Radiological comparison of a FDNPP waste storage site during and after construction.

The clean-up effort that is occurring across the region affected by the 2011 Fukushima Daiichi Nuclear Power Plant accident is unprecedented in its magnitude as well as the financial cost that will eventually result. A major component of this remediation is the stripping of large volumes of material from the land surface, depositing this into large waste storage bags before placing these 1 cubic meter bags into specially constructed stores across Fukushima Prefecture. In this work, using an unmanned aerial vehicle to perform radiological surveys of a site, the time-resolved distribution of contamination during the construction of one of these waste storage sites was assessed. The results indicated that radioactive material was progressively leaching from the store into the surrounding environment. A subsequent survey of the site conducted eight months later revealed that in response to this survey and remedial actions, the contamination issue once existing on this site had been successfully resolved. Such results highlight the potential of low-altitude unmanned aerial systems to easily and rapidly assess site-wide changes over time - providing highly-visual results; therefore, permitting for prompt remedial actions to be undertaken as required. Use of UAV radiation mapping and airborne photogrammetry to produce a time-resolved assessment of remediation efforts within a Fukushima temporary storage facility.

Application of airborne photogrammetry for the visualisation and assessment of contamination migration arising from a Fukushima waste storage facility.

Airborne systems such as lightweight and highly portable unmanned aerial vehicles (UAVs) are becoming increasingly widespread in both academia and industry - with an ever-increasing range of applications, including (but not limited to), air quality sampling, wildlife monitoring and land-use mapping. In this work, high-resolution airborne photogrammetry obtained using a multi-rotor system operating at low survey altitudes, is combined with ground-based radiation mapping data acquired at an interim storage facility for wastes removed as part of the large-scale Fukushima clean-up program. The investigation aimed to assess the extent to which the remediation program at a specific site has contained the stored contaminants, as well as present a new methodology for rapidly surveying radiological sites globally. From the three-dimensional rendering of the site of interest, it was possible to not only generate a powerful graphic confirming the elevated radiological intensity existing at the location of the waste bags, but also to also illustrate the downslope movement of contamination due to species leakage from the large 1m3 storage bags. The entire survey took less than 1 h to perform, and was subsequently post-processed using graphical information software to obtain the renderings. The conclusions within this study not only highlight the usefulness of incorporating three-dimensional renderings within radiation mapping protocols, but also conclude that current methods of monitoring these storage facilities in the long term could be improved through the integration of UAVs within the standard protocol.

A comparison of cardiac output derived from the arterial pressure wave against thermodilution in cardiac surgery patients.

In three clinical centres, we compared a new method for measuring cardiac output with conventional thermodilution. The new method computes beat-to-beat cardiac output from radial artery pressure by simulating a three-element model of aortic input impedance, and includes non-linear aortic mechanical properties and a self-adapting systemic vascular resistance. We compared cardiac output by continuous model simulation (MF) with thermodilution cardiac output (TD) in 54 patients (18 female, 36 male) undergoing coronary artery bypass surgery. We made three or four conventional thermodilution estimates spread equally over the ventilatory cycle. In 490 series of measurements, thermodilution cardiac output ranged from 2.1 to 9.3, mean 5.0 litre min(-1). MF differed +0.32 (1.0) litre min(-1) on average with limits of agreement of -1.68 and +2.32 litre min(-1). Differences decreased when the first series of measurements in a patient was used to calibrate the model. In 436 remaining series, the mean difference became -0.13 (0.47) litre min(-1) with limits of agreement of -1.05 and +0.79 litre min(-1). When consecutive measurements were made, the change was greater than 0.5 litre min(-1), on 204 occasions. The direction of change was the same with both methods in 199. The difference between the methods remained near zero during surgery suggesting that a single calibration per patient was adequate. Aortic model simulation with radial artery pressure as input reliably monitors changes in cardiac output in cardiac surgery patients. Before calibration, the model cannot replace thermodilution, but after calibration the model method can quantitatively replace further thermodilution estimates.

