摘要:

In intensive care units (ICUs), certain parameters must be interpreted taking into account the intrinsic characteristics of each patient or the peculiarities of the clinical case under consideration. Similar temporal evolutions of some parameters in different patients could have different interpretations. Artificial intelligence techniques can aid in resolving this problem through the construction of expert systems (ES). These systems are capable of performing contextual evaluations of the parameters typically monitored in ICUs. This contextual evaluation is usually carried out using symbolic elements. Thus, the symbolic processing of numeric data is an important task to perform. In any event, the assignment of semantic labels to numeric values is always an uncertain and arbitrary process. This suggests the convenience of defining and implementing representation schemes capable of dealing with uncertain knowledge. This paper presents a model for the symbolic processing of numeric variables in which the uncertainty associated with the assignment of literals appears spontaneously. The categorical approach for the symbolic classification of numeric values is a particular case of the proposed model.

ISSN:0363-8855    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Medical expert systems frequently use causal models to capture knowledge and diagnostic-problem-solving expertise. A significant obstacle confronting these systems is providing informative explanations without prohibitive computational expense. The explanations should allow the user to understand the decisions of the expert system and obtain additional details when needed. A new method, calledHyperExplain, has been devised to flexibly link explanations with conclusions generated by a causal reasoning system. This approach creates apatient specific explanatory(PSE) model for the medical expert system that provides decision support from a variety of perspectives. A key feature of this method is the ability to alter the focus of explanations depending upon the problem-solving context and patient manifestations. The method has been implemented in a program that provides diagnostic assistance to physicians in the domain of neurophysiology.

ISSN:0363-8855    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

A four-bed central station that can be connected to any commercial intensive-care bedside monitor was developed. The system is based on a personal computer (IBM®-AT compatible) as a local unit and on a microcontroller Intel®8031 as a remote unit. Four ECG signals are low-pass filtered, multiplexed, sampled at 256-Hz per channel, 8-bit A/D converted, preprocessed, and converted to a serial format RS-232 by the remote unit. The real-time display of the signals is at the standard speed of 25 and 50 mm/sec. Heartrate, alarms, trend plots, and general patient data are shown on an Olivetti®M280 and EGA 13“ color monitor as the local unit. The communication speed was set at 57.6 Kbaud full duplex. Additionally, to reach standard monitoring sweep rates using a 13” screen with 640 x 350 pixels, an ECG data-compression algorithm was implemented in the remote unit. This unit can support up to eight input channels and can work with any personal computer, via RS-232, with the appropriate software. It also allows other signal preprocessing software that could be developed, such as QRS detection or ST segment quantification, to be loaded into its random access memory and to be run under PC command. The development of this system demonstrated the use of a widespread piece of commercial equipment, the PC, in a very specific application, CCU monitoring, assuring low-cost system implementation. This feature is particularly attractive in upgrading existing CCU units in less developed countries.

ISSN:0363-8855    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

A real-time, Automated Anesthesia Record Keeping (AARK) system was constructed using commercially available video hardware. This system can acquire all of the information that is presented visually to an anesthesiologist directly from monitor screens. The information is recorded on VHS format tape. Use of such a system avoids the need for digital processing while capturing all waveforms, trends, data messages and numerics. Since the data are stored directly to tape, subsequent data analysis can be accomplished. This system can be used with virtually any medical monitor.

ISSN:0363-8855    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

In order to obtain a faithful reproduction of the arterial pressure waveform, the dynamic response characteristics of a pressure-monitoring system must possess amplitude and phase linearity, and adequate bandwidth. Numerous tests have been devised to evaluate dynamic-response characteristics of pressure-monitoring systems. It was the purpose of this study to investigate the validity of the more popular tests through computer simulations and models. Two typical pressure-monitoring systems, each consisting of a 7-F thermodilution catheter, either a 12-in. or 48-in. monitoring/administration line and pressure transducer, were simulated as electrical circuits containing resistors, capacitors and inductors. The circuit models were then subjected to “impulse,” “step,” “pop,” “flush,” “stopcock” and “snap” tests to determine each test's ability to provide useful information. Results of the simulations indicated that 3 of the 13 simulations were able to correctly determine the proper resonant frequency and effective damping. Impulse and step tests were shown to be reliable only if the signal could be applied at the catheter tip. The onlyin situtest able to provide useful information was the “snap test” as described in this paper. Computer simulations also demonstrated that an impulse, or perturbation, located within the transducer could not provide correct information in terms of the proper transfer characteristics of the monitoring system. This may not be a suitable method to use in automated or self-correcting monitoring systems.

ISSN:0363-8855    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

The inspiratory muscles in a dog were twitched to cause short-duration inspirations by discharging a capacitor bank into an excitation coil placed over the lower right chest.

ISSN:0363-8855    

出版商:OVID    

年代:1990

数据来源: OVID

ISSN:0363-8855    

出版商:OVID    

年代:1990

数据来源: OVID