Delirium in critically ill patients : diagnosis and treatment

Delirium is defined as a disturbance of consciousness with cognitive changes or perceptual disturbances, which has developed over a short period of time, and is caused by a medical condition or a post-surgical state. Although historically dismissed as an inconvenient and transient problem, recent studies have reported that delirium is associated with more complications, increased length of hospital stay and higher mortality. Although delirium is a prevalent condition in the Intensive Care Unit (ICU), the condition appears to be largely under diagnosed and treated. In this thesis, the diagnostic instruments and methods for screening for delirium in ICU patients available are discussed. The authors have evaluated the Confusion Assessment Method for the ICU (CAM-ICU) and compared the results with groups of experts. Although the CAM-ICU is relatively easy to implement in daily practice and in use, the test characteristics of the CAM-ICU, when compared to experts, are moderate at best. As part of this thesis, the authors studied the effect of implementation of standardized delirium screening with the CAM-ICU on anti-delirium medication use, no significant differences were found. It is often hypothesized that delirium in critically ill patients is – in part - caused by the ICU environment (noise, light et cetera). To study the effect of different ICU environments, the authors have registered the effect of single versus multiple patient room ICUs on the frequency and duration of delirium and sleep. Although no significant beneficial effect on sleep and the frequency of delirium was found, patients in single room ICU’s had a shorter delirium than those in multiple patient rooms. In the final part of this thesis, the authors investigated a possible new delirium treatment with cholinesterase inhibitors (rivastigmine). The authors designed and conducted a randomized, placebo controlled trial to study the effect of rivastigmine when added to the standard delirium treatment in critically ill patients. This trial was stopped early and no beneficial effect of rivastigmine on duration or severity of delirium was found. The author concludes this thesis with two conclusions: firstly, the available screening methods for delirium in critically ill patients do not suffice. Furthermore, the necessity of delirium screening in the ICU is doubtful. Secondly, further research should focus on preventive – nursing – measures and not on pharmacological treatment.