At the philosophical heart of this study is the recognition that the implementation and use of the evidence-base regarding pain management in cardiothoracic critical care is problematic because clinical nursing practice within the context of the multi-disciplinary team is not straightforward; the practice of nursing is mediated through layers of professional hierarchy and power relationships which constrain and limit it. Its contribution to the knowledge base is its account of the effects of the multi-disciplinary team on nursing practice using a Foucauldian discourse analytic framework. Achieving patient throughput was the main goal of care; effective pain management was not prioritised. The underpinning approaches are qualitative; data were collected through observation of practice, interviews and written texts. The 24-hour span of clinical practice was observed within a large cardiothoracic unit for a total period of 5 weeks; 21 qualified nurses (all grades, full- and part-time, purposively sampled) were interviewed. The fllldings of the study impose Foucauldian discourse analysis terms of nonnalisation, hierarchical observation, examination, discipline, docile bodies, surveillance, 'the gaze', and panopticism, as well as the nurses' resistance practices, to describe the techniques of power and authority which are utilised (and resisted) within clinical practice.