Brain metastasis from a primary liposarcoma of the digit: case report.

Soft-tissue sarcomas of the digit are uncommon. We herein report on a patient with a de-novo subungual right thumb liposarcoma with subsequent failure in the brain. The pertinent literature and recommendations for management are presented.

Simulation in anesthesia: the merits of large simulators versus small simulators.

Anesthesia simulation is generally perceived as involving large simulators that provide a limited number of operating room scenarios, especially crisis management. The scope of both anesthesia and flight simulation is much wider, and this review summarizes the range of the former. The areas where simulation has been used include training, education and science. The diversity of its uses may surprise the reader. The models that are used in simulations are important, and these are discussed in part of the discussion. As a result of the current imbalance in perception, I emphasize the merits of small simulators at the expense of large simulators.

Craniofacial electromyogram activation response: another indicator of anesthetic depth.

OBJECTIVE: After finding that craniofacial EMG preceding a stimulus was a poor predictor of movement response to that stimulus, we evaluated an alternative relation between EMG and movement: the difference in anesthetic depth between the endpoint of EMG responsiveness to a stimulus and endpoint of movement responsiveness to that stimulus. We expressed this relation as the increment of isoflurane between the two endpoints. METHODS: We measured EMG over the frontalis muscle, over the corrugator muscle, and between the Fp2 and the mastoid process as patients emerged from general anesthesia during suture closing of the surgical incision. Anesthesia was decreased by controlled washout of isoflurane while maintaining 70% N2O, and brain isoflurane concentrations ((C)isoBrain) were calculated. We studied a control group of 10 patients who received only surgical stimulation, and 30 experimental patients who intermittently received test stimuli in addition to the surgical stimulation. Patients were observed for movement responses and EMG records were evaluated for EMG activation responses. We defined an EMG activation response to be a rapid voltage increase of at least 1.0 microV RMS above baseline, with a duration of at least 30 s, in at least one of the three EMG channels. Patient responses to stimuli were classified as either an EMG activation response without a move response (EMG+), a move response without an EMG activation response (MV+), both an EMG activation response and a move response (EMG+MV+), or no response. We defined the EMG+ endpoint to be the threshold between EMG+ response and nonresponse to a stimulus, and estimated (C)isoBrain at this endpoint. We similarly defined the move endpoint and estimated the move endpoint (C)isoBrain. We then calculated the increment of (C)isoBrain at the EMG+ endpoint relative to the move endpoint. MAIN RESULTS: For the 30 experimental patients, the initial response to a test stimulus was an EMG+ in 14 patients (47%), an EMG+MV+ in 12 patients (40%), and a MV+ in 1 patient (3%); no response occurred by the time surgery was completed in 3 patients (10%). No response occurred in 7 of the control patients (70%). Of the 14 patients with an initial EMG+ response to a test stimulus, 9 patients later had a move response. For these 9 patients, the increment of (C)isoBrain between the EMG+ endpoint and move endpoint was 0.11 +/- 0.04 vol%, (mean +/- SD). CONCLUSIONS: Our results suggest that, given the circumstances of our study, an EMG activation response by a nonmoving patient indicates that the patient is at an anesthetic level close to that at which movement could occur. However, because the first EMG activation response may occur simultaneously with movement, the EMG activation response cannot be relied upon to always herald a move response before it occurs. Our results also suggest that EMG responsiveness to a test stimulus may be used to estimate the anesthetic depth of an individual patient.

Virtual medical trainer. Patient assessment and trauma care simulator.

The Virtual Medical Trainer (VMET) combines multimedia sound and graphics with physiological engines, medical-procedures databases, and 3-D patients to produce an interactive environment that can mimic the cognitive pre-hospital assessment and care demands of a real emergency. VMET uses a reconfigurable component software and training framework that allows a uniform user interface, ease of increasing training complexity, and expansion of the software components. VMET provides an opportunity to experience a range of trauma scenarios prior to the challenge of an actual trauma situation.

A multicenter study of bispectral electroencephalogram analysis for monitoring anesthetic effect.

