Most current management systems of healthcare institutions correspond to a model of market ethics with its demands of competitiveness. This approach has been called managerialism and is couched in terms of much-needed efficiencies and effective management of budgetary constraints. The aim of this study was to analyse the decision-making of nurses through the impact of health institution management models on clinical practice. Based on Foucault's ethical theory, a qualitative study was conducted through a discourse analysis of the nursing records in a hospital unit. The results revealed that the health institution standardises health care practice, which has an impact on professional and patient autonomy as it pertains to decision-making. The results of this research indicate that resistance strategies in the internal structures of health organisations can replace the normalisation and instrumentalisation of professional practice aimed at promoting patient self-determination.