Paediatric emergence delirium: a comprehensive review and interpretation of the literature

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1 British Journal of Anaesthesia, 118 (3): (2017) doi: /bja/aew477 Review Article Paediatric emergence delirium: a comprehensive review and interpretation of the literature K. P. Mason Harvard Medical School, Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children s Hospital, 300 Longwood Avenue, Boston, MA 02115, USA Corresponding author. keira.mason@childrens.harvard.edu Abstract There remain unanswered questions and implications related to emergence delirium in children. Although we know that there are some predisposing factors to emergence delirium, we still are unable to predict accurately those who are at greatest risk. Emergence delirium should be considered as a vital sign, which should be followed and documented in every child in the postanaesthesia recovery period. Standardized screening tools should be adopted for paediatric emergence delirium. Key words: anaesthesia; emergence agitation; emergence delirium; maladaptive behaviour; paediatrics As early as 1960 and 1961, Smessaert and colleagues 1 and Eckenhoff and colleagues, 2 respectively, described behaviour observed in the recovery period. In an effort to understand emergence excitement, Eckenhoff and colleagues 2 reviewed prospectively collected patient records. Emergence excitement was defined as crying, sobbing, thrashing about, and disoriented. The highest incidences of excitement were correlated with the youth of the patient, the excellence of his health, barbiturate and scopolamine pre-anaesthetic medication, cyclopropane or ether anaesthesia and operative procedures associated with pain or emotional stress. Forty years later, we still struggle to identify, prevent, and treat emergence delirium (ED). This review will consider the evolution of emergence agitation (EA) and ED, from their initial identification in the 1960s to the current and future implications of their identification, treatment, and prognostic value (Fig. 1). Identification of emergence delirium In 2002, a prospective evaluation of children (10 months to 6 yr of age), found up to a 30% incidence of inconsolable crying or severe restlessness within the first 10 min of awake children arriving in the postanaesthesia recovery room. 3 In 2003, Voepel-Lewis and colleagues 4 reported an 18% incidence of EA in children 3 7 yr of age, lasting an average of 14 min but up to 45 min. Fifty-two per cent required pharmacological intervention. Emergence agitation was characterized by non-purposeful movement, restlessness, thrashing, incoherence, inconsolability, and unresponsiveness. Otolaryngology procedures, time to awakening, and isoflurane were considered to be independent risk factors. Frequently, delirium and agitation are used interchangeably in the literature. The challenge to proper treatment is to separate EA, ED, pain, and the patient s baseline behavioural tendencies when labelling a child s behaviour as EA or ED. As recently as 2011, we still strive to identify the behaviours associated with ED. In children 18 months to 6 yr of age, those with ED were more likely to display non-purposefulness, eyes averted, staring, or closed, and non-responsivity. Associated behaviours included irrelevant language, activity, and vocalization. 5 Early postoperative negative behaviour after general anaesthesia has been identified in up to 80%. 6 Distinguishing VC The Author Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please journals.permissions@oup.com 335

2 336 Mason 1945 Levy identifies postoperative behavior problems in children with no history of behavior issues (12) 1953 Eckenhoff correlates unsatisfactory anesthesia induction with manifestation of negative postoperative behavior (13) 1960, 1961, 1966 Smessaert and Eckenhoff describe postanesthetic excitement (1,2) Vernon publishers Changes in Children s Behavior After Hospitalization (14) 1990 Sevoflurane introduced in Japan 1991 Post operative agitation first described with Sevoflurane in Japan and suggested to be of higher incidence than with halothane (20) 1995 FDA approves Sevoflurane in United States 1996 Welborn and Lerman in United States report emergence agitation with Sevoflurane and compare to other volatile agents (18,19) 2002 Cole defines up to 30% incidence of inconsolable crying or restlessness in post anesthesia recovery period (3) 2003 Voepel-Lewis describes 18% incidence of emergence agitation in children 3 7 years old which can last an average of 14 minutes (4) 2004 The PAED scale presented for children greater than 2 years age (8) 2006 Kain describes increased incidence ED, post op anxiety and sleep disturbances for up to 14 days postoperatively in those with increased level of preoperative anxiety (16) 2010 A meta-analysis decribes decreased incidence of emergence agitation when alpha 2 agonists are administered with volatile agents (50) 2016 Somaini presents observational data to distinguish acute pain from emergence delirium (78) Schieveld advocates for unified standardized screening tool for delirium, from pediatrics to geratrics (75) Fig 1 Historical time line of noteworthy events for emergency agitation and delirium.

