The taxonomic framework has three levels: domains (‘a sphere of activity, study or interest’), classes (‘a subdivision of a larger group; a division of per-sons or things by quality, rank or grade’) and nursing diagnosis concepts (‘a clinical judgment about individual, family or community responses to actual or potential health problems/life processes. It constitutes the basis for selection of nursing interventions to achieve the outcomes for which the nurse is responsible’). The nursing diagnosis of DCO is placed in the domain Activity/Rest and in the class Cardiovascular/Pulmonary Responses. It is defined as ‘inadequate blood pumped by the heart to meet the metabolic demands of the body’ and related to the presence of one or more defining characteristics such as heart rate/rhythm, altered preload, afterload and/or contractility and behavioural/emotional changes which determine its specific signs and symptoms (NANDA International 2009).