Bispectral analysis (BIS) of the electroencephalogram (EEG) has been shown in retrospective studies to predict whether patients will move in response to skin incision. This prospective multicenter study was designed to evaluate the real-time utility of BIS in predicting movement response to skin incision using a variety of general anesthetic techniques. Three hundred patients from seven study sites received an anesthetic regimen expected to give an approximately 50% movement response at skin incision. EEG was continuously recorded via an Aspect B-500 monitor and BIS was calculated in real time from bilateral frontocentral channels displayed on the monitor. Half of the patients were randomized to a treatment group in which anesthetic drug doses were increased to produce a lower BIS. In the control group, BIS was recorded, but no action taken on the data displayed. A determination of movement in response to skin incision was made in the 2 min succeeding incision. Retrospective pharmacodynamic modeling was performed using STANPUMP to estimate effect-site concentrations of intravenously administered anesthetics. BIS values were significantly higher in the control group (66 +/- 19) versus the BIS-guided group, in which additional anesthesia was administered to produce a lower BIS (51 +/- 19). The movement response rate was significantly higher in the control group at 43% compared with 13% in the BIS-guided group, but response rates were low at sites which used larger doses of opioids. Logistic regression analysis showed that BIS, estimated opioid effect-site concentrations, and heart rate (in that order) were the best predictors of movement at skin incision. This study demonstrates that dosing anesthetic drugs to lower BIS values achieves a lower probability of movement in response to surgical stimulation. BIS is a significant predictor of patient response to incision, but the utility of the BIS depends on the anesthetic technique being used. When drugs such as propofol or isoflurane are used as the primary anesthetic, changes in BIS correlate with the probability of response to skin incision. When opioid analgesics are used, the correlation to patient movement becomes much less significant, so that patients with apparently "light" EEG profiles may not move or otherwise respond to incision. Therefore, the adjunctive use of opioid analgesics confounds the use of BIS as a measure of anesthetic adequacy when movement response to skin incision is used as the primary end point.

A measure of association for assessing prediction accuracy that is a generalization of non-parametric ROC area.

There is a need for a measure of prediction accuracy that generalizes non-parametric receiver operating characteristic (ROC) area to polytomous ordinal patient state. We describe such a measure, prediction probability PK derived from Kim's measure of association. We show that the value of PK equals the value of non-parametric ROC area for dichotomous patient state and is a meaningful generalization of non-parametric ROC area for polytomous state.

EEG Predicts movement response to surgical stimuli during general anesthesia with combinations of isoflurane, 70% N2O, and fentanyl.

OBJECTIVE: Our objective was to evaluate the performance of the EEG as an indicator of anesthetic depth by measuring EEG prediction of movement response to surgical stimuli. METHODS: While using 5 different combinations of isoflurane, 70% N2O, and fentanyl, we measured the EEG of 246 patients during pelvic laparoscopy and observed their movement responses to opening stimuli (defined as skin incision, CO2 needle insertion, or trocar insertion) and also to closing stimuli (defined as sutures during incision closure). The EEG was expressed as F95, the frequency in hertz below which resides 95% of the power in the EEG frequency spectrum. The relations between F95 and movement response were expressed as logistic regression curves. F95-response logistic regression curves, which are analogous to dose-response curves, were calculated for each of the 2 stimuli administered during each of the 5 anesthetic techniques. The prediction of patient responsiveness by F95 was tested using beta (beta), a measure of the slope of an F95-response logistic curve. The presence of shifts among the F95-response logistic curves was tested using the differences in F95 values between curves. Hypothesis tests used a level of significance of P = 0.05. MAIN RESULTS: The slopes of the F95-response logistic regression curves showed a statistically significant ability to predict movement response to stimuli for 9 of the 10 combinations of stimuli and anesthetic techniques. We did not calculate an F95-response logistic curve for the tenth combination because it contained burst suppression, which our EEG analysis method was not designed to process. The F95-response logistic curves were shifted relative to each other, and the shifts were affected by the type of stimulus and the combination of anesthetic agents. Referenced to opening curves, the mean shift of the closing curves was +4.2 +/- 0.3 Hz (mean +/- SD). With increasing doses of fentanyl, the use of 70% N2O, or both, the curves shifted to higher values of F95; the range in shifts was 0.2 to 8.1 Hz. The slope beta values of the F95-response logistic curves and the shifts among the curves were similar to the beta values and shifts that might be expected from changes in anesthetic agent doses. CONCLUSIONS: The EEG, expressed as F95, predicted movement response to surgical stimuli during combinations of isoflurane, 70% N2O, and fentanyl. The F95-response curves shifted upward on the frequency scale for the less intense stimuli and for anesthetic techniques using 70% N2O, fentanyl, or both. F95 prediction of movement response appeared to be related to anesthetic agent doses. Our F95-response curves may provide helpful guidelines for using F95 to titrate the administration of anesthetic agents and for assessing the depth of general anesthesia.

