High-harmonic fast-wave power flow along magnetic field lines in the scrape-off layer of NSTX.

A significant fraction of high-harmonic fast-wave (HHFW) power applied to NSTX can be lost to the scrape-off layer (SOL) and deposited in bright and hot spirals on the divertor rather than in the core plasma. We show that the HHFW power flows to these spirals along magnetic field lines passing through the SOL in front of the antenna, implying that the HHFW power couples across the entire width of the SOL rather than mostly at the antenna face. This result will help guide future efforts to understand and minimize these edge losses in order to maximize fast-wave heating and current drive.

Flooding flows in city crossroads: experiments and 1-D modelling.

This study focuses on the discharge distribution in an intersection of four channels, similar to a city crossroad. The channels and the intersection are all horizontal. Flow enters through two of the channels, and leaves through the other two. The flow is subcritical everywhere, and flow depths are controlled by vertical weirs at the exits of the outlet channels. The main variables that are measured are the flow rates in the four channels. When the weir heights in the outlet channels are the same, the ratio of flow rates in the outlet channels depends only on the ratio of flow rates in the inlet channels; if the outlet conditions are different, other parameters, such as the total flow rate also become important. The flow has also been simulated numerically using a solution of the 1-D Saint Venant equations, with a simple model to predict flow distribution in the intersection. A comparison with the experimental data shows that this model works well for the limited range of experimental conditions studied here. However, further work is needed on a wider range of conditions, closer to real conditions, before the model can be considered valid for practical applications.

The safety and efficacy of cisatracurium 0.15 mg.kg(-1) during nitrous oxide-opioid anaesthesia in infants and children.

We studied the neuromuscular and cardiovascular effects of a single, rapidly administered intravenous dose of cisatracurium 0.15 mg.kg(-1) in 27 infants (aged 1-23 months) and 24 children (aged 2-12.5 years). After midazolam premedication, anaesthesia was induced and maintained with thiopental and alfentanil in addition to nitrous oxide in oxygen. Neuromuscular function was monitored by evoked adductor pollicis electromyography. At least 15 min after intubation, each patient received cisatracurium 0.15 mg.kg(-1) over 5 s. Complete neuromuscular blockade was produced by this dose in all but one infant. The mean (SD) onset time of maximal blockade was more rapid in infants [2.0 (0.8) min] than in children [3.0 (1.2) min], p = 0. 0011. The clinical duration of action of cisatracurium (recovery of evoked response to 25% of control) was significantly longer in infants [43.3 (6.2) min] than in children [36.0 (5.4) min], p < 0.0001. Once neuromuscular function started to recover, the rate of recovery was similar in both age groups. Changes in blood pressure and heart rate after the administration of cisatracurium were negligible in both age groups. Cisatracurium, at a dose of 0.15 mg. kg(-1), was effective and well tolerated in infants and children.

A comparison of standard and a modified method of two resuscitator adult cardiopulmonary resuscitation: description of a new system for research into advanced life support skills.

The study compares two methods of Advanced Life Support by a pair of resuscitators using a bag-valve-mask (BVM) technique. Standard two resuscitator cardiopulmonary resuscitation (CPR) was compared with a modified method of two resuscitator CPR. During the modified CPR one resuscitator held the face mask while the other resuscitator alternates between squeezing the self inflating bag and performing simulated cardiac compressions. Standard CPR was performed at a ventilation:compression ratio of 1:5 while modified CPR was performed at a ventilation:compression ratio of 2:15. Comparisons were made during induction of anaesthesia in 30 ASA I and II patients. Modified CPR produced a greater tidal volume (TV) (P < 0.001), a slower respiratory rate (RR) (P < 0.001) and a faster compression rate (CR) (P < 0.01) (means with (S.D.): modified CPR: TV 990 (220) ml, RR 6 (1) min(-1), CR 82 (8) min(-1); standard CPR: TV 570 (190) ml, RR 10 (2) min(-1), CR 65 (11) min(-1)). A new method for the simultaneous computerised recording of simulated cardiac compressions together with mask pressure and expired gas composition in anaesthetised patients is described.

Health service reform: the perceptions of medical specialists in Australia (New South Wales), the United Kingdom and New Zealand.

