In the present study, the students' performance in auscultation of cardiac patients was similar whether they had received additional teaching with the computer-based teaching program, or had additional traditional bedside training. The strengths of our trial include the randomized design, the similar amount of additional training in both groups, and the blinded questionnaire evaluation.
In a previous study by Horiszny , the ability to correctly interpret simulated heart sounds was better among those who had participated in the teaching session compared to those who did not. However, no other teaching form was offered to those who did not use the simulator, so the better results might be due to more time spent on learning auscultation or to higher motivation among those who attended the teaching session. Another randomized trial revealed advantages using classroom teaching compared to CD-ROM teaching among medical students . In that trial the results were satisfying, but the students had difficulties in classifying murmurs and the second heart sound.
Poor results in both groups
Generally the auscultation skills in the present study were poor. The best score achieved was 28 of 40 points - 70%. Possibly, the time allocated to auscultation training was too brief for obtaining the skills required to make a good auscultation report at this stage of their medical education. This observation is supported by other trials that have evaluated some of the same aspects, both in medical students and doctors .
We found a weak, non-significant negative correlation between the time interval from the last teaching session to the test. This is compatible with the common experience that following a short intensive course, knowledge and skills reach the short memory only. A controlled intervention study concluded that five hundred repetitions of four basic cardiac murmurs significantly improved medical students' proficiency in recognizing basic cardiac murmurs. The authors concluded that cardiac auscultation is, in part, a technical skill . It is, however, hard to get acceptance for more time spent on auscultation training in the congested medical core curriculum.
Limitations of the study
The technical problems with the CAS equipment limited the value of the computer-based training sessions. Our selection of program components from the CAS had not been tried previously, and might have been improved with more experience. Benefits from the CAS system might further have increased, had the equipment been more accessible for the students, or if we had used an auscultation mannequin in addition . We had no pre-intervention test. Hence we cannot know for certain, the value of the additional training in any of the two arms. A more ideal design would have been to randomize the groups at the very first time the students were introduced to heart auscultation, and then keep the same groups throughout the medical education. However, such an approach would be complicated. It would demand at least 5 years follow-up of each student. Furthermore, the Faculty of Medicine in Oslo reorganizes the teaching groups from one term to another, in order to train the students to cope with new group settings. A final limitation to our approach is that we tested auscultation skills only; recently, benefit has been reported from additional teaching on complete cardiac examination with virtual patients .
We had expected to find advantages by using the simulator, since the teaching could introduce each concept step by step, and it allowed the students to carefully study the different cardiac murmurs. However, no demonstrable difference between use of the heart sound simulator and bedside training was found. This does not, however, exclude a value of the computer-assisted auscultation system. With shorter hospital stays and difficulty in faculty recruitment, bedside teaching is a challenge that simulation technology may help to overcome. Given that simulator practice is readily available to students, at variance from patients and instructors, simulator practice may be a reasonable alternative to bedside examination practice.