3 Paediatric emergence delirium 337 Table 1 Paediatric Anaesthesia Emergence Delirium scale. 8 Items 1, 2, and 3 are reverse scored as follows: 4¼not at all; 3¼just a little; 2¼quite a bit; 1¼very much; and 0¼extremely. Items 4 and 5 are scored as follows: 0¼not at all; 1¼just a little; 2¼quite a bit; 3¼very much; and 4¼extremely. The scores of each item were summed to obtain a total Paediatric Anaesthesia Emergence Delirium (PAED) scale score. The degree of emergence delirium increased directly with the total score PAED scale 1. The child makes eye contact with the caregiver 2. The child s actions are purposeful 3. The child is aware of his/her surroundings 4. The child is restless 5. The child is inconsolable between these negative behaviours, most importantly pain and ED, can be challenging. The Face, Legs, Activity, Cry, Consolability (FLACC) scale and the Paediatr Anaesth Emergence Delirium (PAED) scale have been applied in efforts to differentiate between ED and pain in children 2 6 yr of age after tonsilecctomy, adenoidectomy, or both. Inconsolability and restlessness were not reliable enough to differentiate between the two in the early postoperative period. 7 Rather, the presence of no eye contact, no purposeful action, and no awareness of surroundings was found to correlate significantly with ED. There are many scales that have been proposed to identify ED. The limitations of most scales are that they have not been psychometrically tested and that they follow emotional distress and psychomotor agitation as surrogate markers of delirium. The PAED scale, developed in 2004 for children >2 yr of age, has been psychometrically evaluated and is used most commonly (Table 1). 8 This scale has limitations, which include the subjective nature of some of the assessments, inter-rater variability, a high falsepositive rate, and qualifying behaviours that overlap with other negative postoperative diagnosis (pain). The diagnosis of delirium is a DSM (Diagnostic and Statistical Manual) IV and V condition; it is defined as 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 behaviour in the immediate postanaesthesia period. 11 Implications of emergence delirium Although those children who exhibit ED have episodes of short duration, there are indications that there may be effects that linger beyond the recovery period, In 1945, Levy 12 noted that some children exhibited postoperative behavioural problems that had not existed beforehand. Eckenhoff, 13 in 1953, noted a correlation between unsatisfactory anaesthesia inductions and the manifestation of negative postoperative behaviour. In 1966, Vernon and colleagues 14 published Changes in children s behaviour after hospitalization, identifying anxiety (regression, separation, sleep), eating disturbances, aggression, and apathy. Although the effects of hospitalization, not necessarily inclusive of surgery, have been described as early as the 1960s, the effect of ED on postoperative behaviour became of heightened interest a decade ago. Children with ED were at 1.43 times greater risk of having maladaptive behavioural change. 15 Table 2 Post Hospital Behaviour Questionnaire (PHBQ). 14 Reproduced with permission. PHBQ Items I: 4. Does your child need a pacifier? 5. Does your child seem to be afraid of leaving the house with you? 6. Is your child uninterested i n what goes on around him (or her)? 8. Does your child bite his (or her) finger nails? 12. Does your child seem to avoid or be afraid of new things? 13. Does your child have difficulty making up his (or her) mind? 22. Is your child irregular in his (or her) bowel movements? 28. Does your child suck his (or her) fingers or thumbs? II: III: IV: 9. Does your child get upset when you leave him (or her) alone for a few minutes? 17. Does your child seem to get upset when someone mentions doctors or hospitals? 18. Does your child follow you everywhere around the house? 19. Does your child spend time trying to get or hold your attention? 21. Does your child have bad dreams at night or wake up and cry? 1. Does your child make a fuss about going to bed at night? 20. Is your child afraid of the dark? 23. Does your child have trouble getting to sleep at night? 2. Does your child make a fuss about eating? Behavioural changes were assessed using the Post Hospital Behaviour Questionnaire (PHBQ), created in the 1960s and still a gold standard for posthospital behaviour assessment (Table 2). 14 An increased level of patient preoperative anxiety has been associated with an increase in the incidence of ED and up to 14 days of postoperative anxiety and sleep disturbances. 