A randomized crossover trial of Quick Medical Reference (QMR) as a teaching tool for medical interns.

OBJECTIVE: To determine whether the addition of Quick Medical Reference (QMR) to usual educational tools improves an intern's performance in managing clinical cases that test diagnostic and investigative skills. DESIGN: Randomized, controlled, single-blinded crossover study. SETTING: Tertiary care teaching hospital. SUBJECTS: Comprehensive medical interns who are proficient in the use of QMR. INTERVENTION: A total of 16 interns trained in the use of QMR were randomized to work up a total of six diagnostically challenging cases, three using medical textbooks plus access to QMR and three using textbooks and no access to QMR. MEASUREMENTS: The interns provided their solutions to the cases, which consisted of the differential diagnosis and investigations. They were scored by comparing their answers with the consensus answers provided by subspecialty consultants. For each intern, the difference in mean total scores with and without QMR was calculated. RESULTS: The mean difference in total scores was 7.2% benefit (p < 0.05, 95% CI = 0.05 to 14.4) using QMR. The beneficial difference was driven mainly by improvement in diagnostic scores, with the mean difference being 11.6% (p = 0.01, 95% CI = 2.4 to 20.8). Regression analysis showed that the more difficult the case, the greater the benefit of QMR. CONCLUSIONS: Quick Medical Reference may be a useful adjunct to interns in formulating diagnostic strategies for difficult clinical cases. However, since optimal conditions were chosen for QMR benefit in this study design, the small benefit in test scores must be weighed against the time required to teach QMR to interns.

Mitral valve replacement for mitral regurgitation with and without preservation of chordae tendineae.

Left ventricular function was compared in 15 patients who had conventional mitral valve replacement (Group 1) and 12 patients who had replacement with preservation of chordae tendineae and papillary muscles (Group 2) for isolated chronic mitral regurgitation. Function was assessed by radionuclide ventriculography. The two groups were similar in terms of age, preoperative functional class, valve pathology, and preoperative left ventricular function. There was uniform intraoperative and postoperative management by a single surgeon. All patients received porcine bioprostheses. Left ventricular function was assessed 1 day before and 3 to 6 months after the operation. Left ventricular ejection fraction decreased from 0.55 +/- 0.09 to 0.48 +/- 0.14 in Group 1 (p less than 0.01) and did not change significantly in Group 2 (from 0.53 +/- 0.14 to 0.52 +/- 0.16). Left ventricular end-diastolic volume, end-systolic volume, and stroke volume indices decreased significantly in both groups. During maximal postoperative bicycle exercise with the patient supine, left ventricular ejection fraction and stroke volume index increased significantly in Group 2 only. Cardiac output increased in both groups during exercise, but this increase was due to increased heart rate in Group 1 and to increased heart rate and stroke volume in Group 2. These findings suggest that preservation of chordae tendineae and papillary muscles during mitral valve replacement for chronic mitral regurgitation has a beneficial effect on postoperative left ventricular function.