Abstract
The first article of this series on Clinical Safety was dedicated to the epidemiology and systemic preventive policies. In the present review we focus on medical errors with special emphasis on diagnostic type errors. These errors sometimes arise from the elusive characteristics of the disease itself, the way in which the patients present their symptoms, and the characteristics of the professionals themselves. If we consider a general practitioner as a diagnostic machine, --paradigm of "physician as a robot"-- it would be easier for us to accept some cognitive limitations and introduce institutional strategies that would humanise the treatment occasionally received. More specifically we will examine three strategies for improving clinical reasoning: recognising dangerous situations, metacognition, and an internal supervisor.