16 Maladaptive behaviour at up to 1 week after surgery is unaffected by choice of halothane vs sevoflurane. 17 Major contributors to emergence delirium In order to have a better understanding of emergence delirium, it is important to be able to critically review the published literature and have a comprehensive understanding of those factors that have been implicated as contributors to ED. A MEDLINE search was queried from 1946 to October 1, 2016 for keywords pediatric, paediatric, emergence delirium, or emergence agitation. All publications were reviewed and considered, with emphasis on the past 10 yr, although commonly cited and relevant older publications were included. Pertinent papers identified in the references of the searched articles were also reviewed and included, if relevant. A detailed dissection of the degree of association between the cited factors will be examined. Of interest, observations published >60 yr ago have at their core still held true. 13 As EA has often been and still is used interchangeably in reference to ED, I will also use them interchangeably, citing EA or ED according to the mode of citation in

4 338 Mason the primary publication. The sections below review the important findings in the literature related to the proposed contributions to emergence delirium (Table 3). Volatile anaesthetics Although inhalation anaesthesia has been delivered to children for >150 yr, it was not associated with EA until the 1960s, with cyclopropane and ether. 2 The first account of EA in the USA was in 1996, yr after sevoflurane achieved US Food and Drug Administration approval. In Japan, however, sevoflurane-related agitation was reported as early as 1991, 1 yr after its introduction in Japan. 20 Isoflurane, halothane, sevoflurane, and desflurane have all been recognized as contributors to ED and EA, with the suggestion that sevoflurane has the greatest propensity Surgery type Eckenhoff and colleagues, 2 in 1961, cited tonsil, thyroid, and circumcision surgeries as having a higher incidence of emergence agitation. Forty years later, a higher incidence of EA is reported after ophthalmology and otorhinolaryngology procedures. 4 Age Table 3 Proposed contributors to emergence delirium Proposed contributors to emergence delirium Volatile anaesthetics Type of surgery Patient age Parental anxiety Patient anxiety Patient pre-existing behaviour Patient and parent interaction with health-care providers In 1961, up to a 13% incidence of Eckenhoff s postanesthetic excitement was reported in children age 3 9 yr, and 9% cited for those yr. 2 A younger age has been associated with a greater risk of preoperative anxiety 28 and a higher incidence of ED. 8 A prospective cohort study described up to an 18% incidence of EA in those 3 7 yr of age. 4 Parental anxiety Although a direct correlation between parental anxiety and ED has not been examined specifically, a child s increased preoperative anxiety level is correlated with an increased risk of ED. A high level of parental anxiety and parents who are high monitors in the face of stress create a higher level of preoperative anxiety in the child. 28 High monitors are generally described as those who are highly sensitive to perceived threats and who tend to amplify them. Extrapolating from the data, I would suggest that decreasing parental anxiety and making efforts to improve their coping approach in the pre-, peri- and postoperative period could all be helpful strategies to decrease anxiety and ultimately the incidence of ED. Patient anxiety Anxious children (5 12 yr old) who present for tonsilectomy and adenoidectomy without preoperative anxiolytics are at elevated risk (9.7% incidence) of developing ED compared with those without anxiety (1.5% incidence). 16 A child s degree of preoperative anxiety is correlated with their risk of exhibiting ED. A higher score on the modified Yale Preoperative Anxiety Scale (mypas) posed an increased risk of ED; specifically, for every additional 10-point increment, the risk of ED increased by 10%. 15 Pre-existing behaviours A child s temperament, sociability, and cognitive skills are related to his level of preoperative anxiety. 28 As anxiety is a risk factor for ED, those who exhibit certain behaviour and temperament will be at greater risk for preoperative anxiety. Interactions with health-care providers Careful examination of interactions between parents, their children, and health-care providers, using real-time evaluation and a five-point scoring system called the Perioperative Adult Child Behavioural Interaction Scale (PACBIS), reveals that negative interactions and coping are correlated with a higher incidence of EA. 29 Likewise, negative behaviour on induction (2 12 yr) increases the risk of ED and subsequent maladaptive behaviour (Fig. 2). 