Biomedical subjects

M J Lincoln

Publications and source records attributed to M J Lincoln.

7 recordsLinked to original sources

PubMed1992

Iliad's role in the generalization of learning across a medical domain.

Medical informatics could facilitate more effective analysis and use of clinical knowledge by means of expert systems. To be most effective, such systems should be constructed in a manner which is consistent with physicians' cognitive processes. Our past five years' work with a system called Iliad indicates that it provides effective medical training and education. The current research extends our previous work by using a wider array of training and test cases. We also evaluated whether training on specific cases could generalize to improved testing performance on related cases, which featured similar complaints and pathophysiologic mechanisms, but different final diagnoses. In their junior internal medicine clerkship, students (n = 100) completed 1300 Iliad training cases covering 48 diagnoses. The findings indicated improved problem solving on the specifically trained cases as well as the generalization cases. We discuss a possible training model for expert systems such as Iliad.

Computer-Assisted Instruction↗

PubMed1992

Comparison of different information content models by using two strategies: development of the best information algorithm for Iliad.

Iliad is a diagnostic expert system for internal medicine. Iliad's "best information" mode is used to determine the most cost-effective findings to pursue next at any stage of a work-up. The "best information" algorithm combines an information content calculation together with a cost factor. The calculations then provide a rank-ordering of the alternative patient findings according to cost-effectiveness. The authors evaluated five information content models under two different strategies. The first, the single-frame strategy, considers findings only within the context of each individual disease frame. The second, the across-frame strategy, considers the information that a single finding could provide across several diseases. The study found that (1) a version of Shannon's information model performed the best under both strategies---this finding confirms the result of a previous independent study, (2) the across-frame strategy was preferred over the single-frame strategy.

Algorithms↗

PubMed1991

Iliad training enhances medical students' diagnostic skills.

Iliad is a computerized, expert system for internal medical diagnosis. The system is designed to teach diagnostic skills by means of simulated patient case presentations. We report the results of a controlled trial in which junior students were randomly assigned to received Iliad training on one of two different simulated case mixes. Each group was subsequently tested in both their "trained" and "untrained" case domain. The testing consisted of computerized, simulated patient cases for which no training feedback was provided. Outcome variables were designed to measure the students' performance on these test cases. The results indicate that students made fewer diagnostic errors and more conclusively confirmed their diagnostic hypotheses when they were tested in their trained domain. We conclude that expert systems such as Iliad can effectively teach diagnostic skills by supplementing trainees' actual case experience with computerized simulations.

Clinical Clerkship↗

PubMed1991

Exploring a new best information algorithm for Iliad.

Iliad is a diagnostic expert system for internal medicine. One important feature that Iliad offers is the ability to analyze a particular patient case and to determine the most cost-effective method for pursuing the work-up. Iliad's current "best information" algorithm has not been previously validated and compared to other potential algorithms. Therefore, this paper presents a comparison of four new algorithms to the current algorithm. The basis for this comparison was eighteen "vignette" cases derived from real patient cases from the University of Utah Medical Center. The results indicated that the current algorithm can be significantly improved. More promising algorithms are suggested for future investigation.

Algorithms↗

PubMed1991

Iliad training effects: a cognitive model and empirical findings.

Iliad is a diagnostic expert system consisting of an "inference engine" (collection of rules and procedures for making decisions) and a "knowledge base" (collection of medical facts). Iliad's internal medicine knowledge base recognizes 5000 medical findings and covers 1150 diagnostic conditions in 10 subspecialty fields. We used Iliad's simulator mode to train diagnostic skills in junior-year medical students. The results corroborate previous findings documenting Iliad's teaching efficacy. Recent developments in cognitive psychology provide a framework for explaining Iliad's training effects.

Clinical Clerkship↗

PubMed1988

Dissociation between diaphragmatic and rib cage muscle fatigue.

To assess rib cage muscle fatigue and its relationship to diaphragmatic fatigue, we recorded the electromyogram (EMG) of the parasternal intercostals (PS), sternocleidomastoid (SM), and platysma with fine wire electrodes and the EMG of the diaphragm (DI) with an esophageal electrode. Six normal subjects were studied during inspiratory resistive breathing. Two different breathing patterns were imposed: mainly diaphragmatic or mainly rib cage breathing. The development of fatigue was assessed by analysis of the high-to-low (H/L) ratio of the EMG. To determine the appropriate frequency bands for the PS and SM, we established their EMG power spectrum by Fourier analysis. The mean and SD for the centroid frequency was 312 +/- 16 Hz for PS and 244 +/- 48 Hz for SM. When breathing with the diaphragmatic patterns, all subjects showed a fall in H/L of the DI and none had a fall in H/L of the PS or SM. During rib cage emphasis, four out of five subjects showed a fall in H/L of the PS and five out of six showed a fall in H/L of the SM. Four subjects showed no fall in H/L of the DI; the other two subjects were unable to inhibit diaphragm activity to a substantial degree and did show a fall in H/L of the DI. Activity of the platysma was minimal or absent during diaphragmatic emphasis but was usually strong during rib cage breathing. We conclude that fatigue of either the diaphragm or the parasternal and sternocleidomastoid can occur independently according to the recruitment pattern of inspiratory muscles.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1988

Pulmonary telangiectasia without hypoxemia.

We describe an elderly patient with an unusual presentation of hereditary hemorrhagic telangiectasia (Rendu-Osler-Weber disease) involving the lung. He had recurrent "pneumonia" caused by massive hemorrhage from endobronchial telangiectases. When stable, he was normoxic, had no evidence of right-to-left shunting, and had mild pulmonary arterial hypertension. His pulmonary telangiectases may be isolated to the bronchial circulation. We report hemodynamic data and show the first photographs of endobronchial telangiectases.

Aged↗