ObjectivesTo describe the prevalence and characteristics of delirium during the initial evaluation of critically ill patients aged 5–14 years. Method/designThis is a cross-sectional descriptive study in a critical care unit. For six months, all patients were evaluated within the first 24–72 hours or when sedation permitted the use of the paediatric confusion assessment method for the intensive care unit (PCAM-ICU) and the Delirium Rating Scale-Revised-98 items #7 and #8 to determine motor type. We report the characteristics of PCAM-ICU delirium (at least three of the required items scored positive) and of subthreshold score cases (two positive items). ResultsOf 77 admissions, 15 (19.5%) had delirium, and 11 (14.2%) were subthreshold. A total of 53.3% of delirium and 45.5% of subthreshold cases were hypoactive. The prevalence of delirium and subthreshold PCAM-ICU was 83.3% and 16.7% in mechanically ventilated children. The most frequent combination of PCAM-ICU alterations in subthreshold cases was acute onset-fluctuation with altered alertness. The main nursing diagnoses were related to reduced cellular respiration. ConclusionsDelirium is common in critically ill children. It is necessary to assess whether certain nursing diagnoses imply an increase in delirium. Longitudinal studies of subthreshold PCAM-ICU cases are needed to understand their importance better.