30 Strategies to decrease emergence delirium Having identified the possible contributors to ED, the challenge lies in determining how to modify the perioperative experience in order to decrease the incidence of ED. Strategies for improving outcomes range from non-pharmacological techniques, such as behaviour management and distraction techniques, to modification of the delivery of anaesthesia (choice of medications, techniques, and delivery methods). Each strategy will be reviewed and evaluated (Table 4). Behaviour management techniques to decrease preoperative anxiolysis Decreasing anxiety after surgery, regardless of technique (behavioural or pharmacological), has been shown in prospective trials to have equal effects on decreasing ED in those 2 7 yr of age. Specifically, parental presence at inhalation induction vs a cartoon video or a combination of the two had equal effects on decreasing anxiety on induction and equal effects on decreasing ED. 31 Watching cartoons, video goggles, or hand-held video games have been shown to decrease anxiety in some patients as effectively as those who received oral midazolam as premedication In some situations, pharmacological anxiolysis may be preferable to a parent being present at induction. 28 A family-centred approach, ADVANCE, aims at Anxiety reduction, Distraction on the day of surgery, Video modelling and education before the day of the operation, Adding parents to the child s surgical experience, No excessive reassurance, Coaching of parents by staff, and Exposure/shaping of the child via mask practice. After a 30 min average time commitment of the healthcare staff via videotape, pamphlets, and a kit for practising mask induction, the children exhibited less ED than those with midazolam premedication or parent-present induction. 35 Choice of volatile agent and depth of anaesthesia Volatile agents have been implicated in EA and ED, although there is no strong support, in this author s opinion, for one volatile agent rather than another. A meta-analysis in 2008 presented 23 studies (children 3 months to 12 yr old) and reported

5 Paediatric emergence delirium 339 Postoperative behavior changes * * * * = High anxiety = Low anxiety POD# 1 POD# 2 POD# 3 POD# 7 POD# 14 Fig 2 The number of new-onset maladaptive behaviours throughout a 2 week postoperative period as exhibited by groups of children with high and low preoperative anxiety. *Statistical significance; P<0.05, reproduced with permission. 36 Table 4 Strategies to decrease emergence delirium Strategies to decrease emergence delirium 1. Behaviour management 2. Choice of volatile anaesthetic 3. Choice of anaesthetic technique 4. Choice of medications a. Benzodiazepine b. Opioid c. a 2 -Agonist d. Gabapentin e. Melatonin f. Propofol g. Ketamine h. Magnesium 5. Acupuncture 6. Regional anaesthesia 7. pain control more EA with sevoflurane (vs halothane), a finding similar to that shown for non-painful procedures A randomized controlled trial of children 2 8 yr of age demonstrated that depth of anaesthesia (measured by bispectral index values) were not correlated with the incidence of General anaesthesia (measured by the PAED scale). 37 Other studies have found no difference between sevoflurane and halothane Rather, the administration of ketorolac or paracetamol can be effective in diminishing EA. Choice of anesthetic technique-ga,tiva, Induction/ Emergence, Regional Total i.v. anaesthesia (TIVA) vs a general anaesthetic with volatile inhalation agent have been compared to determine whether there is a difference in the incidence of EA or ED. A metaanalysis in 2014 compared 14 studies and demonstrated that propofol resulted in less EA vs sevoflurane in children <15 yr of age. 40 This meta-analysis was limited in interpretation by multiple confounding factors [no standardized scoring system, the administration of analgesics (narcotics and non-narcotics), regional anaesthesia, adjuvant medications, and a range of surgical procedures]. Confounders also existed in the TIVA trial that demonstrated less ED after a propofol remifentanil anaesthetic compared with a sevoflurane anaesthetic in healthy children (2 6 yr) for strabismus surgery. Although the TIVA group exhibited less ED, they also exhibited less pain. 41 Propofol as a maintenance anaesthetic, however, has been shown to decrease EA after sevoflurane inductions. The time to emergence has been proposed as a contributor to EA/ED. A prospective cohort study of 521 children aged 3 7 yr concluded that a shortened time to awakening (emergence) was an independent risk factor for EA. 4 This was corroborated in 2004, with the development and introduction of the PAED scale. 