A field programmable gate array based Langmuir probe system for measurement of plasma parameters at 500 kHz in a high-power impulse magnetron sputtering plasma.

By utilizing Field Programmable Gate Arrays in a configuration similar to that of the Mirror Langmuir Probe, it is possible to bias a single probe at three precise voltages in sequence. These voltages can be dynamically adjusted in real-time based on the measured plasma electron temperature to ensure the transition region is always sampled. The first results have been obtained by employing this method and have generated real-time outputs of electron temperature, ion saturation current, and floating potential on a low temperature pulsed-DC magnetron at 500 kHz. These results are in good agreement with the analysis of a conventionally swept Langmuir probe. This probe is designed with the intention of being implemented on MAST-U to aid in the study of exhaust physics and enable further investigation into filamentary behavior.

Recurrent Pyroglutamic Acidosis in the Context of Undiagnosed Liver Cirrhosis-A Case Report.

Metabolic associated fatty liver disease, previously known as nonalcoholic fatty liver disease, is the most common cause of chronic liver disease across all ethnic groups; however, it remains enormously underestimated.1 , 2 Sepsis, hepatotoxic medications and malnutrition in the acute settings on top of unknown cirrhosis can lead to decompensation and various metabolic complications. Pyroglutamic acidosis is a rarely recognised cause for unexplained high anion gap metabolic acidosis that is felt to be frequently underdiagnosed. Particular patients at risk include women, the elderly, those on regular paracetamol and those suffering with malnourishment or sepsis. Other risk factors include alcohol abuse and chronic liver disease (3). We present the case of a patient with recurrent episodes of pyroglutamic acidosis and encephalopathy in the context of undiagnosed nonalcoholic fatty liver disease with cirrhosis.

Filament identification in wide-angle high speed imaging of the mega amp spherical tokamak.

A new tomographic inversion technique is presented for the identification of plasma filaments in wide-angle visible camera data. The technique works on the assumption that background subtracted images of filaments can be represented as a superposition of uniformly emitting magnetic equilibrium field lines. A large collection of equilibrium magnetic field lines is traced and projected onto the camera field of view and combined to form a geometry matrix describing the coordinate transformation from magnetic field aligned coordinates to image pixel coordinates. Inverting this matrix enables the reprojection of the emission in the camera images onto a field aligned basis, from which filaments are readily identifiable. The inversion is a poorly conditioned problem which is overcome using a least-squares approach with Laplacian regularization. Blobs are identified using the "watershed" algorithm and 2D Gaussians are fitted to get the positions, widths, and amplitudes of the filaments. A synthetic camera diagnostic generating images containing experimentally representative filaments is utilized to rigorously benchmark the accuracy and reliability of the technique. 74% of synthetic filaments above the detection amplitude threshold are successfully detected, with 98.8% of detected filaments being true positives. The accuracy with which filament properties and their probability density functions are recovered is discussed, along with sources of error and methods to minimize them.

Ambient surface mass spectrometry using plasma-assisted desorption ionization: effects and optimization of analytical parameters for signal intensities of molecules and polymers.

Results are presented on the optimization and characterization of a plasma-assisted desorption ionization (PADI) source for ambient mass spectrometry. It is found that by optimizing the geometry we can increase ion intensities for valine and by tuning the plasma power we can also select a more fragmented or less fragmented spectrum. The temperature of the surface rises linearly with plasma power: at 19 W it is 71 °C and at 28 W it is 126 °C. To understand if the changes in signal intensity are related to thermal desorption, experiments using a temperature-controlled sample stage and low plasma power settings were conducted. These show markedly different signal intensities to experiments of equivalent surface temperature but higher plasma power, proving that the mechanisms of ionization and desorption are more complicated than just thermal processes. Four different polymers, poly(methyl methacrylate) (PMMA), poly(ethylene terephthalate) (PET), poly(lactic acid) (PLA), and poly(tetrafluoroethylene) (PTFE), are analyzed using PADI. Mass spectra are obtained from all the polymers in the negative ion mode and from PMMA and PLA in the positive ion mode. For each polymer, characteristic ions are identified showing the ability to identify materials. The ions are formed from bond cleavage with O and CH(2) as common adducts. Ions were detected up to m/z 1200 for PTFE.

