Decision support tools are an important adjunct to medical resuscitation. We initiated a study comparing the use of the traditional code book method versus a computerized decision support system. However, appropriate use of the tools requires correct initial recognition of the dysrhythmia. Using simulation, numerous deficiencies were revealed regarding resident physician dysrhythmia knowledge. Most importantly, the rate of incorrect dysrhythmia recognition required discontinuation of the initial study, reorganization, and implementation of a modified study to achieve the study purpose.