We have used the Leiden anaesthesia simulator, which makes use of a standard anaesthesia machine and monitors, and realistically simulates the anaesthesia work place. After obtaining informed consent, 28 anaesthetists and anaesthesia trainees in one hospital took part in the study. All participants were exposed to a pre-scripted simulated "control" scenario of anaphylactic shock (phase 1). The sessions were videotaped and the performances of individual participants were evaluated using a standardized scoring scheme. During phase 2, the participants were allocated randomly to undergo training in the management of either anaphylactic shock (group A, n = 13) or malignant hyperthermia (group B, n = 15) on the simulator. After 4 months, each participant underwent a blinded evaluation session with a pre-scripted "test" scenario of malignant hyperthermia (phase 3). These sessions were also videotaped and evaluated as for phase 1. The participants in group B responded more quickly, treated better and deviated less from the accepted procedure during phase 3 than those in group A. The total performance of participants in group B during phase 3 was significantly better than those in group A. We conclude that training on an anaesthesia simulator does improve the performance of anaesthetists in dealing with emergencies during anaesthesia.

SummaryA retrospective analysis is presented of all reports of faults, accidents, near accidents and complications associated with anaesthesia in one hospital from 1978 to 1987. 113 074 anaesthetics were administered in that period, of which 97496 were for noncardiac procedures. There were 148 reports; 39 were of dental damage. Peri-operative cardiac arrests during noncardiac surgery were reported 29 times. Sixteen of these were fatal. Anaesthesia was thought to havc played an important role in 13 cardiac arrests ( I per 7500 anaesthetics) and six were not successfully resuscitated ( I per 16 250 anaesthetics). There were 12 reports of postoperative peripheral neuropathies (1 per 9422 anaesthetics). Failure to check, lack of vigilance and inattention or carelessness were the most frequently associated factors with the rest of the reports.

We describe a prospective analysis, in one hospital, of reported significant observations involving unsafe practices and working conditions during anaesthesia. Of the 549 significant observations reported voluntarily during a period of 18 months, 82% involved occurrences which were considered preventable and 27% could have been fatal if they had not been recognized and corrected. Ninety-three percent of incidents did not lead to a negative outcome. Human error was responsible for 411 (75%) reports. Lack of vigilance and failure to check were the most frequently reported factors associated with human error. Significant observations involving errors in drugs administration were the most frequent. Forty-five percent of all reported significant observations were made during maintenance of anaesthesia.

We describe an anaesthesia simulator capable of simulating all possible situations during anaesthesia. The Leiden anaesthesia simulator (LAS) may be used with most commercially available anaesthesia equipment and monitors, which are connected to the simulated patient as they are to a patient. A commercially available intubation manikin attached to an electromechanical lung model represents the patient. The lung allows both spontaneous and mechanical ventilation. Compliance, resistance, tidal volume and ventilatory frequency may be altered by a controlling computer. Carbon dioxide production and oxygen uptake are simulated. Physiological signals (ECG, arterial, pulmonary arterial and central venous pressure waveforms) generated by a signal generator under software control provide input to the monitors. All types of ECG disturbances may be simulated. There are facilities for simulating non-invasive arterial pressure measurement and pulse oximetry. A series of physiological models is being developed to control interactions between the cardiovascular and respiratory variables. During a simulation session, a pre-defined scenario is presented to the trainee. The task of the trainee is to diagnose and treat the problem as if in real life. The simulator experiences on the LAS were judged as highly realistic by 28 subjects. This simulator is currently being used for teaching and training of anaesthetists, trainees and anaesthesia personnel and for research.

Spatial databases have experienced enormous growth in application environments, such as agriculture, environmental studies, geography, geology, city-planning, aerospace industry etc. More recently spatial databases have attracted attention in the database community. A considerable research has been done in physical implementation of spatial databases. This is particularly true of access methods for spatial data [238, 483, 512, 230, 231, 39, 506]. On the other hand, abstract modeling and querying of spatial data have received relatively less attention. The need for such a study becomes even more important because of diverse techniques proposed for representing spatial regions.Like [440] we favor that the logical view and the physical implementation of spatial data should be considered orthogonal issues. The users should be given a simple view of data and freed of the worry of how it is physically represented. This is even more important because physical implementation will continue to be a topic of study for quite some time to come. Conventional database techniques are inadequate in spatial databases because of the spatial structure implicit in spatial querying. We present a model and an SQL-like query language called SpaSQL (read space-Q-L) for spatial data. Without tying ourselves down to a choice of representation of spatial regions, we propose certain desirable closure properties for them to make SpaSQL seamless. Related WorksSeveral techniques of physical representation spatial regions have emerged. One way to represent a region is to lay it on a fine grid, and approximate the region by the set of grid elements covered by the region. Another technique is to describe a region by a chain of arcs, and associating a biLt with each arc to encode whether the region being specified is on the right or left of the arc. A third way is to view a region as a hyper plane in an ndimensional space, and use techniques of computational geometry to manipulate them.