Surface analysis using a new plasma assisted desorption/ionisation source for mass spectrometry in ambient air.

The authors report on a modified micro-plasma assisted desorption/ionisation (PADI) device which creates plasma through the breakdown of ambient air rather than utilising an independent noble gas flow. This new micro-PADI device is used as an ion source for ambient mass spectrometry to analyse species released from the surfaces of polytetrafluoroethylene, and generic ibuprofen and paracetamol tablets through remote activation of the surface by the plasma. The mass spectra from these surfaces compare favourably to those produced by a PADI device constructed using an earlier design and confirm that the new ion source is an effective device which can be used to achieve ambient mass spectrometry with improved spatial resolution.

Two administration methods for inhaled salbutamol in intubated patients.

AIMS: To compare serum concentrations and effects on respiratory mechanics and haemodynamics of salbutamol administered by small volume nebuliser (SVN) and metered dose inhaler (MDI) plus spacer. METHODS: Blinded, randomised, crossover study in 12 intubated infants and children (mean age 17.8 months) receiving inhaled salbutamol therapy. Subjects received salbutamol as 0.15 mg/kg by SVN and four puffs (400 microg) by MDI plus spacer at a four hour interval in random order. Passive respiratory mechanics were measured by a single breath/single occlusion technique, and serum salbutamol concentrations by liquid chromatography-mass spectrometry at 30 minutes, 1, 2, and 4 hours after each dose. Haemodynamics (heart rate and blood pressure) were recorded at each measurement time. RESULTS: There was no difference in percentage change in respiratory mechanics or haemodynamics between the two methods of administration. Mean area under the curve (AUC(0-4)) was 5.86 for MDI plus spacer versus 4.93 ng/ml x h for SVN. CONCLUSIONS: Serum concentrations and effects on respiratory mechanics and haemodynamics of salbutamol were comparable with the two administration methods under the conditions studied. Future studies are needed to determine the most effective and safe combination of dose and administration method of inhaled salbutamol in mechanically ventilated infants and children.

The role of anesthesiologists in Canadian undergraduate medical education.

PURPOSE: To examine the current role of anesthesiologists in Canadian undergraduate medical education (UME). METHODS: A 93-item questionnaire was mailed to the undergraduate course chairs/coordinators for anesthesia at the 16 medical schools in Canada. RESULTS: Of the faculty anesthesiologists in Canada, 1.7%, 4.9%, and 4.9% teach pre-clerkship lectures, seminars, and PBL tutorials, respectively. Annually, anesthesiologists teach an average of 3.3 hr (range: 0 to 15) of pre-clerkship lectures and 12.8 hr (range: 0 to 48) of pre-clerkship seminars at each medical school. The topics most commonly taught by anesthesiologists in pre-clerkship lectures and seminars are pharmacology and perioperative patient assessment, respectively. An anesthesia rotation during clerkship is mandatory at 13 schools, with an average duration of 9.6 dy (range: 5-20 dy). Clerkship teaching methods vary: ten schools provide seminars, eight use videos, six use computers, six use an airway skills laboratory, and four use an anesthesia simulator. The most common topics taught in clerkship anesthesia seminars are airway management and fluid therapy. CONCLUSION: A very small proportion of faculty anesthesiologists participate in Canadian UME at the pre-clerkship level. Considerable variation exists in the amount and format of teaching by anesthesiologists among the Canadian undergraduate curricula, particularly at the pre-clerkship level. However, our results indicate that anesthesiologists are assuming a more important teaching role during clerkship. Our findings may suggest that Canadian medical schools are overlooking the advantages that anesthesiologists offer to UME at the pre-clerkship level, or that many anesthesiologists are reluctant to assume pre-clerkship teaching responsibilities.

Albuterol delivery by metered-dose inhaler in a pediatric high-frequency oscillatory ventilation model.

