On risk factors for pediatric delirium at noon.

Pediatric Critical Care Medicine www.pccmjournal. org 375 Due to critical illness, the brain can react with several neuropsychiatric reaction types, and the most important six are sickness behavior, fever, epilepsy, catatonia delirium, refractory agitation, and coma (1). Delirium is defined as a mental disorder—due to an underlying somatic disorder, its treatments, and or its terminations—characterized by disturbances of attention consciousness, cognition, and motor activity (2). The etiology of delirium in the (P)ICU is usually trifold and synergistic: 1) the underlying disease process, 2) treatments and/or its terminations, and 3) the highly abnormal (P)ICU environment. The presumed delirium pathophysiology is mediated by various interleukin and cytokine pathways leading to an increased blood-brain barrier permeability and neuroinflammatory reactions in cerebro which in turn cause dysregulation of neurotransmitters, especially of cholinergic and dopaminergic pathways, and so to delirium (3). The prevalence of pediatric delirium (PD) at the PICU is estimated to range from 20% to 30% depending on the type of PICU, making it a frequently encountered complication demanding our attention and scrutiny. Indeed, according to Lipowski (4), delirium is “acute brain failure in man,” and as the brain controls the autonomic nervous and endocrine systems, the consequences of this failure may be severe. Because of this, PD progressively has been recognized as a potential serious complication of pediatric critical illness. Just as delirium already is in adults and the elderly. There it is strongly associated with increased morbidity and mortality, and tremendous medical costs. And so in the last decade, the mental status is considered to be one of the six vital signs. Over the past years, delirium has become an increasingly researched topic and now possible risk factors have been gradually identified. These can be divided into predisposing and precipitating factors, and some authors consider contextual factors a third category. Data regarding predisposing factors for specific PD remain scarce. In the adult and geriatric population, the most important predisposing factors of delirium are older age, cognitive impairment (e.g., dementia), chronic physical comorbidities, and psychiatric comorbidity (5). Furthermore, a correlation between severity of illness, for example, measured by Acute Physiology and Chronic Health Evaluation (APACHE) II scores, and occurrence of delirium is now more common knowledge (5, 6). It is important to note that the APACHE II is made up of 12 items, most of which are individual risk factors of delirium. The precipitating factors for the development of delirium in adults and the elderly are given by the apt acronym I WATCH DEATH. Here, every capital stands for a clinically important cause, for example, “I” for infection, “W” for withdrawal et cetera (4). In children, we know that infections and withdrawal are highly prevalent precipitating factors of delirium, and so in analogy, we carefully hypothesize that the other I WATCH DEATH causes also can be considered an important set of precipitating risk factors. Finally, contextual risk factors are environmental factors such as the hospital or ICU setting with all the extra light and noise disturbances, leading to a sensory overload and so directly to sleep-wake disturbances which probably influence the onset and or emergence of delirium. We hypothesize that the abovementioned risk factors (including young age and severity of illness, given by the Pediatric Index of Mortality [PIM] 2) are equally important in the development of PD. The association of pediatric illness severity (measured on the PIM2 scale) and delirium has been described in a prospective study at least once (7). However, to our knowledge, no large studies have been conducted regarding the confirmation of this finding or for the search for other predisposing and precipitating factors of delirium in children and adolescents specifically. Another classification of risk factors is in modifiable and nonmodifiable risk factors. In this classification, modifiable risk factors are those which are caused by—and so can be influenced by—external intervention (e.g., prevention of polypharmacy and lowering of medication dosages, light and noise reduction, improvement of orientation, and patient comfort by means of clocks, calendars, and presence of Copyright © 2015 by the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies DOI: 10.1097/PCC.0000000000000371 Jan N. M. Schieveld, MD, PhD Department of Psychiatry and Psychology Division Child and Adolescent Psychiatry Maastricht University Medical Centre Maastricht, The Netherlands; Mutsaersstichting Venlo, The Netherlands; and Koraalgroep Sittard, The Netherlands