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Biomedical subjects

C B Guest

Publications and source records attributed to C B Guest.

10 recordsLinked to original sources
PubMed2001

Validity and reliability of undergraduate performance assessments in an anesthesia simulator.

PURPOSE: To examine the validity and reliability of performance assessment of undergraduate students using the anesthesia simulator as an evaluation tool. METHODS: After ethics approval and informed consent, 135 final year medical students and 5 elective students participated in a videotaped simulator scenario with a Link-Med Patient Simulator (CAE-Link Corporation). Scenarios were based on published educational objectives of the undergraduate curriculum in anesthesia at the University of Toronto. During the simulator sessions, faculty followed a script guiding student interaction with the mannequin. Two faculty independently viewed and evaluated each videotaped performance with a 25-point criterion-based checklist. Means and standard deviations of simulator-based marks were determined and compared with clinical and written evaluations received during the rotation. Internal consistency of the evaluation protocol was determined using inter-item and item-total correlations and correlations of specific simulator items to existing methods of evaluation. RESULTS: Mean reliability estimates for single and average paired assessments were 0.77 and 0.86 respectively. Means of simulator scores were low and there was minimal correlation between the checklist and clinical marks (r = 0.13), checklist and written marks (r = 0.19) and clinical and written marks (r = 0.23). Inter-item and item-total correlations varied widely and correlation between simulator items and existing evaluation tools was low. CONCLUSIONS: Simulator checklist scoring demonstrated acceptable reliability. Low correlation between different methods of evaluation may reflect reliability problems with the written and clinical marks, or that different aspects are being tested. The performance assessment demonstrated low internal consistency and further work is required.

Anesthesiology↗
PubMed2001

The life long challenge of expertise.

The development and maintenance of expertise in any domain requires extensive, sustained practice of the necessary skills. However, the quantity of time spent is not the only factor in achieving expertise; the quality of this time is at least as important. The development and maintenance of expertise requires extensive time dedicated specifically to the improvement of skills, an activity termed deliberate practise. Unfortunately, determining how to engage in this deliberate practise is not obvious for tasks such as diagnosis, which involve high stakes and are predominantly cognitive nature. Reflection on and adaptation of one's cognitive processes is important; this could be supplanted by seeking out the opportunity to engage in trial and error in low risk environments such as simulators. Regardless, most individuals tend to favour well-entrenched activities and avoid practise. This may be due to lack of awareness of deficiencies in performance. However, it may also be due to the individual's conception of the nature of expertise. Although expertise requires experience, experience alone is insufficient. Rather, the development of expertise is critically dependent on the individual making the most of that experience. As a result, motivational factors are fundamental to the development of expertise. Overcoming deficiencies in self-monitoring is not a sufficient remedy. It is also necessary is that clinicians form an attitude toward work that includes continual re-investment in improvement.

Clinical Competence↗
PubMed2001

A comparison of global ratings and checklist scores from an undergraduate assessment using an anesthesia simulator.

PURPOSE: To determine the correlation between global ratings and criterion-based checklist scores, and inter-rater reliability of global ratings and criterion-based checklist scores, in a performance assessment using an anesthesia simulator. METHOD: All final-year medical students at the University of Toronto were invited to work through a 15-minute faculty-facilitated scenario using an anesthesia simulator. Students' performances were videotaped and analyzed by two faculty using a 25-point criterion-based checklist and a five-point global rating of competency (1 = clear failure, 5 = superior performance). Correlations between global ratings and checklist scores, as well as specific performance competencies (knowledge, technical skills, and judgment), were determined. Checklist and global scores were converted to percentages; means of the two marks were compared. Mean reliability of a single rater for both checklist and global ratings was determined. RESULTS: The correlation between checklist and global ratings was.74. Mean ratings of both checklist and global scores were low (58.67, SD = 14.96, and 57.08, SD = 24.27, respectively); these differences were not statistically significant. For a single rater, the mean reliability score across rater pairs for checklist scores was.77 (range.58-.93). Mean reliability score across rater pairs for global ratings was.62 (.40-.77). Global ratings correlated more highly with technical skills and judgment (r =.51 and r =.53, respectively) than with knowledge. (r =.24) CONCLUSION: Inter-rater reliability was higher for checklist scores than for global ratings; however, global ratings demonstrated acceptable inter-rater reliability and may be useful for competency assessment in performance assessments using simulators.

Anesthesia↗
PubMed1995

Choice of anaesthetic regimen influences haemodynamic response to cemented arthroplasty.