OBJECTIVES: To assess albuterol delivery by metered-dose inhaler (MDI) in a pediatric lung model ventilated by high-frequency oscillatory ventilation (HFOV). The percentage albuterol dose lost in the circuit's expiratory limb and the effects of operating frequency, inspiratory time, and use of a spacer were also determined. DESIGN: Prospective in vitro laboratory study. SETTING: Research laboratory. INTERVENTIONS: A model consisting of a HFOV and circuit, 4.5-mm endotracheal tube, and lung simulator was assembled. Ventilator settings were the following: humidified FIO2 of 1.0; mean airway pressure of 28 cm H2O; operating frequency of 10 Hz; pressure amplitude of 55 cm H2O; bias gas flow to maintain mean airway pressure; 30% inspiratory time; and temperature of 35 degrees C (95 degrees F). Lung simulator compliance and resistance values were consistent with pediatric patients with pulmonary disease. A total of ten MDI canisters were used to administer 2000 microg of albuterol with a spacer. Circuit filters placed proximal to the lung simulator and in the circuit's expiratory limb collected albuterol exiting the endotracheal tube and any albuterol lost, respectively. Filters were rinsed with water and albuterol concentrations determined by high performance liquid chromatography. Albuterol administration was repeated at operating frequencies of 5 and 15 Hz, inspiratory times of 40% and 50%, and with an actuator instead of a spacer. Each test condition was repeated ten times. Analysis of variance or Student's t-test was used to determine significant differences in albuterol delivered or lost among the operating frequencies and inspiratory times, and between the spacer and actuator. MEASUREMENTS AND MAIN RESULTS: Albuterol delivery to the lung simulator was <1% of the administered dose regardless of the operating frequency, inspiratory time, or use of a spacer or actuator. Albuterol lost in the expiratory limb ranged from 3.28% to 14.89% of the administered dose. CONCLUSIONS: These in vitro results suggest albuterol delivery by MDI in a pediatric model of HFOV is negligible, regardless of the operating frequency, inspiratory time, or use of a spacer or actuator.

Albuterol delivery by metered-dose inhaler in a mechanically ventilated pediatric lung model.

OBJECTIVES: To assess albuterol delivery by metered-dose inhaler in a mechanically ventilated pediatric lung model and to determine the influence of the following variables on albuterol delivery: endotracheal tube diameter; type of spacer; humidification; and pulmonary mechanics. DESIGN: Prospective, in vitro, laboratory study. SETTING: Research laboratory. INTERVENTIONS: A model, consisting of a volume-cycled ventilator, pediatric breathing circuit, 4.0- or 6.0-mm endotracheal tube, and lung simulator, was assembled. Ventilator settings were: tidal volume 250 mL; FIO2 0.5; inspiration/expiration ratio 1:3; respiratory rate 25 breaths/min; positive end-expiratory pressure 3 cm H2O; temperature 35 degrees C; and a decelerating flow pattern, using dry and humidified air. Lung simulator compliance and resistance values were consistent with those values reported for healthy childeren (20 mL/cm H2O and 40 cm H20/L/sec) and children with pulmonary disease (10 mL/cm H2O and 60 cm H2O/L/sec). Pulmonary mechanics were verified with a pulmonary function diagnostic system. Ten metered-dose inhaler canisters were used to administer 2000 micrograms of albuterol, using either a collapsible or a rigid spacer. A circuit filter placed immediately proximal to the test lung collected drug exiting the endotracheal tube. The filter was rinsed with water and albuterol concentrations were determined by high-performance liquid chromatography. Each variable was tested in triplicate. MEASUREMENTS AND MAIN RESULTS: Albuterol delivery was significantly (p < or = .05) greater for the 6.0-mm endotracheal tube, rigid spacer, dry air, and pulmonary disease mechanics by multifactor analysis of variance. Drug delivery in humidified air with pulmonary disease mechanics using the rigid chamber was 2.5 =/- 0.27% and 6.3 =/- 0.99% for the 4.0- and 6.0-mm endotracheal tubes, respectively. CONCLUSIONS: These in vitro results suggest that pulmonary disease mechanics and a 6.0-mm endotracheal tube improve albuterol delivery. Future clinical investigations in intubated pediatric patients with pulmonary disease are needed to address the clinical significance of these results.

Prevention of phantom pain after major lower limb amputation by epidural infusion of diamorphine, clonidine and bupivacaine.