Measuring the performance of anesthetic depth indicators.

BACKGROUND: An appropriate measure of performance is needed to identify anesthetic depth indicators that are promising for use in clinical monitoring. To avoid misleading results, the measure must take into account both desired indicator performance and the nature of available performance data. Ideally, anesthetic depth indicator value should correlate perfectly with anesthetic depth along a lighter-deeper anesthesia continuum. Experimentally, however, a candidate anesthetic depth indicator is judged against a "gold standard" indicator that provides only quantal observations of anesthetic depth. The standard anesthetic depth indicator is the patient's response to a specified stimulus. The resulting observed anesthetic depth scale may consist only of patient "response" versus "no response," or it may have multiple levels. The measurement scales for both the candidate anesthetic depth indicator and observed anesthetic depth are no more than ordinal; that is, only the relative rankings of values on these scales are meaningful. METHODS: Criteria were established for a measure of anesthetic depth indicator performance and the performance measure that best met these criteria was found. RESULTS: The performance measure recommended by the authors is prediction probability PK, a rescaled variant of Kim's dy.x measure of association. This performance measure shows the correlation between anesthetic depth indicator value and observed anesthetic depth, taking into account both desired performance and the limitations of the data. Prediction probability has a value of 1 when the indicator predicts observed anesthetic depth perfectly, and a value of 0.5 when the indicator predicts no better than a 50:50 chance. Prediction probability avoids the shortcomings of other measures. For example, as a nonparametric measure, PK is independent of scale units and does not require knowledge of underlying distributions or efforts to linearize or to otherwise transform scales. Furthermore, PK can be computed for any degree of coarseness or fineness of the scales for anesthetic depth indicator value and observed anesthetic depth; thus, PK fully uses the available data without imposing additional arbitrary constraints, such as the dichotomization of either scale. And finally, PK can be used to perform both grouped- and paired-data statistical comparisons of anesthetic depth indicator performance. Data for comparing depth indicators, however, must be gathered via the same response-to-stimulus test procedure and over the same distribution of anesthetic depths. CONCLUSIONS: Prediction probability PK is an appropriate measure for evaluating and comparing the performance of anesthetic depth indicators.

A role for CNS alpha-2 adrenergic receptors in opiate-induced muscle rigidity in the rat.

A number of potential neurochemical mediators of opiate-induced muscle rigidity have been proposed based on the results of systemic drug studies and on knowledge of the brain sites implicated in opiate rigidity. The effects of i.c.v. pretreatment with selected opioidergic, alpha adrenergic and serotonergic drugs on muscle rigidity induced with systemic injection of the potent opiate agonist alfentanil (ALF) were investigated in spontaneously ventilating rats. The opiate antagonist methylnaloxonium (MN; 0.2-14 nmol), alpha-2 adrenergic agonists dexmedetomidine (DEX; 0.4-42 nmol) or 2-(2,6-diethylphenylamino)-2-imidazoline hydrochloride (ST91; 4-400 nmol), alpha-1 adrenergic antagonist prazosin (PRZ; 7-70 nmol) or serotonergic antagonist ketanserin (KET; 18-550 nmol) were injected i.c.v. (10 microliters) and ALF (500 micrograms/kg s.c.) was administered 10 min later. S.c. electrodes were used to record gastrocnemius electromyographic activity. Both MN and DEX dose-dependently and potently antagonized ALF-induced rigidity. ST91 produced shorter-lived, less profound, antagonism of ALF rigidity. PRZ, at the highest dose tested, produced a delayed and modest reduction in ALF rigidity. A large, non-selective, dose of KET incompletely attenuated ALF rigidity. These results lend support to the hypothesis that central opioid and alpha-2 adrenergic receptors mediate opiate-induced muscle rigidity in the rat.