OBJECTIVE: To examine the effect of recent healthcare service changes (including significant resource constraint and a greater role for the non-medical manager) in the United Kingdom, Australia and New Zealand on medical specialists' perceptions of their healthcare organisation goals and service delivery, and their enthusiasm for their work. DESIGN: Postal questionnaire survey, answered anonymously. PARTICIPANTS AND SETTING: Medical specialists employed either part- or full-time in two United Kingdom National Health Service Trusts (one acute, one mental health/community service), an Australian Area Health Service and a New Zealand Crown Health Enterprise in 1995. MAIN OUTCOME MEASURES: Participants' rating of their knowledge of employers' organisational goals, ability to influence management, perceptions of changes in resources and service availability since 1990 and changes in enthusiasm for their work over the past four years. RESULTS: 369 of 521 eligible specialists responded (71%); by country-United Kingdom, 123/186 (66%); New Zealand, 123/160 (77%); Australia, 123/175 (70%). New Zealand specialists were less aware of their employers' organisational goals and had less congruence between these and their own personal goals than United Kingdom or Australian specialists (P < 0.05). Interest in influencing central management was similar in the three countries, but Australian specialists felt management was less likely to follow their advice compared with United Kingdom specialists (P < 0.05). New Zealand specialists perceived that waiting times for non-urgent patients were currently longer than in 1990 compared to United Kingdom specialists (P = 0.02). In all three countries, inpatient beds were perceived to be less available than in 1990, but less so in New Zealand. The ease of replacing equipment was better in New Zealand than in Australia and the United Kingdom (P = 0.00001). More than 50% of participants in all three countries (183/361; 50.7%) reported that their enthusiasm for their work had decreased in the past four years. CONCLUSION: The effects of health service reforms seem to have reduced enthusiasm for work among medical specialists in Australia, the United Kingdom and New Zealand.

Pharmacokinetics of ofloxacin in serum and vitreous humor of albino and pigmented rabbits.

The purpose of this study was to evaluate the pharmacokinetics of ofloxacin in serum and vitreous humor samples from albino and pigmented rabbits by using a recently described animal model which permits robust estimation of parameter values. The drug was administered to rabbits intravenously, multiple vitreous humor and serum samples were taken from each rabbit, and the vitreous humor and serum samples were assayed by high-pressure liquid chromatography. The pharmacokinetic parameters were determined with RSTRIP, an iterative, nonlinear, weighted, least-squares regression program. Eight New Zealand White rabbits and eight Dutch Belted rabbits (split into single-dose and multiple-dose groups) were investigated in this study. The value of penetration into the vitreous humor of albino rabbits (n = 6) was 32.6% +/- 2.12%, with terminal-elimination half-life values of 3.21 and 2.39 h, respectively, for vitreous humor and serum. In pigmented rabbits after a single dose (n = 3) and with a steady-state concentration of drug in serum (n = 4), penetration values were similar, at 30.4% +/- 2.98% and 30.0% +/- 4.12%, respectively (P > 0.10). Following a single dose of ofloxacin, pigmented animals had elimination half-life values from serum and vitreous humor of 2.64 and 4.32 h, respectively. After steady state was achieved, half-life values for serum and vitreous humor were 3.12 and 6.05 h, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of hemorrhagic shock and reperfusion on the respiratory quotient in swine.