8 If a short emergence is a risk for EA, it has been suggested that a delayed emergence may decrease EA. A prospective randomized controlled trial of children (1 12 yr of age) undergoing magnetic resonance imaging with a laryngeal mask airway with sevoflurane, showed a decreased incidence of EA when sevoflurane was transitioned to propofol 3 mg kg 1 (via divided bolus) before emergence. A slow washout with nitrous oxide after a sevoflurane anaesthetic has also been shown to decrease EA. 44 A confounding report, however, showed no difference in EA when a standardized anaesthetic technique was used to compare abrupt with gradual sevoflurane emergence in children (1 7 yr) after urological ambulatory procedures. 45 Choice of medications Benzodiazepines The administration of benzodiazepines has largely been done in the preoperative/pre-induction period in efforts to decrease anxiety. Midazolam is not an effective anxiolytic for all children. In a study of young children, 14.1% did not respond to oral midazolam and instead displayed extreme distress. 46 There are no

6 340 Mason substantive data to suggest that midazolam, diazepam, or clonidine decreases the incidence of ED associated with volatile anaesthetics A recent meta-analysis of 37 papers with sevoflurane, desflurane, or both indicates that midazolam has no preventative role. 51 Although benzodiazepines may not decrease ED, their ability to decrease preoperative anxiety and negative, maladaptive behaviours for up to 7 days warrants strong consideration of their use, particularly in the at-risk patient. 52 Choice of narcotic Narcotics have not been definitively shown to decrease EA or ED. Intraoperative fentanyl i.v. (2.5 lg kg 1 ) did not decrease the incidence of EA exhibited after desflurane or sevoflurane for tonsillectomy, adendectomy, or both. 27 a 2 -Agonists Used in conjunction with volatile anaesthetics, a 2 -agonists, regardless of when administered (pre- or intraoperative) have been found to decrease the incidence and degree of EA and ED. 51 As a premedication, dexmedetomidine at 1 or 2 lg kg 1 intranasally decreased ED in a prospective, randomized, double-blind placebocontrolled trial 53 and may be superior to clonidine (4 lgkg 1 intranasal) in decreasing incidence and severity of EA. 54 Dexmedetomidine i.v. (bolus, continuous infusion, or both) has been shown to decrease the EA after a volatile anaesthetic Dexmedetomidine infusions appear to be more effective than narcotic. A prospective, randomized trial demonstrated that dexmedetomidine (2 lg kg 1 i.v. bolus followed by 0.7 lg kg 1 h 1 ) was more effective than a single dose of fentanyl 1 lg kg 1 i.v. in decreasing EA in children with obstructive sleep apnoea undergoing tonsillectomy or adenoidectomy with sevoflurane. 59 Intraoperative dexmedetomidine 0.3 lg kg 1 i.v. may be more effective than propofol 1 mg kg 1 i.v. in decreasing EA after adenotonsillectomy with sevoflurane. 60 In a double-blind trial, intraoperative clonidine 2 lg kg 1 i.v. decreased the incidence and severity of EA in children who received sevoflurane and a penile block for circumcision. 61 Gabapentin Gabapentin given as an oral premedication (15 mg kg 1 ) decreased the severity of EA in healthy children (3 12 yr) after a sevoflurane anaesthetic for adenotonsillectomy. 62 Melatonin Preoperative oral administration of melatonin (0.2 or 0.4 mg kg 1 ), despite it having no effect on preoperative anxiety, has been shown to have greater benefits than midazolam 0.5 mg orally in decreasing incidence of emergence delirium. A dose-dependent effect was found. The incidence of ED was 25.6% with midazolam and 8.3 and 5.4% with melatonin 0.2 and 0.4 mg kg 1, respectively. 63 Propofol The perioperative administration of propofol i.v. has not been definitively shown to be effective in decreasing ED after a volatile anaesthetic Although a recent meta-analysis demonstrated that intraoperative propofol (1 3 mg kg 1 ) decreased EA in children, there were multiple confounders (midazolam, paracetamol, ketorolac, thiopental, morphine, fentanyl, sevoflurane, desflurane, and painful and non-painful procedures) 65 which, in this author s opinion, make the interpretation of the benefits of intraoperative propofol inadmissible. Ketamine Premedication with ketamine 1 mg kg 1 i.v. may decrease the incidence of early EA (first 20 min) more effectively than midazolam 0.1 mg kg 1 i.v. 66 Premedication with ketamine (6 mg kg 1 orally 30 min before induction) has also been effective in decreasing EA from 56 to 18% after desflurane for adenotonsillectomy. 