Wakeful response to command indicates memory potential during emergence from general anesthesia.

OBJECTIVE: An important aspect of assessing anesthetic depth is determining whether a patient will remember events during surgery. We looked for a clinical sign that would indicate a patient's potential for memory formation during emergence from anesthesia. A clinical sign indicating memory potential could be a useful endpoint for measuring the performance of anesthetic depth monitors and for titrating administration of anesthetic agents. METHODS: We evaluated patients' responses to commands to open the eyes, squeeze the hand four times, and count 20 numbers. These responses were correlated with results on recall, cued recall, and multiple-choice memory tests. MAIN RESULTS: Patients did not have evidence of memory formation until they sustained wakefulness sufficiently long to complete at least four hand squeezes or count four numbers. Of 28 patients, 13 (46%) with this sustained wakeful response had memory. Of 22 patients, 0 (0%) had evidence of memory formation when they demonstrated a brief wakeful response, defined as being responsive to command but unable to complete more than one hand squeeze or count, or an intermediate response, defined as two or three hand squeezes or counts. CONCLUSIONS: We conclude that a brief wakeful response to command indicates that a patient is unlikely to form memories, while a sustained wakeful response indicates that a patient may form memories. Thus, a patient's wakeful response to command could be a useful indicator of potential for memory.

Brief wakeful response to command indicates wakefulness with suppression of memory formation during surgical anesthesia.

OBJECTIVE: In a previous study of patients emerging from anesthesia following surgery, we found that a brief wakeful response to command of an eye opening or single hand squeeze or count was not associated with memory formation, while the response of four hand squeezes or counts was associated with memory. We wanted to determine the anesthetic requirements for obtaining this brief wakeful response endpoint during surgery and to determine if memory occurred at this endpoint during surgical anesthesia. METHODS: Six different combinations of isoflurane, 70% N2O, and fentanyl were administered to 326 patients undergoing pelvic laparoscopy. After insertion of the trocar, anesthesia was reduced while patients were given verbal commands, and they were observed for movement responses to surgery and to command. Patients were classified as either not arousing, arousing with a movement response to surgery, or arousing with a wakeful response to command. For the patients who aroused, we calculated the percentage of arousal responses that were wakeful responses to command. The effect of fentanyl dosage upon the percentage of arousal responses that were wakeful responses to command was determined by using a Mann-Whitney test to compare a group of patients receiving fentanyl 2 micrograms/kg or less, with a group receiving fentanyl 4 micrograms/kg. In a subset of 39 patients, the potential for memory formation was evaluated by presenting a target sound to 29 patients during a period of either no arousal, movement response to surgery, or wakeful response to command; for a control group of 10 patients, no target sound was presented. All 39 patients were tested for memory of the target sound; the results from each group receiving a target sound were compared with the results of the control group, using a Mann-Whitney test. MAIN RESULTS: A total of 68 patients aroused with either a movement response or a wakeful response to command. Wakeful responses occurred with only 1 of 39 patients (3%) receiving fentanyl 2 micrograms/kg or less; but, wakeful responses occurred with 17 of 29 patients (59%) receiving fentanyl 4 micrograms/kg. The difference between the groups was significant at p = 0.01. None of the 68 patients had recall of intraoperative events or unpleasant dreams. None of these patients who were in the multiple-choice memory subset recalled the target sound. There were no statistically significant differences on the multiple-choice memory test between the groups presented with the target sound and the control group. Patient anecdotes suggested that some patients may have had memory of the target sound; but, memory was no more likely in patients with a brief wakeful response to command than in those who responded with a movement to surgical stimulation or those who did not have an arousal response. CONCLUSIONS: A brief wakeful response to a command of opening the eyes or squeezing the hand was not associated with increased memory formation during surgery. A brief wakeful response to command was found during surgery when patients received fentanyl 4 micrograms/kg; but it was rarely found at fentanyl dosages of 2 micrograms/kg or less.