Phantom limb pain may appear in up to 85% of patients after amputation. There is no effective treatment. Perioperative epidural infusion of morphine and bupivacaine, alone or in combination, is effective in preventing phantom limb pain in patients with pre-existing limb pain. Serious side-effects, however, make them difficult to manage on a general ward. Clonidine has been shown to be an effective postoperative analgesia when applied epidurally. To mitigate the potentially serious side-effects of all these drugs, we have studied their combined efficiency in preventing phantom limb pain in a prospective controlled study of 24 patients undergoing lower limb amputation. In the study group (n = 13), an epidural infusion containing bupivacaine 75 mg, clonidine 150 micrograms and diamorphine 5 mg in 60 ml normal saline was given at 1-4 ml/h 24-48 h preoperatively and maintained for at least 3 days postoperatively. The control group (n = 11) received on-demand opioid analgesia. Pain was assessed by visual analogue scale at 7 days, 6 months and 1 year. At 1 year follow-up, one patient in the study group and eight patients in the control group had phantom pain (P < 0.002) and two patients in the study group versus eight patients in the control group had phantom limb sensation (P < 0.05). There was no significant improvement in stump pain. We conclude that perioperative epidural infusion of diamorphine, clonidine and bupivacaine is safe and effective in reducing the incidence of phantom pain after amputation.

Albuterol delivery by metered-dose inhaler with a pediatric mechanical ventilatory circuit model.

STUDY OBJECTIVE: To determine albuterol delivery by metered-dose inhaler (MDI) in an in vitro pediatric mechanical ventilatory circuit model. The influence of a spacing device, endotracheal tube (ETT) diameter and length, and air humidity was also investigated. DESIGN: An albuterol MDI canister was connected to an AeroVent spacer or Airlife MDI adapter and ETT 4.0, 5.0, or 6.0 mm at commercially available and equal lengths. The ETT tip was attached to an in-line filter holder with a 1-microns type A/E glass fiber filter. Ventilator settings were fractional concentration of inspired oxygen 50%, tidal volume 250 ml, inspiratory:expiratory (I:E) ratio 1:3, rate 25 breaths/minute, temperature 35 degrees C, and a decelerating flow pattern. Ten albuterol canisters were activated two times each (total 2000 micrograms) into dry (4.0-, 5.0-, and 6.0-mm ETT) and humidified air (4.0- and 6.0-mm ETT) and repeated in triplicate. Percentage MDI output was determined by weighing the filter before and after drug administration (balance sensitivity 10 micrograms). Significant differences (p < or = 0.05) among the groups with and without a spacer and in dry and humidified air were determined by ANOVA with Scheffe's multiple comparison test. Multiple regression was used to determine significant associations between ETT diameter and length and delivery. MAIN RESULTS: With the AeroVent spacer in humidified air, delivery with the 4.0- and 6.0-mm ETT was approximately 2.3% and 5%, respectively. The spacer and dry air significantly improved delivery. CONCLUSIONS: In humidified air, the dose of albuterol by MDI with an AeroVent spacer should be doubled for children intubated with 6.0-mm ETT, and four puffs administered for every one puff desired for 4.0-mm ETT. The results of this investigation should prove useful in initial clinical trials of albuterol MDI in ventilator-dependent infants and children.

Infantile hypertrophic pyloric stenosis: where should it be treated?

A retrospective analysis in the form of an audit into the management of infantile hypertrophic pyloric stenosis in a district general hospital has revealed that the results are equivalent to that of published data from specialised units. It is stressed in this study that close co-operation has to be maintained between paediatricians and surgeons in the care of these infants. The diagnosis can be made on clinical grounds in the majority of cases. The operation has to be carried out by experienced surgeons and anaesthetists. The morbidity can be minimised under these circumstances and pyloromyotomy can be performed safely in a district general hospital.

Naproxen-associated vasculitis.

Three cases of digital vasculitis attributable to naproxen ingestion are reported. The vasculitic changes were reversed by withdrawal of the drug. These three cases emphasize the need to consider drug sensitivity as a cause of unexplained digital vascular lesions.