Haemodynamic changes during bilateral cemented arthroplasty (BCA) were compared in dogs anaesthetized with isoflurane/N2O (ISOF) or diazepam/fentanyl (100 microg x kg(-1))N2O(FENT). Eight animals were anaesthetized with each regimen. After establishing monitoring and recording baseline values, BCA was performed. Haemodynamic measurements included aortic blood pressure (ABP), pulmonary artery pressure (PAP), right and left atrial pressures, and cardiac output. These were recorded at 30, 60, 180 and 300 sec after BCA. Lungs were removed and examined postmortem using quantitative morphometry. Groups demonstrated similar increases in PAP (ISOF 15 +/- 2 to 32 +/- 7, FENT 19 +/- 4 to 38 +/- 13; P> 0.05 between groups, P< 0.05 vs baseline). The proportion of lung vasculature occluded by fat was not different between groups (ISOF 9.63 +/- 3.38%, FENT 8.85 +/- 2.20%). Stroke volume decreased similarly in both groups (P> 0,05 between groups, P< 0.05 vs baseline). However, ABP decreased within one minute of BCA in ISOF (111 +/- 17 to 55 +/- mmHg, P< 0.05 and two of eight dogs died. All FENT dogs survived and hypotension (118 +/- 20 to 102 +/- 24 mmHg) was transient and less severe (P< 0.05 vs ISOF). Increased heart rate (HR) was noted in FENT following BCA (73 +/- 8 to 108 +/- 25 beats x min(-1); P< 0.05). Baseline HR was higher in ISOF (P< 0.05) and no increase in HR was noted. Systemic vascular resistance decreased in ISOF (P< 0.05), but not FENT (P> 0.05 vs baseline, P< 0.05 vs ISOF). To assess the role of slower baseline HR in FENT (73 +/-8) versus ISOF (131 +/- 5), six FENT dogs were paced (130 beats x min(-1)) with epicardial leads and an AV sequential pulse generator to simulate the ISOF group's baseline HR. Haemodynamic stability was maintained in this group in spite of a more rapid baseline HR. The choice of anaesthetic regimen strongly influenced acute haemodynamic changes in response to BCA.

Anesthetics, Inhalation↗
PubMed1994

Transpulmonary systemic fat embolism. Studies in mongrel dogs after cemented arthroplasty.

We investigated the source of intravascular fat in systemic organs (brain, heart, and kidney) after massive pulmonary fat embolism during cemented arthroplasty. We used a bilateral cemented arthroplasty (BCA) in anesthetized mongrel dogs that simulates a cemented total-hip replacement procedure. We hypothesized that deformable fat globules could pass through the lung vasculature under high pulmonary artery pressure (Ppa). Using quantitative morphometry, we showed that the size of pulmonary vessel occluded by fat decreased from 12.8 +/- 15.2 microns 1 min after BCA to 4.9 +/- 5.1 microns at 120 min after BCA (p < 0.01). Ultrastructural studies demonstrated no evidence of acute inflammation around fat-occluded pulmonary vessels 3 h after BCA. Intravascular fat was found in all brain, heart, and kidney specimens examined 3 h after BCA (n = 6). No anesthetized animal in the "sham" (no BCA) group (n = 3) had intravascular fat at the same time period. Radiolabeled microspheres (15 microns diameter) did not reach the systemic circulation (< 1% nonentrapment) under the high Ppa after BCA. No patent foramen ovale was found in any dog at postmortem examination. We conclude that fat globules can traverse the pulmonary circulation within 3 h of orthopedic surgery. The difference between solid microspheres and fat in transpulmonary passage suggests that the composition, perhaps the deformability, of embolic material influences the lung's filtering capacity.

Animals↗
PubMed1990

Allograft-implant composite reconstruction following periacetabular sarcoma resection.

Ten patients with primary periacetabular sarcomas were treated with internal hemipelvectomy and allograft-implant composite reconstruction. Three patients developed local recurrences, one of which was salvaged with repeat resection. One patient underwent hemipelvectomy for infected wound recurrence. At a mean follow-up period of 25 months (range, 7-85 months; median, 18 months), six of nine patients assessed with the Musculoskeletal Tumor Society functional assessment had satisfactory results, with scores of 21 or better (of a possible 35). Although complications were frequent and functional scores were often limited by the muscle resection required for adequate tumor removal, we remain cautiously optimistic about the early results of this procedure.

Acetabulum↗
PubMed1990

The surgeon simulator.

A new technique of small group surgical teaching has been developed wherein the surgeon takes on the role of the patient. This technique, which incorporates extensive and immediate formative evaluation, has all the advantages of simulation techniques while avoiding the major problems of training, scheduling and cost. This method has been used to teach a wide variety of surgical disease processes with the major emphasis being teaching patient management strategies. Sixty-one medical students have been taught using this method and they have found it superior to conventional seminar teaching, particularly in the domains of problem solving, patient management strategies and thought provocation.

Education, Medical, Undergraduate↗
PubMed1989

Colitis cystica profunda. Review of the literature.

Colitis cystica profunda is a rare benign disorder of the colon and rectum. The disease is important clinically in that it often mimics malignant processes. The clinical features of 144 cases of colitis cystica profunda reported in the literature are reviewed. Controversies surrounding the cause and pathogenesis of the disease are discussed.

Colitis↗
PubMed1989

Survival analysis: a practical approach.

Survival analysis is a statistical method used to calculate the probability of an event such as death or relapse of disease occurring in a patient over time. Survival analysis is important in the interpretation of clinical research, and is frequently encountered in the colorectal literature. In this article, the terminology used in survival analysis is explained, specific examples are presented, and common methods of calculation demonstrated.

Humans↗