolism caused by desorption and, subsequent, increased soluble concentrations of the molecule. After extraction from the soil at the end of the experiment it was clear that the sterile controls held much higher concentrations of naphthalene than the experimental columns. The soil type and treatments showed little difference in the naphthalen concentration extracted from the soil columns. This did not reflect the differences found between soil materials in the batch experiments and was probably due to the masking effect of the soil physical factors on attenuation processes. Unlike naphthalene, phenol, because of its high solubility, was detected in the column leachates at relatively high concentrations. The phenol concentrations were much higher for the Inanda subsoil (approximately 4 mM) than the Inanda topsoil (approximately 2 mM) and Rensburg topsoil (< 1 mM). The Rensburg topsoil produced the lowest phenol concentrations in the leachate and this can probably be ascribed to the larger quantity of micropores in this soil. Thus, it seems that the soil physical features had a pronounced influence on attenuation. Whether this effect was directly on the studied molecule or indirectly, because of the effects on the microbial population, is not known. Inoculation of the columns with a phenol catabolizing population had only a slight increased effect on leachate phenol concentrations from all columns. This increased effect was, however, only prolonged in the case of the Inanda subsoil. The flow rate through the columns affected leachate phenol concentration which was lower with a slower flow rate and, thus, longer retention time. From the column experiments soil physical parameters were suspected of influencing, and possibly overriding, the soil surface effects on microbial activity (capacity to catabolize a organic molecule of interest). Soil porosity, as caused by different soil materials, was suspected of being the most important soil physical parameter influencing microbial activity. To investigate the potential effect of soil porosity, relatively homogeneous porous media i.e. chromatography packing material and acid washed sand were used. These materials had more defined and distinct porosities and were considered to be suitable for investigating the fundamental influence of porosity on microbial activity. Saturated continuous flow columns were used and three types of packing configurations were tested: chromatography packing (CHROM) material (porous particles); acid washed sand (non-porous) (AWS); and a 1: 1 (w/w) mixture of chromatography packing and acid washed sand (MIX). Only a single water soluble molecule, phenol, was used in this phase of the investigation. Bacterial filtration ("filtration" as a component of "attenuation'') was found to be highest for the CHROM and lowest for the AWS materials. This difference in microbial retention affected the phenol catabolism in response to increased column dilution rates. The CHROM and MIX materials had distinctly different porosities than that of the AWS, due to the internal porosity of the chromatography packing. This greater pore size distribution in the MIX and CHROM packing materials created pores with different effective pore dilution rates within the microcosms at similar overall flow rates. The greater pore size distribution in the MIX and CHROM packing materials facilitated pore colonization since some pores did not participate, or conduct, mass flow as occurred in macropores. This led to different microcolonization effects in the macro- vs micropores. Since the MIX and CHROM packing materials had more micropore colonization sites these packing materials showed a greater range of substrate affinities (i.e. Ks values) for the phenol substrate. The extent to which micropore colonization occurred could be detected by the effect it had on phenol breakthrough curves. In the MIX and CHROM materials, microbial colonization caused blocking of micropores with a subsequent effect on the phenol breakthrough curves. The AWS material, however, which had a low inherent microporosity, showed microbially induced microporosity probably due to biofilm development. The fact that the MIX and CHROM packing materials facilitated micropore colonization was also responsible for the greater resistance to, and the recovery from , potentially inhibitory cadmium concentrations. This effect was also apparent in the presence of acetonitrile, although this effect was not identical to that observed with cadmium. Finally, column pressure build up as a function of pore clogging was determined and was found to occur in the order AWS > MIX > CHROM. This was most likely due to fewer potential liquid flow paths with a higher blocking potential in the AWS. Extrapolation of the fundamentals of the above findings led to the conclusion that soil surface- and soil porosity effects are extremely important factors in determining the behavior of soils as bioreactors

PRELIMINARY FINDINGS OF A POTENZIATED PIEZOSURGERGICAL DEVICE AT THE RABBIT SKULL

The number of available ultrasonic osteotomes has remarkably increased. In vitro and in vivo studies have revealed differences between conventional osteotomes, such as rotating or sawing devices, and ultrasound-supported osteotomes (Piezosurgery®) regarding the micromorphology and roughness values of osteotomized bone surfaces. Objective: the present study compares the micro-morphologies and roughness values of osteotomized bone surfaces after the application of rotating and sawing devices, Piezosurgery Medical® and Piezosurgery Medical New Generation Powerful Handpiece. Methods: Fresh, standard-sized bony samples were taken from a rabbit skull using the following osteotomes: rotating and sawing devices, Piezosurgery Medical® and a Piezosurgery Medical New Generation Powerful Handpiece. The required duration of time for each osteotomy was recorded. Micromorphologies and roughness values to characterize the bone surfaces following the different osteotomy methods were described. The prepared surfaces were examined via light microscopy, environmental surface electron microscopy (ESEM), transmission electron microscopy (TEM), confocal laser scanning microscopy (CLSM) and atomic force microscopy. The selective cutting of mineralized tissues while preserving adjacent soft tissue (dura mater and nervous tissue) was studied. Bone necrosis of the osteotomy sites and the vitality of the osteocytes near the sectional plane were investigated, as well as the proportion of apoptosis or cell degeneration. Results and Conclusions: The potential positive effects on bone healing and reossification associated with different devices were evaluated and the comparative analysis among the different devices used was performed, in order to determine the best osteotomes to be employed during cranio-facial surgery

Semiannual review of research and advanced development, volume 1 Progress report, 1 Jul. - 31 Dec. 1967

Launch vehicle development, lunar and planetary explorations, physics and astronomy, and bioscience research and technolog