67 Intraoperative ketamine (1 mg kg 1 i.v. followed by a 1 mg kg 1 h 1 infusion) may be equally effective as dexmedetomidine (1 lg kg 1 i.v. followed by 1 lg kg 1 h 1 infusion) in preventing EA after strabismus surgery with sevoflurane. 68 Magnesium Magnesium sulphate may decrease the incidence and severity of EA. A randomized, controlled, double-blind study concluded that postinduction magnesium sulphate (30 mg kg 1 i.v. followed by 10 mg kg 1 h 1 ) decreased the incidence and severity of EA after sevoflurane for adenotonsillectomy. There was no difference in pain scores between the magnesium and control group, suggesting that the effect was attributed to the magnesium. 69 Acupuncture A prospective, randomized, double-blind controlled study demonstrated that intraoperative electrical stimulation of the heart 7 acupuncture site in healthy children (1.5 8 yr) resulted in decreased ED after a variety of ambulatory surgeries. 70 Regional anaesthesia Although regional anaesthesia may decrease pain and narcotic requirement in the postoperative period, there is no definitive evidence to suggest that, in combination with sevoflurane, it decreases EA/ED The effect of caudal blocks on EA is confounded by their analgesic effect. A prospective randomized, double-blind study of children (1 6 yr) showed that ilioinguinal/ iliohypogastric blocks did not decrease ED after a sevoflurane anaesthetic, despite equal pain relief between those with and without blocks. 72 Minimize pain It is important to ensure that there is adequate analgesia, as pain behaviour can be misinterpreted as EA or ED (some of the pain behaviours overlap with those behaviours that are identified using the PAED scale, for example). Controlling for pain, there is a suggestion that fentanyl can decrease EA. Using an up down method with fentanyl ( lg kg 1 i.v.) for adenoidectomy with desflurane, although different doses conferred equal analgesia in recovery, the dose of fentanyl 2.5 lgkg 1 i.v. decreased EA. 73 Thoughts for the future Whether there are long-term or permanent effects of ED has yet to be studied. Long-term effects beyond 14 days have not been examined. To date, maladaptive behaviour up to 2 weeks after surgery has been identified. Delirium in the intensive care unit and postoperative delirium in the elderly, however, can have more grave implications and consequences. Poorer outcomes, increased health-care costs, and even cognitive dysfunction, have all been attributed to delirium in these patient populations. In children, however, ED has not been carefully examined for longer-term consequences. The patient s pre-existing temperament, anxiety, and coping behaviour are important factors in predicting emergence delirium. The anaesthetic technique

7 Paediatric emergence delirium 341 and agents administered (or not administered) are also important contributors. Only a few studies have used BIS to guide anaesthetic management in the paediatric studies being examined for ED. In adults, however, the depth of anaesthesia extrapolated from intraoperative BIS and EEG in some instances, predicts not only postoperative delirium, but also morbidity and mortality. 74 Prospective, randomized trials are needed to determine whether intraoperative BIS levels affect ED and subsequent maladaptive behaviour. Summary We must carefully design large studies to evaluate the risk factors for ED prospectively, eliminating as many confounders as possible. In order to compare outcomes between studies, or even to share data between research groups, it is essential that everyone uses the same tools. Standardized screening and evaluation tools should be adopted by all researchers of paediatric ED Emergence delirium should be considered a vital sign, which should be followed and documented on every child in the postanaesthesia recovery period. Currently, ED assessment is not being performed consistently. Even in the paediatric intensive care unit setting, where >20% may have delirium, 78 a majority of children are still not being screened for delirium. 