OBJECTIVES: Respiratory quotient, the ratio of CO2 production to oxygen consumption (VO2), is principally affected by the fuel source used for aerobic metabolism. Since the respiratory quotient, VO2, and CO2 production cannot be directly measured easily, indirect calorimetry is commonly used to determine the value of these variables at the airway level (i.e., airway respiratory quotient, airway VO2, and airway CO2 production). However, under nonsteady-state conditions, a variety of phenomena can alter the relationship between true metabolic activity and measurements determined by indirect calorimetry. During exercise, for example, airway respiratory quotient increases as anaerobic threshold is reached because of the disproportionate increase in airway CO2 production that results from the CO2 liberated through the buffering of excess hydrogen ions by bicarbonate. We hypothesized that hemorrhage and reinfusion might change airway respiratory quotient in a consistent manner as shock is produced and reversed. DESIGN: Prospective laboratory study. SETTING: University animal laboratory. SUBJECTS: Eight pigs (25 +/- 2 [SD] kg), anesthetized with fentanyl and relaxed with pancuronium bromide, and mechanically ventilated on room air. INTERVENTIONS: The animals were sequentially hemorrhaged and then autotransfused while metabolic and hemodynamic measurements were obtained, using continuous indirect calorimetry and continuous applications of the Fick principle. Hemoglobin, arterial lactate concentration, and blood gases for calibration were measured serially. Analysis of variance was used to compare various periods in time. MEASUREMENTS AND MAIN RESULTS: Between baseline and peak hemorrhage, and between peak hemorrhage and postreinfusion, all of the following variables changed significantly (p < .05): airway VO2 (baseline 6.4 +/- 0.9 mL/min/kg, peak hemorrhage 3.9 +/- 0.6 mL/min/kg, postreinfusion 7.0 +/- 1.4 mL/min/kg); airway CO2 production (baseline 5.5 +/- 0.9 mL/min/kg, peak hemorrhage 4.5 +/- 0.9 mL/min/kg, postreinfusion 6.0 +/- 1.4 mL/min/kg); airway respiratory quotient (baseline 0.87 +/- 0.07, peak hemorrhage 1.16 +/- 0.07, postreinfusion 0.87 +/- 0.05); lactate concentration (baseline 2.4 +/- 1.2 mmol/L, peak hemorrhage 6.7 +/- 1.9 mmol/L, postreinfusion 5.1 +/- 2.0 mmol/L); and delta PCO2 (venous PCO2-PaCO2) (baseline 4.5 +/- 3.6 torr [0.6 +/- 0.5 kPa], peak hemorrhage 12.1 +/- 5.3 torr [1.6 +/- 0.7 kPa], postreinfusion 2.7 +/- 2.7 torr [0.4 +/- 0.4 kPa]). CONCLUSIONS: Airway respiratory quotient increases in hemorrhagic shock and decreases again as shock is reversed during reinfusion. This phenomenon appears related to the buffering of excess of hydrogen ion during hemorrhagic shock.

Sources of stress and satisfaction in crown health enterprise senior medical staff.

AIM: To report the sources of stress and satisfaction in the specialist workforce of three crown health enterprises (CHEs). METHOD: Ninety eight specialists in Northland Health, Waitemata Health and Southern Health completed a questionnaire rating 39 factors for causing stress and satisfaction in their daily work. RESULTS: The commonest sources of stress for specialists were keeping up to date, carrying a heavy clinical workload and time pressure generally. There were significant differences between specialty groups as well as regional differences. Specialists in two CHEs found dealing with management a major stressor. This finding is a major difference from previous overseas studies. CONCLUSIONS: Doing the job properly, having a job that seems worthwhile, having control of one's professional life and a job that is interesting provide the greatest sources of work satisfaction for medical specialists.

Optical properties of a planar turbulent jet.

A planar heated air jet was constructed. Its flow properties were characterized and shown to be both reproducible and in good agreement with the results of turbulence theory. The optical properties of the jet were studied with the help of a 632.8-nm He-Ne laser beam. The random phase modulations imposed on the wave front of the beam traversing the jet were measured by interferometric means, and their spectra and variance were determined. The one-dimensional phase fluctuation spectrum obeyed a -8/3 power law as predicted by theory, whereas the phase variance (?(2)) depended on the jet temperature and was studied for values to as high as 0.4 (rad)(2)).

Feasibility of continuous oxygen delivery and cardiac output measurement by application of the Fick principle.

Continuous mixed venous oxygen saturation (SVO2) measurements from fiberoptic pulmonary artery catheters, arterial oxygen saturation (SaO2) measurements from pulse oximetry, and minute-by-minute oxygen consumption (VO2) measurements from indirect calorimetry can be used for near-continuous estimation of cardiac output (Qt) and oxygen delivery (DO2) by application of the Fick Principle. Assumptions required for calculation of blood oxygen contents include constant hemoglobin concentration (Hgb) and constant or negligible physically dissolved oxygen. First, the influence of these assumptions on continuous Qt and DO2 determinations was tested. Unmeasured changes in Hgb resulted in substantial error in calculated Qt, whereas calculated DO2 was minimally affected. Both Qt and DO2 were little altered by errors in PaO2 or PVO2. Second, the effects of SVO2, SaO2, and VO2 measurement errors on Qt and DO2 calculations under normal and extreme conditions were quantified. Relative errors in SVO2 were increased by a factor of 4.2 in Qt estimations and by a factor of 3.2 in DO2 measurements under normal conditions. These factors increased with increasing SVO2, and thus, Qt and DO2 became increasingly unreliable as oxygen extraction fell. Third, we compared continuous measurements of Qt and DO2 with intermittent measurements made by thermodilution cardiac output and blood sampling, and found correlation coefficients of 0.85 for Qt and 0.89 for DO2. Fourth, common measurement errors in VO2 and DO2 calculated in this way were found to bias regressions between VO2 and DO2, and this bias could be minimized only if the DO2 range were high and SVO2 were low.(ABSTRACT TRUNCATED AT 250 WORDS)

Fick-derived hemodynamics. Oxygen consumption measured directly vs oxygen consumption calculated from CO2 production under steady state and dynamic conditions.

