Emergence agitation/delirium: we still don't know

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http:// creativecommons.org/licenses/by-nc/3.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. CC First described in the early 1960s, emergence agitation is a clinical condition in which children experience a variety of behavioral disturbances, including crying, sobbing, thrashing, and disorientation, during early emergence from anesthesia [1]. Although emergence agitation is not a new phenomenon in clinical practice, it is of growing interest because its incidence appears to be increasing with the widespread use of sevoflurane. Agitation is a state of mild restlessness and mental distress. Agitation can arise from any number of sources, including pain, physiological compromise, or anxiety [2]. Sikich and Lerman [3] defined emergence delirium as " a disturbance in a child's awareness of and attention to his/her environment with disorientation and perceptual alterations, including hypersensitivity to stimuli and hyperactive motor behavior in the immediate postanesthesia period. " Emergence agitation and emergence delirium have been used interchangeably in most of the literature. Despite numerous attempts to explain the causes of emergence agitation/delirium, there is no definitive explanation. Possible causes include pain, preoperative anxiety, type of surgical procedures, personal characteristics of the patient, and type of anesthetics, although no sole factor can explain the etiology of emergence agitation/delirium [4], in large part due to the greatest obstacle to understanding emergence agitation/delirium is the lack of a standardized tool to assess it. The reported prevalence of emergence agitation/delirium varies greatly in the literature, ranging from 10% to 80% [5,6], depending on the definition and criteria of emergence agitation/delirium. Sikich and Lerman [3] recently developed the Pediatric Anesthesia Emergence Delirium (PAED) scale, which incorporated cognitive-related assessment items in addition to agitation behaviors, and were able to provide more reliability and validity than other scores. However, they did not provide a validated threshold value in the PAED scale to indicate emergence agitation/delirium. Comparing study results is therefore difficult because of the differences in definitions and the variety of unvalidated scales. Various attempts have been made to reduce the problem of emergence agitation/delirium. Many drugs, including propofol, fentanyl, clonidine and dexmedetomidine, have been investigated to attenuate the incidence of emergence agitation/delirium [7]. In this issue of the Korean Journal of Anesthesiology, Lee et al. [8] studied the clinical usefulness of a single dose of propofol (1 mg/kg) at the …