79 Currently, the PAED scale is the most widely used and validated means of identifying delirium. It is important to recognize, however, that the PAED assigns scores based on exhibited behaviour. An important consideration, however, is that even at baseline not all children can make eye contact, have purposeful actions, show an awareness of surroundings, or maintain calm behaviour (all behaviours which are assessed and scored by the PAED). Specifically, infants and those with behavioural, neurological, or developmental challenges may always score high on some or all the qualifiers. Particularly in the stressful pre- or postoperative period, any child may exhibit behaviours that do not reflect his usual behaviour. For this reason, a baseline, preoperative PAED score should be assessed and documented on every child. This preoperative score may be useful to provide a comparative reference point in the recovery room, specifically in efforts to decrease risk of false positives, particularly in those children for whom it may be difficult to distinguish between pain, a variant of baseline behaviour, general agitation, and delirium. This author asserts that by adopting the PAED as a pre- and postoperative assessment tool, scores should be documented as soon as the child arrives in the recovery unit, in conjunction with the routine initial intake vital signs. Upon any change in behavioural status (or after an intervention to alleviate pain or delirium), the PAED score should be reassessed. The PAED score must always be evaluated in relationship to the pain score, with vigilant attention to those patients who are not able to express pain verbally (infants or those neurologically, developmentally, or behaviourally challenged). Differentiating between pain and delirium can be challenging, and frequently delirium may be mistaken for pain behaviour. Although there is not yet a gold standard to differentiate between the two, as their behaviour may overlap, careful observation should be able to differentiate acute pain from emergence delirium. Emergence delirium tends to be accompanied by failure to make eye contact and a lack of awareness of surroundings. Acute pain behaviour tends to exhibit abnormal facial expression, crying, and inconsolability. 80 Differentiating between the two entities is crucially important to guide treatment. There are currently no validated goldstandard interventions for postoperative ED, as there have been no trials that have specifically aimed at evaluating or comparing treatment options. Currently, the best approach to mitigating ED should be founded in its prevention, rather than in its treatment. In the postanaesthesia care unit, if in doubt whether the exhibited behaviour is ED or acute pain, treatment should err by treating for pain in conjunction with, in this author s opinion, a single dose of an a 2 -adrenergic agonist. A PAED score should be documented before discharge from the recovery room, and patients should remain until the PAED score reaches their preoperative baseline. In order to further the understanding of ED in children, it is crucial that prospective studies of large enrolment are performed, collecting data that are standardized with respect to terminology and identification. 77 Standardized data collection will enable us to compare results across all spectra. Once we agree on a unified approach to data identification and collection, we will then be better equipped to identify risk factors, preventative and therapeutic treatment outcomes, and to follow both short- and long-term outcomes from ED. Declaration of interest None declared. References 1. Smessaert A, Schehr CA, Artusio JF Jr. Observations in the immediate postanaesthesia period. II. Mode of recovery. Br J Anaesth 1960; 32: Eckenhoff JE, Kneale DH, Dripps RD. The incidence and etiology of postanesthetic excitment. A clinical survey. Anesthesiology 1961; 22: Cole JW, Murray DJ, McAllister JD, Hirshberg GE. Emergence behaviour in children: defining the incidence of excitement and agitation following anaesthesia. Paediatr Anaesth 2002; 12: Voepel-Lewis T, Malviya S, Tait AR. A prospective cohort study of emergence agitation in the pediatric postanesthesia care unit. Anesth Analg 2003; 96: Malarbi S, Stargatt R, Howard K, Davidson A. Characterizing the behavior of children emerging with delirium from general anesthesia. Paediatr Anaesth 2011; 21: Vlajkovic GP, Sindjelic RP. Emergence delirium in children: many questions, few answers. Anesth Analg 2007; 104: Somaini M, Sahillioglu E, Marzorati C, Lovisari F, Engelhardt T, Ingelmo PM. Emergence delirium, pain or both? A challenge for clinicians. Paediatr Anaesth 2015; 25: Sikich N, Lerman J. Development and psychometric evaluation of the pediatric anesthesia emergence delirium scale. Anesthesiology 2004; 100: American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders: Fourth Edition-Text Revision. Washington, DC: American Psychiatric Association, American Psychiatric Association. DSM-5 Development, American Psychiatric Association. All Rights Reserved Wilson Boulevard, Suite 1825, Arlington, Va Przybylo HJ, Martini DR, Mazurek AJ, Bracey E, Johnsen L, Coté CJ. 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