Indirect calorimetry is being used increasingly as a tool for hemodynamic monitoring via the Fick equation. This investigation was undertaken to examine the use of carbon dioxide elimination (VCO2A) and related respiratory quotient (RQA) to calculate oxygen uptake (VO2A) and estimate oxygen consumption (VO2) during steady-state and dynamic hemodynamic conditions. Nine patients undergoing abdominal aortic surgery were studied intraoperatively and Fick-derived hemodynamic measurements were made using a monitoring system employing indirect calorimetry, pulse oximetry, and pulmonary artery oximetry. Comparisons were made between measured VO2A and calculated VO2A derived from the VCO2A and the initial RQA (RQi), which is assumed not to change. Prior to aortic crossclamping (steady state), there were no significant differences between the measured and calculated methods with respect to oxygen consumption (184 +/- 24 ml/min vs 185 +/- 17 ml/min), oxygen delivery (753 +/- 141 ml/min vs 769 +/- 178 ml/min), and cardiac output (4.7 +/- 0.6 L/min vs 4.7 +/- 0.7 L/min). However, immediately following aortic unclamping (dynamic state), the RQA changed precipitously from the baseline RQi. Consequently, significant differences between the measured and calculated methods were noted in oxygen uptake (213 +/- 41 ml/min vs 193 +/- 25 ml/min, p < 0.001), oxygen delivery (780 +/- 297 ml/min vs 716 +/- 296 ml/min, p < 0.001), and cardiac output (5.8 +/- 2.2 L/min vs 5.3 +/- 1.8 L/min, p < 0.001). Additionally, following unclamping, the peak VO2A was 242 +/- 49 compared with a cVO2A of only 198 +/- 22 (p < 0.01). We conclude that the use of VCO2A to calculate VO2A may lead to erroneous measurements under dynamic conditions, such as unclamping of the abdominal aorta.

Continuous hemodynamic monitoring: an integrated invasive-noninvasive approach using the Fick principle.

This paper reviews a continuous integrated computer based approach to monitoring oxygen supply (DO 2) and consumption (VO 2) relationships. A description of the technologic methodology and potential advantages over intermittent thermodilution monitoring are discussed. Lastly, the preliminary results of investigations in two populations (abdominal aortic surgery and adult respiratory distress syndrome) are presented.

The role of liaison psychiatry in an AIDS unit.

The experience of a liaison psychiatry team working in the setting of an AIDS unit is described. Several clinical themes are identified which highlight crucial issues with regard to both diagnosis and management. These issues are illustrated by case histories. Discussion draws attention to the value of using a biopsychosocial model in order to understand aetiology and to formulate appropriate management. Issues related to staff involvement provide a further theme for discussion.

Zidovudine-related mania.

Two patients with the acquired immunodeficiency syndrome (AIDS), who had no past psychiatric history, developed a mania-like illness soon after commencing treatment with zidovudine. The neurotoxic effects of zidovudine have been described previously, but to our knowledge no reports of a psychiatric disorder that is related to the drug have appeared. Our report emphasizes the need to monitor patients with AIDS for neuropsychiatric problems.

Prediction of quality of life in a cohort of end-stage renal disease patients.

In order to assess the physical, psychological and social impact of end-stage renal disease (ESRD) 102 patients on maintenance dialysis were assessed on standardized self-report measures, a structured interview schedule, a physician assessment and biochemical data. Patients were assessed on two occasions, 18 months apart. Principal components analysis was used to develop a small number of dimensions to characterize quality of life. Multiple regression analysis of patient variables on initial factor scores (cross-sectional analysis) showed that; hospital dialysis and length of time on dialysis were predictive of more psychological distress; males were less compliant than females; patients on peritoneal dialysis made a poorer adjustment to their illness; and, hospital dialysis was predictive of more social distress. As long term predictors (prospective analysis): initial level of psychological distress predicted long-term level of psychological, social distress and illness adjustment; and initial level of compliance predicted long-term level of compliance.