Pretreatment with sedative-hypnotics, but not with nondepolarizing muscle relaxants, attenuates alfentanil-induced muscle rigidity.

STUDY OBJECTIVE: To evaluate and compare the efficacy of various pretreatment agents to attenuate or prevent opioid-induced muscle rigidity using a well-established, previously described clinical protocol. DESIGN: Prospective, controlled, single-blind, partially randomized study. SETTING: Large medical center. PATIENTS: ASA physical status I-III patients undergoing elective surgical procedures of at least 3 hours' duration. INTERVENTIONS: The effect of pretreatment with nondepolarizing muscle relaxants (atracurium 40 micrograms/kg or metocurine 50 micrograms/kg), benzodiazepine agonists (diazepam 5 mg or midazolam 2.5 mg), or thiopental sodium 1 mg/kg on the increased muscle tone produced by alfentanil 175 micrograms/kg was compared with a control group (given no pretreatment). MEASUREMENTS AND MAIN RESULTS: Rigidity was assessed quantitatively by measuring the electromyographic activity of five muscle groups (biceps, intercostals, abdominals, quadriceps, and gastrocnemius). Rigidity also was rated qualitatively by attempts to initiate and maintain mask ventilation, attempts to flex an extremity, and the occurrence of myoclonic movements. Pretreatment with the two nondepolarizing muscle relaxants had no effect on the severe muscle rigidity produced by high-dose alfentanil. Whereas thiopental was only mildly effective, the benzodiazepines midazolam and diazepam significantly attenuated alfentanil rigidity (p < 0.05). CONCLUSION: This study suggests that benzodiazepine pretreatment is frequently, but not always, effective in preventing opioid-induced muscle rigidity.

Improved safety and efficacy in adaptive control of arterial blood pressure through the use of a supervisor.

This paper presents a dual approach to adaptive control of arterial blood pressure using sodium nitroprusside. In the clinical environment, a controller must be aggressive to achieve specific step response characteristics (less than 10 min settling time, less than 10 mm Hg overshoot), yet conservative enough to prevent overreactions to large disturbances, which are common in both the operating room and the intensive care unit. These mutually exclusive requirements make it difficult to design a closed-loop controller for this environment. To prevent possible overreactions, while maintaining proper step response, an aggressive adaptive controller has been designed to achieve the desired step response, and a SUPERVISOR has been designed around the adaptive controller to limit potential overreactions in the presence of disturbances. Simulations and dog experiments demonstrate the potential for increased safety and efficacy using this dual approach to the control of a complex physiological system.

Supervisory adaptive control of arterial pressure during cardiac surgery.

A supervisory adaptive controller has been designed for the closed-loop control of mean arterial pressure during cardiac surgery, using sodium nitroprusside. This controller consists of a pole-placement and proportional-plus-integral feedback regulator, multiple-model adaptation, and a supervisor. The pole-placement and proportional-plus-integral regulator was designed to meet aggressive step response characteristics. Multiple-model adaptation was chosen to ensure rapid and stable adjustments for changes in key patients parameters. The supervisor was designed to provide safety and efficacy of control during disturbances that are common during cardiac surgery. We studied the ability of this supervisory adaptive controller to regulate arterial pressure during cardiac surgery on nineteen patients. The controller, through the action of the supervisor, detected and responded appropriately to the great majority of disturbances. This study demonstrated that supervisory adaptive control has the potential to provide clinically acceptable regulation of arterial pressure.