ABSTRACT
The term evidence based nursing signifies a systematic process of search, assessment and application of the most up-to-date investigation for decision taking. In practice the process can be applied in four steps: formulation of the question, a search of the bibliography, a critical analysis of the validity of the results, and putting the obtained findings into practice. Nursing practise must be based on the best available scientific results. Professional nurses are more accustomed to acting according to tradition with scarce scientific rigour. It is necessary to introduce investigation as an instrument to allow resolution of problems with practice and to offer the best possible care alternative. The evidence contributed by investigation is evaluated according to criteria of validity and utility. There are several scales to assess the methodological rigour of investigation studies as well as to recommend a practice or technique as appropriate, or not, according to the scientific evidence available.
